GENES!S, MORPHOLOGY AND CLASfiEFiCATION OF SOME TILL DERWED CHERNOZEMS OF EASTERN NORTH DAKQTA Thesis for the Degree 0? DLI. D. Yt‘iiCEIGAN STATE UREVERSETY Charis—s Edward Redmond 1964 THESIS This is to certify that the thesis entitled Genesis, Morphology and Classification of some Till Derived Chernozems of Eastern North Dakota presented by Charles Edward Redmond has been accepted towards fulfillment of the requirements for _£_h_._D_.__ degree in WHO 8 / ,‘, / -‘ A , r I \/ ./ . ( ,. I ,/ / '- 1:; // 1/ (/ fl 1 [Ag/L.» (IL! L‘; " hfajor professor * r Date '44:- //',/I6/ 0-169 LIBRARY Michigan State University 1 n GENESIS. MORPHOLOGY AND CLASSIFICATION OF SOME TILL DERIVED CHERNOZEMS OF EASTERN NORTH DAKOTA BY Charles Edward Redmond A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Soil Science 1964 ABSTRACT GENESIS. MORPHOLOGY AND CLASSIFICATION OF SOME TILL DERIVED CHERNOZEMS OF EASTERN NORTH DAKOTA by Charles Edward Redmond This study was undertaken to evaluate the nature and cause of observed morphologic differences among three groups (If Chernozem soils developed from friable. calcareous loam izill of Mankato age in eastern North Dakota. One group, the Forman soils, have fine textured B horizons with strongly developed prismatic structure, and thick clay or clay-organic films on the ped faces. The second group, the reddish Forman soils. have weaker structural development, some clay films, and upper B horizons with reddish hues suggestive of iron oxide accumulation. The third group. the Barnes soils, have moderately developed prismatic structure, and only patchy thin clay films. The mechanical analyses made on six profiles (two from each group) revealed that the sola of the Forman soils were much finer textured than those of the Barnes or reddish Forman soils. The shrinking and swelling of the B horizon has created a self-mulching effect in the Forman soils. The distribution of sand sizes was very similar in all the profiles. Mineralogical analyses were made on only three profiles. one from each of the three groups. The Charles Edward Redmond mineralogical analyses of the fine and very fine sand fractions indicated a similarity among the three profiles. The per- centages of fine plus very fine sand heavy minerals in the Barnes and reddish Forman profiles are about double that in the Forman profile. In spite of this, the composition of the heavy fraction is practically identical in the three profiles. with pyroxenes and amphiboles the dominant heavy minerals. Shale was very abundant in the sand fractions from the Barnes profile, moderately abundant in those from the Forman profile, and relatively scarce in those from the reddish Forman profile. The presence of this shale has had some effect on profile development. Montmorillonite was the dominant clay mineral in all horizons of the three profiles. There is some evidence of illite formation by potassium fixation in the sola of all three profiles. Field examination, binocular microscope studies, and mechanical analyses indicate that clay is more abundant in the B horizons than in the A or C horizons. The magnitude of the difference is greatest in the coarser textured profiles. It has not been shown conclusively that the higher clay content of the B horizons is due to illuvia- tion, and there are indications that it may be primarily a stratification phenomenon. Few optically oriented clays were present on the thin sections from the B horizons. No conclusion was reached regarding the movement of iron <3xides in these soils. because of the variable results <5btained when different analytical methods were used. Charles Edward Redmond Detailed studies of thin sections from three profiles indicated that the fabrics in their B and C horizons were distinct. The distribution of carbonates in the soil mass is felt to be related to pore size distribution. In the Forman and reddish Forman soils, the carbonates are con— centrated into pockets, while they are distributed evenly through the soil mass in the calcareous horizons of the Barnes soils. The Cca horizons of all the profiles contained‘ more carbonate particles of clay size than the other horizons, even where the other horizons contained more total carbonates. The calculation of gains and losses in these pro- files produced results that were not entirely logical, due to stratification in the original materials. This stratifi- cation was brought out by the laboratory studies, although the profiles were selected for their lack of apparent stratification in the field. It is therefore probable that all the till plain soils are at least partially stratified. Most of the morphologic differences among the three groups of soils can be traced directly or indirectly to differences in the original materials. There is no evidence to suggest that different soil forming processes are acting, or have acted, on the three groups of soils, although the rate and direction of these processes may be modified somewhat by the nature of the materials on which they act. .From an agricultural standpoint. the morphologic differences discussed are insignificant as factors affecting crop yields, Charles Edward Redmond compared with differences in growing season and rainfall that exist among the areas where the soils occur. ACKNOWLEDGEMENTS The author wishes to acknowledge his appreciation to the many individuals, organizations, and institutions without whose cooperation this study could not have been completed. As my advisor, Dr. E. P. Whiteside has given patient guidance and valuable assistance throughout the course of the study. In addition to Dr. Whiteside, Mr. C. A. Mogen of the Soil Conservation Service, and Professor H. W; Omodt of North Dakota State University. gave valuable guidance in the definition of the problem and in making the field studies. The assistance of the Soil Survey Laboratory, SCS, Lincoln, Nebraska in making the routine analyses was greatly appreciated. Dr. J. S. Allen and M. L. McMurtrie of the laboratory assisted with the field sampling. Drs. G. D. Smith and L. T. Alexander approved the use of the laboratory facilities; and Drs. F. J. Carlisle and R. B. Grossman have been very cooperative in the release and interpretation of the results. The author expresses his appreciation to his guidance committee: Drs. E. P. Whiteside, A. E. Erickson. K. Lawton, B. G. Ellis, and R. L. Cook of the Soil Science Department: ‘Drs. B. T. Sandefur and M. M. Miller of the Geology Department, and Dr. G. L. Johnson of the Agricultural Economics Department: ii for their assistance in planning a suitable course of study. Drs. Whiteside, Erickson, Lawton, and Sandefur also provided skills and equipment necessary for the completion of the laboratory studies. The author wishes to thank Dr. H. D. Foth for his fine photography of the thin sections, and Mr. B. Muckerjee for checking some of the mechanical analyses. Mr. O. C. Rogers aided in placing the soils in the proper place in the 7th Approximation. The constant encouragement and under- standing of Professor I. F. Schneider have contributed greatly to the completion of the study. Finally, the author appreciates the opportunity he has had to discuss this problem with his colleagues: the graduate students and soil survey personnel of North Dakota and Michigan State Universities, and the soil scientists of the Soil Conservation Service. iii Chapter TABLE OF CONTENTS I. INTRODUCTION . . . . . . . . . . . . . . . . . II. REVIEW OF LITERATURE . . . . . . . . . . . . . A. Chernozem Soils 1. Early Russian work 2. Processes of Chernozem formation 3. Development processes beyond the Chernozem stage 4. Regional intergrades Iron Studies 1. Nature and significance of iron in the soil 2. Determination of free iron oxides Mineralogy l. Mineralogy of the sand fractions 2. Clay Mineralogy III. FIELD STUDIES . . . . . . . . . . . . . . . . A. Nature of the Area 1. Location and boundaries 2. Topography and drainage 3. Geology 4. Climate 5. Vegetation 6. Soils 7. Agriculture Field Procedure 1. Methods employed in sampling and describing soils 2. Field characteristics of profiles sampled in 1958 3. Profiles selected for further study 4. Description of the sites sampled in 1959 iv \lrbth Hi4 (Db- 18 19 22 22 25 29 29 29 30 35 38 4O 41 46 51 51 52 59 63 Chapter Page C. Conclusions from Field Studies 69 IV. LABORATORY PROCEDURES . . . . . . . . . . . . 71 A. Preliminary Studies on Samples Collected in 1958 71 B. Analyses on Profiles Sampled in 1959 by the Soil Survey Laboratory, SCS, Lincoln, Nebraska 73 C. Iron Investigations 76 1. Free iron oxides 76 2. Total iron 79 D. Mineralogical Analyses 79 1. Lime-free mechanical analysis 79 2. Mineralogical studies of the fine and very fine sand fractions 80 3. Clay mineralogy 84 4. Quartz determination 86 5. Thin section examination 87 V. RESULTS AND DISCUSSION . . . . . . . . . . . . 89 A. Introduction 89 B. Uniformity of Original Material 90 1. Purposes and method of evaluation 90 2. Textural uniformity 91 3. Mineralogical Uniformity 101 C. Textural Morphology of Profiles 103 1. Data from mechanical analyses 103 2. Discussion 112 D. Mineralogy of the Sand Fractions 118 1. Procedure 118 2. Results 119 3. Discussion 128 E. Clay Mineralogy 153 1. Results 153 2. Discussion 153 Chapter Page F. Fabric Analysis 159 l . Purpose and content 159 2. Quality of the thin sections 160 '3. Proportion of components on the thin sections 160 4. Oriented clay films 180 5. Examination of coarse fragments 183 6. Binocular Microscope examination 192 7. Bulk density 198 8. Summary of fabric analysis 200 G. Cations on the Exchange Complex 203 1. Results 203 2. Discussion 206 H. Organic Matter Content and Accumulation 212 1. Results 212 2. Evidence of organic matter accumulation 212 3. Discussion 214 4. Summary 220 I. Iron Content 220 1. Results 220 2. Discussion 222 J. Soil Reaction, Salinity, and Carbonate Content 232 1. Soil reaction 233 2. Soil salinity 233 3. Carbonate content 234 K. Accumulations, Losses, and Redistributions of Constituents in the Profile . 238 1. Method of evaluation 238 2. Data used in the calculations 241 3. Discussion 244 VI. SUMMARY . . . . . . . . . . . . . . . . . . . 272 A. Comparison of the Original Materials 272 1. General nature and stratification 272 2. Color 272 3. Texture 273 vi Chapter 4. Mineralogy 5. Carbonate content 6. Shale and chert content 7. Overall characterization of the original materials Comparison of the Developed Profiles 1. Textural profile development 2. Organic matter accumulation 3. Carbonate redistribution 4. Movement of iron oxides C. Probable Soil Genesis 1. General considerations 2. Genesis of the individual profiles D. Soil Classification 1. Classification under the present system (1938 Yearbook, as modified in 1949) 2. Classification under the proposed system (7th Approximation) E. Practical Applications F. Needs for Further Research VII. CONCLUSIONS AND SPECULATIONS . . . . . . . . . LITERATURE CITED . . . . . . . . . . . . . . . . . . . APPENDIX . vii Page 273 274 274 275 275 275 276 277 277 278 278 278 284 284 285 288 290 294 297 303 10. ll. 12. LIST OF TABLES Conditions in various procedures for the extraction of free iron oxides . . . . . . . Selected climatic data from four stations in the study area . . . . . . . . . . . . . . . . . Nature of a toposequence of soils found in the several drainage positions on the till plain . . . . . . . . . . . . . . . . . . . Relationships among well drained, till derived, Chernozem soils in eastern North Dakota . . Characteristics of profiles and sites sampled in 1958 . . . . . . . . . . . . . . . . . Field characteristics of profiles sampled in 1959 . . . . . . . . . . . . . . . . . Variations in the ppm. of iron extracted by the thioglycolic acid method on different dates . . . . . . . . . . . . . . Percentages of free iron oxides extracted from samples from profile SS9ND-291 by four methOdS C O O O O O O O O O O O O O O O O 0 First order basal spacings of common clay minerals in Angstrom units, when treated in different ways . . . . . . . . . . . . . Textural uniformity of original materials as indicated by the size distribution of quartz and garnet in the shale and chert free sand fractions . . . . . . . . . . . . Textural uniformity as indicated by the size distributions of quartz, total sand, and carbonate-free sand . . . . . . . . . . . . Textural uniformity of original materials in ten profiles based on sand size distribution viii Page 21 39 44 47 53 61 77 78 85 93 97 99 Table Page 13. Mineralogical uniformity of original materials, based on quartz—garnet ratio; and composite textural and mineralogical uniformity . . . . . . . . . . . . . . . . . 102 14. Particle size distribution in three profiles, based on the mechanical analysis of acid treated samples . . . . . . . . . . . . 105 15. Sand size distribution, based on the mechanical analysis of acid treated samples . . . . . . 106 16. Particle size distribution in ten profiles, based on mechanical analyses made by the soil survey laboratory; using a procedure in which carbonates are not removed . . . . 107 17. Sand size distribution in ten profiles, based on mechanical analyses by the soil survey laboratory . . . . . . . . . . . . . . . . . 111 18. Vertical clay distribution relationships in ten profiles . . . . . . . . . . . . . . . . 115 19. Percentages of light minerals, heavy minerals and shaleplus chert in the sand fractions . 120 20. Mineralogical composition of the heavy fraction of the fine and very fine sand fractions . . 121 21. Mineralogical composition of the light portions of the fine and very fine sand fractions . . 124 22. Percentages of quartz, garnet, and non- resistant minerals in the total sand size fractions and in the total soil . . . . . . 125 23. Ratios or relative abundance of minerals . . . . 127 24. Percent differences in the percentage of heavy minerals among horizons with mineralogically similar original materials in profile 37-3 . . . . . . . . . . . . . . 133 25. Percent difference in the percentage of heavy minerals among horizons with mineralogically similar original materials in profile 2-1 . 135 26. Percent difference in the percentage of heavy minerals in the horizons of profile 50—2, and that in the C3 horizon . . . . . . . . . 137 ix Table 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. Page Estimated percentages of quartz in the non- sand fraction . . . . . . . . . . . . . . . 149 Proportion of components in thin sections, expressed as percentages of the total length of traverse . . . . . . . . . . . . . 163 Composition of ground mass types T through Z . . 164 Comparison of directional differences on horizontal sections as opposed to comparable differences on vertical sections, with respect to the percentages of grains and pores . . . . . . . . . . . . . . . . . . . 179 Numbers of coarse fragments of different types, by profile and horizon . . . . . . . . . . . 185 Surface and edge weathering by profile and horizon . . . . . . . . . . . . . . . . . . 186 Summary of coarse fragments by degree of weathering . . . . . . . . . . . . . . . . . 189 Bulk densities . . . . . . . . . . . . . . . . . 201 Hydrogen as a percentage of the exchange capacity, and depthtn which hydrogen occurs in measureable amounts, six profiles 204 Percentage of the exchange complex occupied by potassium and sodium . . . . . . . . . . . . 208 Estimated percentage of calcium plus magnesium on the exchange complex . . . . . . . . . . 211 Organic matter accumulation, 13 profiles . . . . 215 Total iron and free iron oxide content of the upper horizons of three profiles . . . . . . 221 Ratios between total Fe203 and percent non- resistant heavy minerals of fine and very fine sand size in the upper horizons of three profiles . . . . . . . . . . . . . . . 223 Organic carbon/thioglycolic acid extracted Fe203 ratios in the upper horizons of six profiles . . . . . . . . . . . . . . . . . . 224 Table 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. Percentage of total and clay size carbonates, and percentages of total carbonates in the clay vs. non clay fractions in selected horizons from three profiles . . . . . . . Data for the calculation of weight changes . weight and volume.changes, profile 37-3, Forman . . . . . . . . . . . . . . . . . . Clay formed, gained and lost, profile 37—3 . . Weight and volume changes, profile 2-1, reddish Forman . . . . . . . . . . . . . . Clay formed, gained, and lost, profile 2—1 . . Weight and volume changes, profile 50-2, Barnes . . . . . . . . . . . . . . . . . Clay and silt formed, gained and lost, profile 50-2 0 o o o o o o o o o o o o o o o o o o Routine analysis,data, Barnes profile 50-1 . . Routine analysis data, Barnes profile 50-2 . . Routine analysis data, Forman profile 37-3 . . Routine analysis data, Forman profile 41-1 . . Routine analysis data, reddish Forman prOfile 2"]. o o o o o o o o o o o o o o o Routine analysis data, reddish Forman PrOfile 2-2 0 o o o o o o o o o o o o o 0 xi Page 234 242 246 251 254 259 263 268 304 308 312 317 322 327 Figure 1. LIST OF FIGURES Map of North Dakota, showing the study area, and its subdivisions . . . . . . . . . . . Typical landscape View in eastern North Dakota . . . . . . . . . . . . . . . . . . View of till plain in eastern North Dakota Topographic relationships of soils and drainage classes . . . . . . . . . . . . . X—ray diffraction tracings . . . . . . . . . a. Profile 37-3, Forman b. Profile 2-1, reddish Forman c. Profile 50—2, Barnes Photograph of a portion of the horizontal thin section from the C2 horizon of Forman prij-le 37-3 0 o o o o o o o c o o o o o 0 Photograph of a portion of the vertical thin section from the B1 horizon of Forman PrOfile 37"3 o o o o o o o o o o o o o o 0 Photograph of a portion of the vertical thin section from the 321 horizon of reddish Forman profile 2-1 . . . . . . . . . . . . Photograph of a portion of the horizontal thin section from the Cca horizon of Barnes prOfile 50-2 0 o o o o o o o o a o o o o o xii Page 31 33 34 45 157 157‘ 157w 158 165 168 170 171 CHAPTER I INTRODUCTION A large portion of eastern North Dakota consists of an undulating till plain, or ground moraine, on which the zonal soils are northern Chernozems. For the most part, these soils are developed in friable, medium textured glacial till; presumably of Mankato age. The typical well drained soils of this area are classified in the Barnes series. This study was undertaken to determine the nature and genesis of a group. of soils in the southern part of the area, now called Forman, which are finer textured and more strongly developed than the typical Barnes soils. Also studied were a group of soils with reddish B horizons and moderately strong development, to which the name reddish Forman has been applied. Until the Forman series was correlated in Sargent county in 1961, all the soils included in this study were officially in the Barnes series. The Barnes series was established in Lamoure county, North Dakota in 1914, and included all the well and moderately well drained till plain soils in the eastern Dakotas and western Minnesota. The series, as so defined, was widely mapped, and was an extensive soil on most of the soil maps published between 1910 and 1925. The Barnes series thus became well known, to farmers as well as to soil scientists. Since 1925, the Barnes series has been narrowed considerably by the recognition of textural profile and drainage profile differences at the series level. The separation of the finer textured Forman soils, dealt with in this study, is another in the series of divisions of the formerly broad Barnes series. The Forman soils were first recognized in the soil survey of Sargent County in the early 1950's. Two representative profiles were sampled in 1956, in order to get laboratory data to test the proposed separation of these soils from the Barnes series. At that time, soil scientists in Minnesota opposed the separation, feeling that the Forman fit their concept of Barnes better than the coarser textured soils which we in Nbrth Dakota felt to be typical of the Barnes series. The reddish Forman soils were first noticed while doing the field work for this study. Their correlation has never been proposed, and they are officially still part of the Barnes series. We felt that the reddish B horizons might prove interesting in view of the proposed iron studies. In this study, it was decided to go beyond the usual routine analyses for soil correlation purposes, and to determine what, if any, mineralogical and fabric differences exist among the Barnes, Forman, and reddish Forman soils. It Was felt that such analyses would provide some information as tC> what extent the observed morphologic differences among these soils are inherited from differences in the original materials, and to what extent they are due to differences in the soil forming processes which have acted on those materials. CHAPTER II REVIEW OF LITERATURE A. Chernozem Soils 1. Early Russian Work a. Recognition of the Chernozems as a distinct group and early ideas on their genesis. Chernozem soils have received considerable attention ever since the study of soils as such began. This stems from the fact that they are of widespread occurrence in European Russia, where most of the early pedologists did their work. Glinka (as translated by Marbut, 1927) has summarized the early views on the formation of VTschernozems” which we now call Chernozems. According to Glinka, these soils first attracted attention because of their dark color and high humus content. Lomonosoff was the first to speculaueon the formation of the Chernozem soils. He postulated a biological, rather than mineralogical or geologic origin of the dark color. This fact was known by the peasants who worked the soils, but it was some time before the idea received the support of other pedologists. Mbst of the early pedologists proposed a marine origin of the dark colored soils. Opinion varied as to 4 whether the soils were deposited in an extension of the Black Sea, or by a similar extension of the Arctic sea. Geologists of the period considered the deposits now recognized as glacial as Arctic sea deposits. In a slightly later period, a swamp origin was favored. The dark surface layers appeared not unlike those of the vast bogs of northern Russia. Some felt that these bog deposits had been carried southward by an extension of the Arctic sea. A trend of thinking badk toward Lomonosoff's original biological proposal was began by Rupprecht in 1866. He proposed that the Chernozems had developed under grass vegetation and dry conditions. KarpinSki in 1873 agreed with the dryland origin, but because of the widespread occurrence of these soils on loess deposits, he felt that this type of parent material was responsible for the particular type of profile development. The present ideas of Chernozem formation were first proposed by Dokuchaev in 1883. He found that the amount and kind of humus in the soil varied according to climatic and vegetation belts. He therefore reasoned that a combin- ation of these two factors climate and vegetation, were responsible for the development of the Chernozem type of profile. Most pedologists of this period were willing to accept this hypothesis, and it has received general support to the present time. b. Recognition and description of sub-groups. deuchaev recognized several varieties of Chernozems which he differentiated according to the kind and amount of organic matter in the profile. The northernmost variety was not studied in detail by Dokuchaev, but he considered it to be transitional to the Podzols. It occurred in the part of the Chernozem zone, where the climate was coolest and most moist. South of the northern Chernozems lay the ordinary Chernozems. These soils had a combined thickness of A1 and A21 horizons of about 28 inches. Tongues of A1 extended into the A2 which had prismatic structure. Farther south near the center of the Chernozem zone lay the deep or fat Chernozems. In these soils the A1 plus A2 horizons had a thickness of 40 inches or more, over half of which was Al. The A2 had prismatic structure and there were accumulations of carbonates and salts in its lower extremities. Still farther south were the southern Chernozems which had a grayish color, and in which carbonates were present closer to the surface. Nikiforoff (1936) gives humus contents as follows, for the varieties of Russian Chernozems. Northern, 4—7%; Ordinary, 6-10%; Deep or fat 10-l3%.or more; Southern, 4-6%; Leached, 6-9%. (The leached variety is between the northern and ordinary varieties of Dokuchaev.) 1A2 is used here as it appears in the literature. Descriptions of this horizon indicate that it is what we now consider the B. (It seems pertinent to mention at this point that in European Russia, the rainfall belts have an east-west orientation, paralleling the temperature belts: whereas in North America they run north and south crossing the temper- ature belts. Thus some changes observed from north to south in Russia are comparable to those observed from east to west in this country. The southern Chernozem, for example, is transitional to the Chestnut soils, and such soils occur along the west edge of the Chernozem belt in North Dakota.) 2. Processes of Chernozem Formation The transformation of the original material, which showed only geologic differentiation, into the Chernozem profile consisting of Al, B, Cca, and C horizons, is the net result of several simultaneous soil forming processes. Most obvious and widely accepted are the accumulation of organic matter in the Al horizon, and the redistribution of lime in the profile. Less obvious, and more subject to debate are the saturation of the exchange complex by basic cations, the formation and movement of clays, and the movement of sesquioxides. Various workers have studied these processes, singly and in aggregate, and a brief summary of the work on each follows. a. Accumulation of organic matter. Nikiforoff (1936) described the qualities of the grassland vegetation under which the Chernozem soils have developed which are conducive to the accumulation of organic matter. All the organic matter tied up in the green parts of the plants, and most of that tied up in the roots, are returned to the soil annually. This is in direct contrast to forest vegetation, in which large amounts of organic matter are tied up in trunks and limbs for extended periods. Although resistant plant parts remain in the soil for several years, the organic matter turnover is considerably more rapid in the case of grasses than in that of woody plants. Nikiforoff further points out that the organic matter content of a mature Chernozem soil is constant; and represents a balance between annual gains and losses. The level at which this balance is maintained depends on the rate of organic matter production, as compared to the rate at which it is lost. This is a climatic function. Jenny (1941, p. 170) reports that in the plains region of the United States, organic matter contents increase with increasing rainfall, and decrease with increasing temperatures. Higher rainfall results in more lush vegetation, which in turn returns more organic matter to the soil. Higher tempera- tures increase the rate at which organic matter is brdken down and lost. In the Russian Chernozem belt, discussed by Glinka (1927) and Nikiforoff (1936) the organic matter icontent is highest in the center, and declines to both the north and south. This, they point out is because the Northern Chernozens are transitional to Podzols: and organic matter production in the south is limited by an extended dry period during the growing season. Nikiforoff (1936) indicates that the organic matter content of the Chernozem profile typically declines gradually with depth; and that there is no clear cut lower boundary of the layer of organic matter accumulation. This character- istic is shown very well by the profiles used in this study; as well as by those studied by Wilding and Westin (1961), Nygard et. a1. (1952) and Robertson (1961). It is less obvious in the Orthic Black soil studied by St. Arnaud (1962). b. Mbvement and accumulation of carbonates and salts. Marbut (1935) divided the soils of the United States into two broad groups, the Pedocals and Pedalfers: the former containing zones of carbonate accumulation, and the latter lacking them. Chernozem soils, with their well developed Cca horizons were typical examples of the Pedocal group. Nikiforoff (1936) states that the formation of secondary carbonates is not unique to the Chernozem soils. These can form anywhere the necessary ingredients; C02 from the decomposition of plant remains, and basic cations from the weathering of minerals; are available. It is the distribution of the carbonates thus formed in the soil profile which Nikiforoff considers unique to the Chernozemic type of soil development. He considered the position of the zone of carbonate accumulation in the profile to be a function of the relative amounts of downward and upward moving 10 water passing through the profile. The same conclusion was reached by Redmond and McClelland (1959) who investigated the formation of zones of carbonate accumulation in Chernozem and associated soils in North Dakota. They postulate that the carbonates move into the horizon of accumulation both by leaching from above and capillary transport from below. Calcium carbonate has a rather low solubility in water, but this solubility is increased substantially under conditions of high carbon dioxide pressure. Jenny (1941b) states that the carbon dioxide released by the respiration and decomposition of the grass roots results in sufficient pressure to mobilize the calcium carbonate and permit its movement in percolating waters. The movement of gypsum and other soluble salts is thought by Nikiforoff (1936) to proceed by similar mechanisms. Because these salts are more soluble than calcium carbonate, they are carried deeper into the profile. Glinka (1927) and Nikiforoff (1936) noted that the depth to the layer of calcium carbonate accumulation de— creased from north to south in the Russian Chernozem zone. The same decrease is noted from east to west in the North American zone. These facts are consistent, if it is recalled that the moisture belts are shifted by 90 degrees between the two areas. Redmond and MbClelland (1959) observed that relatively minor differences in topographic position are accompanied by appreciable differences in the position of the horizon of carbonate accumulation. 11 c. Base saturation Nikiforoff (1936) considers thesaturation of the exchange complex by basic cations as a process in Chernozem development. Mest other workers seem to feel that this was the original situation, and leaching has not proceeded far enough to replace these ions with hydrogen. As will be pointed out later, this replacement is indicative of degra- dation. d. Mevement of clays The evidence for or against the movement of clays in a soil profile is based upon the presence of an illuvial horizon higher in clay than the horizons above and below. Transported clays are thought to orient themselves upon deposition in the illuvial horizon to form clay ?Skins or films? on ped faces and in pores (Buol and Hole, 1959). The movement of clays is almost certain to have occurred in Gray Brown Podzolic, Gray Wooded, Solonetz, and Podzol soils, but whether or not it has occurred in Chernozem soils seems debatable. The early Russian work summarized by Glinka (1927) does not consider clay movement as a part of Chernozem formation. Hewever, Nikiforoff (1936) mentions ?glassy coatings? on ped surfaces in the NOrthern Chernozems of Russia, his descriptions of which are similar to those we would apply to clay films. Kubiena (1938) mentions ?accumulations of transported organic and inorganic colloids? on ped surfaces and in root 12 channels. Bourne and Whiteside (1962) indicate that some clay movement has occurred in a Montana Chernozem, and that the transported clay is montmorillonite; Larson et. a1. (1947) noted well developed textural B horizons in Nebraska Chernozems, but were unable to tell if they were due to clay movement or to weathering in place. Thorp et. a1. (1949) divided the Chernozems into minimal, medial and maximal sub groups on the basis of the strength of development of the textural B horizon. The minimal group had no clay pickup in the B, the medial group had some increase in clay in the B, and the maximal group had a definite clay-pan horizon. These workers considered the Barnes series (as defined at that time) as a medial Chernozem. St. Arnaud (1961) observed weak textural B horizons in Orthic Black (Chernozem) soils in Saskatchewan. Pawluk and Bentley (1956) found no textural B horizons in the Alberta Chernozems they studied. Robertson (1961) indicated no clay movement in Manitoba Chernozems until degradation had begun. NYgard et. a1. (1952) observed textural B horizons in degraded Chernozems, but felt that they were absent or very weak in the true Chernozems, of which they considered the Barnes series to be a typical example. Wilding and westin (1961) observed clay films in the B horizons of well drained Chernozem soils in South Dakota (about 45 miles south of the area of this study) but were unable to decide whether 13 these horizons were the result of clay movement, weathering in place, or stratification. The 7th approximation mentions soils both with and without textural B horizons, among those presently classified as Chernozems. Summarizing, textural B horizons are commonly, but not necessarily present in the true Chernozems. There is uncertainty regarding the origin of these horizons. Most workers are not sure that clay movement occurs before the stage where the true Chernozem begins to be degraded. e. Movement of sesquoxides. The movement and accumulation of sesquioxides is not considered a major process in Chernozem development. Joffe (1949, p. 274) states that there is no movement of sesquioxides in the Chernozem soils because of the high pH and abundance of basic cations. Alexander et. a1. (1939) found no free iron oxide in the clay fraction of the B horizon of a Barnes profile from Grant County, South Dakota, Foth and RieCken (1954) found that free iron oxide was related to clay content in Prairie and Chernozem soils in northwestern Iowa. St. Arnaud (1961) found some redistri- bution of iron oxides in the Orthic Black soil which he studied. This was also related to clay movement. Caldwell and Post (1942) indicated no accumulations of iron oxides in Chernozems in Minnesota. Pawluk and Bentley (1956) found no movement of sesquioxides prior to the start of the degradation process. 14 In summary, some workers have found small accumu- lations of iron oxides associated with clay accumulations. Since the origin of the clay accumulations is uncertain, it is likewise uncertain whether or not the iron oxide accumu- lations are the result of movement in the profile. 3. Development Processes Beyond the Chernozem Stage The preceding section has summarized the processes which have acted on the original material to produce the Chernozem soil profile. These processes continue to act beyond this stage of development. In some areas these processes reach a stage of equilibrium such that the stage which we recognize as the Chernozem persists for extended periods. In other areas, conditions are such that the Chernozem is one of the preliminary stages, and the balance occurs in a more advanced stage. This section deals with development beyond the stage we know as the Chernozem, toward the Solonetz and Planosol or the Podzol. a. Solonetz and Planosol development The genesis of Solonetz soils is discussed fully by Westin (1953). McClelland et. a1. (1959) state that in the area of this study, Solonetzic soils develop under local conditions of impeded drainage and sodic parent material. Farther south in the Chernozem zone, Planesol soils with dense clay pans are felt to represent. advanced stages of development beyond that of the Chernozem and Prairie soils (Allaway and Rhoades, 1951; Godfrey and Riecken, 1954). 15 True clay pan Planosols are absent from the area of this study, and Soloth type planosols are restricted to small closed depressions. It appears that this area is north of that where well drained Chernozems are developing into Planosols. b. Podzolization: the development of Gray Wooded soils Glinka (1927) stated that the northern (coolest and most moist) Chernozems in Russia were intergrading to a podzolic type of soil. Since the area of this study occurs in the coolest and most moist part of the North American Chernozem zone, it might be expected that the soils of this area would also show some evidence of podzolization. Pawluk and Bentley (1956) studied a development sequence of Chernozem to Gray WOoded soils in Alberta. They found that as the podzolization process progressed, the struc— ture of the upper B of the Chernozem changed from prismatic to blocky to platy. The Gray Wooded A2 began to form in what was formerly the upper B of the Chernozem. Accompany- ing these visible changes was an increase in K, H, and Na on the exchange complex at the expense of Ca and Mg. Iron oxides began to accumulate in the B as soon as degradation began, but there was no distinct textural B until the 5th of their 7 development stages. Similar changes were- found in the development sequences studied by St. Arnaud (1961) and Robertson (1961): the latter working only a short 16 distance north of the area involved in this study. NYgard et. a1. (1952) studied a similar sequence of soils to the east in Minnesota. Their comparison of the true Chernozem (Barnes) with the degraded Chernozem (Waukon) indicates a development sequence similar to that indicated by the Canadian work. This work indicates that there is a transition between Chernozem soils and soils which show evidence of podzolization. Nikiforoff (1936) aptly points out that it is impossible to tell if thistransition represents a develop- mental sequence, or whether there is a geographic area where a soil with a combination of Chernozemic and Podzolic properties represents the mature soil under those conditions of climate and vegetation. 4. Regional Intergrades Soils in all four directions from the area of this study have been investigated by various workers for a variety of purposes. These studies permit geographic relationships to be projected beyond the actual study area. a. Northward To the north, the grassland of the Chernozem area becomes mixed with the aspen of the Gray WOoded soil area. The changes in soil characteristics accompanying this vege- tation change in adjacent areas of Manitoba are described by Robertson (1961). --., u 1-.,- iv..- . t«.- , 6“: red. .3: r I ...v 1.. fi.-' 17 b. Eastward Soils on the east side of the Red River Valley have been studied by NYgard et. a1. (1952). There is a gradual degradation of the Chernozem profile with increased moisture, and development of a profile similar to the Gray WOoded profiles to the North. The study area is farther north than where Chernozems grade into Brunizems as rainfall increases. c. Southward Chernozem soils continue to the south for a great distance, but are developed under progressively warmer climatic conditions. Superimposed on the gradual climatic transition are the fairly abrupt boundaries of the various advances of the Pleistocene glaciations. Thus as one goes south he encounters older and more weathered Chernozems (Flint, 1955). d. Westward The soils of western North Dakota are described by Mogen et. a1. (1959). The Zonal Chestnut soils are lighter colored and contain carbonates at shallower depth than the Chernozem soils of this study area. The boundary between the two zones is rather abrupt in Nerth Dakota, since the fairly sharp southwest border of the Mankato till occurs in the same general area as the gradual climatic Chernozem- Chestnut boundary. 18 B. Iron Studies 1. Nature and Significance of Iron in the Soil The mineral iron in the soil can be divided into two broad categories: that forming part of the crystal lattices of silicate minerals, and that occurring as "free" iron oxides. These oxides occur as coatings on mineral grains, and possibly as intergrowths with the clay minerals. The iron in these oxides was released from the silicate lattices upon the weathering of the minerals. Rankama and Sahama (1949) state that most of the iron in igneous rocks occurs in the lattices of pyroxenes, amphiboles, and ferro-magnesian micas. Sand size fragments of these minerals are found in soils, and since they are relatively unstable (Goldrich, 1938) it can be assumed that they weather and release the lattice iron during the period of soil formation. Recognizing that the silicate iron is ultimately released when the minerals weather, it is still the iron oxides which are considered to be the mobile fraction of the soil iron. The redistribution of these oxides in the profile is well accepted as part of the process of podzolization (Stobbe and Wright, 1959). Such authorities as Marbut (1936), and Joffe (1949) indicate that free iron oxides do not move in the Chernozem soils because the neutral to mildly alkaline reactions in these soils favor the formation of insoluble iron compounds. They do recognize such movement in the dedraded Chernozems, and consider it as an indication 0f degradation. l9 Halvorson (1931) discussed the relation of CO 2 pressure and pH to the solubility of iron compounds. He stated that very little iron remained in solution above pH 6.5. Olson (1947) found iron solubility in soils to be related not only to pH, but also to the amount of free iron oxides present. Thus iron movement could occur more readily at a given pH in a soil with more free iron oxides, i.e., with more weathered mafic minerals. Rankama and Sahama (1949) state that iron is capable of forming complexes with organic matter, and that these complexes are capable of movement as colloidal sols. Starkey and Halvorson (1927) indicate that iron can remain in solution as organic compounds at higher pHs than it can as inorganic compounds, since the organic compounds are less ionized. Franzmeier (1962) presents a thorough review of the proposed methods of iron movement; including organic and inorganic colloidal complexes, and ionic solution. 2. Determination of Free Iron Oxides Numerous workers have devised methods for the removal of iron oxides from the surfaces of mineral grains without disrupting their crystal lattices. Most of these procedures 'were devised with the objective of cleaning the grains to sharpen the x-ray pattern, rather than that of the quanti- tative determination of the oxides removed. Paddick (1948) used a solution of thioglycolic acid to extract the free iron oxides from calcareous soils. The thioglycolic acid 20 also formed a color complex with the iron, which followed Beer's law, thus permitting the quantitative determination of the iron extracted by a colorimeter. Jackson (1956) used dilute HCl as an extractant, and determined the amount of iron removed colorimetrically, using orthophenanthroline to develop the color. Kilmer (1960) used a solution of sodium hydrosulfite as an extractant and determined the iron extracted by titration with potassium dichromate. This pro- cedure is rather complex, but is reported to give consistent results. Deb (1950) reviewed several of the extraction and determinative procedures in use at that time, including those developed by Tamm, Jung, Scarseth and Allison, Dion, and Truog. He found a great deal of variability in the amount of iron removed from the same soil by the various methods. Being dissatisfied with all the methods he tried, Deb devised his own extraction procedure, using Na23204 as an extractant under conditions of low temperature and pH. Mehra and Jackson (1960) used the same extractant, but buffered the system to pH 7.3. Much of the variability observed by Deb (1950) can be explained by the diversity of conditions under which the extraction is made. Mehra and Jackson (1960) compared four common extracting procedures. The following table summarizes 'the conditions of the four extractions. 21 Table 1. Conditions in various procedures for the extraction of free iron oxides. Method Conditions Mehra & Jackson Truog Deb Haldane Extractant NaZSZO4 - NaCl NaZS- NaZSZO4 Zn—NH4C1- (NaHCO3 buffer) NH Cl- Oxalic acid Oxalic acid pH 7.3 3.5 to 10 3.5 3.6 Temperature 80 95 40 20 Time (hrs) 1 6 3 3 The following data from Mehra and Jackson (1960) indicate the magnitude of the variation between methods. Soil or Mineral % Fe203 Mehra & Jackson Truog Deb Haldane Miami B 1.0 2.5 1.5 1.3 vermiculite 4.5 6.0 4.2 5.9 Nontronite 0.5 2.9 2.8 4.1 Glauconite 0.8 0.6 0.7 0.6 Nontronite (fine) 0.2 7.9 8.0 2.3 vermiculite (fine) 6.3 10.3 7.8 8.7 In summary, the very existence of so many methods for the determination of free iron oxides would indicate that none of them is completely satisfactory. Apparently, each method removes only a certain group of iron compounds. For this reason, values obtained using any of these methods Inust be considered relative, rather than absolute. 22 C. Mineralogy 1. Mineralogy of the Sand Fractions a. Differential stability of mineral species Each mineral species has a distinct chemical compo- sition and a distinct set of physical properties. Because of these differences each mineral has a different ability to resist the same forces of weathering. Several weather- ing sequences, or scales of weatherability have been devised, based on the differential ability of the minerals to with- 'stand weathering. The positions of the individual minerals vary slightly from one scheme to the next, but in general they all follow the Bowen reaction series, with the minerals formed at the highest temperatures being the least resistant to weathering. Goldrich (1938) presents the following sequence in order of increasing resistance to weathering: olivine, augite, hornblende, biotite, plagioclases (anorthite ‘to albite) K feldspars, quartz, and muscovite. Pettijohn (1957) feels that the position of quartz and muscovite are reversed in the above sequence. Certain of the minerals which are good indicators of the degree of weathering are present in the soil in very small amounts. Many of these minerals contain heavy elements such as iron and titanium, and therefore have high specific gravities. It is therefore often convenient to make specific gravity separations in the sand fractions in order to concentrate the heavy minerals. These 23 separations are easily made by the use of heavy liquids, as discussed by Milner (1940) and Pettijohn (1957). The heavy mineral fractions of soils contain minerals with a wide range of resistance to weathering, including some of the most resistant (e.g., zircon) and some of the most easily weathered (e.g., augite). Pettijohn (1957, p. 506), after reviewing the weathering scales of several previous workers, proposes the following sequence, in order of decreasing resistance: muscovite, rutile, zircon, tourmaline, garnet, biotite, apatite, staurolite, epidote, hornblende, augite, orthorhombic pyroxenes, diopside, and actinolite. In an earlier paper, Pettijohn (1941) states that as a general rule the mineral suite becomes less complex as the deposit ages, due to the disappearance of the less resistant species. He mentions that pyroxenes and amphiboles are common in pleistocene deposits, while they are rare in older deposits. b. Applications to soils problems Marshall (1940) and Milner (1940, chapt. 14) discuss the application of mineralogy to soils. Stephen (1959) presents a review of the uses to which mineralogy has been put in the study of soils. He points out especially the usefulness of changes in the mineral suite as indicators of lithologic discontinuities. Marshall and Haseman (1942) and Barshad (1955) have used mineralogy to measure the changes that have taken place during the development of soil profiles from uniform 24 original materials. Although the details vary slightly, both these studies involve selection of a resistant indicator mineral, which has not changed in amount, vertical distri— bution, or size distribution during soil profile development. It was assumed that the percentage of this indicator mineral in the assumed original material at present is that which originally existed throughout the profile. Present differences in percentages are due to the addition or removal of other constituents. Marshall and Haseman (1942) state that the mineral selected as the indicator should be one which is not formed in pedogenesis, and is immobile. These workers used zircon as an indicator, but indicate that tourmaline, garnet, rutile, or anatase could also be used. Barshad (1955) adds quartz, or a combination of several resistant minerals to this list. Bourne and Whiteside (1962) and St. Arnaud (1961) have used total quartz as the indicator. This eliminates the errors involved in working with minerals that are present in very small quantities in the soil. Raeside (1959) cautions the use of such indicators where chemical and physical changes are suspected. He indicated that quartz and zircon are subject to solution, and that garnet can be broken down by physical weathering. c. Regional studies Since Pleistocene deposits are relatively recent, one should expect them to contain complex mineral suites, 25 containing weak, as well as resistant minerals. Pettijohn (1941) mentions the high content of pyroxenes and amphiboles in these deposits. St. Arnaud (1961) found the heavy mineral fraction of an Orthic Black (Chernozem) soil from Saskatchewan dominated by hornblende, garnet, magnetite, hematite and opaque minerals. Bailey et. a1. (1957) and St. Arnaud (1961) found appreciable K feldspars in the sand fractions of Wisconsin till. Milner (1940) states that orthoclase does not persist for long in a hydrous environment. Bourne and Whiteside (1962) found a predominance of amphiboles, micas, and pyroxenes in the heavy very fine sand and silt fractions of a Chernozem profile from Montana. 2. Clay Mineralogy a. Weathering The clay fraction in soils contains, in addition to finely divided grains of the common minerals of the coarser fractions, certain minerals unique to the clay fraction. The latter, known as clay minerals, have physical and chemical properties which make their occurrence in the coarser fractions impossible, while making them quite stable in fine particles. The structure and properties of these minerals is fully discussed by Grim (1953). Jackson et. a1. (1948) propose the following weathering sequence for clay size particles. The order is from least to most stable: (1) gypsum, (2) calcite, (3) olivine and hornblende, (4) biotite, (5) albite, 26 (6) quartz, (7) illite, (8) hydrous mica intermediates, (9) montmorillonite, (10) kaolinite, (ll) gibbsite, (12) hematite, (13) anatase. As weathering proceeds, one would expect a disappearance of the less stable minerals, and a concentration of the more stable. b. Clay minerals in soils Grim (1953, p. 360) states that illite is the dominant clay mineral in North American tills of Pleistocene age. Montmorillonite is more common in the weathered ?gumbotills.? This is consistent with Jackson's sequence, since illite is less stable than montmorillonite. Alexander et. a1. (1939) estimated the composition of the clay fraction of the B horizon of a Barnesl profile from Grant County, South Dakota. The dominant minerals were kaolinite and hydrous mica, and there were smaller amounts of montmorillonite, iron oxide, quartz and calcite. Caldwell and Rest (1942) report soluble silica contents of 6.54, 5.86, 4.75 and 5.65 Per cent in the clay fractions of the A1, B1, B2 and C horizons 1soil profile in western Minnesota. St. Arnaud of a Barnes (1961) found both montmorillonite and illite throughout the profile of an Orthic Black (Chernozem) soil. He feels that the illite could have been formed by potassium fixation. Bourne and Whiteside (1962) also found illite and montmorillo— nite to be the dominant clay minerals in a loess derived Chernozem. Bailey et. a1. (1957) found appreciable kaolinite in glacial materials in Michigan. lAs classified by the authors. 27 c. Clay formation Grim (1953, pp. 342-343) states that calcareous shales weather to a combination of illite and montmorillonite if both Mg and K are present. The presence of Mg favors montmorillonite formation, and the presence of K favors the formation of illite. Ca tends to favor montmorillonite, but its influence is much less than that of Mg. Removal of both Mg and K results in kaolinite formation. Stephen (1959) traces the formation of vermiculite from the biotite and hornblende of basic igneous rocks. He also states that restricted drainage favors montmorillonite formation in areas where vermiculite formation occurs under well drained conditions. d. Recognition of clay movement It has been mentioned that most of the workers investigating the formation of Chernozem soils have been uncertain regarding whether or not clay movement has occurred. Buol and Hole (1959) as well as other workers have considered the presence of optically oriented clay films or skins as evidence of clay movement. Brewer (1956) states that while thick, strongly oriented, clay films indicate movement, mere anisotropism does not. He states that weathering of clays in place, with subsequent movements due to wetting and drying can cause enough orientation to make the clays anisotropic. He states further that clay movement should be reflected iby an increase in bulk density and a decrease in porosity‘ 28 in the illuvial horizon. Brewer has also noted thick clay films in Solonetz soils in which the clays were not optically oriented. CHAPTER I I I FIELD STUDIES Field studies are an extremely important part of research of this type. The existence of the problem toward which this research is directed was made known through field observations, and it is hoped that the results obtained from it can be of use in the solution of field problems. Samples were collected for use in making some of the quantitative determinations. The objective of the study was, however, not to characterize soil samples, but to characterize soils as they occur in the field. Thus the laboratory data are only as meaningful as the representa- tiveness of the samples on which they were obtained. An attempt has been made to relate the laboratory findings to features that can be observed in the field. This section includes descriptions of the area in which the field studies were made, and of the techniques used in making them, as well as the conclusions reached on the basis of these field studies. A" Nature of the Area 1. Location and boundaries This study was conducted on the till plain, or ground Inoraine, that covers extensive areas in eastern North Dakota. 29 30 The area is bounded on the east by the bed of glacial Lake Aggassiz (Red River Valley), on the west by the Altamont Moraine, on the north by the Canadian boundary, and on the south by the South Dakota state line. The area is delineated by the solid line in Figure 1. The north-south dimension of the area is about 200 miles, between 46 and 49 degrees north latitude. The area has a width of about 200 miles, between 98 and 101 degrees west longitude along the Canadian boundary, and narrOWSto a width of about 75 miles along the South Dakota state line. The eastern boundary of the till plain is rather distinct, being marked by the Pembina Escarpment in the far north, and a series of beach ridges and deltas farther south. A strip of very stratified till that occurs just west of the highest beach ridge was excluded from the study area. On the west, the east, or inside, edge of the Altamont Moraine is very sharply defined in some areas and is very diffuse in others. Probably the sharpest part of this boundary is west of Ellendale, where the line of hills marking the edge of the moraine is visible for 20 to 30 miles to the east. In Stutsman County, where the boundary is crossed by highway U.S.-10, there is a gradual transition from till plain to moraine as one proceeds westward. 2. Topography and drainage The typical landscape on the till plain consists of a complex of knolls and closed depressions, such as shown 311 Figure 1. 3lba Map of NOrth Dakota, showing the study area, its subdivisions, and the location of the profiles studied. 0 Profiles sampled in 1958 0 Profiles sampled in 1959 1. 2. 3. 4. 6. Soil Areas Forman reddish Forman Barnes Maida-Edgely Kief Renville 32 in Figures 2 and 3. The knolls have convex slopes of four to eight per cent, and rise eight to 20 feet above the depression. The depressions range in size from a quarter acre to a quarter section or more, there being more of the smaller size. Such a depression is shown at the left in Figure 2. Most of the natural drainage is into such depressions, many of which are partially filled with water in the spring and early summer. The water level is gradually lowered by evaporation and seepage losses, until all but the largest are dried up by early fall. Streams in which flow can be observed are few and far between. The Park, Forest, Turtle, and Goose Rivers rise in swamps in the northeast part of the area, and flow east to join the Red River of the North. There is little surface drainage in the northwest part of the area. Waters from this area move into the Devil's Lake basin by seepage, or remain in local depressions until evaporated. Drainage from the southeast part of the area is pri- marily into the Sheyenne, Maple, and Wild Rice Rivers, all of which are tributaries of the Red River of the North. The Sheyenne drains a larger proportion of the study area than any other single stream. Its huge valley, cut when the river was carrying large volumes of glacial meltwater, is a striking landscape feature, extending across the till plainfrom Lisbon to Cooperstown. Drainage from the southwest part of the area is primarily into the James River and its principal tributary, Figure 2. 33 A typical landscape view of eastern North Dakota. At the left is one of the closed depressions, into which most of the runoff flows. The well drained soils dealt with in this study occur on positions similar to the knoll at the right of the picture. A small terminal moraine can be seen in the background. Figure 3. 34 View of till plain area in eastern Nbrth Dakota. The area in the foreground is typical of those in which the sampling for this study was done. Well drained Chernozems occur on the small knolls. The area in the batkground has less relief, and is dominated by moderately well and imperfectly drained soils. 35 Pipestem Creek. The waters of the James eventually flow to the Gulf of Mexico, while those of the other streams mentioned flow to Hudson's Bay. 3. Geology According to Leonard (1908, 1916), the study area was covered by glaciers during all of the four major glacia— tions of the Pleistocene epoch. The uppermost glacial deposits, in which the present soils are developed, is, according to Leonard, of late Wisconsin age. He felt that the Altamont Moraine was the terminal moraine of the latest Wisconsin glaciation. Flint (1955), working in adjacent areas of South Dakota, is in agreement with Leonard's earlier work. It is generally accepted, therefore, that the surficial deposits are of the latest Wisconsin, or Mankato, advance: and that the terminal moraine of this advance is the Altamont Moraine. Clayton (1960) investigated tills in Kidder County, and found deposits from several Wisconsin advances. The area of his work lies just ?outside? the Altamont Moraine. The fact that exposures of pre-Mankato till are found just outside this moraine, and are not found inside it, supports the contention that this moraine marks the farthest extent of the Mankato advance. Ruhe and Scholtes (1956) date the Mankato advance at about 12,000 years B.C. The only radiocarbon dating from the area is reported by Moir (1957). This was made 36 on buried coniferous wood found near Tappen in Kidder County. The age of this wood was about 11,480 years. This corre- lates with the Two-Creeks interglacial period, which separated the Mankato and Cary substages of the Wisconsin glaciation. The author accompanied Moir on his first visit to the area. The wood was found in a small drainageway, in an area of morainic topography. The drainageway was eroded into the moraine, and was definitely not a major drainageway before the construction of the Altamont Moraine. The tree was probably growing in Cary material during the Two-Creeks interval, and was buried as the moraine was built ahead of the Mankato advance. All of the evidence points to the conclusion that the surface till east of the Altamont Moraine, is of Mankato age. This till is somewhat laminar, even where not obviously stratified. It is light olive brown (2.5Y 5/4, moist) in color, and contains about fifteen percent calcium carbonate. The till is underlain by Pierre shale over practically the entire study area. The depth to the shale ranges from 20 to 200 feet over most of the till plain. The shale is close enough to the surface to appreciably effect soil profile development only in a few small areas. Among the more prominent outcrops of the shale is the Pembina Escarpment in eastern Cavalier and western Pembina counties. The shale influence on profiledevelopment is very strong in this area (Area 4 in Figure l). The shale also is close to the Surface in an area southwest of Edgely in Lamoure and 37 Dickey counties (also shown as Area 4). There are small out- crops along the sides of the Sheyenne and James River valleys. Although the study area is primarily a till plain, there are other glacial landforms, which although relatively small in extent, are striking landscape features. Small terminal moraines mark the boundaries of minor fluctuations during the Mankato advance. Such a moraine is seen in the background in Figure 2. These moraines are not easily distinguished from the surrounding till plain. An increase in average slope to 12 to 20 per cent, together with an increase in the stratification of the drift are the best indicators of these moraines. Outwash channels and outwash plains are scattered throughout the till plain area. The original material in such areas was deposited by rapidly flowing glacial melt— waters. Most streams in the area have their headwaters in outwash channels on the till plain. A typical outwash area on the till plain is that along Bear Den Creek in western Ransom and eastern Lamoure Counties. Large out- wash plains also occur in Nelson and Towner Counties. The effects of glacial meltwater can also be observed in the stratification of glacial drift. There are large areas in Wells County (Area 5 in Figure 1), and along the west edge of the Red River Valley where the dominant original material is glacial till that has been modified considerably by moving water. The soils of such areas were not included in the Study because of the complications caused by the stratification. 38 4. Climate Eastern North Dakota has a cool sub-humid climate, characterized by long cold winters and short hot summers. Mean January temperatures range from 10°F in the lower James River Valley, to -20F in northern Cavalier County. Most of the study area has mean January temperatures of 0 to 80F. Mean July temperatures range from 700F in the south to 66°F in the north. While the maximum intensity of the summer heat is about the same throughout the area, the length of time it takes to warm up to this, and the length of time for which it persists are variable. Crops in Walsh and Cavalier Counties are usually 2 to 4 weeks behind those in Ransom and Sargent Counties. Precipitation throughout the study area ranges from 18 to 21 inches with a spring and summer maximum. This pre- cipitation is more effective in the north, where cooler temperatures reduce the evaporation losses. Excess water.is often a problem in low areas, while high areas in the same field may be suffering from drought at the same time. The cold winter temperatures and lack of snow cover contribute to deep frost penetration in this area. Redmond and MCClelland (1959) reported the effects of frozen sub- soil layers on the behavior of the ground water table. Frozen soil persists at depth after the surface has thawed out, and even after the beginning of the spring rains. 39 Selected climatic data for four weather stations in the study area are presented in Table 2. taken from Climate and Man (1941). The data are Forman is in the far south, valley City in the south central, Lakota in the north central, and Langdon in the far northern part of the study area. Table 2. Selected climatic data from four stations in the study area. Forman Valley City Lakota Langdon Ave. Jan. temp. 7.1 6.4 -.6 —.7 Ave. July temp 71.4 70.5 65.7 65.8 Max. temp. recorded 110 116 105 112 Min. temp. recorded -45 -41 -45 -51 Average growing season, days 128 123 117 110 Precipitation, in. Jan. 0.48 0.52 0.72 0.63 Feb. 0.63 0.48 0.57 0.64 Mar. 0.72 0.57 0.47 0.76 Apr. 1.99 1.56 1.59 1.16 May 2.84 2.78 2.08 1.98 June 3.43 3.23 3.00 3.22 July 2.89 2.75 2.45 2.45 Aug. 2.73 2.01 2.42 2.42 Sept. 2.03 1.72 1.30 2.21 Oct. 1.30 1.06 0.91 1.02 Nov. 0.59 0.73 0.88 0.77 Dec. 0.57 0.44 0.96 0.64 Annual 20.20 17.85 17.35 17.90 Although the present climate is relatively uniform over the study area, there is no guarantee that this climate has persisted in all parts of the area for the same length of time. Assuming that the glacier withdrew to the north, the till in the southern part of the area has been exposed to 4O sub-aerial weathering processes, and the present climate, for somewhat longer periods than that in the north. The predominance of till and the relative scarcity of outwash in the area indicates a slow retreat, so this time difference may have been considerable. Thus although the soil materials throughout the area have been exposed to about the same climatic conditions and weathering processes, the length of time of their exposure may have varied enough to cause some differences in soil profile development. 5. Vegetation The vegetation on well drained sites throughout the study area consisted of tall grass prairie, with an admixture of middle grasses along its western boundary. MCClelland et. a1. (1959), list the following dominant species: blue gramma (Bouteloua Gracilis), needle and thread (Stipa Comata), little bluestem (Andropogon Scoparius), western wheatgrass (Agropyron Smithii), slender wheatgrass (Agropyron Trachycaulum) and prairie cordgrass (Spartina Pectinata). Cattails and sedges are present in depressional areas. The only visible difference in vegetation between the north and south portions of the study area, is the presence of aspen in the pot holes in the far north, and their absence farther south. Present vegetation can be considered constant throughout the area, but as with. climate, little is known of differences which may have existed in the past. 41 6. Soils McClelland et. a1. (1959) present a description of the soils of eastern North Dakota, including those on the till plain. Brief descriptions of the great soils groups of the area are given in the North Central Regional Publication No. 76, ?Soils of the North Central Region,? (1960). Most of the descriptive material in this section is based on the personal observations of the author made in connection with this study, and during routine soil surveys in the area. The zonal soils of this area are classified as northern Chernozems. These soils occupy the well and moderate- ly well drained positions. A generalized well drained Chernozem profile developed in loam till parent material, consist of the following horizons. A1 4 to 7? thick; black loam; high in organic matter, with granular structure. B p 8 to 16? thick; brown clay loam with prismatic structure. Cca 8 to 18? thick; light gray silt loam with little structure, and very strongly calcareous. C Light olive brown loam till: calcareous, with a tendency toward platy structure. There are, of course, marked deviations from this typical profile, and it is with the description and explanation of some of these variations that this study deals. Soils in the lower drainage positions may be developed either under the influence of ponding, or high water tables. The type of profile developed in the two situations is quite 42 different. In the former case, the soils are classified as Humic Gley in the poorly and very poorly drained positions, and as Humic Gley intergrading to Chernozem in the imper— fectly drained positions. The Humic Gley soils occur in places that are periodi— cally flooded. Over the years this has imparted a lacustrine influence to the upper portion of the profile. The profile consists of a thick black Al horizon overlying a gleyed B horizon which grades into the calcareous C. In areas of loam till original material, textures in the A and B horizons are commonly clay loam to silty clay loam, due to the inwashing of fine particles by runoff waters from adjacent high areas, and/or to the formation of clays in place. In areas where poor drainage conditions exist due to the presence of high water tables, the soils are classified as Calcium Carbonate Solonchak. These soils range in drain— age from moderately well to poorly drained. The A1 horizon is dark gray to black, and is usually calcareous. This rests directly on a very strongly calcareous nearly white, Cca horizon. The lime content then decreases gradually into the C. The genesis and morphology of these soils is discussed by Redmond and McClelland (1959). Solonetz and Solodized Solonetz soils occur in areas of restricted drainage where the original material is high in sodium. The sodium keeps the soil colloids dispersed, allowing eluviation to proceed at a more rapid rate than in soils where the colloids are floculated. The profile consists 43 of a dark gray A1, a light gray A2; columnar B, and C horizons. An accumulation of lime, salts and gypsum occurs just below the B in the Solonetz soils, but have been leached out of the Solodized Solonetz soils. Planosols are believed to be former Solonetz soils that are now highly leached. Areas where Solonetzic soils occur in the low landscape positions were avoided in collecting samples for this study, because of the possible effect of the excess sodium on soil profile development. Saline spots occur in areas of restricted drainage, especially those in which water tables are high. The till throughout the area contains moderate amounts of soluble salts in all drainage positions, but they are leached to sufficient depths in the well and moderately well drained profiles to eliminate salinity problems with crops grown in these drainage positions. Chernozemic Regosols occur on the tops of knolls and on steep slopes, where exposure to sun and wind reduces the amount of effective moisture for soil development, and where erosion removes the surface soil faster than the soil forming processes can deepen it. The profile of these soils consists of a very thin, light gray Al horizon, overlying a weakly expressed Cca horizon that is little higher in carbonate content than the underlying C. The general nature of the soils occurring in the various drainage positions are summarized in Table 3, and their distribution is shown diagramatically in Figure 4. 44 mxfiouoa O .mum .m< .Hm AcoHomv Homocmam ponumoa hamconum .o uso>mo o .moo .mum .me .Ha upmaoHom omuaooaom consume seamhunmo .p mucosa: O .moo .mum .m4 .Hd nuocoHom pocumoa Doc .m Afioacom amass Hoom 0p uoomnomEH muoaam> U .moo .mo< Monucoaom mouwo Awanwu HwUMBV Hoom SHHoEmm O .mou .mod RococoHom moomv Amanmu Houm3v uommuomEH ou oponmpoz Hamcumm 0 .mm .Hm swam CHEST Amcapcomv Hoom anm 0 .mm .Hd ocmnmnoucfl Eonocumcu I Sofia Ufiasm Amcflpaomv uoomuomEH mo>m O .moo .m .Hd Eonocumnu Hao3 maoumuocoz monumm O .mou .m .Hm Emuocnocu Haw: whom U .moo .d Honommm UHEmNosuoco o>flmmooxm Aamanoumfi HmchHno mCONHuom moose HHom umouw mmmcamun Has» smoa maomnum Home: mo oocmsomm mcHESmmmv mmfiuom_ .eemad Heep may no mGOHuHmom mmmcamnc wooenm> on» ca canon mHHom mo mocoooomomou m we onoumz .m wanna .. I... .. F... To > a .05 ._ muhnrvhuvn..v \mu manage OWN UHZ~$NQ~740CMV 3~zn.~gu~.~ -i~eavn 45 .mommmao ommcflmuc can mHHOm mo madamCOHumaon Uflcmmumomoa .c ouomflm momoam X m cu m momon X om ou m mmmoam R v o» m oHQmu nouns 30H manna nmum3 amen Zqum AQHB MZHdmoz ZHflAm AQHB 9 A. .mQ R a 2 . s H mgomozmq so meta. m , s s , m . M N i N ._ .pocflmnp .pocflmnp manoom ou mauoomuomfiw .maomocmam .OH manoom >Ho> can hauoom .mhoaw UHEsm .m .Uocflmuc .Uocflmuc hauoomuomfiH manoom ou mauoomuomEe .NuocoHom .m .mopmnmuoucH moaw oafiom I Eonocnmco .d .cocwmuc mauoom .xmsocoHom moumo .m .cocflmuo Haoz maoumnopoa .mEoNocHonu .m .Uocflmup mauoomnomsfl .stocoHom moomu .o .pocwmuc Hao3 .mEoNocuoso .m .pocHMH© HHoB maoumuopoe .xmsocoHom moomo .o .cocflmup mao>fimmo0xo .maomommm UHEoNocnocO .H QZWGHQ AHOm 46 The proportion of the various drainage classes in a given landscape depends upon the average slope and the local water table conditions. Well drained soils seldom make up over thirty per cent of landscapes in which slopes average four per cent, but commonly make up forty to fifty per cent of landscapes where six to eight per cent slopes dominate. Calcium Carbonate Solonchak, Solonetz, and saline soils are common in areas of high water tables and are absent or very scarce in areas of low water tables. The proportion of well drained soils in a given type of landscape tends to increase from northeast to southwest within the study area. Some differences in the till have been recognized at the series level. The well drained series developed in several variations of the Mankato till are listed in Table 4. The Renville soil area (area 6 in Figure 1) has not received active attention during the course of this study. The differences between the firm and friable loam tills should be the basis of another study. 7. Agriculture The study area is within the spring wheat belt: and hard red spring wheat is the most important cash crop. Wheat occupies 35 to 40 per cent of the cropland in the south, where it competes with corn and 50 to 65 per cent in the north, where the growing season is too short for corn. A considerable proportion of the wheat acreage in the north consists of durum. 47 H .Q.Z mo .3 OH .m.D 0» .Z mcflpcouxo undemoao>wp daemons N.H .Hmm .m.D mo .m .oo .m.z mo .m cmEHom mcouum .Emoa mean I Emoq .oo Hoflambmo ca muomm v .moo >oxUHQ pom ousoama chmumoz maompm ucoEmoHo>mc oaflmonm xmoz o .oo noeam>mo cumummm spam: ucoamoam>oo oaamoum muonpm Emoa >oamnm mono mooH mausom 0 chHQ Haas mo .Hoo .3.z mHHH>com Emoa Bush Hmm .m.D mo .m .oo .Q.z mo .02 m .moum Spoon CH Haom DcmcflEOQ mocumm Emoa oaflmaum a onsmflm mucouusouo CH moms mo swam Hmumcow mmaumm HHHE mo mama .muoxmo nonoz snoummm ca mason Eonocnmso .pobflnop Haas .Uocflmup HHmB mcoEm mmflnmcoflumHom .w manna 48 Fields are large. Most quarter sections (160 acres) can be worked as single fields if desired. There are numerous instances where it is possible to work across a whole mile. Taylor (1960) reports average farm sizes of 500 to 600 acres in 1959. Share rental of land is very common in the area, and part of a farmer's operations may be several miles from home. Cropland makes up 60 to 70 per cent of the land in farms. The remainder is in permanent pasture or wild hay. Corn is important only in the southern part of the area, occupying 16 per cent of the cropland in Sargent County. In the north the growing season is too short for corn to reach maturity; and this crop occupies less than one per cent of the cropland in Cavalier and Towner Counties. Barley accounts for 6 to 20 per cent of the crop acreage in most of the area, but this percentage increases to 26 per cent in Cavalier County. Oats account for 15 to 20 per cent of the cropland in the southern counties. This figure drops to less than 10 per cent in the north. Flax is another crop of considerable importance throughout the area. Small beef herds are kept by over 90 per cent of the farmers in the till plain area. Wild hay is harvested in the swamps for winter feed, and many farmers include alfalfa or other legumes in their rotations on the croplands. Pasture is of both permanent and rotational types. 49 Fertilizer use is increasing in this area, but it is not yet a standard practice. No one questions the fact that fertilizers will increase yields, if there is adequate moisture. The trouble is, at planting time, nobody knows what the moisture situation will be later in the season. In a dry year, fertilizer may even reduce yields. Thus many farmers are reluctant to take the risk of applying fertilizer at the time of planting. The soils are usually deficient in phosphorus, often low in nitrogen, and usually contain adequate potassium. Micro nutrients are not critical on the crops of the area. Soil reaction is about ideal for most crops, and application of lime is very rare. Excess lime, while harmless in itself, ties up native and applied phosphorus as unavailable calcium phosphates, making higher phosphorus applications necessary on high lime soils. The management of soil water is the number one problem facing farmers in this area. The low areas are too wet, while high areas in the same field are commonly suffering from drought. Tile drainage is not economical with present crops and yields. Irrigation is feasible in only a few areas where a water source is especially convenient. The author doubts that the till soils can take much irrigation, without introducing serious salt problems. Land values in 1959 averaged 25 to 35 dollars an acre, with slightly higher values in the north than in the south. At 30 dollars an acre, a half section farm 50 carries a price tag of $9,660, which is a considerable investment. For this reason the person going into farming in this area usually prefers to buy his machinery and rent the land for a while. Farm houses are for the most part, modern and are well kept. Electricity is almost universal in rural areas. Most of the country towns have populations of 100 to 400 people, and are centered around the country grain elevator. Most county seat towns have populations of 1,000 to 2,500. There are few towns of over 2,500 population. These towns are trading centers, and have little in the way of industry. The area is well served by railroads. Most county elevators are located along a main or branch line of a rail- road. The branch 1ines are maintained primarily for the removal of the grain crop; regular freight and passenger business being next to nothing. Over half the state high- ways are paved, and the rest are good gravel. Most county roads are gravel. They get a bit rough and muddy after a heavy rain, but are better than pavement when icy. There is a road allowance on every section line, and most of these can be driven in late summer and fall.1 1Data in this section are taken from "Handbook of Facts About N.D. Agriculture.? The original source of most Of these figures is the U.S. census of agriculture. The generalizations were made by this writer. 51 B. Field Procedure 1. Methods employed in sampling and describing soils A number of inspection trips were made into the study area during the 1957 and 1958 field seasons. Some of these were made for the specific purpose of examining the soils of a given area, but many more were trips of an in- formal nature, on which soil observations were made. In l958pits were dug to depths of four to five feet at a total of 33 locations, scattered over the study area. Detailed soil profile descriptions were taken from the sides of these pits, and from auger holes below the depth of the pits. Core samples were taken where possible, but since 1958 was a-dry year, usable cores could not be taken at all the sites. Small bulk samples from each horizon were also obtained. Typical well drained sites on the till plain are under cultivation, and therefore disturbed sites were included in the sampling. Virgin sites on these soils are few and far between. Unplowed areas usually have been left for some reason that makes them atypical of the area. Standard procedures were usually employed in taking the descriptions and the data was recorded on standard soil description forms (SCS 232). There was one deviation from standard describing procedure. A small envelope sample was taken indoors, where it was used for the deter- mination of color and texture. Each envelope was given a Coded number. This eliminated some of the personal bias 52 from the color and texture determinations, since it was impossible to tell what horizon was being evaluated at a particular time. Moist and dry colors were determined against a background of neutral gray blotting paper, using daylight fluorescent bulbs as a light source. Textures were determined at the same time. This procedure eliminated differences in outdoor light from day to day, and eliminated bias from the texturing. On the other hand, texture deter- minations on samples are not as accurate as those made at the site of the profile. 2. Field characteristics of profiles sampled in 1958 The field characteristics of most of the profiles included in this study are summarized in Tables 5a to 5e. Some of these sites had been sampled previously for other purposes, and laboratory data were available on the profiles at such sites. The data in the table, however, is based entirely on field determinations. No standard procedure for recording clay films was available at the time of sampling, so the following numerical system was devised, and is used in Table 5. 1. Patches of thin films 2. Continuous thin films 3. Patches of moderate films 4. Continuous moderate films 5. Patches of thick films 6. Continuous thick films In the fractional clay film designations presented in Table 5, the numerator refers to vertical ped faces, and the denominator to the horizontal ped faces. For example, the 53 Table 5a. Characteristics of profiles and sites sampled in 1958. Location of profiles sampled in 1958. Distances and Reference direction from Profile County Sect-TWp.-Rg. pt. reference point No. N W FlA Ransom 16-136-56 N 1/4 cor. 450'W; 40's F1B Cass 19-137-55 NW cor. 200's; 120'E F2A. Sargent 6-132—55 NW cor. 1825'E; 150's F2B Ransom 18-133—55 SE cor. 300'N; 150'W F3A* Sargent 18—130-55 NW cor. 1250'E; 150's F3B** Sargent 16-130-55 N 1/4 cor. 485'W: 560's F4A*** Dickey 8—129-60 W 1/4 cor. 860'E; 340'N F4B**** Dickey 5-129—60 SE cor. .3 mi. W; 1/4 mi. N FSA Lamoure 16-135-59 S 1/4 cor. 240'N; .2 mi. E F5B Lamoure 8-134-59 N 1/4 cor. 600'W; 160's F6A Stutsman 35-140—66 NW cor. 1200's; 180'E F6B Stutsman 9-139-66 SW cor. .3 mi E; 60'N BlA Barnes 5—137-60 E 1/4 cor. 75’N; l35'W B1B Barnes 9-138—60 SW cor. 145‘N; .2 mi. E BZA Cass 23-138-55 N 1/4 cor. 200‘s; 500'W BZB Cass 6-138-55 SW cor. 450'N; 140‘E 32C Cass 7-139-54 SW cor. 1150‘N: 60'E B3A# Steele 28-144-56 SW cor. 270'N; 75'E B3B" Barnes 20-142-56 SE cor. 400'N; 90'W B4A Nelson 18-150-57 SE cor. 410'W; 120'N B4B Nelson 30—150-58 SW cor. 1200'N; 140'E BSA Walsh 31-158-58 NE cor. 400'WI 50'S' B5B Walsh 27-157-58 SW cor. 300'N: 400'E *At site of SS6ND4l-2 **At Site of SS6ND4l-5 ***At site of SS3NDll-2 ****At site of $53ND11-1 #At site of SS3ND46-l "At site of S53ND 2-1 54 Table 5b. Properties of profiles sampled in 1958. Profile Site Series* Ap or Al horizon %.slope Exposure Relief Thick Color** Text. FlA 1 E 6' F 8 10YR2/1 L F13 1 N 4-6‘ F 6 do. L F2A 3 sw 6-8' F 4 do. L" F2B 2 N 6' F 5 do. L F3A 1 E 3-4' F 8 do. L F3B 2 w 25' F 3 do. L F4A 5 NW 10-25' F 4—1/2 do. L F43 8 W’ 25' F 7 do. L FSA 4 NE 10' RF 3-1/2 do. L F53 3 S 8' RF 4 do. L? F6A 2 S 12' F 7 do. L F63 4 W 8' F 5 do. L 313 5 SE 8-10' RF 6 10YR3/2 SiL 313 3 N 8' RF 6 10YR2/l L BZA 2 S 6' B 9 do. L 323 1 S 6' 3 9 do. L 32c 4 S 10' 3 7 do. L 83A 4' E 8' 3 6 do. SiL 333 1 E 8' 3 8 do. L B4A 2 S 20' B 4 do. L 348 4 S 10' B 5 do. L BSA 4 SW 8‘ B 8 do. L 353 2 E 6' 3 5 do. L :: Forman : Reddish Forman : Barnes **Moist color (Munsell notation) L? Loam grading to clay loam. 55 moon mo mmmcm one .sumconum omofl>flo Doc muons m muflucm “0H mam.h can mwoa soo3uwn m5: m moumoaocfl Hoaoo mcfi3oaaom# .oNHm mm co>fim NH ousuoouumesa H\m no H\m macs seesaw: .mnoaoo noxumo sues ooumooss madam amao .m.o« .oo H\¢ Ramos .oo seem o mmm oooe>ao poo o\e mom 44~\emaoa oo o «mm o\o Homo> m\omSoH o a o\o Homo> m\mSm.~ o as mam .oo «\me Home m\ewm q as «em .06 o\a Ramos «\mem.~ mono m mmm .oo m~\mm some ssm\¢mwoa oo o «mm oooa>eo soc o\m Home «\emwoa o m can m\mm nose «\emsoa q o o\o Ramos *4m\¢maoa q o mam oooa>no poo o\o .uooo m\mm>oa o m «mm H\H homuse «\emwoa o o .oo .oo #m\emaoa o m mam ma\me HENIHSo «\omon o m H\H nose #e\¢m>oa q s «Hm o\o .oo 4*m\m»m.~ go o o\o .oo 4*m\¢msOH no s mom m6\mo Home 44~\emaoa go o «\v Home ssm\vmsoa go 6 tom m\m Somme o\oam.m no oa m\o Roms #e\¢mwoa no u mmm H\mmm Home m\mwm.~ new m m\e some #~\omaoa no «\Huo Ems oooe>no so: o\o Home ««~\emwoa doom s mam mH\mH Romeo «\wmaoa o m me\mo .oo e\¢ESoH q «\Hum «as .oo me\o Home 4.m\¢mwoa gem m mmm .oo mm\o some ase\omaoa so m mmm .oo o\o .oo *4m\qmwoa anew m mum oooHSHo poo mv\m¢ Home m\o»m.~ so oa «mm ma\ma homuas m\¢maoH go o mmm\mmm .oo «\emeoH no e mam m~\m~ someL ~\mwm.m go o mm\me some «\ewm.~ no a ass a. .h . U stsmuflu Uflhum HOHOU . UXTB mTSUCH k. . .m . U “I; . HUSHDm .HOHOU . UXOB mmflocfi .xoeee .xoaee um3oq m Momma daemoum .mmma CH ooamamm moaflmoum mo mGONflHOS m mo mmeunmmoum .om wands 56 Table 5d. Properties of Cca and C horizons of profiles sampled in 1958. Profile Her. Texture Type Structure C.F.***Base color FlA Cca SiL B mO-lpr 2.5Y5/4 C L do. FlB Cca SiL? FB ml-2pr do. C SiL,L do. F2A Cca SiCL F mlpr 1/0 do. C L 2.5Y5/2 F2B Cca SiL F mlpr 2.5Y5/4 C SiCL,SiL do. F3A Cca L F clsbk do. C .L,CL do. F33 Cca SiL F m2pr 2.5Y5/3 c CL,SiL 2.5Y5/4 F4A Cca L F clpr do. C L do. F43 Cca SiL F m2pr 2.5Y5/3 C CL,L 2.5Y5/4 F5A Cca SiL F m 2.5Y5/2 c L 2.5Y5/4 F5B Cca L? F m 2.5Y6/2 c L 2.5Y5/4-5/6 F6A Cca L F c2abk do. c L,SiL 2.5Y5/4 F6B Cca SiCL F c2pr 13/0 2.5Y5/55 C SiL,CL 2.5Y5/2 BlA Cca SiL,L FB vclabk 2.5Y5/4 C L do. BlB Cca L FB clbk do. c SiL L 2.5Y5/3,4/4 BZA Cca L i B clpl 2.5Y5/2 C L 2.5Y5/4 BZB Cca none C' L 2.5Y5/4-5/2 B2C Cca L B mlsbk 2.5Y5/3 c L,SiL 2.5Y5/4 33A Cca L B clpr 13/13 do. c L * 2.5Y5/3 BBB Cca SiL B mc2pr 1/0 2.5Y3/2-4/2 c SiL,L * 2.5Y5/4 B4A Cca SiL B ch—lpr 2.5Y6/3 c ' SiL,L ** 2.5Y6/3-5/2 B4B Cca L B mlpr 2.5Y7/4 C L,SiL (strat) * 2.5Y5/4 BSA Cca L B c2pl * 2.5Y6/2 C L * 2.5Y5/2-5/3 353 Cca L 3 mlpl 2.5Y5/3 __l C L * 2.5Y5/4 ** *Clay films *thiceable amount of shale **High in shale 57 Table 5e. Special features of profiles sampled in 1958. Profile Features FlA Forman: transitional to Barnes area. Stoney. FlB FZA FZB F3A F3B F4A F4B FSA F5B F6A F6B BlA BlB B2A B2B B2C B3A Little stratification. A good transitional profile. Forman development. Close to edge of Barnes area. Silty C indicates some stratification. Close to, but not on, a small terminal moraine. Strongly developed Forman. Typical Forman Cca. very strongly developed. Tongueing to considerable depth. Colors dark. Sampled to represent Forman series in Sargent Co. Correlation. Probably about modal in terms of development. Shallow to lime. Sampled as mate to F3A. More relief than at most of the other sites. A virgin site. Modal Forman development. Originally sampled as Barnes, for characterization. We felt it had enough development to qualify as weak Forman. Sampled as mate to F4A. Definitely Forman. Poor site because of steep slope on which it occurs. Located on the side slope of a major drainage channel. Reddish upper B. Weak end of Forman. ’ do. do. Forman type Cca. Taken where till plain grades into Altamont Moraine. Strongly developed. very strong development. Lime in Cca almost all in nodules. Near west edge of study area. Sampled as strong Barnes. Further examination revealed it to be weak Forman. Reddish hues in B. Forman Cca. very similar to BlA. Grading toward Hamerly. Till is partially water- worked. with a stone line at 28?. Not a good profile. Too deep to lime for good Barnes. Till may be waterworked. Good profile, but amount of well drained soil is limited in the immediate area. Originally sampled as the modal Barnes. We think it is on the strong side. 58 Table 5e.—-Continued. Profile Features BBB The original type location for Barnes. Now site is destroyed by widening road. B4A Stronger development than expected in this area. Till is more shaley as we move north. B4B Pebble line between B and Cca indicates stratifi- cation. The upper profile looks like good till, but the lower part is questionable. BSA Some development seems to have started in the upper B. Still a Barnes profile. The till is quite shaley. BSB Good Barnes, but till is shaley. Modal Barnes development and Cca. clay film designation for the upper B of profile FlA is 45/23. This means that the vertical ped faces have a continuous coating of moderate films, with patches of thick films; and that the horizontal ped faces have continuous thin films, with patches of moderate films. The terms thin, moderate, and thick are purely relative and are applicable only among the soils of this study. Type ?F? Cca horizons have the lime concentrated into small nodules or pockets, with the intervening matrix relatively low in carbonate content. In type ?B? Cca horizons, the lime is dispersed throughout the mass. Type F3 is transitional. All otherébsignations are as proposed in the ?Soil Survey Manual.? Six profiles taken on shaley till in Cavalier County, and two profiles taken on shallow till deposits over 59 solid shale in western Lamoure County were omitted from Table 5. On the basis of the field studies, it was decided to eliminate these shaley areas from further investigations in connection with this research problem. It was decided that the differences between these shaley soils and the others involved in the study could be explained by the high shale content of the original material. A report on these soils was prepared and submitted to the regional correlator for his use in establishing and correlating series to cover these shaley situations. In addition to the field studies, a number of laboratory tests were run on the bulk samples obtained from these 33 profiles. 3. Profiles selected for further study On the basis of these preliminary field and laboratory investigations, six profiles were selected for re-sampling for use in detailed laboratory studies. The sites were selected to represent certain stages in the continuum of development from strong to weak. Sites where profiles had been sampled and analyzed previously were not considered. .The profiles were taken where the till, at least to the naked eye, was not stratified. All six profiles were taken on well drained sites in cultivated fields. Those taken on east or northeast slopes were taken close enough to the crest of a knoll so that snow accumulation does not result in abnormally moist conditions. Care was taken to 6O stay off distinct morainic ridges. Areas where well drained soils occur in association with Solonetz were avoided. Profiles F2A and F2B were selected to represent the strongest development observed in the Forman soils. Profiles BlA and B1B were selected to represent the weak end of the Forman soil development. The reddish hues in the B horizons of these profiles promised to be interesting in View of the proposed iron study. Profiles BSA and B5B were selected to represent the North Dakota concept of the Barnes series. They contained a little more shale than is typical over most of the Barnes soil area, but were well within the range of texture and structure allowed in the series. Pits were reopened at these six sites in the summer of 1959, and samples were obtained for use in further labora- tory analyses. This sampling was done in conjunction with the S.C.S. Soil Survey Laboratory in Lincoln, Nebraska. Dr. J. S. Allen of the laboratory staff participated in the field sampling. The samples were divided, one portion going to the Lincoln Laboratory for routine analyses, and the other being brought to M.S.U. for mineralogical analyses by the author. The properties of these six profiles, determined in the field are summarized in Table 6. Detailed descriptions of these profiles are included in the Appendix. 61 xnmmo meNE xnmmme xnmmo xnmmm xnmm .N Homo Home Home homo HmmE HQmE .H ououuouum .c ~\mwm.m m\vwm.m m\owm.m m\v%m.m N\omwoa N\oIm\mwm.m uoHoo .m AU AU AU do no 40 ououxme .m o m 0H o o o monocfl .mmocxoece .H AnoBOAq somehow m .Q meNEm xnmmEm Rammm xnmmam xDMmm xnmm> .m Home Home Home Home ammo HmmE .H ousuoouum .m H\mm%oa H\o : mcoc moo: H\m = H\m = Auoeuouxov uoHoo .o m\eam.m m\omwoa m\omsm.s m\omsOH m\amw0H «\mmsoa Auoeuoueflv uoHoo .m AU AU 40 do no no ououxoe .N o o m m o o monocfl .mmoconEB .H AHoQQSL somehow .m .0 q A a q a dam mhduxme .m H\waoa H\waoa a\mmwoa H\waoa H\mmwoa a\mmwoa HoHou .N m m m m m o monucfl .mmoconEB .H GONHHOE mw .m .th .0 .0 .m .m .0 MOHHOM 3? m 3m 2 so am zz ousmooxm .m Re Re Rm Rm Re Rm macaw .m mmm amm mam mam Ems mmm oeemono mm .H ouwm .d Uflumfluwuomumco NIom HIom NIN HIN mlao mlhm .oz daemoum mocuwm cmEuom phantom cmEuom moeuom Heom .mmma SH oonEmm moafimouo mo moflumflnouomumso oaoflm .m magma 62 .oomnm .oomnm .oNAm «co>Am me ohsuosuum .mEOAqucou umAOE ou Momma mHvou .ooe 30A .oo& .oo& .oo& 30A .o zvoQ .9 goes 30A Ema: amen noes 30A .o o>onm .m Eommhw .m o\m»m.w ¢\mwm.m o\mwm.m o\mwm.m o\m%m.m ¢\mwm.m MOAOU ommm .N A A A A A0 A .m .U A A A A0 Aflm AU .o .Q o do do no so A .m .m onsuxoe .A coueuom o .h 30A «005 now: goes .ooe 30A Esmmao .d HQAU HQAU HQNU>U Homo Home HQAU ousuuumpm .m m\owm.m m\owm.m o\me.~ «\owm.m m\mwm.m «\mwm.m w0Aoo ommm .m . AHm Aflm AU AU Aflm AHm muauxma .H souenom moo .m 63 4. Description of sites sampled in 1959 a. Forman Profiles SS9ND37-3 and SS9ND41-1 were sampled at the sites of profiles F2B and F2A respectively. They are located in an area northeast of Gwinner in northern Sargent and southern Ransom Counties. The strongly developed Forman soils occupy most of the well drained sites in this area. These two profiles were the finest textured and most strongly developed of those included in the original field study. Slopes in the area are three to four per cent, and are short. There is little outwash in the immediate area. Drainage is into closed pot holes at first, and eventually into the Sheyenne River through Dead Colt Creek. The area lies be— tween the beds of glacial Lakes Aggassiz and Dakota. If a water link ever existed between the two lakes, it is possible that this area was submerged. Colors in both profiles are darker than one would expect in well drained soils. These colors are due to the tongueing of material from the Ap horizon down between the peds in the B horizon. Both profiles are situated on what are definitely well drained positions. Profile SS9ND37-3 is located 310 feet north and 165 feet west of the southeast corner of section 18, T.133 N.; R. 55 W. It is situated halfway up the slope from a shallow natural drainageway to a low knoll. A well entrenched natural drainageway, a tributary of Dead Colt 64 Creek, lies about 400 feet to the east. Moderately well drained soils dominate the landscape, with well drained soils restricted to knolls such as the one on which this profile was sampled. The fine texture of the plow layer was evident from the fact that clods up to one foot in diameter were present after plowing in a relatively dry condition. A1 material extended to depths of 22 inches in narrow tongues between the peds of the B. The Cca horizon has the "white- eye? lime distribution typical of the Forman soils. Clay films were very evident in the field, although they were covered by and intermixed with organic coatings. Profile SS9ND4l-1 is located 1825 feet east and 150 feet south of the northwest corner of section 6, T.132 N.: R.55W. This is about three miles south of profile 37-3. This profile is nearly as fine textured as profile 37-3, and has about the same degree of development. The profile is situated on the crest of a small north-south ridge, that slopes into small depressions on the east and west. Slopes are short, and have gradients of three to four per cent. Lime is encountered at a fairly shallow depth. The Cca is typical for the Forman soils. There is considerable gypsum present in the lower C. Tongueing of Al material is not as pronounced as in profile 37—3, but extends to depths of about 15 inches. Clay films are evident in the B. 65 b. Reddish Forman Profiles SS9ND2-1 and SS9ND2-2 were sampled at the sites of profiles 31A and B1B, respectively. These profiles are located in the Svea School area northwest of Litchville in southwestern Barnes County. The till plain in this area is fairly uniform, with short slopes that average four per cent. Well drained soils occupy 50 to 60 per cent of the landscape. This is a considerably higher proportion than in most till plain areas of this relief. There is a corresponding deficit of Calcium Carbonate Solonchak soils, indicating an absence of high water tables. The two profiles are about 4—1/2 miles apart across the till plain. Except for a small local lake bed 3/4 miles north of profile 2—1, the intervening area is all till plain. A glacial drainage channel, filled with outwash deposits, occurs northeast of profile 2-2; and drains into the Sheyenne River near Kathryn. Another drainageway occurs 2 to 3 miles west of the two profiles, and drains south to the James River near Dickey. The entire area is devoid of distinct morainic ridges. The reddish hues(intermediate between lOYR and 7.5YR) in the B horizons of the well drained soils in this area were immediately obvious to the author on his first inspection of the area. Both these profiles were first thought to represent the strongly developed end of the Barnes series. It was later decided that they had enough Clanilms to qualify as the weakly developed end of the 66 Forman series. The colors are brighter and the organic content lower in these profiles than in the strongly developed Forman profiles. The Cca horizons are more similar to those of the Forman than to those of the Barnes soils. Profile SS9ND2-l is located 80 feet north and 135 feet west of the east quarter corner of section 5, T. 137 N., R.60W. The profile is located halfway up the side of a small hill that has a height of 10 feet and side slopes of 5 per cent. The local drainage is into closed depressions. There is moderate sheet erosion, and chunks of B horizon material are common in the plow layer. Thin clay films were observed in the B horizon. There is considerable gypsum in the lower C horizon. Pebbles were mostly granitic, with little shale present. Profile SS9ND2-2 is very similar to profile 2-1. It is located 145 feet north and 0.2 miles east of the southwest corner of section 9, T.138 N.; R 60 W. It is located on the crest of a small knoll with three per cent side slopes. This is slightly less than the average slope in this vicinity. The local drainage is into closed de— pressions. Erosion is slight, and granitic stones are numerous throughout the profile. The depth to free carbonates varies from 20 to 30 inches around the pit, there is some gypsum present in the lower C horizon. 67 c. Barnes Profiles SS9ND50-l and SS9ND50-2 were sampled at the sites of profiles BSA and B5B, respectively. These profiles are located in the Adams~Fairda1e area of western Walsh County; in the northern part of the till plain. This area is only 15 or 20 miles south of the area that was dropped from the study because of the high shale content of the till. At the time of sampling, it was recognized that profile 50-1 was more strongly developed than profile 50—2. Neither was thought to be as strongly developed as the Forman soils. The two profiles are located about seven miles apart. There are no distinct moraines between them, although there are several outwash-filled drainage channels in the area. These eventually drain into the Forest River. Slopes in the area average four per cent and are short. Steeper slopes are present along the major drainage channels. Well drained soils are restricted to distinct knolls and ridges. There are appreciable amounts of Calcium Carbonate Solonchak soils in the low areas. There are also some Solonetz soils in the vicinity of Adams, but these occur in rather broad flat areas, that are distinct from the surrounding till plain. Profile 50-1 is located 200 feet west and 50 feet south of the northeast corner of section 31, T.158 N.; R. 58 W. It is situated 2/3 of the way up a four per cent slope on the southwest side of a small knoll. Drainage is into a closed depression to the southwest and erosion is slight. 68 This profile has slightly stronger development than is modal for the Barnes series. Most of the coarse fragments are shale. The upper B horizon is redder, and contains more clay films than the lower B horizon. Most of the lime in the Cca horizon is disseminated, as is typical in the Barnes series. Profile S59ND50—2 is located 280 feet east and 200 feet north of the southwest corner of section 27, T. 157 N.; R. 58 W. It is located 2/3 of the way up the four per cent south slope of a convex knoll on the till plain. This profile was thought to typify the North Dakota concept of the degree of development, in the Barnes series. There is more shale in the Cliorizons of this profile than occurs over most of the geographical range of the series; but this is the only criticism of this profile. The depth to free carbonates is extremely variable within the area of the sampling pit. The lime seems to be concentrated in areas where the path of downward moving water is obstructed by large stones. The lime is finely divided and disseminated throughout the soil mass, as is typical in the Barnes series. Clay films, if present, are maSked by organic tongues and coatings in the upper B horizon. Pebbles are mostly shale. There is considerable gypsum in the lower C horizon. 69 C. Conclusions from Field Studies The following conclusions regarding the similarities, differences and relationships among the soils studied were reached on the basis of the field investigations. These conclusions were reached without the aid of the results of subsequent laboratory investigations. 1. The Forman soils have the finest textured B horizons. However, the amount of increase in clay content over the A and C horizons is often greater in the coarser Barnes soils. The structure in the B horizons of the Forman soils is stronger than that in the B horizons of the Barnes soils. This is true of the secondary and tertiary structure units as well as the prisms making up the primary structure. Prismatic structure extends only to the top of the Cca horizon in the Barnes soils, whereas it extends well into the Cca horizon in the Forman soils. Tongueing of material from the A1 horizon down between the peds in the B horizon is more common and extends to greater depths in the Forman soils than in the Barnes soils. The Cca horizon of the Forman soils consists of a matrix relatively low in carbonate content, into which are set small pockets of loose lime and small carbonate concretions. The carbonate in the Cca horizons of the Barnes soils is finely divided, 70 and disseminated through the soil mass. Forman soils are dominant in the southern part of the study area: Barnes in the central and north. Small areas of one are found in the general area where the other is dominant. The Reddish Forman soils are in some ways more similar to the Barnes soils, and others more similar to the Forman soils. Barnes and Forman should be separated at the series level. The separation should be on a regional basis, and both series should be mapped in only a few borderline counties. Differences in the utilization of the Barnes and Forman soils are due to differences in atmospheric climate, rather than to soil differences. CHAPTER IV LABORATORY PROCEDURES A. Preliminary Studies on Samples Collected in 1958 1. Determination of bulk density The bulk density was determined on triplicate natural clods (portionsof peds) from each horizon of the profiles examined in 1958. The clods were oven dried and weighed. A thread of negligible weight was attached to each clod. A different color thread was used on each of the triplicates to aid in identification during the process. The clod was then dipped into molten paraffin, and quidkly removed before the parrafin could penetrate the pores to any appreciable distance. The dipping was repeated until there was a waterproof coating around the clod. The coated clod was then weighed in air, and suspended in water. This permitted the calculation of bulk density as follows. W2 - W1 = Wp v1 (wz - w3) v2 = v1 - Vp; vp = §§ 211. V2 71 72 W1 :: Wt. of uncoated clod in air W2 :: Wt. of parrafin coated clod in air W3 :: Wt. of parrafin coated clod in water Wp :: Wt. of parrafin v1 :: vol. of coated clod, i.e., vol. of water displaced v2 :: Vol. of uncoated clod vp :: Vol. of parrafin coating Dp :: Density of parrafin. Determined previously. BD :: Bulk Density of the oven dried clod. This method is simple and gave reproducable results. The Soil Survey Laboratory determined bulk densities in a similar fashion on several horizons from the profiles sampled in 1959, using much larger clods. Their results were in close agreement with those obtained by the author using the smaller clods. In addition bulk density was determined on the 3 x 3 inch cores taken at the time of sampling the profiles in 1958. This was a dry year and for this reason useable cores could not be obtained at all sites. The values obtained by the clod method will be used in all calculations involving bulk density. 2. Analyses by soil testing laboratory. North Dakota Agricultural College The soil testing laboratory at N.D.A.C. determined pH, soluble salt and available phosphorus on numerous samples from the 1958 profiles. This data was helpful in ascertaining the representativeness of some of the profiles, but was not used as such later in the study, since no distinct differences were brought out. 3. Microscopic examination Material from each horizon of the profiles sampled in 1958 was examined under the binocular microscope. 73 Especial attention was given to bleached sanigrains, clay films, lime and iron concretions, and the degree of decomposi- tion of coarse fragments of more than one mineral species. Microscopic examination did little to change the field classification of clay films. The other data was useful in selecting the profiles to be used for further study. Results of this examination will be incorporated into the discussion where applicable. B. Analyses on Profiles Sampled in 1959 by the Soil Survey Laboratory,SCS, Lincoln, Nebraska Routine chemical and physical analyses on the six profiles sampled in 1959 were made by the Soil Survey. Laboratory at Lincoln, Nebraska. ‘Dr. J. S. Allen of the laboratory assisted with the field sampling. The methods used are those regularly employed at the laboratory. In addition to the six profiles sampled in direct connection with this study, data from the analyses on other profiles by this laboratory are used for purposes of comparison at several points in the discussion. 1. Mechanical analysis The pipette method of making mechanical analysis, as proposed by Kilmer and Alexander (1949) was used, including the improvements of Kilmer and Mullins (1954). This pro- cedure does not remove carbonates. 74 2. pH A glass electrode pH meter was used to measure the pH of 1:1, 1:5, and 1:10 soil:water suspensions. 3. Organic matter a. Organic carbon was determined by wet combustion following a modification of the Walkley-Black method as proposed by Peech, et.a1. (1947). b. Nitrogen was determined following a modification of the A.O.A.C. procedure (A.O.A.C. 1945, p. 4). 4. ?Free iron? Free iron was determined according to the procedure outlined by Kilmer (1960). 5. Calcium carbonate equivalent Calcium carbonate equivalent was measured by treating the soil sample with concentrated HCl and measuring the volume of CO2 evolved. This method makes no distinction between the carbonates of calcium and magnesium. 6. Electical Conductivity Soluble salt content was estimated from the electical conductivity of a soil solution as measured with a standard wheatstone bridge. 7. Gypsum Gypsum was determined by precipitation with acetone, as outlined in U.S.D.A. Handbook 60 (1954). 75 8. Moisture Moisture percentages at saturation, and at tensions of 1/10, 1/3, and 15 atmospheres were determined by the procedures described in U.S.D.A. Handbook 60 (1954). 9. Cation exchange capacity The cation exchange capacity was determined by the direct distillation of adsorbed ammonia as proposed by Peech et. a1. (1947). 10. Extractable cations and anions. a. Calcium was determined by precipitation as calcium oxalate. b. Magnesium was determined by precipitation as magnesium ammonium phosphate. c. Hydrogen was determined by the triethanolamine method. The above three methods are described by Peech et. a1. (1947). 6. Sodium and potassium were determined on both the original soil extract and the saturation extract with the Bedkman DU flame photometer. e.Bicarbonate, sulphate and chloride were determined on the saturation extract using the methods described in U.S.D.A. Handbook 60 (1954). 76 C. Iron Investigations 1. Free iron oxides It was felt that any iron that had moved in the profile would occur as loosely held coatings on the mineral grains. It was desired to remove these coatings of iron oxides, without removing any iron from the lattices of the minerals. The thioglycolic acid method proposed by Paddick (1948) was selected for this purpose, because of its simplicity, pH tolerance, and applicability to calcareous soils. The amount of Fe203 extracted by this method seemed unusually low. Although duplicate samples run in the same batch gave close agreement, it was impossible to duplicate the results on different days. By varying such details as pH, reaction time and temperature, it was possible to obtain wide fluctuations in the amounts of iron extracted. The magnitude of these fluctuations is indicated in Table 7. The thioglycolic acid extraction was compared to several other methods of extraction. Samples from reddish Forman profile SS9ND2-l were used for this comparison. The other methods of extraction were as follows: 1. The samples were shaken for five minutes with 0.06 N. HCl and filtered. Iron was determined on the filtrate by the orthophenanthroline method of Jackson (1958). 77 he .mm mm .mv .wo .No HH ow .mm HHH mm .HOH .mo .mo HHH .mc .mm HHH .nm .om >H me on .bh HH .wh .No HH omm .mmm HH mm .mm H NmH .HNH H .hh .bb H com .mom H oom .omH H omm H moo . mm .om ooH .NoH om .sm mmA .emA .om .ms HH omA .ooA moA .noA .emA .omA HHH .mm .mm HHH .omH .me >H moH ~ooH .omH HHH .NOH .om HH own .mhm HH mm mom .omm H Nmo .bmo H .cmH .HNA H omH,.moH H one .ooo H oom H m omH .ooA .mmH .mmH >H onH .moH omH .cmH vNH .¢MH omH .ooH HHH.moH .moH HH HoH .ooH oHH .mHH .mHH .mHH HHH .mMH .mmH HHH mum .omm HH me mHH .gHH HHH .OAH ~NOH HH ch .moh HH m mom .Hmm H .omm ~vmmHH .moH .va H moH .va H 005 .omh H own H H m omH .omH .omH .NmH HHH NMH H .OHH ~NMH H m ohH .mmH NNH .mHH on .mom wmA HHH .mmH .hmH >H .HHH .NNH HHH mmH .hom NSH .omH .mom .mHm HHH moA .moH Hem .Hmo HHH mmH .moH HH .moH ~mom >H .oom ~Hom HH Hmm .moH .omH HH oooH .omOH HH mom .oeo H was .ooo H ohH .ohA H .vom .omH H omm ~om0H H mom H A NIom Hlom HIHv MIhm NIN HIN con ueAESZ eHHHOHm HHom IHHom .meHHmoum HAM Mom moo eEmm ecu :0 con meueoHHmeH co mSOHumcHfiueueo ewe emeo come cH ensmHH umeH ecB .AeHHHOHQ come chuH3V eueo esmm ecu co can eueB meHmEem uecu eeuMUHocH Aeneas: cmfion ease eca .meueo uceHeH IMHo co oocuea oHue UHHOUHHmOch ecu HA oeuoeuuxe couH Ho Ema ecu SH mGOHueHHe> .s eHAeB 78 2. The method of extraction proposed by Mehra and Jackson (1960). 3. Analyses were made by the soil survey laboratory using the method of Kilmer (1960). The amounts of free iron oxides extracted by the four methods from the various horizons of this profile are presented in Table 8. Table 8. Percentages of free iron oxides extracted from samples from profile SS9ND-2-l by four methods. Horizon Ap BZl B22 Cca Method Paddick (1948) 0.25 0.19 0.22 0.12 Mehra and Jackson (1960) 1.25 0.71 0.35 0.28 Kilmer (1960) 1.0 1.4 1.1 0.8 Dilute HCl 0.002 0.003 0.005 0.03 This data indicate a great variability in amount, and probably in kind, of iron oxides removed. Each method evidently measures a different group of iron compounds. The methods of Paddick, and Mehra and Jackson, indi- cate the highest percentages of free iron oxides in the Ap horizons, with a gradual decline with depth. This parallels the distribution of organic matter, and suggests that these methods are extracting some of the iron held as organic complexes. If a considerable proportion of the iron were held in the organic form it would explain the low amounts extracted with HCl. 79 The Kilmer method indicates an iron oxide distribution paralleling the clay content, and this suggests that the iron compounds it extracts from the solum are in some way related to the clays. 2. Total iron Total iron was determined on extracts obtained from a HF digestion as proposed by webber and Shives (1953). This method permits the dissolving of silica without the need of a sodium carbonate fusion. The soil material is dissolved in HF and H2804 and evaporated to dryness. The residue is then taken up in HCl. The iron in the extracts was determined colori- metrically, using the orthophenanthroline method proposed by Jackson (1958). For purposes of comparison, the iron content of a few of the extracts was determined by the Fe(SCN)3 procedure as outlined by Jackson (1958). The two methods of determination gave comparable results. D. Mineralogical Analyses 1. Lime-free mechanical analysis A mechanical analysis was made on a lime-free basis on duplicate samples from the first seven horizons of pro— files 37-3, 2-1, and 50-2. This represented a depth of 35 inches in profile 37—3 and 60 inches in the other two profiles. This mechanical analysis was made for purposes of comparison with that made by the Soil Survey Laboratory, P» H 80 in which lime was not removed, and to Obtain samples of the size separates for mineralogical analysis. The standard pipette method of Kilmer and Alexander (1949) was used in these analyses. After the removal of the organic matter, the samples were treated with sufficient 0.1 N in HCl to destroy the amount of carbonates present. It was found, by experience, that acid concentrations of about 6N destroyed some of the clay minerals. The sand fractions from this mechanical analysis were used for subsequent density Separations, quartz determinations, and the determination of per cent shale. After the aliquots for the determination of silt and clay had been obtained, the settling cylinders were re- stirred and allowed to resettle. After the proper time interval, the upper 10 to 20 cm of suspension were siphoned off. This was repeated until essentially all the clay had been removed. Samples of this clay were used for the x-ray characterization of the clay fraction. 2. Mineralogical studies of the fine and very fine sand fractions The fine and very fine sand fractions from the lime- free mechanical analysis were separated into heavy and light fractions using 1, 1, 2, 2 tetrabromoethane, adjusted to S.G. 2.80 with nitrobenzene.. The separation was made on a set of two glass funnels, placed one above the other. The upper funnel was filled with heavy liquid. The sample was added and stirred three times at five minute intervals, 81 then allowed to set for one hour. The heavy minerals, i.e., those with S.G. greater than 2.80, settled into the stem of the funnel, which was closed with a stopcock. After an hour, the stopcock was opened, and the heavy minerals fell into a clean filter paper on the lower funnel. They were then washed with acetone to remove the tetrabromoethane, dried, and weighed. After removing the filter paper containing the heavy minerals, the lower funnel was fitted with a clean filter paper, and the stopcock on the upper funnel opened again, allowing the light minerals to fall into the filter paper. The heavy liquid drained through the filter paper into a clean erlenmyer f1aSk. This liquid had been in contact with nothing but the grains and the filter paper, and could therefore be reused with little or no weight adjustments. A waste flask was then placed beneath the lower funnel, and the remaining light grains were washed from the upper funnel with acetone. The washing continued on the filter paper. The light grains were then dried and stored. (The heavy liquid lost into the waste flaSk can be reclaimed by distilling off the contaminating acetone. It was found that the liquid could be brought back to S. G. of about 2.7 with an aspirator pump, since acetoneboils off easily at room temperature under low pressure.) The heavy minerals were mounted on slides in a synthe— tic resin (araclor, Monsato, R.I. = 1.66). One slide was made from each of the duplicate sand fractions from mechanical tax on. ‘A 'y ll! "(1 (7 82 analysis. In most cases the entire yield of heavy minerals was placed on the slide. Identification of the mineral grains was made using the standard procedures of optical mineralogy and sedimentology. Unknown grains were compared with known samples of the common minerals in the laboratory of Dr. B. T. Sandefur of the M.S.U. Geology Department. The text of Milner (1940) was used as a constant reference during the identification; 300 to 400 grains were identified on each slide. Dryden (1931) suggests 300 as a good compromise between the accuracy of large samples and the convenience of small ones. Any light minerals found on the heavy slides were noted, and corrected for in the final tabulations. A sample of the light fraction, containing at least 300 grains was placed on a slide in a drop of immersion oil of index 1.531, as measured by an Abbe refractometer. Quartz, orthoclase, muscovite, and plagioclases could be identified in this mount, but it was difficult to separate the individual plagioclases. Three hundred to 400 grains were identified on each of these mounts, following the same procedure as was usedvith the heavy fraction. In order to get a separation within the plagioclase series, a second set of mounts were made, using an immersion oil of index 1.543. The only identification made on these mounts was whether or not the indices were all lower than that of the oil. It was assumed that a grain whose indices were all below that of the oil was either orthoclase or a sodic 83 plagioclase such as albite. The grains tabulated as albite represent the difference between the percentage of orthoclase on the first mount, and the percentage of lowjndex minerals on the second mount. The percentage of Na-Ca plagioclases was determined by subtracting the percentage of quartz plus muscovite on the first mount from the percentage of high index minerals on the second mount. Exactly 300 grains were identified on each of the second set of mounts. Any contamination by heavy minerals was noted, and corrected for in the final tabulation. Shale, chert, and other microcrystalline grains were common in the light mineral fractions of all three profiles, but were much less abundant in those from the reddish Forman profile than in those from the Forman or Barnes pro- files. Such particles were also present in the heavy mineral fractions from the Barnes profike. Shale and chert particles were considered as neither light nor heavy minerals, but as a separate category. Multiple species grains were very common, especially in the fine sand fractions, where up to 10 per cent of the grains were composed of more than one mineral. Most of the quartz grains found contaminating the heavy mineral fractions contained intergrowths of biotite or hornblende. Mixed species grains dominated by one large grain were tabulated as one of the species of which the large grain was a member. If there were two grains of about the same size, one of each was tabulated. Very complex grains were 84 included with the shale and chert category. Muscovite presented a problem. Most of it came out in the light fraction. The grains tend to stick to con- tainers, and to each other, and are easily blown about by 'air currents. Therefore, the numbers tabulated are not quantitative expressions of the amount actually present in the sample. 3. Clay Mineralogy Qualitative characterizations of the clay fractions of the first seven horizons from profiles 37—3, 2—1, and 50-2 were made by means of x-ray diffraction. Grim (1953, chapter v) discusses x—ray diffraction as a means of characterizing the clay minerals in a sample of clay. The clay samples used were from the lime-free mechani— cal analysis and were obtained as described in section D1. Samples were prepared for x-ray as follows. A portion of the sodium saturated suspension from the mechani- cal analysis cylinders was placed on a porous plate held in a metal holder. Suction was applied, and a film of clay was deposited on the plate. The platy nature of the clay mineral particles caused them to orient themselves on the plate such that the c (unique) crystallographic axis was perpendicular to the plate. The clay film was leached with three increments of 0.1 N MECli which contained 3% glycerol by volume. The film was then washed with distilled water, air dried, and placed in a dessicator over CaC12. The sample was then x—rayed 85 as a magnesium saturated, glycerol solvated, oriented aggre- gate. After x—raying, the sample was returned to the holder and the Mg on the exchange complex replaced by K, by means of leaching with 0.1 N KCl. The excess KCl was washed from the sample with distilled water, using the AgNO3 test for chlorides to determine when this had been accomplished. The sample was then air-dried, dried at 110 degrees, and x-rayed again as a K saturated aggregate. Following this, the plate was heated to 500 degrees and x—rayed the third time. The x-ray diffraction patterns for the three treatments were then used to identify the clay minerals in the sample. Table 9 gives basal spacings for the common clay minerals when subjected to these three treatments. Table 9. Fir t order basal spacings of common clay minerals, in when treated in different ways. Mg. Sat., K Sat. K Sat. Mineral Glycerol 110O 500° Interstratified 20 plus 10 10 Montmorillonite 18 10 10 Illite 10 10 10 vermiculite 14 10 10 Chlorite l4 l4 l4 Kaolinite 7 7 decomposed The analysis was made on a Norelco x-ray unit with an attached goniometer and automatic recorder. The scanning was done at the rate of 1 degree 2 9 per minute over a range of 2 to 20 degrees 2 0. K alpha radiation was used, from a copper target and a nickel filter. The voltage was 35 Kv, 86 and the current 20 milliamps. One degree diversion and scatter slits and an 0.006 inch receiving slit were used. Other dial settings were: time constant 4 seconds, multiplier 0.8, and scale factor 4. 4. Quartz determination Pollock et. a1. (1954) have discussed the application of x-ray diffraction patterns of silica minerals to studies of soil genesis. Bailey et. a1. (1957) made extensive use of x-ray diffraction in characterizing pleistocene parent materials of Michigan soils. In this study, x—ray diffraction was used to determine the quartz content of the medium plus coarse sand fraction of the three profiles on which the lime- free mechanical analyses were made: and of untreated samples of the entire soil from the major horizons of the six profiles used in the study. The samples were ground to very fine sand size using an agate mortar and pestel. The samples were then ground to silt size with a mechanical mortar and pestal. A mechanical mixer was used to mix the sand or soil sample with the internal standard, which in this case was calcium fluorite, as recommended by Klug and Alexander (1954, pp. 410-438).- A standard curve was constructed, using pure quartz and calcium carbonate as a filler. A Straight line was obtained when the ratio of the heights of the quartz and fluorite peaks were plotted against the percent of quartz. 87 The goniometer was run over the 3.35 A quartz peak and the adjacent 3.16 A fluorite peak three times for each sample. In the case of the total soil, duplicate samples were run from each major horizon, giving six sets of peaks (one quartz and one fluorite per set) per horizon. In the case of the coarse and medium sands, one sample was run from each of the duplicate mechanical analysis samples, again giving six sets of peaks per horizon. The ratio between the heights of the quartz and fluorite peaks for each sample was determined by dividing the total height of the three fluorite peaks by the total height of the three quartz peaks. (A base value for each peak was deducted in computing its height.) The percent quartz corresponding to this ratio was then read off the standard curve. 5. Thin section examination Thin sections were prepared from natural soil aggre- gates by Cal-Brea Incorporated of Brea, California. The plane in which the section was to be made was indicated by tying a fine wire around the ped. Where the orientation of the ped could still be determined, both vertical and horizontal sections were made. Where the orientation was not certain, a single section was made, and assumed to be unoriented. It must be assumed that the thin sections were made according to instructions. They were in good condition and had a uniform thickness of 0.03 mm as indicated by the 88 birefringence of quartz grains (Rogers and Kerr, 1933, p. 77). The slides were systematically examined with a Spencer microscope as described under the section on fabric analyses in Chapter V. CHAPTER V RESULTS AND DISCUSSION A. Introduction The extent to which the observed morphologic differences among the profiles studied, and among the several horizons within each of these profiles, are due to: (a) differences in the original materials, and (b) differences in the nature and rate of the soil forming processes that have acted on these materials, are considered in this chapter. Original material is the material from which the present soil was developed, regardless of its position in the profile. It is not necessarily the same as the C horizon, which is that part of the present soil profile, which at the time of the field investigations, was felt to be composed of material similar to that from which the solum developed. This study was not designed to evaluate the influence of time on soil profile development. It has been assumed that the original materials were deposited during the last advance of the Wisconsin glaciation, and that soil forming processes have been in operation since the withdrawal of that ice sheet from the area. 89 90 B. Uniformity of Original Material 1. Purpose and method of evaluation The differentiation of the original glacial till into the distinct horizons of the Chernozem profile may be the result of soil forming processes controlled by the climate and vegetation of the region. However, the morphologic differences that lexist among these horizons can be entirely attributed to the action of the soil forming processes only if the original materials from which these different horizons developed were similar. It is therefore necessary to evaluate the uniformity of the original material prior to evaluating the extent of soil formation and development. The profiles studied were felt to be developed from uniform materials on the basis of field observation. The subsequent laboratory evaluations served to test the validity of the field evaluation of uniformity. The uniformity of the original materials may be evaluated by comparisons of components of the present soil horizons which have not changed in size or amount during the soil development process. Present differences in such components must be attributed to differences in the original materials. The best criterion for evaluating the textural uniformity of the original materials, is the size distri— bution of the particles of a resistant mineral. In 'this study, quartz was the only such mineral for which a 91 size distribution was obtained over a range of particle sizes. Similar data for garnet were obtained in two size fractions, fine sand and very fine sand. The best criteria of mineralogical uniformity of the original materials are the ratios between the proportions of two or more resistant mineral species. Quartz and garnet are the only two resistant minerals present in sufficient quantity in the profiles studied to permit calculations of reasonably accurate ratios of this sort. 2. Textural uniformity a. Textural uniformity as evaluated by the size distribution of resistant minerals. Comparisons of the particle size distributions of resistant minerals among the several horizons of a soil profile are the most reliable means of evaluating the textural uniformity of the original materials of these horizons. In the profiles studied, quartz was the only resistant mineral present in sufficient quantity to be precisely measured in several size fractions. Quartz determinations were made on the very fine sand, fine sand, and combined medium and coarse sand fractions. The percentages of all quartz particles 0.05 to 1.0 mm. in diameter in the three size fractions very fine sand (0.05 to 0.10 mm.), fine sand (0.10 to 0.25 mm.), and medium to coarse sand (0.25 to 1.0 mm.) was therefore used as the primary criterion for evaluating the textural 92 uniformity of the original materials. Part of the quartz in the medium and coarse sand fractions (as determined by x—ray diffraction), occurred as components of shale and chert particles. The fact that the numbers of shale and chert particles increase appreciably with depth, indicates that such particles are subject to breakdown by weathering in the upper layers. The quartz included in shale and chert is therefore not immune to size changes, and was therefore not included in this evaluation. Shale and chert were also excluded when determining the relative abundance of the various sand fractions. The percentage of quartz grains 0.05 to 1.0 mm. in diameter in each of the three size classes is given in Table 10. A difference in original materials, as indicated by the quartz size distribution, is indicated by a change in the Roman numeral in the column headed ?texture of material." The same Roman numeral is used for the same texture of material each time it occurs in the profile. Each profile is treated independently in this table. The size distribution of garnet was also determined, but over a narrower size range. Table 10 also includes the percentages of garnet 0.05 to 0.25 mm. in diameter in the 0.05 to 0.10 and 0.10 to 0.25 mm. size classes. Roman numerals are again used to indicate textural differences or similarities as indicated by garnet size distribution. Garnet size distribution is based on counting Of'nfineral grains in only the very fine and fine sand size H as Hm H «.mm o.om o.oH so H ow em H m.mm m.w~ m.oH mo HH em me H v.mm m.mm m.mH mo HH He om HHIH o.mm o.mm «.mH moo HH em as H m.~m m.Hm m.mH mmm HH so om H s.s¢ o.Hm o.o~ Ham H No mm H m.mm «.mm o.mH me Amecuemv mlom eHHHOHm H me am H m.sm o.mm o.o~ «mo HHH mo em HHIH H.sm o.m~ m.mm Ame H me mm H o.oe o.om e.m~ moo H me mm H o.He m.mm H.om moo HH mm mm H o.¢o m.om m.m~ «mm H mm me H m.me m.Hm m.mm Ham H mm we H o.mm o.mm ¢.m~ as 3 Homeuos rmHooeHo Hum «HHHoum 9 HH oo ow HH o.om m.om m.mH «o H No mm HHH m.me m.m~ o.m~ moo H as om HH m.em o.om o.mH mm HH Hm me H m.me e.Hm m.vm «mm H He mm H m.om H.mm s.m~ Hmm H mo mm H m.mm m.mm m.mm Hm H Rm mm H o.ov m.mm m.om me AceEHomv mlhm eHHHOHm OH.OImo.o mm.OIOH.o .EE mm.o ou mo.o uecumm Mo K o.HImm.o mm.OI0H.o OH.OImo.o GONHHom .meo eNHm .EE o.H ou no.0 .Nuneso NO X uecHe co oemeA HeHHeueE Ho eHDuxeB .umHo eNHm NuHmoo co cemec HeHHeueE Ho enouxee .mGOHuueHH ccem eeHH uueco oce eAecm ecu CH uecuem one Nuneao Ho mcoHuSAHHuch eNHn ecu HA oeueoHccH me mHeHHeueE HeCHmHHo Ho huHEHOHHco Honouxee .OH eHQmB 94 fractions. It is therefore used in evaluating the overall textural uniformity only when a borderline case is indicated by the quartz size distribution. Quartz size distribution indicates texturally uniform original materials down through the B22 horizon in Forman profile 37-3; below which a change is indicated between each horizon. The lower horizons contain relatively more quartz in the medium and coarse sand fractions. In the B3 and CZ horizons this is compen- sated for by lower proportions in the very fine sand fraction, and in the Cca horizon by lower proportions in the fine sand fraction. The most striking horizon to horizon difference is that between the B22 and the B3 horizons. The garnet size distribution indicates a somewhat different pattern than that indicated by the quartz size distribution. The proportion of garnet in the very fine sand fraction is higher in the 321 and C2 horizons than in the rest of the profile. In reddish Forman profile 2—1, textural uniformity is indicated throughout the profile on the basis of quartz size distribution, although the proportion of very fine sand quartz is higher in the C21 horizon than in the horizons above and below. For this reason, the C22 horizon is assumed to represent the original material of this profile for the purposes of the calculations in section K. The possible disconformity of the C21 horizon is substantiated by the garnet size distribution. This horizon contains a much higher proportion of very fine sand size garnet o. u- M. f) (I) f\ 95 than the horizons above or below. There is an abnormally high proportion of fine sand size garnet in the B22 horizon. The quartz size distribution indicates texturally uniform original materials throughout Barnes profile 50-2. There is a possible disconformity in the Cca horizon, in which there is a relatively high proportion of medium and coarse sand size quartz, and a low proportion of very fine sand size quartz. There is a slightly higher percentage of fine sand size garnet than very fine sand size in the Ap, C3 and C4 horizons. In the remainder of the profile, a considerably higher percentage of the garnet occurs in the very fine sand size fraction. b. Sand size distribution as a criteria of textural uniformity Quartz size distribution, as outlined in the above section, is the most reliable means of evaluating textural uniformity. However,.its determination requires several analyses which are too time consuming to be made on all the profiles on which an evaluation of textural uniformity is desired. It is therefore advantageous to find other criteria of uniformity, that are more simple to determine, and which are related to the more reliable quartz size distribution. Particle size distribution analyses were made on all the profiles used in this study. The sand size distri- bution was felt to be the best criterion of textural uniformity 96 in the profiles on which detailed mineralogical analyses were not made. Since the sand size distribution was also known in the profiles on which quartz size distribution was determined, it was possible to compare the two criteria of uniformity. In addition, carbonate-free particle size distribution analyses were made on the same profiles. Therefore carbonate-free sand size distribution could also, be evaluated as a criterion of textural uniformity. The textural uniformity of materials as indicated by the three criteria: quartz size distribution (from Table 10), sand size distribution (from Table 17), and carbonate—free sand size distribution (from Table 15) are compared in Table 11. The data in Table 11 indicates that textural dif- ferences in original materials indicated by the size distribution of carbonate-free sand agrees more closely with those indicated by the size distribution of quartz, than do those indicated by the size distribution of total sand. This is to be expected, since the mineralogical analyses on which the quartz size distribution is based, were made on the sand fractions from the carbonate-free mechanical analyses which yielded the sand size distribution in Table 15. The size distributions of total sand were determined on samples kept separate since the time of sampling, and not treated to remove carbonates. Total sand size distribution is less reliable than quartz size distribution as a criterion of textural uniformity 97 Table 11. Textural uniformity as indicated by the size distributions of quartz, total sand, and carbonate- free sand. Texture of original material as indicated Profile, soil, by the size distribution of: and horizon Quartz Total Carbonate—free sand sand 37—3 Forman Ap I I I Bl I I I B21 I I I B22 I I I B3 II I II Cca III I II C2 II I I C3 I C4 I C5 I 2-1 reddish Forman Ap I I I B21 I I I B22 I I I Cca I I I Ccs I I I ,C21 I I II C22 I I I 50-2 Barnes Ap I I I 321 I II I B22 I II I Cca I-II II I C2 I II I C3 I II I C4 I II I because of the presence of weatherable mineral and rock fragments in the sand fractions. These include pyroxenes, amphiboles, shale, chert, calcium carbonate particles, and igneous grains or fragments. Such grains may have been reduced in size during the process of soil formation in some horizons, thus changing the sand size distribution. 98 In spite of these difficulties, the sand size distribution is more stable than most other properties determined in routine analyses. It is therefore probably the best criterion of textural uniformity in profiles on which quartz determinations were not made. The textural uniformity of materials for ten profiles, based on only the sand size distribution (from Table 17) is presented in Table 12. This evaluation is most reliable in the reddish Forman profiles, which contain relatively little shale, and is least reliable in the very shaley Barnes profiles, 50-1 and 50-2. This table includes four previously sampled profiles in addition to those sampled in connection with this study. Those four profiles illustrate certain textural relationships not evident in the other six profiles. The sand size distributions indicate textural uniformity of original materials throughout Forman profiles 37-3 and 41-2, reddish Forman profile 2-1, and Barnes profile 46-1. There is uniformity exclusive of the Ap horizon in reddish Forman profile 2-2 and Barnes profile 50—2. In the latter two profiles, the finer sand fractions are relatively more abundant in the Ap horizons than in the rest of the profiles. This may be due to a breakdown of sand grains by frost action. However, the same tendency is not evident in the other profiles, which are equally susceptible to frost action. 99 Table 12. Textural uniformity of original materials in ten profiles based on sand size distribution. SS9ND37-3 SS9ND4l—l SS6ND4l-2 SS6ND4l-5 Texture Texture Texture Texture of of of of Hor. material Hor. material Hor. material Hor. material Ap I Ap I Ap I Al I Bl I B21 I B2 I B21 I B21 I B22 I B3 I B22 II B22 I Cca II Ccal I B3ca I B3 I C2 II Cca2 I Cca III Cca I C3 II Cca3 I C1 III C2 I Ccs III C I C2 III CB I C5 III C4 I C6 II C5 I Reddish Forman Profiles SS9ND2-l SS9ND2-2 Texture of Texture of Horizon material Horizon material Ap I Ap I B21 I 321 II B22 I 322 II Cca I Cca-cs II Ccs I C21 II C21 I C22 II C22 I Barnes Profiles S59ND50-1 S59ND50-2 SSBND46-1 853ND2-l Texture Texture Texture Texture of of of of Hor. material Hor. material Hor. material Hor. material Ap I Ap I Alp I Alp I B21 II B21 II B2 I A12 II B22 III B22 II Ccal I BZ II Cca II Cca II Cca2 I Cca II C21 II C2 II C1 I Ccsl II C22 II C3 II C2 I Ccs2 I Ccs II C4 II C3 I Cl I C2 I 100 The original materials of Forman profiles 41-1 and 41-5 are obviously stratified. In both, there is relatively more of the finer sand fractions in the non-calcareous horizons, as compared with the C horizons. This may be caused at least in part, by the presence of numerous carbonate concretions in the Cca and C horizons, although this was not true in profile 37-3, in which these concretions are equally abundant. In addition, the middle portion of the C horizon of profile 41-1 contains higher percentages of fine and very fine sand (and also of silt) than the horizons above and below. This material is likely wind and/or water modified till. In Barnes profile 50—1, stratification is confined to the solum. There are higher percentages of the finer sand fractions in the B22 horizon than in the horizons above and below. The sand size distribution is uniform through the C horizon, and is very similar to that in the B21 horizon. Barnes profile SSBNDZ-l is stratified, with higher proportions of medium and coarse sand in the A and lower C horizons than in the B or upper C horizons. In summary, the size distributions of quartz, garnet, and total sand indicate the presence of some stratification in some of the profiles selected as non-stratified in the field. Genetically significant differences in particle size distribution evidently occur within materials assigned a uniform texture class designation in the field. 101 In the profiles where textural differences existed in the original materials, some of the present textural differences can be assumed to be inherited from them. In the profiles in which the original material appears to have been texturally uniform, the present textural differences can be assumed to have originated during the process of soil development. 3. Mineralogical uniformity of original materials Mineralogical analyses were made on only three profiles: profile 37-3 representing the Forman soils, profile 2—1 representing the reddish Forman soils, and profile 50-2 representing the Barnes soils. Mineralogical uniformity will be evaluated by means of comparisons of the ratios of quartz to garnet in the various horizons. These are the two resistant minerals present in sufficient amounts so as to be measured fairly accurately. The ratio of fine plus very fine sand size quartz to fine plus very fine sand garnet is presented in Table 13. The mineralogy. of the original materials is indicated with Roman numerals, as was done with textures in Tables 10 to 12. The ratios are calculated on the basis of the shale and chert free sand fractions. This table (13) also includes a composite of textural and mineralogical uniformity, based on quartz size distribution and the quartz-garnet ratios. Additional variability is indicated when garnet size distribution is also included in the composite evaluation of uniformity. d u. a»... v. :Zflvnu five. nu. I....~.I,v.\, ....-.-a—a _..I. ~.v...v‘..n,.t— \rd..-AI..i-L-t. pi: HHH-.4HI. HII~.I- I.» «J \A.~ m.e--4fidih-.-d . I}; .zrufio,‘ . ..... ._ F...uH~..Ao~.IJIIH.UH~m.:.~ Harare H.....I.~.~Huvfiflv~ rU . . , I N - .Ivfllfivaflu H nIIdILJvHHMZ t Q} ~ LIV VA.“ CNN» 102 H H H H H so so H H H H H mo mo HHH HH H H H me No HHH HH H H H «H moo HHH HH H H H os «mm HH HH H H H on Hmm H H H H H as do Amooommv muom oHHeouo HH H HH H HH mmH «no >H HHH HH H HH NmH Hmo HH H HH H HH moH moo H H H H H HNH moo HHH HH H H H ooH «mm HH H HH H HH omH Ham H H H H H mmH do Acmeuom cmHoooHv Hum oHHHouo H> HH > HH H . emH .uo > H >H HHH HH omH moo >H H HHH HH HH mmH mm HHH HH H H H emH mam HH H HH H HH eoH Ham HH H HH H HH moH Hm H H H . H H mHH do Aomsoomc musm oHHeooo oeoSHecH .umHo SOHquHHumHo mmoHeHecHE enouxeu Ho uecuem\NuHesU uecuem mm> o H cONHHom eNHm uecnmm eNHm uecHew o eHouxeu SOHquHHumHo AeHHeueE mo Nuueso mm> o H mmHoeHecHE ode euHmomEoo eNHm uuueso hmOHeHeCHS OHueH enouxeu euHmomEoo .HuHEHochs HeeHmOHeHeCHE use Hensuxeu euHmomEoo use aoHueH uecnmmINuHmoo co semen .mHMHHeueE HechHHo Ho HuHEHochs HeononuecHz .mA eHcme 103 There is considerable variability in the mineralogy of the original materials of profile 37-3, Forman. Garnet is more abundant relative to quartz in the Ap, B22, and C2 horizons. The differences in mineralogy do not in all cases coincide with textural differences. This indicates that mineralogy and texture vary independently in this profile. In reddish Forman profile 2-1, garnet is more abundant relative to quartz in the Ap, B22, and Cca horizons. The indicated differences in this profile are not clear cut, and are probably not great enough to clearly establish the existence of two distinct types of original material. Mineralogy is more variable than texture, and varies independently from it. Complete mineralogical and textural uniformity are indicated in Barnes profile 50-2. This is true only if the large numbers of shale and chertparticles are taken into account in computing the percentages of the minerals, and the size distribution of the sand. A possible exception is the B21 horizon where the silt content is low compared with that in the remainder of the profile. C. Textural Morphology of Profiles 1. Data from mechanical analyses Mechanical analyses were made on acid treated samples from three profiles. The acid treatment destroyed the carbonate particles regardless of their 104 size, and the resultant size distribution is supposedly that of non-carbonate mineral particles. The particle size distributions obtained on the acid treated samples are presented in Table 14. The distribution of sand among the five sand fractions, as determined in this analysis, is shown in Table 15. The particle size distributions for ten profiles, as determined by the routine mechanical analysis procedure of the soil survey laboratory, in which carbonates are not removed, are presented in Table 16. The sand size distributions based on these analyses are shown in Table 17. Tables 16 and 17 include data from four profiles sampled and analyzed prior to this study. These are among the profiles examinedin 1958, and illustrate textural relationships not present among the six profiles sampled in 1959. In the tables to follow, each horizon is assigned a Roman numeral indicative of its probable original material; considering both texture and mineralogy. These do not coincide with those in Table 13, and are the result of a more liberal interpretation of the requirements for assumed uniformity. This liberalization was necessary in order to make some of the calculations to follow. It appears that the till is quite heterogeneous and for this reason, strict requirements of uniformity cannot be adhered to. 105 Table 14. Particle size distribution in three profiles, based on the mechanical analysis of acid treated samples. Horizon Percentage of size fractions V.Co.S. Co.S. Med.S F.S. V.F.S. Sand Silt Clay Text. Profile 37—3 (Forman) I Ap 1.5 3.2 3.9 9.1 8.8 26.5 43.5 30.0 CL II B1 1.0 2.4 2.7 6.5 7.7 20.3 39.1 40.6 C-CL II B21 1.4 3.2 3.2 6.8 9.6 24.2 33.5 42.2 C II BBca 1.4 2.3 2.1 4.9 8.6 19.3 36.5 44.2 C II Cca 1.6 2.1 2.2 5.1 8.4 19.4 40.1 40.5 C-CL I C2 2.1 3.5 3.7 8.6 9.2 27.1 43.4 29.5 CL Profile 2—1 (reddish Forman) I Ap 2.3 5.0 6.5 17.0 15.0 45.8 30.0 24.2 L II B21 2.3 4.8 6.0 15.1 15.0 43.2 30.5 26.3 L I 322 3.0 5.2 6.6 15.5 15.3 45.6 28.8 25.6 L I Cca 2.6 5.1 6.1 15.9 15.5 45.2 30.0 24.8 L II Ccs 2.4 5.0 6.0 16.0 17.5 46.9 29.3 23.8 L II C22 3.2 5.2 7.0 15.8 16.9 48.1 27.9 24.0 L Profile 50-2 (Barnes) I Ap 4.4 8.9 6.1 12.1 9.8 41.3 38.5 20.2 L II B21 4.1 8.1 5.1 12.0 9.2 38.5 31.1 30.4 CL I Cca 5.3 7.6 5.0 11.3 8.9 38.1 40.3 21.6 L I C2 6.0 9.4 6.8 13.3 14.5 50.0 32.9 17.1 L I C3 6.3 10.2 8.4 15.6 15.0 55.4 27.6 17.0 L I C4 6.2 10.3 7.3 14.2 11.5 49.5 31.7 18.8 L 106 Table 15. Sand size distribution, based on the mechanical analysis of acid treated samples. Percentage of sand in Size fractions Horizon V.Co.S. Co.S. Med. 8. F.S. V.F.S. Profile 37-3 (Forman) I Ap 5.7 12.3 14.4 34.5 33.1 II B1 5.1 11.5 13.7 31.9 37.8 II B21 5.0 13.0 14.2 30.8 36.0 I B22 9.8 13.5 13.1 29.4 34.2 II B3 7.5 11.8 10.8 25.4 44.5 II Cca 8.2 10.9 11.2 26.4 43.3 I C2 7.7 13.0 13.7 32.0 33.6 Profile 2-1 (reddish Forman) I Ap 5.0 10.9 14.2 37.4 32.5 II B21 5.2 11.1 14.0 35.3 34.4 I 322 6.5 11.4 13.3 34.8 34.0 I Cca 5.7 11.4 13.5 35.2 34.2 II Ccs 5.3 10.9 14.4 34.7 34.7 II C21 5.6 12.6 14.5 30.2 37.1 II C22 6.6 10.9 14.4 33.0 35.1 Profile 50-2 (Barnes) I Ap 10.5 21.5 14.8 29.3 23.9 II B21 9.5 20.5 14.4 31.7 23.9 I B22 11.2 21.6 14.5 31.5 21.2 I Cca 13.9 20.0 13.2 30.0 22.9 I C2 12.0 18.8 13.6 26.6 29.0 I C3 11.4 18.6 15.2 28.2 26.6 I C4 14.2 21.6 14.5 27.9 21.8 107 A 0.00 m.Hv 0.mm h.0 0.HH 0.0 0.0 H.0 00I00 00 A 0.00 b.0o v.00 b.0 0.0 0.m 0.0 0.H omIHo mU AHm ¢.h0 0.0m 0.0H o.m 0.0 S.H 0.H 0.0 HoImm moo AU 0.o0 0.om 0.00 0.0 c.0H 0.0 0.0 0.0 00I00 mu AU o.h0 o.mm 0.00 0.0 o.MH 0.0 0.0 o.m 00Io0 00 AU ¢.Hm 0.0m c.0m H.0 m.HA 5.0 0.0 m.m VNIMH e00 AU A.¢m n.0m 0.00 0.0 0.HH 0.m 0.0 0.H MHI0 000 AU 0.mm 0.00 H.Hm 0.0 o.HH m.o 0.o 0.0 0Im H00 AU p.00 o.hm 0.00 0.0 m.HH o.o 0.v 0.0 0I0 mm AceEHomv HIHoQZ0mm eHHHOHm A h.m0 0.0o 5.50 H.0 0.0 o.m 0.0 0.0 00Imm mo AHO 0.00 0.00 H.00 0.0 0.0 0.0 h.0 0.H mmlmo cu A0 0.00 0.0g 0.H0 o.b m.h 0.0 H.m H.H mvlmm 00 AU 0.0m 0.00 0.m0 0.h m.o 0.0 m.m o.0 mmI00 00 AU 0.0m c.0o 0.00 m.o 0.o 0.0 0.0 0.H 00I00 e00 AU 0.0m 0.00 0.H0 0.0 0.b 0.0 0.0 o.H 00ISH mm 0 m.H¢ 0.0m v.00 0.0 H.b 0.0 h.0 H.H hHIMH 000 AOIU A.Ov 0.om 0.00 o.h 0.0 H.m h.0 0.0 0HI0 H00 A0 0.00 0.00 0.H0 0.0 m.h 0.0 .0.0 S.H 0I0 H0 AU 0.om S.Ho m.¢0 m.h 0.0 m.m H.m m.H 0I0 04 ACeEHomv MlthZ0mm eHHHoum .uxee HeAU uHHm 0Com 00> 0 m 0 0e: moo mou> cuoem CONHHom mCOHuoeHH eNHm CH HeHHeueE HHom Ho e0euCeeHem .0eHOHumeo uOC eHe meueCOAHeU ceHc3 CH eHCUeUOHQ e 0CHmC “SuoueHOAeA >e>H50 HHom CHOUCHA ecu >3 eer memmHeCm HMUHCcheE C0 cemmc .meHHHOHQ Ceu CH COHuCAHHumHo eNHm eHoHuHem .0H eAAeB 108 AUm AUm I4 AIA A HUI—IUI—‘lI—lI—‘l AU AU AU AU AU AU AU AU AU AU AU o.H0 0.00 H.oo 0.0H 0.0H 0.0 0.00 0.00 0.00 0.0H 0.0H 0.0 0.00 0.H0 0.oe 0.HH 0.0H 0.0 0.00 0.00 H.0o 0.0H 0.0H 0.0 0.00 0.00 0.00 0.HH 0.0H 0.0 0.H0 0.00 0.00 0.0H 0.oH 0.0 AquHHm> cmHooem .Cmsuomv 0I0szmm oHHuoum H.00 0.00 e.Ho 0.0H 0.0H 0.0 0.00 0.00 0.00 0.0H 0.0H 0.0 0.00 0.00 0.00 0.HH 0.0H 0.0 0.00 H.00 0.00 o.HH o.eH 0.o 0.00 0.H0 0.0a H.0H 0.0H 0.0 0.00 0.00 0.0o 0.0H 0.0H 0.0 0.00 0.00 0.00 0.0H 0.0H v.0 LoomHom> cmHooom .Cmanomv HI002000 oHHmonm 0.00 0.00 0.00 0.0 0.0H 0.0 0.00 0.00 0.00 0.0 0.0H o.0 0.00 0.00 0.00 0.0 0.0H 0.0 0.00 H.00 0.00 H.HH 0.HH 0.0 0.00 0.00 0.00 0.oH 0.0H 0.4 0.00 0.00 0.00 0.0H 0.0H 0.0 0.00 H.0o 0.00 0.0 0.0H H.o Homeuomv A0000 0IH002000 oHHuonm 0.00 0.00 0.00 H.0H 0.HH 0. 0.00 0.00 o.00 0.0 o.HH 0.0 0.00 v.00 H.00 0.0 0.0H 0.0 0.00 H.00 0.00 0.0H 0.HH 0.0 0.00 H.00 0.00 0.0H 0.HH 0.0 0.00 0.H0 0.00 H.0H 0.HH 0.0 0.H0 0.00 0.00 0.0 0.0A 0.0 AcmSHoEVAemmv 0IH002000 oHHeoum O‘OOO‘LOOW LOOKOLOLOLO momHmm O MMNMNN mOWI-IMLOFLO mound-odd I‘LDI‘O‘Nfi'I-l MNNNMNN r-INr-lfi‘d‘lnln 00inl\0I00 00IhH bHer ¢HI0 00U HNU melmeu 00m H0m 00 NNU HNU woo woo 00m HNm 00 0o H0 000 mo0m 000 H00 0000 0000 Hmoo mm 00 mHe 109 H 0.00 0.00 0.00 0.0 0.0H 0.0 4.0 0.0 00-00 0o 0 0.00 0.00 0.00 H.0H 0.0H 0.0 0.0 4.0 00-H4 0o 00 0.00 0.04 0.00 0.0 0.0 0.4 0.0 0.H H4-00 Ho Ho 4.00 0.00 H.00 0.0 0.HH 0.0 0.0 0.4 00-H0 0moo 00 0.00 0.00 0.00 0.0 0.0H 0.0 0.0 0.0 H0-0H Hmoo 0 0.00 0.00 0.04 0.0H 0.0H 0.0 0.0 0.0 0H-0 .00 00 0.00 0.00 0.40 0.0 0.0H 0.0 0.4 0.0 0-0 6H0 Amocommv A0000 H-04CZ000 oHHHouo H 4.00 0.00 4.04 0.0 4.0H 0.0 0.0 0.0 00-04 40 H 0.0H 0.00 0.04 0.0H 0.0H 0.0 H.0 0.4 04-00 00 0 0.00 0.00 4.00 0.0 0.0H 0.0 0.0 0.4 00-00 00 Ho H.H0 4.00 0.00 0.0 0.0H 0.4 0.0 0.4 00-0H moo Ho-H 0.00 0.00 0.00 0.0 4.0H 0.0 0.0 4.0 0H-HH 000 00 0.00 0.00 0.00 0.0 0.0H 0.0 0.0 0.0 HH-m H00 0 0.00 0.00 0.04 0.0H 0.4H H.0 0.0 0.0 0-0 00 Ammonmmv 0-00o2000 oHHuoum H 0.00 0.00 0.04 0.0 0.0H H.0 0.0 0.4 00-H0 moo H 0.H0 0.00 0.00 0.0 0.0H 0.0 H.0 0.0 H0-00 000 H 0.00 0.00 0.00 0.0 0.0H 0.0 0.0 0.0 00-00 H00 00 0.00 0.00 0.00 0.0 0.0 0.4 0.0 0.4 00-0H moo H 0.00 0.00 4.00 0.0H 0.4H 4.0 0.0 0.H 0H-0H 000 000 0.00 0.00 0.04 0.0 0.0H 4.0H 0.0 0.H 0H-0 H00 0 0.40 4.00 4.04 0.0 0.0H 0.0 0.0 0.4 0-0 00 Amooummo H-0002000 oHHeona .oxoe 00Ho oHHm 0000 00> 0 m 0 0oz moo moo> 00000 couHHoe mCOHuUeHH eNHm CH HeHHeueE HHom Ho e0euCeoHem .UeCCHuCOUII.0H eHAeB llO u—‘ln-Jt-Jn-l-Jr-‘l-Jo—‘l N.ma m.NN m.mN N.mm H.0m H.mm m.mm m.HN H.mm o.mm H.mv H.m¢ m.mm m.hm m.mm m.¢m 5.5% N.mm o.mm b.Hm o.¢m H.mm N.bm N.¢¢ 0 Fl omoomxomo H H r-lr-ld‘fl'fl‘mO‘Ln O H N.®H h.NH N.m m.oa h.HH m.ma m.ma ¢.ma 00000000 A0000 0-002000 0000000 \ommmdwrxom O O O MNNMNMMQ' hmmmvvom fimmammmm [\Hoowmma mmommmmb oolhfi hvlmm mmlam HMIflN flNImH mHIm mlm 0U 00 0000 0000 MUD 00 000 000 lll Table 17. Sand size distribution in 10 profiles, based on mechanical analyses by the Lincoln Soil Survey Laboratory. Horizons and depths are as in Table 16. V.Co. Co. Med. Fine V.Fine V.Co. Co. Med. Fine. V.Fine Profile S59ND37-3 (Forman) Profile S59ND4l—l (Forman) 6.2 12.7 13.5 36.7 30.9 10.8 14.7 13.5 34.6 26.4 8.0 11.3 13.2 35.0 32.5 7.1 13.5 13.8 36.7 28.9 2.7 12.3 14.1 37.3 33.6 5.5 13.0 13.0 37.6 30.9 5.4 13.2 14.2 34.8 32.4 10.2 15.4 14.5 34.9 25.0 6.6 13.7 13.7 33.9 32.1 9.6 17.6 16.1 34.6 22.1 4.8 12.1 12.6 35.1 35.4 7.1 17.2 16.0 35.6 24.1 11.4 14.8 12.3 31.8 29.7 5.7 12.9 12.1 28.6 40.7 5.1 14.2 11.9 33.5 35.3 5.6 12.7 12.7 34.8 34.2 8.0 13.5 11.5 34.0 33.0 6.2 15.3 14.8 35.1 28.6 9.4 14.4 13.3 33.6 29.3 Profile $56ND41—2 (Forman) Profile S56ND4l-5 (Forman) 9.2 17.2 12.9 31.5 29.2 4.9 13.6 14.3 35.0 32.2 6.4 17.2 16.4 31.9 28.1 5.9 11.2 15.9 40.0 27.1 8.9 15.1 14.5 32.0 29.5 4.2 9.3 11.1 37.6 37.8 11.3 15.8 15.3 30.3 27.3 11.8 13.2 12.3 31.4' 31.3 12.3 17.6 15.8 28.8 25.5 13.9 15.6 15.4 30.6 24.5 9.4 17.1 16.8 30.5 26.2 16.4 14.7 15.0 30.0 23.9 10.8 17.2 15.9 30.3 25.8 14.6 15.4 15.6 29.6 24.8 . Profile SS9ND2-1 (Forman,reddish) Profile SS9ND2-2(Forman,reddish) 7.8 12.2 13.4 39.5 27.1 8.7 14.7 14.9 36.3 25.4 6.5 12.0 13.9 41.0 31.3 6.6 13.2 15.8 39.9 24.5 6.3 11.9 13.1 38.0 30.7 5.3 12.7 14.9 40.4 26.7 7.1 10.6 11.5 35.4 28.0 6.9 13.2 15.2 38.0 26.7 8.3 11.9 12.2 37.4 30.1 5.4 12.9 13.8 38.3 29.6 5.9 11.6 12.8 38.7 31.3 5.2 13.4 13.6 38.3 29.5 5.1 '11.1 12. 39.8 1.4 _ Profile SS9ND50-l (Barnes Profile 859ND50-2 (Barnes) 11.9 15.2 14.9 34.2 23.8 11.5 19.3 15.5 31.9 21.8 3.4 15.9 22.1 40.9 17.7 7.8 15.7 15.7 36.8 24.0 4.4 13.0 14.1 36.5 32.0 9.0 16.5 15.6 35.6 23.3 14.3 17.4 13.7 29.3 25.3 12.9 17.0 14.6 32.2 23.3 14.8 20.3 13.8 28.1 23.1 10.6 19.2 14.6 33.0 22.6 9.3 17.9 15.6 32.2 25.0 9.5 17.1 15.4 32.8 25.2 12.0 18.2 15.2 31.3 23.3 13.4 17.2 14.9 31.6 22.9 Profile S53ND46-1 (Barnes) Profile 853ND2-1 (Barnes) 7.3 13.4 15.1 35.6 28.6 8.1 15.2 16.7 37.1 22.9 8.9 13.3 16.0 38.1 23.7 77.5 13.8 15.8 35.7 27.2 8.9 15.3 15.8 35.6 24.4 6.6 12.9 14.6 34.1 31.8 11.9 16.6 15.5 33.0 23.0 11.2 14.7 15.0 34.4 24.7 6.6 15.1 15.4, 34.7 28.2 9.1 15.1 15.1 34.2 26.5 8.7 15.7 15.3' 34.6 25.7 12.4 16.9 15.5 31.8 23.4 10.2 14.9 15.5 34.0 25.4 9.9 17.1 16.5 33.2 23.3 9.8 17.0 17.3 33.9 22.0 I 112 2. Discussion a. Nature and reliability of the data The mechanical analysis data from the Soil Survey Laboratory (Table 10), is based on the analysis of a single sample from each horizon. The analyses were made by a well tested and standardized procedure. The laboratory prefers to analyze single samples from duplicate profiles, rather than analyze duplicate samples from a single profile. The analyses of the acid treated samples were made on duplicate samples from each horizon of the three profiles. The procedure was not as well standardized as that used by the soil survey laboratory. Difficulty was encountered in dispersing some of the acid treated samples and some of the analyses had to be repeated several times. b. Comparison of the results of the mechanical analyses of acid treated and untreated samples The two mechanical analyses were made on samples that were separated since the time of field sampling. Some variation in the particle size distribution of the two samples is to be expected. These differences should, however, be small in the non—calcareous A and B horizons. This, in general, is the case. The difference in clay content as determined by the two methods in the Ap horizon of reddish Forman profile 2—1, is enough to make the B:A clay ratio over 1.20 in one case, and under 1.20 in the other. In general, the differences were sufficiently small to be -A‘. ‘_ .0-.. I! 4. ‘\ .._,_ J '4'; ll) f_) 113 explained by the fact that the analyses were made on separate samples. Rather large differences were expected and obtained in the calcareous Cca and C horizons, where carbonate particles of various sizes were destroyed by the acid treat— ment. c. Evaluation of texture Textural class names will be used infrequently in this discussion because of the large number of horizons whose texture is on. or very close to. the loam-clay loam boundary. Most of the significant textural differences are those within, rather than between, textural classes. Percentage of clay will be used in place of textural class as a measure of the texture of the profiles to be discussed. d. Textural relationships 1) Vertical clay distribution The vertical distribution of clay in the profile is an important criterion of soil classification. The proposed SYStem of classification (7th approximation) proposes the Separation of medium textured soils on the basis of BzA Clay ratio at the great group level. If the B:A clay ratio exceeds 1.20, the B horizon can be considered as an argillic horizon (provided it meets the other requirements). Mollisols having argillic horizons are separated from those lacking then“ There are three general patterns of clay distribution evidfiént among the ten profiles for which particle size distribution 114 data are presented in Table 16. The first of these patterns is one of generally high clay content throughout the profile, with relatively small horizon to horizon differences. The B horizonscfifprofiles with this distribution barely qualify as argillic horizons. Although they contain high percentages of clay, they are hardly enough more clayey than the A horizons to qualify. This pattern of clay distribution is typical of the Forman soils. The second pattern is one of rather low percentages of clay in the A and C horizons, with B horizons that contain considerably higher percentages of clay. The B horizons of such profiles can easily qualify as argillic horizons if they can be shown to be due to the illuviation of clay. This pattern of clay distribution occurs in the reddish Forman profiles, and in some Barnes profiles. The third pattern is one of relatively low clay content throughout the profile, with only small horizon to horizon differences. The B horizons contain little more clay, percentagewise, than the A or C horizons, and thus do not qualify as argillic horizons. This pattern is common in the Barnes soils. Information regarding the clay distribution in the ten profiles under consideration is presented in Table 18. The BzA and B:C clay ratios, and the type of clay distri- bution are indicated for each profile. The portion of the 115 B horizon containing the highest percentage of clay was used in calculating the B:A clay ratios, as well as the B:C ratios. The portion of the C horizon most similar texturally to the assumed original material of the B horizon, was used in calculating the B:C clay ratios. Table 18. Vertical clay distribution relationships in ten profiles. Pattern of %.c1ay in B % clay in B Profile Series No. clay dist. % clay in A. % clay in C 37-3 Forman 1 1.22 1.21* 41—1 Forman 1 1.05 0.97 41-2 Forman 1 1.01 1.02* 41-5 Forman 1 1.07 1.01 2-1 reddish Forman 2 1.25 1.25 2-2 reddish Forman 2 1.31 1.22 50-1 Barnes 2 1.25 1.21 50-2 Barnes 2 1.50 1.35* 46-1 Barnes 3 0.97 0.97* 2-1 (1953) Barnes 3 1.08 0.92* *Percentage of clay-size carbonates estimated. The clay content of the C horizons as presented in Table 16, includes carbonate particles of clay size. Since the B horizons are carbonate—free, no such particles are present in the B horizons. Therefore, the percentage of clay from the C horizons used in calculating these ratios, is the percentage of non-carbonate clay in the carbonate—free soil. It is interesting to note that where the profiles are apparently developed from uniform original materials (Table 17) the two ratios are essentially equal (37-3, 41—2, 2—1, and 46-1). On the average, however, the B/A ratios are about 116 eight percent greater than the B/C ratios. The 1.20 B:A clay ratio divides these profiles into two groups. The division does not coincide with the proposed series boundaries and borderline cases are very common. The resultant problems of classification are outlined in Chapter VI. 2) Vertical silt distribution On a natural soil basis, the percentage of silt is relatively constant with depth in most profiles. However, a portion of the silt in the calcareous horizons consists of silt-size carbonate particles. Thus the percentage of non-carbonate silt usually declines with depth in the profile. It is obvious that silt should be considered as part of the dynamic part of the soil, rather than part of the unchanging soil Skeleton. In Barnes profile 50-2 and Forman profile 37-3, it is fairly certain that the higher silt content in the upper horizons is due in part to the breakdown of coarse shale and chert particles to grains of silt size. Shale and chert fragments of sand size are much less abundant in the upper, siltier, portions of these two profiles, than in the C horizons. 3) vertical sand distribution The size distribution within the sand fraction is quite similar between horizons, and between profiles. The differences are so slight that their significance is question- able. (This means that the differences in texture of 117 original materials, as indicated by sand size distribution, are of small magnitude.) Fine sand is the most abundant in most horizons, followed closely by very fine sand. In the few cases where fine sand is not most abundant it is second, close behind very fine sand. Medium and coarse sand are present in roughly equal proportions, each being about half as abundant as fine or very fine sand. Medium and coarse sand vary the least in relative abundance within the profile. very coarse sand is by far the least abundant, and most variable in relative proportion, of the sand fractions. The percentage of total sand tends to vary inversely to that of clay, since the percentage of silt is relatively constant with depth. Total sand makes up 20 to 30 per cent of the soil in the Forman profiles, and 35 to 45 per cent in the others. e. Summary of textural morphology Some profiles contain definite textural B horizons, while others do not. The B horizons in the finest textured profiles contain the highest percentages of clay, but the differences in clay content between horizons are larger in the coarser textured profiles. The textural uniformity of the original materials of the profiles containing textural B horizons indicates that they have developed due to soil forming processes. The percentage of silt tends to remain constant with depth, while those of sand and clay vary inversely to each 118 other. The sand size distribution is surprisingly similar in all profiles. The median sand size is between 0.10 and 0.25 mm. in all horizons of all profiles. In very general terms, the Forman profiles are high in clay and silt. The reddish Forman profiles contain moderate amounts of clay, and relatively little silt. The Barnes profiles are relatively low in clay and high in silt. D. Mineralogy of the Sand Fraction Complete mineralogical analyses were made on the fine and very fine sand fractions from the first seven horizons of: profile S59ND-37-3 representing the Forman soils, profile SS9ND2-l representing the reddish Forman soils, and profile SS9ND50-2 representing the Barnes soils. The analyses extend to a depth of 35 inches in the Forman profile, and to 60 inches in the other two profiles. In addition, the percentage of shale plus chert, and quartz content were determined on samples of the coarser sand fractions in these horizons. 1. Procedure The heavy liquid separation described in Chapter IV divided the fine and very fine sand fractions into heavy and light portions. Shale and chert particles encountered during the identification process were tabulated as a third category, regardless of whether they occurred in the heavy or light fraction. 119 2. Results The percentages of light minerals, heavy minerals and shale plus chert in each horizon are tabulated in Table 19. This table also gives the percentages of heavy and light minerals when shale and chert are disregarded (i.e., heavy plus light minerals equals 100 per cent). The percentages of shale plus chert in the very coarse, coarse, and medium sand fractions are shown as the last items in Table 19. The Roman numerals assigned are indicative of textural and mineralogical differences and similarities in original materials, and are the same as those assigned in Table 14. The percentages (by number of grains) of the individual minerals in the heavy fractions are listed in Table 20. The total number of heavy mineral grains identified in each case is also indicated in this table. The non-resistant mineral group tabulated in this table, and referred to in the following discussion, includes pyroxenes, amphiboles, and heavy micas as a group. The percentages (by number of grains) of the various mineral species in the light fractions are listed in Table 21. The percentages of some of the more important minerals in the total size fraction, and in the total soil are presented in Table 22. This table also includes the data from which quartz size distribution was calculated to evaluate initial profile uniformity. Ratios involving the relative abundance of some of the important minerals are Presented in Table 23. .vF-...¢.. .IF. 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I“ m. 0 .Nn I.HI . 0|“: z N flW-LKI 9‘ \ y 1 V‘ 101' , . 0 H \f r PU. - 0L. PU. . 0, MN ~ ~ u .‘v n «.10 .~ J id 591‘ \fl.\r a... mlv 0‘s pJ- N U v.5 fl). F~ 6v .0 INN-.9 u41vaa:-n- AQ-lv ”MW-JHUU fi-,\mwupmvh.MV~NuHMuflH-Vfinm Hm I IuvanM‘ :U NIfiN.-.v..on Percentages II 321 I B22 II BB II Cca I C2 FS VFS FS VFS FS VFS FS VFS FS VFS VFS II Bl FS 28 29.8 25.7 23.7 32.9 32.4 28.4 20.1 31.5 754 708 4.8 2.2 10.5 5.6 759 364 417 717 817 1.4 707 5.3_ 8.6 4.8 3.4 692 639 697 641 Forman Profile 37-3. I Ap VFS FS Mineralogical composition of the heavy portion of the fine and very fine sand 29.9 26.4 31.2 27.9 34.5 fractions, Horizon Size Fraction Table 20a. 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Percentages of quartz, garnet, and non- resistant minerals in the total sand size fractions and in the total soil. Quartz Med. & Co.S F.S. V.F.S Proféle Non- Hoigzon Tot. Shale Med. Med. & Co.S & Co.S FS Soil VFS Soil SS9Nd 37-3, Forman I Ap 76.9 80.9 47.9 4.4 46.3 4.1 II Bl 68.5 70.7 46.0 3.0 43.6 3.3 II B21 69.2 70.9 52.0 3.0 46.3 3.2 I B22 73.2 78.0 43.5 2.4 37.8 2.5 II B3 57.5 76.7 31.0 1.5 31.0 1.5 II Cca 55.5 77.4 31.5 1.6 30.3 2.6 I C2 59.3 78.9 36.9 3.2 28.0 2.6 C4 C5 S59ND 2—1, Not Reddish Deter— Forman I Ap 68.5 mined 36.5 5.5 42.5 6.4 II B21 78.8 41.1 6.2 41.7 6.2 I B22 73.6 Little 37.6 6.0 38.1 5.8 I Cca 67.1 Shale 35.2 5.7 43.0 6.7 II Ccs 89.6 Present 44.3 7.1 42.0 7.3 II C21 62.8 36.3 5.1 47.7 8.2 II C22 70.4 39.9 6 3 45.2 7.6 S59ND 50-2, Barnes I Ap 63.0 70.0 43.4 5.2 43.1 4.2 II B21 65.2 70.9 42.1 5.1 44.4 4.1 I B22 58.0 73.9 39.3 4.6 32.2 2.5 I Cca 49.1 62.4 33.9 3.8 24.5 2.2 I C2 39.0 52.6 32.6 3.7 25.1 3.1 I C3 47.0 58.9 34.3 4.2 28.3 2.6 I C4 37.9 48.7 31.0 4.6 25.3 3.0 SS9ND 41-1, Forman Ap B22 C2 C5 S59ND 50-1, Barnes Ap B21 C21 126 %2 36.5 Total Quartz Garnet Non Resistant in Soil F.S. V.F.S. Minerals :23 F.S. V.F.S. TOEW OM tall Free Soil Soil FS Soil VFS Soil FS Soil VFS Soil 35.1 38.9 0.50 0.046 0.28 0.025 1.81 0.16 1.87 0.17 -- -— 0.33 0.021 0.27 0.021 1.50 0.10 1.28 0.10 30.8 30.9 0.35 0.020 0.25 0.017 1.66 0.10 1.34 0.10 31.2 32.7 0.32 0.018 0.33 0.023 1.35 0.08 1.82 0.12 -- -- 0.22 0.011 0.13 0.011 1.30 0.06 1.51 0.13 25.9 33.2 0.22 0.011 0.16 0.013 1.19 0.06 1.30 0.11 24.0 32.9 0.23 0.020 0.22 0.020 1.32 0.12 1.40 0.13 34.8 42.4 28.6 34.0 43.2 44.8 0.25 0.044 0.29 0.049 1.40 0.22 1.91 0.28 39.5 40.2 0.16 0.024 0.24 0.036 1.10 0.16 2.23 0.33 33.0 33.4 0.34 0.054 0.17 0.026 1.83 0.30 1.70 0.26 38.2 47.2 0.28 0.045 0.27 0.042 1.49 0.24 2.05 0.32 34.5 43.8 0.22 0.035 0.22 0.038 1.04 0.17 1.59 0.28 33.4 37.5 0.13 0.018 0.24 0.041 1.04 0.15 2.15 0.37 34.4 32.7 0.26 0.041 0.20 0.034 1.07 0.17 1.71 0.29 39.7 42.6 0.70 0.085 0.48 0.047 2.48 0.30 2.57 0.25 44.8 45.4 0.40 0.048 0.68 0.062 1.88 0.22 3.31 0.30 41.3 41.7 0.48 0.056 0.54 0.042 2.32 0.27 3.00 0.23 36.1 47.9 0.35 0.040 0.46 0.041 2.58 0.29 3.19 0.28 28.1 35.3 0.35 0.042 0.39 0.051 2.96 0.35 3.12 0.38 34.9 41.0 0.53 0.066 0.47 0.044 2.86 0.35 3.27 0.30 30.9 36.8 0.44 0.065 0.40 0.048 1.80 0.26 2.22 0.26 33.4 35.5 52.6 53.9 43.2 56.5 25.0 32.6 31.9 34.2 31.3 31.8 .0000 00000 000 C0 0000c0on0m no 000000000 .c0000000 0000208 >>00£ 000 :0 0000200000 no 00000000 .c000o000 0000005 00000 000 00 0000000000 00 0000000 .00000000 0N00 0:0 00 0m00a0000m no 000000 127 m 5 05 00.0 00.5 00.0 «0.0 50.0 00.5 mm 05 0o 0 0.0 m0 0m.0 00.0 50.0 00.0 00.0 mm.m 00 00 mo 0 5.5 00 00.0 00.0 00.5 00.0 00.0 00.0 00 mm mu 0 m.m0 00 00.0 m0.m 05.0 60.5 m0.m 00.0 mm 50 000 0 0.00 mm m0.0 0m.0 00.0 00.0 00.0 0~.5 00 m0 mam 0 5.00 50 00.0 m0.m 00.0 no.0 mm.0 mm.0 00 000 0N0 00 0.0 05 50.0 00.0 «0.0 05.0 00.0 00.5 00 m0 00 0 000000 .muom 0000000 00 m0.m 00.0 00.0 00.0 00.0 00.0 0mm 000 «NU 00 «5 50.0 00.0 00.0 00.5 00.5 0m.m 000 m5~ 0ND 00 50 50.0 00.0 00.5 m5.0 00.0 m0.0 000 mom 000 00 00 «0.0 mm.5 00.5 om.0 0~.0 05.0 000 000 000 0 00 00.0 00.0 00.0 50.0 «5.0 00.0 000 000 «N0 0 m0 mo.m O5.m 00.0 m0.0 0m.m 00.0 050 5mm 0mm 00 om 00.m «0.0 00.0 m0.m mm.0 mm.m 500 000 00 0 casuom 0000000 .0um 0000000 mm0 05.m 5~.5 00.0 00.0 0m.m mm.m 5N0 000 mu 0 000 ~m.m 00.5 m0.5 mm.0 m0.5 «0.5 000 m00 000 00 m00 00.m 05.0 m5.m 00.0 m0.m 0~.5 000 0m0 mmm 0 000 5m.0 05.0 0~.0 00.0 00.0 m0.5 000 000 0N0 00 In: m0.m 0m.0 00.0 0m.0 00.5 0m.5 000 mm0 00 00 000 mm.m 00.m 05.0 50.m 00.5 05.0 000 mm 00 0 205000 .mu5m 0000onm 00> 00 00> 00 00> 00 00> 00 00> 00 00> 00 0000000000000000 000000000C0z 000000 005000 0000000000 000000 00I0z .000000Icoz 0000000000000 000000H0C02 00N0005O 0000050 000050 00009 mulmz 0c000000nlcoz E 000050 00009 I. ll .00000006 00 00:00:500 0>00000H no 000000 .00 00008 128 3. Discussion a. Percentage of shale and chert 1) Significance of shale and chert in genetic studies The fragments included in this category were all considered to be shale during most of the course of this study. Only after most of the tabulations had been made, and the fragments ground for the quartz determination, was it discovered that some of the fragments were chert rather than shale. Therefore, it is necessary to treat shale and chert as a single category throughout the discussion. There is good evidence that shale and chert particles weather readily to particles of silt or clay size. The percentage of shale and chert in the coarser sand fractions of Forman profile 37—3, and Barnes profile 50-2 increase sharply with depth in the profile (Table 19). In the Barnes profile, the horizons with low shale plus chert content contains more non-carbonate silt than those in which the percentages of shale plus chert are high. This does not hold in the Forman profile. Thin section studies (section F) indicate that increasing the magnification of the objective from 4x to 20x reveals no additional shale or chert fragments on the thin sections. This suggests that such fragments are broken down into particles of rather fine size, soon after the onset of weathering. as .3 Q0. 0.0. nu. A» T: ph 32 129 It is, therefore, essential that such fragments be excluded from any sand fractions that are to be considered as stable indices by which to evaluate soil development. Shale or chert fragments are easily identified with a common binocular microscope. It is suggested that in future studies of soil genesis, the sand fractions be given a preliminary qualitative examination for shale and chert content. If shale and chert fragments are found to be numerous, a quantitativedetermination of their abundance should be made. The shale and chert particles of sand size should not be considered as part of the stable soil skeleton. Such fragments should be disregarded in computing sand and quartz size distributions to be used in calculating profile changes. The weathering of shale and chert may be importad: in profile development, so it must be included in the calculation of original weights. A suggestion is to consider shale and chert fragments separately from the rest of the sand, as has been done with Barnes profile 50-2 in Table 48. 2) Percentage of shale and chert in the individual profiles studied Profile 37-3 (Forman) There is a rather sharp increase in the percentage of shale and chert with depth in all sand fractions in this profile. The most abrupt increase is from the B22 to the B3 horizon, which is also the upper boundary of free 130 carbonates in the profile. The fact that there are lower percentages of coarse size shale and chert fragments in the upper part of the profile, with no corresponding increase in the percentages of these particles in the finer sand fraction indicates that they weather directly to particles of silt or clay size. This is supported by the high percentages of silt in the horizons with low shale and chert content, and also by thin sections in which numerous coarse, but few fine shale and chert particles were observed. The quartz-garnet ratio, used as a criterion of mineralogical uniformity, does not reflect the same pattern as the shale and chert distribution. It is, therefore, probable that the low percentages of shale and chert in the sand fractions in the upper horizons is due to a size reduction by weathering or mechanical breakdown and not to a difference in the shale content of the original materials. Profile 2-1 (Reddish Forman) The percentage of shale and chert in the fine and very fine sand fractions is relatively low, and is about constant with depth.. In the coarser fractions, the number of shale and chert particles was too low to permit a reliable count. The percentages in the fine and very fine sand fractions are highest in the horizons whose original materials had low quartz—garnet ratios. The lack of appreciable differences with depth indicates that the original materials in this profile were low in shale and chert. 131 Profile 50-2 (Barnes) This is the most shaley profile studied in detail. This is natural, due to the closeness of the profile to the shale outcrops on the Pembina Escarpment. As in profile 37-3, the C horizons contain higher percentages of shale and chert than the solum. In this profile the quartz-garnet ratio indicated complete mineralogical uniformity of the original materials. Thus the lower percentage of sand size shale and chert in the solum than in the original material or C horizon must be assumed to be due to size reduction by weathering. As in profile 37-3, the indications are that the coarse shale and chert fragments weather directly to particles of silt or clay size. b. Percentage of heavy minerals 1) Nature and reliability of the data .The values for percent heavy minerals presented in Table 19 are based on the analyses of duplicate samples. These values were corrected for heavy grains found in the light fractions, which were very few, and for light grains found in the heavy fraction, which were more numerous. Average differences between duplicates were 14.4 per cent of their average percentages in the fine sand samples, and 23.1 per cent in the very fine sand fractions. Horizon to horizon differences of 30 per cent in the fine sand and 45 per cent in the very fine sand are assumed to be 132 significant. Unless otherwise stated, shale and chert are excluded and the sand fractions are assumed to consist only of light and heavy minerals. 2) Profile 37—3 (Forman) The percentages of heavy minerals decrease with depth in the Forman profile when expressed on the basis of the total size fractions. This is due primarily to an increase in the percentages of shale and chert with depth. When shale is not considered, the percentages of heavy minerals in the fine sand fraction still decrease with depth, but insignificantly. The greatest horizon to horizon decrease in percent heavy minerals of fine sand size occurs between the 321 and B22 horizons. The original materials of these horizons were mineralogically different, according to the quartz/garnet ratios shown in Table 13. A marked increase in the percentage of heavy minerals in the very fine sand fraction also occurs at this position (Table 19). Most horizon to horizon differences in this fraction can be traced to differences in the original materials. There are two types (mineralogically) of original material in this profile (Table 13). One, occurring in the Ap, B22 and C2 horizons, had a lower quartz/garnet ratio than the other, which occurred in the remainder of the profile. The differences between the percentages of heavy minerals in the upper horizons, and the lowest mineralogically 133 similar horizon are listed in Table 24. Table 24. Percent difference in the percentage of heavy minerals among horizons with mineralogically similar original materials in profile 37-3. Horizons with Horizons with initially low initially high Horizon Quartz/Garnet ratios Quartz/Garnet ratios Fine sand Very fine sand Fine sand Very fine sand Ap +19 -2 Bl +16 -13 321 + 8 - 2 B22 -10 +9 B3 0 +82* Cca O 0 C2 0 O *Significant. The percentages of fine sand heavy minerals are slightly, but not significantly higher in the upper than in the lower horizons. Since the heavy fractionis composed largely of non-resistant minerals, this suggests a lack of weathering. The only significant difference is that between the heavy mineral contents of the very fine sand fractions of the supposedly similar B3 and Cca horizons. This must be at least partially discounted, since the value for the B3 horizon is based on the analysis of a single sample. The percentages of heavy minerals in the two Size fractions are not significantly different in the upper 134 horizons, indicating a lack of size reduction of the non- resistant mineral grains. 3) Profile 2-l, reddish Forman There are rather wide horizon to horizon fluctuations in the percentages of heavy minerals in both the fine and very fine sand fractions of this profile (Table 19). In the fine sand fraction, the percentages are higher in the horizons with original materials having low quartz-garnet ratios. The pattern of fluctuation changes but little when shale and chert are disregarded, since the percentages of these are uniformly low throughout this profile. In most horizons, the percentage of heavy minerals is higher in the very fine sand fraction than in the fine sand fraction. The difference between the two is greatest in the upper B horizon, and there is a possibility that there has been a physical breakdown or solution of the less resistant minerals in this part of the profile. The differences between the percentages of heavy minerals in the upper horizons and the lowest horizon with mineralogically similar original materials are listed in Table 25. The horizon to horizon differences in heavy mineral content in this profile are too eratical and too small to be entirely caused by soil weathering processes. The only significant difference, according to the criteria established, is that between the heavy mineral contents of 135 Table 25. Percent difference in the percentage of heavy minerals among horizons with mineralogically similar original materials in profile 2—1. Horizons with Horizons with Horizon initially low initially high Quartz/Garnet ratios Quartz/Garnet ratios Fine sand Very fine sand Fine sand very fine sand Ap - 9 +16 B21 -30* +36 B22 +20 0 Cca O 0 Ccs —25 + 3 C21 -25 +22 C22 0 0 *Significant. the finesand fractions of the Ap and C22 horizons. The heavy mineral content indicates that the B21 and Ccs horizons are more similar to the C21 horizon than to the C22. The garnet size distributions, Table 13, indicate that the reverse is true. In selection of the base horizon, the resistant garnet was given more weight than the total heavy mineral content, which consists primarily of non-resistant minerals. There is a suggestion that the mineralogy of the 321 horizon is different from that of the C22 horizon. This is suggested, but not clearly indicated, by the quartz/garnet ratios (Table 13). 4) Profile 50—2, Barnes The percentages of heavy minerals are quite uniform With depth in this Barnes profile when calculated on the 136 basis of the total Sand size fractions, in spite of the fact that the percentages of shale and chert increase with depth. When shale is not considered, the fine and very fine sand fractions of the C horizons, with the exception of the C4 horizon, contain higher percentages of heavy minerals than those of the solum. The percentages of heavy minerals are higher in the very fine sand fraction than in the fine sand fraction, throughout the profile. The difference between the percentage of heavy minerals in the two size fractions is greatest in the BZlhorizon, indicating a physical breakdown of the non-resistant heavy mineral particles in this part of the profile. Quartz-garnet ratios indicate mineralogical uniformity of the original materials in this profile exclusive of their shale and chert content. Thus the present differences in the percentage of heavy minerals may be assumed to be due to differential weathering. The percentage difference between the percent heavy minerals in the fine and very fine sand fractions of each horizon in the prdfile and that in the C4 horizon are tabulated in Table 26. The C4 horizon contains lower percentages of fine and very fine sand heavy minerals than most other horizons in the profile, although the original material was assumed to be mineralogically similar. The solum contains lower percentages of heavy minerals than the C2 or C3 horizons, and this may indicate weathering of the less resistant Species. 137 Table 26. Percent difference in the percentage of heavy minerals, in the horizons of profile 50-2 and that in the C4 horizon. Horizon Fine sand Very fine sand Ap + 4 -19 B21 —25 + 7 B22 - 2 +45* Cca +18 +41 C2 +36* +29 C3 +38* +19 C4 0 O *Significant. 5) Comparison among the heavy mineral content of three profiles The percentages of heavy minerals in the fine and very fine sand fractions of profile 50-2 (Barnes) are 25 to 35 per cent higher than in the other two profiles. Since the percentages of fine and very fine sand are relatively high in this profile, Table 14, the percentage of heavy minerals in the total soil is considerably higher than in the Forman profile. The higher percentages of fine and very fine sand in the reddish Forman profile (2-1), offset the difference in heavy mineral content between it and the Barnes profile, Table 22. The percentages of heavy minerals in the fine and Very fine sand fractions of Forman profile 37-3 and reddish Forman profile 2-1 are comparable. The percentages Eire usually slightly higher in the fine sand fraction in 138 Forman profile, and in the very fine sand fraction in the reddish Forman profile. The higher percentages of fine and very fine sand in the reddish Forman profile result in higher percentages of heavy minerals in the total soil in this profile than in the Forman profile, Table 22. c. Composition of the heavy mineral fraction 1) Nature and reliability of the data Mineral identification was made on duplicate slides from the fine and very fine sand fractions of each horizon. At least 300 grains were identified on each of the slides. In the samples from Barnes profile 50-2, there were numerous shale and chert fragments in the heavy fraction, and 300 grains exclusive of these were identified._ The percentages of the mineral species in the heavy fraction are presented in Table 20. These percentages were obtained by adding the number of grains of each mineral species on the duplicate slides and dividing by the total number of grains on the two slides. This was felt to be superior to averaging the percentages on the duplicate slides, since more weight was given to slides, on which larger numbers of grains were identified. There were 10 to 20 mineral species identified on each of the slides. The rather complex composition of the heavy mineral fraction is, according to Pettijohn (1941), typical of a recent or unweathered deposit. For purposes Of discussion, the pyroxenes, amphiboles, and heavy micas 139 are collectively referred to as non-resistant minerals. The pyroxenes and amphiboles comprise a very large proportion of this group with green augite and pyroxenes weathered beyond identification as the dominant individual species. The latter are similar to augite in form, but are so dark due to the accumulation of surface weathering products that they appear opaque under plane polarized light. Convergent polarized light passes through these grains and reveals them to be green in color, and to have extinction angles and refractive indices similar to those of augite. Such grains are referred to as ”weathered pyroxenes? throughout the discussion. The non-resistant minerals dominate the heavy fractions in all horizons of the three profiles. Among the resistant heavy minerals garnet is present in far greater quantity than any of the others. Garnet was identified with the most certainty of any of the mineral species. Almandite is the dominant garnet species, making up over 90 per cent of the garnet grains identified. The others are green or orange in color. No attempt was made to tabulate the numbers of the individual garnet Species. Such minerals as zircon, corundum, staurolite, epidote, Ifiatile, apatite, and tourmaline were identified with r“easonable certainty, but were present in such small cIllantities that their individual discussion is not 140 warranted. The unidentified category consists of grains whose optical properties were not clear due to coatings, congestion on the slide, or weathering; as well as multiple mineral grains. 2) Profile 37-3 (Forman) The composition of the heavy mineral fraction is fairly constant in this profile (Table 20) both between horizons and between the two size fractions. Horizon to horizon differences in the percentages of non-resistant minerals are less than 15 per cent and of garnet, less than 20 per cent. The percentages of non-resistant minerals in the heavy fraction indicate a greater degree of uniformity than the ratio of quartz to garnet, which was used as a criterion of mineralogical uniformity of the original materials. Since these minerals are not resistant, this indicates a lack of weathering, unless weathering has acted to reduce original variability. The percentages of non-resistant minerals in the sand fraction (Table 22) of the Ap horizon are higher than those in the B horizon. This suggests that either the zone of maximum weathering occurs in the B horizon rather than at the surface, or that there were mineralogical (differences between the original materials of the A and 13 horizons. The composition of the heavy fraction differs Eis much between horizons whose original materials were a:ssumed to be mineralogically similar, as between those 141 whose original materials were thought to be mineralogically different. This is indicated by the similarities in the magnitudes of the differences in the non-resistant/garnet ratios (Table 23) between supposedly similar and dissimilar horizons. Within the non-resistant heavy minerals, the percentage of augite decreases, while those of hornblende and weathered pyroxenes increase with depth. This is not a clear cut trend, and the differences in relative abundance are so small as to make their significance doubt- ful. In most horizons, the percentage of augite is higher in the fine sand, and that of hornblende in the very fine sand fraction. Other heavy minerals such as zircon, rutile, and epidote are most abundant in the B horizons, but are present in only small amounts. While the heavy mineral fractions of the several horizons in this profile are quite uniform in composition, the small differences that do exist suggest that the maximum amount of weathering in this profile has occurred in the upper part of the B horizon. It is likely that temperature and moisture conditions favorable to weathering are more persistent here than on the immediate surface. The fluctuations in the percentage of garnet are in part -inherited from mineralogical differences in the original rmaterials. The zone of greatest weathering in this profile coincides Wtith that where Pawluk and Bentley (1956) found the first 142 traces of the A2 horizon as they traced the degradation of a Chernozem toward a podzolic type of soil. The weathering indicated in this profile may be a precursor to such a develop— ment, but the predominance of non-resistant minerals in the heavy fraction indicates this weathering to be in a very early stage. 3) Profile 2-1 (reddish Forman) The composition of the heavy mineral fractions in this profile is more uniform (Table 20b) than is indicated by the quartz/garnet ratios used to evaluate mineralogical uniformity. The horizon to horizon differences in the percentages of non-resistant minerals and garnet are so small that their significance is questionable. The small differences that do exist seem unrelated to the quartz/garnet ratios used to evaluate mineralogical uniformity. Garnet forms a higher percentage of the heavy minerals in the fine sand than in the very fine sand fraction. The percentage of garnet varies more from horizon to horizon in the fine sand than in the very fine sand fraction. Within the non-resistant group of heavy minerals, horizon to horizon differences are small and erratic. The percentage of hornblende is generally higher in the very fine sand than in the fine sand heavy minerals, while the reverse is true of the percentage of weathered pyroxenes. 143 The percentage of augite is higher in the very finesand fraction in those horizons designated as having original materialI(Table 13). In the other horizons it is equally abundant in the two size fractions. 4) Profile 50—2 (Barnes) The compositions of the heavy mineral fractions in this profile (Table 20c) are very consistent, both between the two size fractions and among the various horizons. This is consistent with the mineralogical uniformity of the original material indicated by the quartz/garnet ratios, Table 13. Horizon to horizon differences in the percentages of non-resistant minerals and garnet may be too slight to be significant. The non-resistant/garnet ratios (Table 23) indicate the most weathering in the solum, particularly in the upper B horizon or A horizon. Within the non-resistant mineral group, the per— centage of augite decreases with depth, relative to those of hornblende and weathered pyroxenes. Hernblende is more abundant in the very fine than in the fine sand fraction throughout the profile, The dominant heavy minerals, even in the horizons felt to be weathered, are non-resistant minerals, indicating that any weathering is in a very early stage. 5) Comparisons among the profiles The composition of the heavy mineral fractions in the three profiles is more similar than would be expected, 144 considering the other morphologic differences among these profiles, and the differences in the percentages of total heavy minerals. The same heavy minerals are present in all three profiles, and in roughly the same proportion. (The notable exception is the high percentage of weathered pyroxenes in reddish Forman profile 2-1.) The differences in the composition of the heavy fractions among the profiles is too slight to be considered significant. The high proportion of non—resistant heavy minerals in all three profiles indicatesthat while weathering may have started, it has not proceeded far in any of them. There seems to be no relationship between the degree of similarity and depth in the profile. The percentage of garnet in the heavy mineral fractions is more variable than that of non-resistant minerals, probably due to the fewer number of grains identified. The profile to profile difference in the composition of the heavy mineral fractions are of similar magnitude in the fine and very fine sand fractions. d. Percentages of light minerals The percentages of light and heavy minerals do not add to 100, due to the presence of shale and chert, Table 19. On this basis, the percentages of light minerals are lowest in Barnes profile 50-2, in which the percentages of both heavy minerals and shale and chert are relatively high. The percentages of light minerals are 145 higher in the solum than in the C horizons of profiles 37;3 (Forman) and 50-2 (Barnes) and are about constant with depth in profile 2—1 (reddish Forman). This difference is due primarily to the higher percentages of shale and chert in the C horizons of the first two mentioned profiles. Differences between horizons, and among profiles, are small when expressed on the basis of the non-shale and chert sand fractions. e. Composition of the light mineral fractions As in the case of the heavy minerals, the compositions of the light fractions (Table 21), are similar within and between profiles. The percentages given for muscovite in Table 21 must be considered only approximate, due to the difficulties in handling the grains which have been discussed in Chapter IV. 1) Profile 37-3 (Forman) The data for the C4 and C5 horizons is based on identifications in the sand fractions from the mechanical analyses made by the soil survey laboratory. This probably explains the different composition in the light fractions of these horizons, since the data for the other horizons are based on identifications on the sand fractions from the carbonate free mechanical analyses. Other than this, the horizon to horizon differences are not great enough to merit discussion. 146 2) Profile 2—1 (reddish Forman) Herizon to horizon differences in this profile are very small,and are probably not significant. The light mineral composition is very similar in the two size fractions. 3) Profile 50-2 (Barnes) There is a slight decrease in the percentage of quartz in the very fine sand light minerals with depth. There is no similar trend in the fine sand fraction. The percentage of socium-calcium plagioclases increases with depth in both sand fractions. The light mineral fraction of this profile is the most variable of the three studied, although the original materials were indicated to be mineral— ogically uniform by the quartz—garnet ratios. 4) Comparisons among profiles The percentages of the mineral species in the light mineral fractions are very similar in the three profiles. In the 23 horizons analyzed the percentage of quartz in the very fine sand light minerals is between 45 and 55, in 18, and is within these same limits in the fine sand fraction in 15. Other constituents are similarly present in comparable amounts in the three profiles. Thus the analysis of the light mineral fraction reveals the three profiles to be mineralogically similar. Differences are evident when the percentages are expressed on the 147 basis of the total soil, due to differences in the amount of sand in the three profiles. f. Quartz content and distribution The quartz content and distribution in several of the sand fractions has been discussed previously, since these have been used as criteria of textural and mineralogical uniformity. This section deals with the total quartz content, including sand and non-sand size quartz grains, as well as quartz occurring as part of composite fragments. 1) Nature and reliability of the data The values for total quartz in Table 22 are based on the x-ray diffraction of duplicate ground samples. Three pairs of peaks (one quartz and one calcium fluorite peak per pair) were Obtained on each of the duplicate samples. The average heights of the quartz and fluorite peaks were used to determine a percentage of quartz for each sample. The percentages for the two duplicates were then averaged to give the values in Table 22. The duplicate percentages differed from the mean by an average of 7.7 per cent. Horizon to horizon differences of double this value, or 15 per cent, will be considered significant. The carbonate and organic matter free values were calculated from those obtained on the total soil. 148 2) Finely divided quartz The four sand fractions on which quartz determinations were made contained a fairly small proportion of the total quartz in all three profiles. This means that there is considerable quartz in the non-sand fraction. The average quartz contents of the non—sand fractions necessary to account for the remainder of the quartz not accounted for by the sand fractions (an estimate was made for the contribution of very coarse sand) are listed in Table 27. The table also gives a quartz percentage for the silt fraction, assuming that there was no quartz in the clay fraction. The presence of appreciable fine quartz throughout the profiles indicates that it was present in the original materials and has not been formed by the breakdown of coarser fragments during soil formation. 3) Profile 37—3 (Forman) The percentage of total quartz decreases with depth in this profile on a natural soil basis (Table 22), due primarily to the higher percentages of carbonates in the lower horizons. The decrease is not apparent below the Ap horizon when the quartz contents are expressed as percentages of the organic matter and carbonate free soil. The concentration of quartz in the plow layer indicates the weathering and removal of the less resistant constituents 149 when this layer is compared to the C2 and 822 horizons believed to have been originally similar. Table 27. Estimated percentages of quartz in the non- sand fraction. % of total quartz Horizon not accounted for Estimated percent quartz in by sand non-sand silt (assuming none in clay) Profile 37-3 (Forman) I Ap 62 33 55 II B21 67 31 59 I 322 71 28 70 II Cca 85 35 69 I C2 80 36 60 Profile 2—1 (reddish Forman) I Ap 51 44 90 II B21 46 32 59 I B22 38 24 44 I Cca . 35 30 55 II Ccs 43 36 64 II C21 42 30 57 II C22 38 27 51 Profile 50—2 (Barnes) I Ap 59 43 60 II 821 59 43 86 I B22 63 42 59 I Cca 64 48 76 I C2 57 37 56 I C3 60 41 66 I C4 56 37 54 The percentages of quartz in all sand size fractions are higher in the non-calcareous horizons than in the calcareous horizons. The percentages are about 25 per cent higher in the medium and coarse sand fractions than in the fine and very fine sand fractions throughout the profile. 150 This indicates that the less resistant mineral fragments were reduced in size by glacial action or previous weather- ing cycles more than quartz fragments. This illustrates one way in which sand size distribution is related to mineralogy of the original materials. The decrease in the percentage of medium and coarse sand quartz from the Ap horizon to the B1 horizon is greater than the percentage decrease in total medium and coarse sand. This indicates that the accumulation or concentration of coarse fragments in the surface layer is primarily one of quartz sand. This suggests that weathering, rather than erosion is responsible for the concentration, since the latter process would tend to leave coarse fragments of diverse resistance, while the former process would result in a concentration dominated by the more resistant mineral species. The combined quartz content of the four sand fractions on which quartz determinations were made (coarse, medium, fine, and very fine) account for only a small percentage of the total quartz (Table 27). This is due in part to the fact that textures in this profile are moderately fine to fine and therefore these sand fractions make up a small proportion of the total soil. Although some of the fine (non-sand) quartz may have been formed by the breakdown of coarser fragments the presence of rather large quantities in all parts of the 151 profile indicates that most of it was present in the original materials. If the original materials were high in silt size quartz, layers in which silt size particles are concentrated (such as the C4 horizon) would be expected to have high quartz contents. This seems to be consistent with the estimated quartz content of the silt in these profiles. 4) Profile 2-1 (reddish Forman) Horizontb horizon differences in the percentages of total quartz (Table 22) are not great enough to be considered significant. The minor fluctuations follow the same pattern as total sand content. The percentages of quartz in the medium and coarse sand fractions were not corrected for shale in this profile because there were not enough shale particles present to furnish a sample for x—ray diffraction or to greatly influence the quartz sand size distribution. Horizon to horizon differences in the percentage of quartz in the medium and coarse sand fractions are too small to be considered significant. The medium and coarse sand contains percentage- wise 50 to 100 percent more quartz than the fine and very fine sand fractions throughout the profile. The combined quartz content of the four sand fractions on which quartz determinations were made (very fine, fine, medium, and coarse) accounts for a higher proportion of 152 the total quartz in this profile than in the other two (Table 27). This is partly due to the high sand content, i.e., the four fractions make up a higher percentage of the total soil, and partly to the low shale content of the sand fractions. 5) Profile 50-2 (Barnes) The percentage of total quartz decreases slightly but irregularly with depth in the profile, and the decrease is not enough to be considered significant. The maximum percentage of total quartz on a carbonate and organic matter free basis (Table 22) occurs in the Cca horizon, in spite of the fact that this horizon contains large amounts of shale and is not particularly high in sand. The percentage of quartz in the medium and coarse sand fractions clearly decreases with depth in the profile, on both total and non-shale bases. The maximum occurs in the 321 or B22 horizons. The percentages of quartz in the medium and coarse sand fractions roughly parallel those in the fine and very fine sand fractions although the coarser fractions contain 20 to 50 percent more quartz. There is considerable non-sand quartz throughout the profile (Table 27). 6) Comparisons among the profiles The percentages of total quartz (Table 22) are more similar than those of total sand (Table 14) among the three 153 profiles. In all three profiles, the medium and coarse sand fractions contain higher percentages of quartz than the fine and very fine sand fractions. This difference is less in profile 50-2 (Barnes) than in the other two profiles. All three profiles contain considerable quartz in the non- sand fraction (Table 27). E. Clay Mineralogy 1. Results A qualitative evaluation of the clay mineralogy in the major horizons of three profiles was made by means of x-ray diffraction. The clay samples were obtained from the suspensions prepared in connection with the carbonate- free mechanical analyses. The treatment given these samples is outlined in Chapter IV. The tracings made by the recorder attached, to the x—ray unit are shown in Figures 5a, b, and c. It was impossible to obtain useable x—ray diffraction curves from the acid treated samples from the Cca and C horizons of the Barnes or Forman profiles. The tracings shown for these horizons in Figures 5a and 5c were obtained on samples taken from soil suspensions dispersed with sodium hydroxide. 2. Discussion a. The general pattern In all the samples, the dominant peak in the Mg. saturated, glycerol solvated condition (treatment 1) indicates 154 a basal spacing of 18 to 20 Angstroms. This peak is felt to be due to montmorillonite, although it indicates a basal spacing slightly greater than the 17.7 Angstroms character- istic of pure montmorillonite in the glycerol solvated condition. The peak as a whole is rather broad, but several sharp sub-peaks rise from the top of it. Smaller peaks indicate either clay minerals with either 7 or 10 Angstrom basal spacings in most horizons, but both are indicated in only a few cases. When the samples are saturated with potassium and heated to 110 degrees C (treatment 2), the main peak collapses, and shifts toward 10 Angstroms. In some cases, for example in the C horizon of the Forman profile, no definite peaks are present following this treatment, although there is a series of indistinct peaks indicating spacings of 10 to 15 Angstroms. This is due to the partial, but incomplete removal of the interlayer water from the montmorillonite. The original 10 Angstrom peaks persist, but are entirely or partially covered by the shifting of the larger montmorillonite peaks. These 10 Angstrom peaks are assumed to be due to the presence of illite. The small 7 Angstrom peaks are unaffected by this treatment, and are in some cases the dominant peaks following this treatment. After heating to 500°C. (treatment 3), a single peak, lower and sharper than that following treatment 1, appears 155 at 10 to 10.2 angstroms. This peak appears even on the tracings from horizons where no distinct peaks were observed following treatment 2. This peak is the combined effects of the now-dehydrated montmorillonite, and illite. The 7 Angstrom peaks do not appear following this treatment, indicating that the additional heating has destroyed the mineral causing them. These peaks are felt to be the 002 reflection of chlorite. The 001 chlorite peak at 14.4 Angstroms is obscured by the strong montmorillonite peak. Peaks were also evident on most of the tracings, but were trimmed off in preparing the figures. b2 Discussion by individual profiles 1) Profile 37—3 (Forman) The x—ray diffraction tracings for this profile are shown in Figure 5a. The identifiable clay minerals are montmorillonite, illite, and chlorite. The B21 horizon of this profile contains more chlorite than any of the other horizons in this profile, or in the other two profiles. The tracings from this horizon show 7.2, 4.67, and 3.6 Angstrom peaks, which are the 002, 003 and 004 reflections of chlorite. The 001 reflection is obscured by the montmorillonite peak. The 10 Angstrom illite peaks were strongest in the non-calcareous horizons. This suggests the possibility that illite has formed through the fixation 156 of potassium by montmorillonite in the upper part of the profile. In addition to the B21 horizon, 7 Angstrom chlorite peaks are present in the tracings from the Cca and C horizons. 2) Profile 2-1 (reddish Forman) Montmorillonite is the dominant clay mineral in all horizons. In addition, 10 Angstrom illite peaks are present in the upper horizons, especially in the Ap horizon. weak 7 Angstrom chlorite peaks are shown in the lower horizons. 3) Profile 50-2 (Barnes) Montmorillonite is the dominant clay mineral in all horizons. Chlorite peaks are present in the tracings from all horizons, but are very weakly expressed in those from the A and B horizons. Ten Angstrom illite peaks are best expressed in the non—calcareous horizons. c. Summary The three profiles cannot be distinguished on the basis of clay mineralogy alone. Montmorillonite is the dominant clay mineral in all horizons of the three profiles. Illite and chlorite are also present in all three profiles, the former most evident in the A and B horizons, and the latter in the Cca and C horizons, (except for the B21 horizon of profile 37-3, in which chlorite was abundant). The presence of more illite, relative to montmorillonite, in 1573. Figure 5. X-ray diffraction curves for Forman profile 37-3, and reddish Forman profile 2-1. Treatments 1. Mg. saturated, glycerol solvated 2. K saturated, 110 C. 3. K saturated, 550 C. 37'31 158 Treatments 1. Mg saturated, glycerol solvated - 2. K saturated, 110 C FiWBIJre 5c. X—ray diffraction curves for Barnes profile 50—2. 159 the sola than in the C horizons suggests the possibility that illite is being formed through potassium fixation. In addition to the clay minerals, the clay fractions contain fine particles of primary minerals, such as quartz, feldspars and calcite, and possibly the micas. The 3.35 and 4.25 Angstrom quartz peaks were present on the tracings from all horizons. It has also been calculated in the previous section, that a relatively high percentage of the quartz in these profiles occurs in the non-sand fraction. Analyses by the soils survey laboratory indicate that 5 to 20 percent of the clay fractions of the Cca and C horizons consist of finely divided carbonates. These had been removed from the samples on which the clay mineralogy was evaluated. F. Fabric Analysis 1. Purpose and content This section deals with the make-up of the entire soil mass, not only in terms of its composition, but also in terms of the spatial relationships among the constituents. The discussion is based to a large extent on the examination of thin sections under the petrographic microscope, and on observations of debris samples with the binocular micro- scope. 160 2. Quality of the thin sections The thin sections were prepared as outlined in Chapter IV. They were of good quality, were clear and easy to use. They had a uniform thickness of about 0.03 mm., as indicated by the yellow interference colors shown by the quartz grains in the section (Rogers and Kerr, 1933, p. 77). The usefulness of the sections was limited only by the dense nature of the soil material. The components were so tightly paCked, and occurred in such small particles, that in many cases they could not be identified (See Figure 6). A few pore spaces were filled with grinding compound, but this was easily recognized by its color and texture. 3. Proportion of component parts on the thin sections a. Means of determination The thin sections were systematically examined with the Spencer microscope, using a 10 power ocular and a 4 power objective lens. In general, two traverses were made lengthwise of the slide, and four traverses crossways of it. (This varied with the shape of the section.) The total length of the traverses on each slide averaged about 110 mm. The distance along each traverse was divided into four categories according to the type of material being passed over. (This was done much as soil boundaries are drawn while making a traverse while mapping soils in the field.) The categories (mapping 161 units) recognized on these traverses included: 1. Pore spaces, more than 0.1 mm. wide in the direction of the traverse. 2. Solid grains, more than 0.1 mm. wide in the direction of the traverse. a. Igneous pebbles, or single grains of quartz or feldspar. b. Shale (fine poly-mineralic) or chert (microcrystalline silica). 3. Lime concentrations or concretions. 4. Ground mass. This category included areas where the individual components were too small to be measured at this scale of magnification. The ground mass appeared to vary between thin sections and two or more kinds often appeared on the same section. The 4 power objective was replaced by a 20 power objective, and 5 randomly chosen areas of ground mass were examined on each thin section. The micrometer scale on the microscope was not fine enough to permit actual measurement of the individual components of the ground mass. Estimates of the proportion of pores and fine sand grains were made in each area of ground mass studied. There was considerable area where the individual components were still too small to be identified. Such areas were designated as light or dark ground mass on the basis of color. Thus category 4 above was subdivided as follows: 4. Ground mass a. fine pores b. fine grains c. ground mass 1. light 2. dark 162 On the basis of the high and low power examinations, seven types of ground mass were recognized. These were designated as ground mass types T through Z, and are described in a later section. b. Results The proportions of the various components on the thin sections are presented in Table 28. Two sets of values are given for each profile. The first is that based on the systematic scanning of the thin section using a 4 power objective. In the second set of values, the additional grains and pores identified with the 20 power objective were deducted from the ground mass category and added to the grain and pore categories. c. Types of ground mass Seven types of ground mass were recognized on the basis of color, size of components, and percentages of fine grains and pores as revealed by the examination with the 20 power objective. These types apply to areas designated as ground mass in the examination made with the 4 power objective. The percentages of the component parts in each of these ground mass types are tabulated in Table 29. A detailed description of each type follows. Description of ground mass types T. This ground mass type occurs in the lower B and throughout the C horizon of Forman profile 37-3. It was 163 Table 28. Proportion of components in thin sections, expressed as percentages of the total length of traverse. Profile 37-3 (Forman) Horizon AP Bl B21 B22 B3 Cca C2 C3 C4 C5 Components (4X objective) Ground mass Type V U T T T T T T T % 82.9 73.0 70.4 81.5 78.1 77.6 80.4 78.3 68.4 85.3 Grains,% 6.5 5.4 5.0 3.7 3.2 2.8 2.6 11.1 6.5 6.5 Pores,% 10.6 21.6 24.6 14.8 16.0 19.1 15.1 6.0 18.1 7.4 Lime Concr.% 0.0 0.0 0.0 0.0 2.8 0.7 1.9 5.0 6.8 1.1 (20X objective) Ground mass Dark 62.0 51.2 49.3 40.7 39.0 38.8 40.2 39.1 34.2 42.1 Light 0.0 10.9 10.6 28.6 27.3 27.2 28.1 27.4 23.9 29.5 Grains 27.4 16.3 15.5 16.0 14.6 14.4 14.7 23.4 16.2 19.4 Pores Same as above Profile 2-1 (reddish Forman) Horizon Ap B21 B22 Cca Ccs C21 C22 Components (4X objective) Ground Mass Type v x w w w w w % 72.2 68.4 81.7 77.4 74.1 81.7 83.9 Grains %» 6.6 8.9 9.6 11.2 8.5 4.4 8.2 Pores % 21.2 22.7 8.7 13.5 15.6 11.2 7.9 Lime concr.% 0.0 0.0 0.0 0.9 1.8 2.7 0.0 (20X objective) Ground mass Dark 54.1 23.8 19.1 18.6 18.5 20.4 21.0 Light 0.0 20.7 26.8 26.1 26.0 28.6 29.3 Grains 24.7 26.0 32.3 33.5 30.7 28.9 33.4 Pores 21.2 29.5 21.8 20.9 23.0 19.4 16.3 Lime Concr. As above 164 Table 28.--Continued. Profile 50-2 (Barnes) Horizon Ap B21 B22 Cca C2 C3 Components (4X objective) Ground mass Type v z z Y Y Y % 59.1 64.6 63.2 62.5 65.8 62.6 Grains % 14.5 9.9 9.3 7.7 9.8 5.6 Pores % 25.0 20.1 17.2 23.6 18.1 14.8 Shale %» 1.4 5.4 10.3 5.7 5.9 14.8 Lime concr.% 0.0 0.0 0.0 0.5 0.4 2.2 (20X objective) Ground mass Dark 44.3 26.2 25.3 12.5 13.2 12.5 Light 0.0 19.4 19.0 31.3 32.8 31.3 Grains 29.3 22.8 21.9 20.2 23.0 18.1 Pores 25.0 26.6 23.5 29.8 24.7 21.1 Shale and lime concr. As above Table 29. Composition of ground mass types T through Z. Composition, per cent Ave. Fine Fine ground mass bulk Type grains pores light dark density Occurrance T 15 O 35 50 1.59 Forman: C, 1wr. B U 15 0 15 70 1.55 Forman, upr. B V 25 0 0 75 1.42 3 Ap horizons W 30 10 35 25 1.64 red. Forman, C & 1wr. B X 25 10 30 35 1.59 red. Forman, upr. B Y 20 10 50 20 1.47 Barnes, C Z 20 10 30 40 1.48 Barnes B 165 Figure 6. Photograph of a portion of the horizontal thin section from the C2 horizon of Forman profile 37-3. Note the very dense appearance of the soil mass, and the scarcity of fine pores. The dense areas are ground mass type FTF. The white areas are pebbles. A large pore crosses the photo from northeast to southwest. Magnification 200x. 166 defined on the basis of the examination of the horizontal sections from the B22 and Cca horizons of this profile. It is characterized by a lack of fine pores, and an overall dense appearance. The light portion of the ground mass consists primarily of silt particles, that can be faintly made out individually under high magnification; while the dark portion consists of areas where no individual particles can be identified, even with high magnification. Traces of fine, highly birefringent lime are spread over the ground mass in some areas. There is a concentration of silt particles along the major pores that traverse the ground mass areas, with the darker mass of clay particles coming in 0.05 to 0.10 mm. back from the edge of the pore. This ground mass type covers 65 to 85 percent of the area of the thin sections on which it occurs, with the same range on both horizontal and vertical sections. The dense nature of this type of ground mass is indicated in Figure 6, which is a photograph of a portion of the horizontal thin section from the C2 horizon of the Forman profile. U. This ground mass type occurs in the upper part of the B horizon of profile 37-3, Forman. It is characterized by heterogenity, being composed of an aggregation of sub-masses with distinct colors and fabrics. It is dense, but less so than Type T. The very few fine pores are filled with organic material, which hides any clay films that might be present. 167 This ground mass type covers 70 to 75 per cent of the thin sections on which it occurs. There are no visible clay films along the large pores, and in many cases the areas adjacent to the pores appear to contain less clay than the interiors of the peds. The heterogenity isjllustrated in Figure 7, which is a photograph of a portion of the verti— cal thin section from the Bl horizon of the Forman profile. The heterogenity is due at least in part to the physical mixing caused by alternate wetting and<3rying, or freezing and thawing. Material from the Ap horizon, high in organic matter, falls into the cracks between the peds, and this is responsible for the high percentage of dark colored ground mass in this type. V. This ground mass type occurs in the three Ap horizons studied, and is characterized by intense organic staining. The dark colors make the identification of individual components difficult if not impossible. The three Ap horizons were grouped together, since the differences which probably exist among them are masked by the organic matter. This type covers 83, 72, and 59 per cent, respectively, of the unoriented thin sections from the Ap horizons of the Forman, reddish Forman, and Barnes profiles. W. This ground mass type occurs in the B22, Cca, and C horizons of reddish Forman profile 2-1. This type was described and defined on the horizontal thin section from the Cca horizon, and the vertical thin section from the C21 168 Figure 7. Photograph of a portion of the vertical thin section from the B1 horizon of Forman profile 37-3. Note the heterogenity of the color pattern, and the ?churned up? appearance of the soil mass. This is typical of horizons where physical mixing is important. The ground mass areas are type U. Maginification, 200x. 169 horizon of this profile. This type of ground mass is characterized by a loose appearance. The color pattern is blotchy, with some areas having intense color, and others being almost colorless. Individual silt grains can be identified in the less colored portions, but not in those with intense color. The birefringence is greatest in thin curved or straight bands, which are randomly oriented in the soil mass, and are not associated with the pores. The fine pores are arranged in a dendritic pattern. This ground mass type covers 70 to 85 per cent of the thin sections on which it occurs. X. Type X ground mass is confined to the 821 horizon of profile 2—1, (reddish Forman). It has a blotchy appearance such as that described for type U, but is redder, and contains more sand fragments and fine pores. It appears denser than type W, and is darker due to organic staining. The variation in color can be seen in Figure 8, which is a photograph of a portion of the vertical thin section on which this type occurs. Many of the coarse fragments are weathered around the edges. The maximum birefringence occurs in randomly oriented patches and in thin bands adjacent to large pebbles. A few very thin, discontinuous, oriented clay films parallel some of the larger pores. This ground mass type covers about 68 per cent of both the horizontal and vertical thin sections from the horizon where it occurs. Y. Type Y ground mass occurs in the Cca and C horizons of Barnes profile 50—2. It has a loose appearence when Figure 8. 170 Photograph of a portion of the vertical thin section from the 321 horizon of reddish Forman profile 2-1. The white area in the center of the photo is a large pore or crack between peds. The difference in color between the two sides of the photo are not due to photography, but illus- trate the variability of color within the B horizons. The ground mass is type X. Magnification 200x. 171 viewed under low power, but the areas designated as ground mass are actually quite dense when viewed under higher magnification. Numerous fine pores penetrate these dense areas. The fine grains in the ground mass are oriented along the major pores. The smaller pores are partially filled with lime and other debris, probably grinding compound. Coarse shale particles are very numerous in the horizons where this ground mass type occurs. The finer shale particles, if present, blend into the ground mass and cannot be identified. The areas remaining as ground mass under high magnification have a blotchy color pattern. Individual silt grains can be identified in the lighter portions only. The entire ground mass is highly birefringent due to the presence of finely divided lime, which is dis- seminated throughout the soil mass. The ground mass tends to shrink away from the large grains, leaving them surrounded by voids. This ground mass type covers 60 to 66 per cent of the thin sections on which it occurs. The nature of this type of ground mass is shown in Figure 9, which is a photograph of a portion of the horizontal thin section from the Cca horizon of the Barnes profile. Z. Type Z ground mass occurs in the B horizon of Barnes profile 50-2. It is quite similar to type Y, but is darker colored due to organic staining, and lacks the birefringent lime. The fine shale particles, if present, Figure 9. 172 Photograph of a portion of the horizontal thin section from the Cca horizon of Barnes profile 50-2. The ground mass is type Y. Note the looseness of this soil mass as compared to that from the Forman profile (Figure 6). A large pore crosses the photo diagonally. The numerous fine pores do not show up in this photo. The greenish shade is due to lighting. Magnification 200x. ' 173 blend into the ground mass to the extent that they cannot be distinguished, even under high power. The strongest birefringence is in thin bands along the fine pores, and surrounding the coarse fragments. The blotchy color pattern evident in the other B horizon types, (U, X) is also present here. Small iron stains cause reddish colors in local areas of the ground mass. This ground mass covers 62 to 65 percent of the area of the thin sections on which it occurs. d. Discussion 1) Nature of the data Anderson and Binnie (1961) discuss the statistical validity of converting linear measurements such as those made in this study, into volume percentages. The percentages given in Table 28 are based on the total length of traverses on all the sections from a given horizon. Had percentages been calculated for each traverse and then averaged for the horizon, the results would be slightly different. Adding all the traverses together gives more weight to the longer traverses, which cover more of the section, and which should therefore be more representa— tive. The data from horizons from which two sections were made are more reliable than that on horizons from which only one was made. The amount of variation in the percentage of a component among the various traverses across a thin section is inversely proportional to the percentage of the section made up by the component. The percentages of 174 grains and pores are less variable when those identified with the 20 power objective are added to those identified with the 4 power occular alone. 2) Variations within the profiles Profile 37—3 (Forman) The percentage of ground mass is high, ranging from less than 70 per cent in the C4 horizon to more than 85 per cent in the C5 horizon. There is no clear relationship between the percentage of ground mass and depth in the profile. The low percentage of coarse grains is consistent with the fine texture of the profile. There are very few fine pores anywhere in the profile, although there are numerous coarse pores. The maximum percentage of pores occurs in the upper part of the B horizon, where alternate wet- ting and drying produces large cracks between the peds. The thin sections were made from dry material. If they had been made from moist material, the proportion of pores would have been much lower. The material between the large pores is very dense. The break between ground mass types T and U occurs between the B21 and 322 horizons, rather than at the bottom of the B horizon, as might be expected. This suggests that either the lower B horizon has only lost its lime, while the upper part has undergone additional modifi- cations, or that the two parts of the B horizon developed_ from different original materials. The proportion of dark ground mass declines from the Ap to the B22 horizon paralleling the decline in organic matter content. 175 Profile 2-1 (Reddish Forman) The percentage of ground mass on the thin sections ranges from less than 70 to more than 80 per cent. The highest percentages occur in the lower B and lower C horizons, and the lowest percentage in the upper B horizon. The break in ground mass types occurs between the 321 and B22 horizons, due primarily to the larger percentages of dark ground mass in the 821. The fabric of the lower B and C horizons are very similar, except that carbonates have been removed from the lower B. The percentage of grains increases from the upper to the lower part of the B horizon. The highest percentage of pores occurs in the upper B horizon, where shrinking produces voids between the peds. Profile 50-2 (Barnes) The percentage of ground mass is 60 to 65 per cent in all horizons. The proportion of this which is dark is highest near the surface where there is a great deal of organic staining. The break in ground mass types occurs between the B22 and Cca horizons, as opposed to the middle of the B horizon in the other two profiles. Shale fragments are common throughout the profile, but are most common in the thin sections from the B22 and C3 horizons. Increasing the magnification from 40X to 200x revealed no additional shale particles. The absence of finer shale fragments, especially in horizons where breakdown 176 was assumed to have occurred, suggests that relatively coarse shale fragments weather directly to particles too small to be observed with the 200x magnification (i.e., to silt or clay size). Large pores are most numerous in the B horizon, where shrinkage on drying produces large voids between the peds. There are numerous fine pores throughout the profile. The percentages of component parts are not clearly related to depth in this profile. 3) Comparisons among the profiles The percentages of the component parts observed with the 40X magnification were closely related to texture. The percentage of ground mass was highest in the fine textured horizons of Forman profile 37-3, and the percentages of grains are highest in the relatively coarse textured horizons of Barnes profile 50-2. The percentage of ground mass is much lower in profile 50-2 than in the other two profiles. The compositions of the thin sections from profiles 37-3 and 2-1 are quite similar. In both profiles the highest percentage of pores is in the B horizon, where cradks are produced by alternate freezing and thawing, or wetting and drying. Thin sections from the C horizons of both profiles contain areas of lime concentration; a fact consistent with the binocular microscope and field examinations. In both profiles, the type of ground mass changes between the upper and lower portions of the 177 B horizon. This indicates either that carbonate removal and structure development in the lower B horizon precedemajor changes in fabric or that the two parts of the Bliorizon developed from different original materials. The fabric in the C horizons of the two profiles are similar, but that in profile 2-1 contains a few fine pores, whereas that in profile 37-3 does not. The thin sections from Barnes profile 50—2 reveal that the fabric in this profile is considerably different from those in the other two. The percentage of ground mass is lower, and those of shale fragments and pore space higher, in this profile than in the other two. The type of ground mass changes at the bottom, rather than the middle of the B horizon. This indicates that changes in fabric occur shortly after the leaching of carbonates. 3) Orientation of component parts The degree of orientation of the component parts should be reflected in the differences in their percentages of occurrence on the horizontal and vertical thin sections from the same horizon. The horizontal sections were made in planes roughly parallel to the ground surface. All points on the section should represent the same depth, and therefore no significance should be attached to differences in the percentages of components between the traverses made in the two directions on these sections. On the vertical thin sections, one direction parallels the ground surface, and thecther is perpendicular to it. The differences in 178 the percentages of component parts on such sections are indicative of orientation. Unfortunately, the directions were not marked on the vertical thin sections, so it is not known which direction parallels the ground surface. Orientation should be most evident in components such as grains and pores. In Table 30 the differences in the percentage of pores and grains obtained in the traverses made in the two directions on the vertical sections are compared with the comparable differences on the horizontal sections. The figures in the table were obtained by dividing the differences in percentage between the long and short traverses, by the average percentage for the entire section, and multiplying the result by 100. Only horizons from which both horizontal and vertical slides were made, and traversed in both directions are included in this tabulation. The data in this table do not indicate a distinct orientation of grains, pores, or shale (in profile 50-2). In 8 of the 13 cases included in the table, the percentage of pores varied more with direction on the horizontal slides than on the vertical slides. Only in the B21 horizon of profile 50-2 is there appreciably more directional variation on the vertical slide than on the horizontal. The directional differences in the percentage of grains are greater on the horizontal sections than on the 179 Table 30. Comparison of directional differences on hori- zontal sections as opposed to comparable differences on vertical sections, with respect to the percentages of grains and pores. Constituent Pores Grains Orientation . Horizontal Vertical Horizontal vertical of thin section (difference between long and short traverses expressed as a percentage of the average.) Profile and Horizon 37-3 B1 46 34 43 6 B21 19 10 29 55 B22 5 9 70 32 B3 22 25 31 94 C21 10 13 88 12 2-1 B21 16 28 0 5 322 33 13 28 7 Cca ll 8 ll 43 C22 56 48 48 14 50-2 B21 8 4 45 24 B22 28 16 20 22 Cca 20 3 27 17 C2 18 13 44 38 Shale 50-2 B21 7 11 322 42 16 Cca 30 23 C2 171 13 vertical in 8 out of the 13 cases included in the table. Exceptions are found in the 321 and B3 horizons of profile 37-3, and the Cca horizon of profile 2-1. In these horizons the directional differences in the percentage of grains are greater on the vertical sections than on the horizontal. 180 It had been expected that the flat-lying shale particles in profile 50-2 would show a definite orientation, but this was not the case. The percentage of shale particles varied more with direction on the horizontal thin sections than on the vertical. 4. Oriented clay films Clay films were observed in the field on the B horizons of all three profiles, and on the Cca horizon of profile 37—3. These observations were substantiated by examination with the binocular microscope, on samples from both the 1958 and 1959 profiles. Buol and Hole (1959) and Brewer (1956) have indicated that clay which has moved in the soil profile should be deposited in an orderly fashion, such that it is optically oriented. The presence of optically oriented clay flows is one of the criteria for the recognition of argillic horizons, according to the 7th Approximation (1960). The thick clay films on the exteriors of the peds which were Observed in the field did not show up in the thin sections. Small bands of optically oriented clays were found along fine pores in the upper B horizons of all three profiles from which thin sections were made, especially in profiles 50-2 and 2-1. The clay films identified on the thin sections were nowhere near extensive enough to account for the heavy films observed in the field. The field descriptions indicate the maximum of clay films in the 181 Fonnan soils, yet the thin sections from profile 37—3 contain the fewest optically oriented clay films. There are three possible explanations for the discrepancy between field observation and thin section study. The thick films observed in the field occurred on the exteriors of the peds. The thin sections were made from natural peds, so the thick films should appear around the perimeters of the horizontal thin sections. In this position, the films could have been destroyed in the process of making the slides. However, it seems unlikely that the removal would be so complete if this were the case. Another possible explanation is that what were considered to be clay films in the field were only organic coatings on the peds. Organic ped coatings were recognized in the field, but were thought to cover clay films. The ped surfaces glisten when moist, indicating that clay as well as organic matter is present. If the coatings identi— fied as clay films in the field are not clay films, we ‘ have made a serious error in field observation, which will cause trouble in classifying the soils under the provisions of the 7th Approximation. The third, and most likely explanation is that the clay coatings are present, but the clays in them are not optically oriented. Brewer (1956) has observed thick clay films on Solonetzic soils, in which the clays were not oriented. The soils used in this study are not Solonetzic, and contain but little sodium. However, the 182 strongly developed prismatic structure in these soils is not greatly different from that in the Solonetz soils. In profile 37-3 in particular, there is strong evidence of physical mixing. Tongues of material from an Al horizon originally only 3 or 4 inches thick extend to depths of 20 inches. The 2:1 type clay minerals in the B horizons cause marked expansions and contractions. The resultant mixing perhaps prevents the illuvial clay from becoming optically oriented. There is no doubt a cyclic process of shrinking and swelling. Some A horizon material falls into the cracks each time they open, and cover the previously deposited clay films. Thus the coatings are composed of alternate thin layers of organic matter and clay. Even if the clay in this position were optically oriented, it would not show up well because of the masking effect of the surrounding organic matter. The generally high birefringence in the ped interiors does not aid in the recognition of oriented clay films. Certain areas in the ped interiors have a much higher birefringence than adjacent areas. This is especially true in the B horizons. There are thin bands of pressure oriented clay films around the coarse grains, where these are firmly imbedded in the dense ground mass. Such films result from the pressure created when the ground mass expands against the pebble. 183 5. Examination of coarse fragments a. Selection and purpose Five coarse fragments were examined on each of the thin sections. These included single grains of quartz or feldspar, multiple grain igneous fragments, carbonate concretions, and fragments of shale and chert. They were examined for surface and edge weathering, pressure orientation of surrounding clay, and location with respect to other soil features. Most of these fragments were of very coarse sand and fine gravel size, but a few of medium and coarse sand size were included, in cases where there were not enough of the larger fragments on a particular thin section. The fragments were randomly selected, and are not necessarily statistically representative of the coarse fragments in the horizons from which the thin sections were made. b. Definitions of the categories and classes used in evaluating the extent of weathering include: 1) Kind of fragment 1. Single grains of hard minerals, such as quartz and feldspar. 2. Fragments of sedimentary rock, such as shale or lime concretions 3. Granitic or other igneous rock fragments, consisting of severalto many individual grains, usually representing several mineral species, and including both light and heavy minerals. 4. Igneous rock fragments consisting of one large grain and several small ones, or of two to four medium sized grains. 184 2) Degree of surface weathering. 0. No weathering. l. A faint pattern of cracks is developed on the surface. No weathering products visible. 2. Small amounts of weathering products are present in the fine cracks, and in surficial depressional areas. 3. There are either moderate amounts of weathering products over the entire surface of the fragment, or there are heavy accumulations on some, but not all, of the component grains. 4. Large amounts of weathering products are present over the entire fragment. 3) Degree of edge weathering. 0. No weathering. 1. Faint cracks extend inward from the edge of the fragment. These are free of weathering products. 2. Weathering products are present in the mouths of the fine cracks. 3. Large cracks extend into the grain, and small pieces are broken off, or are about to be broken off. Moderate to large amounts of weathering products are present in the mouths of the cracks. 4. The fragments are definitely split into two or more pieces, otherwise similar to 3. 5. Rinds of weathering products extend along the edge of the fragment, and well into the cracks. c. Results The number of fragments showing each of the degrees of weathering defined above are tabulated by grain type, profile, and horizon in Tables 31, 32, and 33. d. Discussion The resistance of quartz to weathering is illustrated by the fact that a high percentage of the quartz fragments are unweathered, compared to feldsaprs and fragments of mixed mineral species (Table 32a). Single grains of hard 185 .mGONHHo: mm 0cm Hm mmpDHocH* onH we eN 0H mm mmHHmonm m Hmuoa om HN h m 0H mcouHuon U .mHmuoa mN mH g N m mcouHuoc moo .mHmuOB om mm HH N Nm chNHuon m .mHmuOB mH m N o e mcouHHoc m .mHmuoe mv wN v v MH HmuOB 0H m o H m O 0H s N N N mou 0N OH H H m m m a H o o m 3.63 mmcumm om mN m N vH Hmuoe OH 0 o H m O 0H m N o H moo 0N 0H m H w m m N o o m a 3-3 cmEuom SmHupmm mm mN HH g Hm Hmuoa mN m m w m U m N o o m moo 0v mH n o mH *m m m H o H a 843 cmEHom Hmuos mxuou msHmum mxuou mum mHmnmCHE couHuom mHHmoum msomcmH sHmum HHmEm Hmum>wm lusmEHpmm mo puma mo tam HHom wHQHUHSS a meMH mco mucmemmum mchnm mHmch .CONHHoc tom mHHwoum an .mmmwu ucmeMMHp mo mucmammum mmumoo mo mumafisz .Hm OHQMB 186 Table 32a. Surface and edge weathering bg profile and horizon; Single grains of ar minerals. Degree of weathering Profile and . Surface Edge Horizon or Mineral 0 1 2. 3 4 0 l 2 3 4 5 37-3 A 0 l 0 0 0 1 0 0 0 0 0 B 8 5 4 l 0 10 l 4 2 0 l Cca 2 0 l 0 0 3 0 0 0 0 0 C 5 2 2 0 0 6 0 1 1 l 0 Total 15 8 7 l 0 20 1 5 3 l 1 2-1 A 3 0 0 0 0 2 0 1 0 0 0 B 2 l l l l 2 0 3 l 0 0 Cca l 0 0 0 0 1 0 0 0 0 0 C 2 0 2 0 0 3 0 l 0 0 0 Total 8 l 3 l l 8 0 5 1 0 0 50-2 A 0 0 0 0 0 0 0 0 0 0 0 B 2 3 2 O 1 2 l 2 2 0 1 Cca 0 0 l l 0 0 0 0 0 1 l C l l 0 l 0 l 0 0 2 0 0 Total 3 4 3 2 l 3 1 2 4 1 2 3 Profile total 26 13 13 4 2 31 2 12 8 2 3 Quartz l9 7 0 0 0 18 1 4 2 l 0 Orthoclase 6 4 9 2 2 8 l 6 5 1 3 Albite l 2 4 2 0 5 0 2 1 0 0 A horizons 3 l 0 0 0 3 0 l 0 0 0 B horizons 12 9 7 2 2 14 2 9 5 0 2 Cca horizons 3 0 2 1 0 4 0 0 0 1 l C horizons 8 3 4 l 0 10 0 2 3 l 0 187 Table 32b. Surface and edge weathering by profile and horizon; fragments of sedimentary rocks. Degree of weathering Profile and Surface Edge Horizon 0 l 2 3 4 0 l 2 3 4 5 37—3 C 0 2 l 0 l 3 0 0 l 0 0 2-1 B 0 0 1 O 0 l 0 0 0 0 0 C l 0 0 0 0 l 0 0 0 0 0 50-2 B 1 0 0 0 0 l 0 0 0 0 0 Cca 0 l 0 l 0 0 0 0 2 0 0 Total 2 3 3 l l 6 l 0 3 0 0 Lime 1 2 2 0 l 4 l 0 1 0 0 Shale l l l l 0 2 0 0 2 0 0 Table 32c. Surface and edge weathering by profile and horizon: fragments consisting of one large and several small grains, or of a few medium sized grains. Degree of weathering Profile and Surface Edge Horizon 0 l 2 3 4 0 l 2 3 4 5 37-3 A 0 0 1 0 0 0 0 0 1 0 0 B l 2 3 1 0 2 2 1 2 0 0 C 0 0 2 0 l 2 0 l 0 0 0 Profile 1 2 6 l l 4 2 2 3 0 0 2-1 B 1 l l 0 0 2 0 0 l 0 0 Cca 0 l l 0 0 0 0 0 l 0 1 C 3 0 l 0 0 3 l 0 0 0 0 Profile 4 2 3 0 0 5 l 0 2 0 1 50-2 A 0 0 l 0 0 1 0 0 0 0 0 B 0 l 0 0 0 l 0 0 0 0 O Cca 0 2 0 0 0 0 0 2 0 0 0 Profile 0 3 l 0 0 2 0 2 0 0 0 3 profile total 5 7 10 l l 11 3 4 5 0 l A horizons 0 0 2 0 0 l 0 0 1 0 0 B horizons 2 4 4 1 0 5 2 1 3 0 0 Cca horizons 0 3 1 0 0 0 O 2 l 0 1 C horizons 3 0 3 0 1 5 1 l 0 0 0 188 Table 32d. Surface and edge weathering by profile and horizon, multiple grain igneous fragments. Degree of weathering Profile and Surface Edge Horizon 0 l 2 3 4 0 l 2 3 4 5 37-3 Ap 0 0 l l 1 l l 0 0 l 0 B 3 5 2 4 l 6 l 5 3 O 0 Cca 0 2 0 0 0 2 0 0 0 0 0 C 2 0 3 l 3 5 2 2 0 0 0 Profile 5 7 6 6 5 l4 4 7 3 1 0 2-1 Ap 0 2 0 0 0 0 l 0 0 l 0 B l 0 6 2 l 4 1 2 2 l 0 Cca 4 l 2 0 0 3 0 0 0 4 0 C 3 l l l 0 5 0 0 l 0 0 Profile 8 4 9 3 l 12 2 2 3 6 0 50-2 Ap 1 0 2 l 0 1 1 0 l l 0 B 0 2 3 3 2 4 l 2 2 l 0 Cca 0 0 2 2 0 3 0 0 0 0 1 C 0 2 2 l l 4 0 2 0 0 0 Profile 1 4 9 7 3 12 2 4 3 2 1 3-profile Total 14 15 24 16 9 38 8 13 9 9 l A horizons l 2 3 2 l 2 3 0 1 3 0 B horizons 4 7 11 9 4 14 3 9 7 2 0 Cca horizons 4 3 4 2 0 8 0 0 0 4 l C horizons 5 3 6 3 4 14 2 4 1 0 0 189 Table 33. Summary of coarse fragments by degree of weathering. Degree of weathering Type of Surface Edge fragment Number of fragments 0 l 2 3 4 0 l 2 3 4 5 Single grains of hard minerals Quartz l9 7 0 0 0 18 l 4 2 l 0 Orthoclase 6 4 9 2 2 8 l 6 5 l 3 Plagioclase l 2 4 2 0 5 0 2 1 0 0 Total 26 13 13 4 2 31 2 12 8 2 3 Sedimentary fragments shale l l l 1 0 2 0 0 2 0 0 lime l 2 2 0 1 4 l 0 1 0 0 Total 2 3 3 1 l 6 l 0 3 0 0 Fragments of one large and several small grains Dominantly: Quartz 2 3 2 0 l 6 l 2 0 0 0 Orthoclase l l 3 1 0 0 2 1 3 0 0 Plagioclase 0 2 l 0 0 l 0 l 1 0 0 Mixed 2 l 4 0 0 4 0 0 1 0 1 Total 5 7 10 1 1 ll 3 4 5 0 1 Multiple grain igneous fragments 14 15 24 16 9 38 8 l3 9 9 1 TOTAL 47 38 50 22 13 86 14 29 25 ll 15 A horizons 4 3 5 2 1 6 3 l 2 3 0 B horizons 19 20 23 12 6 35 7 19 15 2 2 Cca horizons 7 7 7 4 0 12 0 2 3 5 3 C horizons l7 8 15 4 6 33 4 7 5 l 0 190 minerals make up only a third of the fragments studied (Table 31) but account for over half the fragments on which no surface weathering was observed (Table 32a). Edge weathering was observed on about equal proportions of the single and multiple species fragments, the proportion being small in both cases. No surface weathering was observed on only a fifth of the multiple species fragments (Table 32c). Differences were usually observed in the amount of weathering among the several component grains making up the multiple species fragments. Weathering occurs on the surfaces of the less resistant components of such fragments before these components are split apart. The greatest number of weathered multiple species fragments were observed on the thin sections from the B horizons. Among the fragments composed of one large and several small grains, those on which the least evidence of weathering was observed were those in which the large grain was quartz. Sedimentary rock fragments were studied in numbers too small to permit the evaluation of their weathering sequence. The coarse fragments studied were situated in a variety of positions with respect to other soil constituents. Some were completely surrounded by dense ground mass, while others sat loosely in large pores. A narrow void was observed between many of the fragments and the surrounding ground mass. Thus is likely the result of the shrinkage 191 of the ground mass as the soil dries out. In many such cases, there is a rim of birefringent soil material just outside the void. When the ground mass becomes wet,-it expands up against the coarse fragment, and the resultant pressure causes the clay in the outer rim of the ground mass to become oriented, creating the observed birefringence. Sixteen of the 170 coarse fragments examined were surrounded by distinct rims of optically oriented clay and 29 others were partially surrounded by less distinct rims. The phenomenon is most evident in the B horizons, and is not related to the type of coarse fragment. On the basis of this study, the following sequence is suggested in the weathering of coarse fragments. The first step is the development of a pattern of fine cracks on the surface of the fragment. These tend to follow twinning striae in the feldspars, and to occur in concave areas on the surfaces of quartz grains. Weathering begins in these cracks, and spreads back from them across the surface of the grain. Edge weathering begins where the fine cracks intersect the edge of the grain, and spreads in both directions along the edge of the grain. The splitting of grains is due to a more sudden type of physical weathering and can occur anywhere in the sequence of chemical weathering. There were numerous cases where neither surface or edge weathering was observed on grains that had been split. 192 6. Binocular microscope examination a. Mode of observation Material from each horizon of the profiles sampled in 1958 was examined under the binocular microscope during the winter of 1958—59. These examinations were made primari- ly to supplement field observations on the extent of clay films, carbonate concretions, and decomposition of igneous pebbles. The material examined was felt to be very similar to that obtained in the sampling in 1959 at the same sites. The results obtained on the samples taken in 1958 are felt to be applicable to the profiles sampled in 1959, although the depths and designations of the horizons are slightly different. b. Results Detailed descriptions of the findings for three profiles are reported here, with reference made to other profiles where applicable. The three discussed in detail are those taken at the sites of the profiles on which thin section studies were made. 1. Profile F2B (at site of profile 37-3 Forman) 0-5" High in organic matter. Some fine sand grains are held loosely on the exteriors of the peds. These are stained with organic matter. 193 5-16" Cleavage faces on the peds are rounded, due to the presence of heavy clay films and organic matter. The clay was detected, since it glistened when moistened. The organic coating lies outside the clay film and makes it difficult to observe. There are no sand grains on the exteriors of the peds, but some are held in the clay-organic coatings and are not in contact with the ped interior. 16-27" A few clay films are present on the vertical ped faces. The organic coatings end in the upper part of this horizon. The lime is concentrated into small pockets, and is soft and finely divided, rather than concretionary. These pockets of lime are distributed throughout the soil mass, but are most numerous around some of the large pebbles. Some of these pebbles are completely surrounded by a rim of concentrated lime. 27-45" There are no clay films. The lime is concentrated into pockets that are larger and more prominent than those in the above horizon. They resemble patches of snow on the bare ground. They are not concretions, since they are no harder than the surrounding soil mass. The lime concen— trations are not oriented with respect to pebbles. A higher proportion of the coarse fragments are shale. 45-60“ Very dense, with few pebbles. Part of the lime occurs as true concretions, which are large, prominent, and uniformly distributed through the soil mass. There are some iron stains, but no iron concretions. 194 Profile F2A has similar characteristics. No true lime concretions were found in this profile, but the pockets of lime concentration became harder with depth. There were small concretions of iron oxides in some of the reddish mottlings. 2. Profile BlA (at site of profile 2—1, reddish Forman). 0-6" All the sand grains have organic coatings. Con— siderable B horizon material included. 6-13" Continuous moderate to thick clay films, which are not covered by organic matter. No sand grains are held in these films. There are a few iron stains, but no con- cretions of iron oxides. 13-21" Lime is concentrated into pockets, but is not concretionary. There is evidence of physical breakdown in igneous pebbles. The former component grains of these pebbles are still in the same general area, but are separated from each other. The lime concentrations are oriented around such coarse fragments. Numerous flakes of muscovite occur loose in the soil mass. 37-60" The amount of lime concentrated into pockets decreases gradually with depth, until at 60 inches it is practically all disseminated. The lower most of these con- cretions are very soft, and follow root channels and pores. Coarse fragments are practically all igneous, and some are breaking up as described in the above horizon. There are some iron stains, especially around the decomposing pebbles. 195 Profile B18 is very similar to the profile described above. Clay films were observed to a slightly greater depth (37?), and there were still a few lime concentrations at 60 inches. 3. Profile ESE (at the site of profile 50-2 Barnes) 0-5" There are numerous bleached sand grains, mostly of very fine sand size, on the exteriors of the peds. 5-14" Clay films are present, but are very thin and patchy. There are thick organic coatings on the exteriors of the peds, which may mask more extensive clay films. 14-17" Transitional layer in which light clay films are still present, but calcareous, with finely divided lime present on the ped surfaces. The coarsest fragments are igneous pebbles, but there are numerous shale particles of coarse sand size. 17-34" High in lime, which is finely divided, and disseminated through the soil mass. There is no trace of clay films. Coarse fragments include both shale and igneous pebbles. There are a few faint iron stains. 34-60" The only concentrations of lime are along the root channels, but intervening areas contain large amounts of finely divided, disseminated lime. Fragments of heavy minerals and some gypsum crystals are present. High in shale. A few iron stains are present, including some on the shale particles. 196 Profile B5A contains more concentrations of soft lime, but no concretions. This profile contains very large amounts of shale. Reddish iron stains and iron concretions are more numerous in profile BSA than in profile B5B. c. Discussion 1) Clay films The microscopic examination of peds and crushed samples supported the field observation of clay films. In only a few cases were the field designations on clay films changed on the basis of this examination. Clay films were observed to greater depths in profile 37—3 (Forman) than in any of the other profiles. 2) Lime concretions Some lime was found to be concentrated into small pockets in the Cca and<1horizons of all profiles, but to a much lesser extent in the Barnes profiles than in the Forman or reddish Forman profiles. Few of these concentra— tions were concretions in the true sense of the word, being composed primarily of soft, finely divided lime particles packed together in a small pocket. These concentrations were most pronounced in Forman profile 37-3, where they were most numerous in the Cca horizon, and decreased in abundance with depth. The deepest' concentrations areconfined to Vthe sides of pores, and coatings on pebbles; whereas those in the upper calcareous horizons are distributed throughout the soil mass. 197 The maximum development of these concentrations is in horizons in which the ground mass of the fabric is very dense. There are few fine pores, but a fair number of coarse pores traversing these horizons. As the soil dries out, soil water moves toward these large pores, since the soil material adjacent to them dries out first. The lime is deposited in the large pores, especially where they are partially obstructed. The relative scarcity of surfaces on which the lime can be precipitated results in its con- centration in the few pores available. In fabrics where numerous fine pores are present (as in profile 50-2), there is less concentration of the lime, since areas where it can be precipitated are scattered throughout the soil mass. The theory outlined above has not been proven, but seems the best explanation of observed differences in lime distribution that is consistent with the information available. 3) Iron stains The reddish mottlings found in the C horizons of all the profiles are caused by stains of iron oxides. There are small concretions of these oxides in the centers of a few of the stained areas. Iron stains are also present on the surfaces of some of the shale particles. These mottlings are a manifestation of the iron in the glacial 198 till, and are not in themselves indicative of restricted natural drainage. 4) Disintegrating pebbles The number of disintegrating igneous pebbles found in the binocular microscope examinations were considerably greater than that indicated by the thin section studies. This probably results from a greater ability to recognize the pockets formerly occupied by such pebbles in the debris preparations where they can be observed in three dimensions, than on the two—dimensional thin sections. 7. Bulk density The discussion of bulk density is included under the general heading of soil fabric, since it too involves the entire soil mass. a. Results The bulk density values obtained by the clod method (described in Chapter IV) in the profiles sampled in 1959, and in those sampled at the same sites in 1958 are shown in Table 34. Bulk densities were also calculated from core samples taken in several of the profiles studied in 1958. It was decided to discontinue core sampling because the dry condition of the soil in the summer of 1958 made it impossible to get good cores. Of the six sites sampled in 1959, core samples were obtained only at the sites of the Forman profiles. The bulk density values calculated from 199 these cores are included in Table 34 for comparative purposes, but are felt to be less reliable than those obtained by the clod method. Most of the discussion, and all of the calculations, involving bulk density in this and subsequent sections, are based on the values obtained by the clod method on the profiles sampled in 1958, since this is the most complete set of data. The values obtained using the large clods taken from the profiles sampled in 1959 are felt to be equally reliable, but this data is available on only a limited number of horizons. b. Pattern of bulk density in the profile There is a tendency for the bulk density to increase with depth in all profiles. The Cca horizons do however have lower bulk densities than the B horizons in a few pro— files. The very low bulk densities of the Ap horizons is due in part to the high organic matter content, in part to the fact that they have been disturbed, and possibly in part to the loss of constituents such as clay, without a collapse of the skeleton of the fabric. Brewer (1956) states that illuviation of clay into the B horizon should cause an increase in its bulk density. The B horizons of the profiles under consider- ation have bulk densities higher than those of the A horizons, yet lower than those of the C horizons. These horizons still show some evidence of illuviation. 200 The amount of clay necessary to produce a clay film should not change the bulk density of a horizon by much, especially in View of the low bulk densities of the clay minerals. There are also situations where the illuviation of clays could actually help decrease the bulk densities of the illuvial horizons through their contribution to the shrink—swell potential of the soil material. This shrinking and swelling produces cracks, into which A horizon material can fall. This material has a low bulk density and therefore decreases the bulk density of the B horizon into which it falls. For these two reasons, increased bulk density should not be required of anilluvial horizon. There is generally good agreement in the bulk density values obtained on the small clods from the 1958 profiles, and those obtained on the large clods from the 1959 profiles, at least in the Forman and reddish Forman soils. The large clods gave much lower values for the Barnes profiles. The bulk density values in the C horizons correlate well with texture and thin section observations. 8. Summary of fabric analysis The evidence regarding the presence of illuvial clay in the B horizons of these profiles is somewhat contradictory. Field observation, and examination with the binocular micro— scope indicates the presence of clay films on the exteriors of the peds. No oriented clay films were observed on the thin sections in these positions, and the B horizons have .meOU =m x m mUMUHHmHHu mo ommuw>¢# .50 m on m .50 OH on m .mumm HmHCHmC .kumEMHp CH .mUoHo mumoHHmHHu mo mmmum>m>usm HHom an mHmmHMCd .kuwfimHv CH .mtoHU OHMUHHQHHH mo mmmum>me 050,—” =..H¢Imm me.H :omunH mm.H :mmuom mm.H =0Hun >~.H =mmuom mm.H =¢uH mm.H =HHum #mmmH .mmuoo Hm.H soonmm . . omoH :OQUOV 00.4.. ..Nm-I.V.V @504” ...O®.Iom HN-oH iomlom . om.H =o¢umm mo.H =¢vuom mo.H =mmumm mo.H =m~umH om.H :oouee mo.H scones me.H =mmumH s¢.H =omu~m oo.H =mmuvH em.H =mHumH houH :mmueH m¢.H HHNIHH mq.H =vHum mv.H =wHum mm.H =¢Huo mm.H =mHum mv.H =wHu¢ mm.H =¢Hu¢ mm.H =muo mm.H =muo HH.H =ouo mv.H =ouo NN.H =euo m¢.H zwuo 44mmmH .mUOHo HH.H =mmusm mm.H =Hmunm em.H :mmnem mo.H :ooume mm.H somuHe Ho.H =emumH oo.H =mmueH so.H =¢NI¢H oo.H :mmumH mo.H =mmuvm mo.H =mHum H6.H =vHum nm.H =mHnm om.H =mum 4mmmH .mnoHo .6.s shown .o.s shame .6.s spawn .6.3 shows .o.n spawn .o.s suomo coHumcHsumnmo muom Huom mum Hum Hue munm .oc mHHmonm meHmm CmEHom CmepmH CmEHom HHom .AmmHHmouo my mmmH cH omHosmm mmHHmoum mcu Scum mmuoo Co meHEkumu mm pCm HmmHHMOHm mv mmmH CH ~HmmHHmonm my mmmH CH pmuomHHou mmHmEMm Co ponumfi UOHU OCH an UOCHEHmumU mm mwsHm> huHmCmU xHCm .wm wHQMB 202 lower bulk densities than the C horizons. Most other workers have been likewise uncertain regarding the movement of clay in Chernozem soils prior to degradation. On the basis of all the information collected during this study, we must concur with the field observations, and conclude that some clay movement has occurred. Most future soil classification must be based on field observations, and thus such observations must be weighted heavily. It is not known for sure why clay films do not show up in the thin sections. The best explanation is that the illuvial clay occurs as a complex with, or in very close physical association with, organic matter. In such situations, the optical properties of the clay are masked or modified by the organic matter, and the films are not oriented nor birefringent. The distribution of carbonates in the soil mass is related to the abundance and size of pores. Where pores are fine and numerous, the carbonates are disseminated, whereas when pores are few and coarse, the Carbonates are concentrated. With the exception of clay films, the analysis of fabric is in general agreement with field observations and mechanical analysis data. There is a clear difference between the fabrics of the assumed original material (C horizons) of the Barnes and Forman profiles, and to a lesser extent between those of the Forman and reddish Forman profiles. 203 G. Cations on the Exchange Complex 1. Results Exchangeable cations and cation exchange capacity were determined by the Lincoln Soil Survey Laboratory, on. all horizons from the six profiles sampled in 1959. A 1.0 N ammonium acetate extraction procedure was used. The results of these determinations are included in Tables 50 to 55, in the Appendix. In all horizons, the sum of the exchangeable cations (H, Na, K, Ca and Mg) exceeds the indicated cation exchange capacity, in some cases by a very substantial amount. The sum of the cations is compared to the determined exchange capacity in Table 35a. The Soil Survey Laboratory explains this discrepancy (personal communication) as being due to the dissolving of calcium and magnesium carbonates by the ammonium acetate. Some of the calcium and magnesium ions from the dissolved carbonates are then measured as exchangeable cations. While it is true that the discrepancy is much greater in the calcareous horizons, it also exists in the non- calcareous A and B horizons. The presence of as little as 0.5 per cent calcium carbonate equivalent in these horizons would be enough to account for the discrepancy if it were all dissolved. Such amounts might not be detected by the methods used for the determination of carbonates. 204 OhH HON mmN mH mN Nm X * m.NN N.hN o.NN m.N m.m m.o .mE .wocmumMMHu >.mm >.o¢ n.mm m.vH H.mH 0.5N .mE .mCOHumo mo ECm N.mH m.MH H.0H m.NH N.mH n.0N .mE ..u.m.o CwEHom CmepwH ~NIN mHHHOHm me NmH th hmH 0H 5H ON X * m.nm o.NN m.mm v.0N v.m ¢.m H.¢ .wE .woCmumHMHp ¢.om ©.mm o.m¢ w.mm ¢.HN H.mN m.¢N .mE .mCOHumo mo ECm H.mH ©.mH m.MH o.mH o.mH h.mH N.0N .mE ..o.m.o CmEHom CmepmH ~HIN mHHmoum mow ©NN CHN NQN hNH Ne mH 0N X % ©.¢m m.mN @.¢N m.wN o.mH 0.0H h.¢ ¢.h .mE .mUCmHOMMHU m.©© H.H¢ H.©m m.mm H.Nm m.mm m.mN 0.0m .mE mCOHumO mo 55m h.HH o.NH m.HH o.HH H.¢H m.mN N.mN ©.mN .wE ..O.m.o CwEHom .HIHv wHHmonm NhH ooH mmH CMH 00H mH wH HN mN X % m.vN m.vN o.mN N.NN m.ON N.m m.m H.@ m.@ .mE .mOCmemet N.mm m.o¢ m.o¢ m.mm m.wm m.mm ¢.¢m m.mm H.mm .mE mCoHumo m0 ECm w.¢H m.mH m.mH ©.©H @.mH m.mN m.mN v.mN ©.mN .mE ..U.m.o sashes .munm mHHmonm o o o o moo moo mmm Hmm Hm mg CONHHOE .mmHHMOHQ me CH Am: UCm .M .wz .mv mCOHumo pmusmmma oCu mo 85m may on >uHoQOo mmCmCUxm COHumo pmHCmmmE may mo COmHHmmEoo .mmm OHQMB 205 meMCUxm pmusmmmfi mo qu0 Mom mm wUCmeMMHU mum mmCHm> mmmquUHmme .HHom Ho .m 00H Hog A.mEV.mmCHm> pCmHm>HCqHHHHE muHommmo mMN N.mm m.mv h.¢H wwH m.HN b.0m m.¢H NON ®.mm o.mm v.HH th o.NN H.hm H.mH th o.vN m.bm m.MH HCH m.ON h.mm m.vH mmCHmm meHmm hmH H.MN m.hm h.¢H HmH m.mN m.ov w.¢H .Nlom mo m.NH m.Nm m.mH OHHMOHm om. m.m m.mN ¢.mH ~Hlom OHHMOHm 0H m.m m.mN m.NN 0H ¢.m m.mN ¢.0N mm 0.0 N.0m N.¢N hm h.m m.mm N.mN R « .mE .moCmHmmmHu .mE ~mCoHumu mo 55m $8 ..U.w.o X * mE .mUCmeMMHp owe smCOHUMU MO 85m 005 5000000 206 The exchange capacities are expressed as milliquivalents per 100 grams of total soil, including carbonates. The exchange capacities of the non-carbonate soil is no doubt higher than the indicated values, but this should not effect the comparison with the sum of the cations, which is also expressed on the basis of the total soil. An alternative cause for the discrepancy is the possible fixation of ammonia by the soil clay. This results in the determined exchange capacity being too low by an amount equal to the quantity of ammonium ion fixed. This is a common occurrence in saline and alkali soils (U.S.D.A. Handbook 60, 1953, p. 20). The soils under consideration are neither saline nor alkali, so the appli— cability of this theory is questionable. Regardless of its cause, the discrepancy between the sum of the cations and exchange capacity makes the data less valuable, and necessitates certain assumptions, before certain types of calculations can be made from this data. 2. Discussion a. Hydrogen on the exchange complex Pawluk and Bentley (1956) and Robertson (1961) indicate that the replacement of basic cations on the exchange complex by hydrogen is one of the early steps in Chernozem degradation. Therefore, the presence of appreciable exchangeable hydrogen should be indicative of incipient degradation. 207 The percentages of the exchange complex, and of the sum of the cations, accounted for by hydrogen, together with pH and the depth to which exchangeable hydrogen occurs in measurable amounts, are shown in Table 35b. Table 35b. Hydrogen as a percentage of the exchange capacity (cec) and total cations (tc), pH, and depth to which exchangeable hydrogen occurs in measurable amounts. Depth to which exch. Horizon QPof ;}of gzif ‘izif H occurs in Soil Series measurable & pH cec tc pH cec tc pH cec tc pH cec tc amts. Profile Forman 37-3 6.4 24 19 6.5 18 15 6.8 13 11 7.2 10 8 179 Forman 41-1 7.2 11 9 7.4 10 8 7.7 2 2 139 reddish Forman 2-1 6.3 25 20 6.7 l6 14 7.4 11 9 19V reddish Forman 2-2 6.8 22 17 6.7 20 16 7.1 13 ll 249 Barnes 50-1 7.5 9 7 7.1 11 11 7.6 12 9 179 Barnes 50-2 7.6 9 7 7.5 8 7 7.9 l 1 15V Exchangeable hydrogen was not determined on previously sampled profiles from this area, so wider compari- sons cannot be made. The amount of exchangeable hydrogen in the calcareous horizons was too low to be measured. In such horizons any exchangeable hydrogen would combine with soil water to decompose the carbonates, releasing calcium and magnesium ions which would then saturate the exchange complex. 208 The Barnes profiles contain lower percentages of exchangeable hydrogen than the Forman or reddish Forman profiles. The highest percentages of exchangeable hydrogen occur in the reddish Forman profiles, in which carbonates are leached to the greatest depths. It appears that hydrogen has begun to replace calcium and magnesium on the exchange complex in the sola of all six profiles. b. Potassium on the exchange complex The percentage of the exchange complex and total cations accounted for by potassium are shown in Table 36a. These percentages decrease with depth in all six profiles. The sharpest declines are from the A to the upper B horizons. The amount of exchangeable potassium seems to be related to organic matter content. Table 36a. Exchangeable potassium as a percentage of the exchange capacity (cec) and total cations (tc) in six profiles. Soil series Forman reddish Forman Barnes Profile no. 37-3 41-1 2-1 2-2 50-1 50-2 K as % of: cec tc cec tc cec tc cec tc cec tc cec tc Horizon Ap 4.7 2.7 1.9 2.8 3.6 3.6 7.7 5.8 4.6 1.8 4.6 4.6 B1 2.4 2.4 - 321 3.1 2.3 1.8 2.7 2.6 1.7 3.6 3.0 3.3 0.8 3.1 2.3 B22 2.8 2.1 3.9 2.3 2.9 2.2 4.0 3.2 3.0 2.5 2.0 1.3 Cca 1.6 0.8 1.8 1.2 3.0 1.3 2.1 0.7 2.2 0.9 Ccs 2.2 0.7 3.0 0.7 C 1.1 0.5 2.0 0.4 2.9 1.1 2.9 1.0 2.0 0.8 2.4 0.8 C 2.1 0.8 5.1 0.9 2.9 0.8 2.9 1.4 1.6 1.0 2.6 0.9 C 2.6 1.0 2.3 0.8 2.9 1.1 2.8 0.9 C 2.8 1.1 1.6 0.5 209 Sodium on the exchange complex The percentages of the exchange capacity and total cations accounted for by sodium are shown in Table 36b. Table 36b. Exchangeable sodium as a percentage of the cation exchange capacity, cec, and of the total cations, in six profiles. Soil series Profile no. Na as % of: reddish Forman 2-2 cec tc 50-1 cec tc Barnes Horizon AP B1 B21 822 Cca Ccs 0000 O l-4 verso wrak: (D O 26.410.018.7 27.210.920.4 in the A or B horizons. in the C horizons of the reddish Forman profiles is surprising— ly high, of their occurrence, leached in the profiles. associated with high water tables and restricted drainage. The occurrence of high sodium contents in the presence of good drainage conditions indicates that the C horizons of these profiles are derived from materials containing sodium bearing minerals in appreciable quantity. Sodium is much more abundant in the C horizons than The amount of exchangeable sodium in view of the good drainage conditions in the area and the depth to which carbonates are High sodium content is usually 50-2 cec tc I£1000 O p I—‘\l\l oxmtn rHFJN 210 The sola of all six profiles contain but little exchangeable sodium, only a quarter to a tenth as much as the sola of Solonetz soils from the same area. This indicates success in the attempt to select profiles in which the structure is not sodium induced, as it is in the case of the columnar B horizons in the Solonetz soils. d. Calcium and magnesium on the exchange complex Calcium and magnesium are considered together in this discussion, since if the discrepancy between the measured cation exchange capacity and the sum of the cations is due to the dissolving of carbonates, it would be necessary to know the relative proportions of calcium and magnesium carbonates dissolved, in order to arrive at the correct value for the two cations individually. The percentages of the exchange capacity and total cations accounted for by calcium plus magnesium are shown in Table 37. The percentage of the exchange capacity accounted for by these ions was estimated by subtracting the sum of exchangeable hydrogen, potassium, and sodium from the measured exchange capacity, and equating the remainder to calcium plus magnesium. In doing this, the assumption is made that all the discrepancy is due to the dissolving of calcium and magnesium carbonates. Such an assumption is probably not entirely valid, especially in the non-calcareous A and B horizons. 211 Table 37. Percentage of total cations (tc), and estimated percentage of the cation exchange capacity (cec) accounted for by calcium plus magnesium in six profiles. Soil Series Forman reddish Forman Barnes Profile no. 37—3 41—1 2-1 2-2 50-1 50-2 Ca + Mg as %.of: cec tc cec tc cec tc cec tc cec tc cec tc Horizon Ap 71 78 87 88 71 76 70 77 86 90 86 88 B1 79 82 B21 83 86 88 89 81 84 74 79 85 88 88 90 B22 86 89 93 95 85 88 82 85 82 86 92 97 Cca 90 95 97 98 91 96 - — 91 97 90 96 Ccs - - - - 80 94 88 97 - — - - C 81 92 90 98 74 90 74 91 88 95 83 94 C 74 90 83 97 71 92 71 86 80 92 80 93 C 71 89 79 93 — - - — 82 93 78 93 C 70 88 78 96 - — - — — - - — The percentage saturation of the exchange complex is highest in the lower B horizons, where the percentages of sodium, hydrogen, and potassium, are all relatively low. The percentage is lower in the upper horizons because of the higher percentages of hydrogen and potassium, and in the lower horizons because of the higher percentage of sodium. The percentages of calcium plus magnesium are lowest in the reddish Forman profiles, where pH values are lowest, and leaching depths are greatest. The percentage saturation with calcium and magnesium in the reddish Forman profiles is less than that reported by Nygard et. a1. (1952) on a Waukon soil profile which they considered to be a degraded Chernozem. 212 e. Summary The difference between the distribution of cations in the six profiles is one of degree rather than of kind. The exchange complexes are all dominated by calcium and magnesium. Hydrogen has begun to replace these basic cations in the horizons from which carbonates have been leached. The percentage of sodium increases with depth, while that of potassium decreases. The data on exchange— able cations is quantitatively unreliable, because of the discrepancy between the sum of the exchangeable cations, and the determined cation exchange capacity. This is thought to be due to the dissolving of carbonates in the calcareous horizons, but no satisfactory explanation of its occurrence in the A and B horizons has been established. H. Organic Matter Content and Accumulation 1. Results Organic carbon, nitrogen, and C:N ratio were determined by the Lincoln Soil Survey Laboratory. The results of these determinations are included in the tables of routine analyses in the Appendix. The conversion of organic carbon to organic matter is made by multiplying the percentage of organic carbon by 1.72. 2. Evidence of organic matter accumulation The accumulation of organic matter is well recognized as a process in the development of Chernozem soils. This 213 process has certainly been operative in all the profiles involved in this study. a. Evaluation of the accumulation The following procedure was devised for evaluating the amounts of organic matter accumulated. The percentage of organic matter in each horizon was multiplied by the thickness of the horizon to give a value which, for lack of a better name, has been called organic matter units. The units for each horizon were added together to give a value for the entire profile (to the depth of the assumed original material). This method is less accurate than the calculation of the actual weights of accumulated organic matter, but permits comparisons among profiles on which no bulk density determinations were made. (The actual weights of organic matter accumulated have been calculated for three profiles, and are included in the tables of gains and losses.) The amounts calculated by this method tend to be high” because the horizons of accumulation have lower bulk densities than the assumed original materials. The percentage of organic matter in the assumed original material is applied to the present weight of the profile, and this amount assumed to have been present originally. The difference between this amount and that now present is assumed to have accumulated. 214 The amounts accumulated for the entire profile, and for the non-calcareous portion of the profile were calculated in this manner for the six profiles sampled in connection with this study, as well as for several other profiles which were included for comparative purposes. Profiles SS7SD 15—3 and 15—10 are profiles of Coddington loam which are developed on Cary, rather than Mankato till. These profiles are 70 miles south of the study area and were included to compare the effects of greater age and warmer climate. Profiles $56ND4l—5 (F3B) and SSBND ll-l (F4A) are well drained, virgin profiles from the southern part of the study area. They were included to illustrate the differences between the organic matter content of virgin and cultivated soils. Profiles S56ND4l-6 and SSBND2-2 are moderately well drained profiles from the southern part of the study area. Profile S56ND4l-4 is a Humic Gley soil from the same area. These three profiles are included to illustrate the change in organic matter content with drainage in a local area. The amounts of organic matter accumulated in these 13 profiles is indicated in Table 38. 3. Discussion a. Pattern of accumulation Glinka (1926) mentions that the zone of organic matter accumulation in the true Chernozem soils has no clear lower boundary. Instead, the organic matter content 215 m as we mm.Hm Ho.Ho 0H.o m cu m momm Humor CoumCHUUOU OHImH thmw oH mm Ho sm.om 6H.m6 no.0 e on m momm Amumov COHOCHUUOU mImH memm mH ON mm ON.>¢ mm.mm NH.O g0 .mU mmCHmm Nlom Qmem HH mN HO 5N.¢m NO.mO HH.O moo ~NNU mmCHmm Hlom Qmem vH mm mm mm.mv gm.HO th.O NNO .HNU CmEHom CmHUpmH NIN OZOmm OH me be mm.hm OO.mm OH.O NNU .HNO cmEHom CmHUpmH HIN nzmmm H em mm mm.N¢ mm.¢O HN.O mu .mou .mU Cmanom HIHv QZOmm m Ne mm mo.mO O0.0m hH.O mo .go .mO CmEHom mnem szmm HHom mCONHHOC mCONHHOC am no d AmuHCCv AmuHCCV HmHHmHmE HMHHmumE \wHHmoum msomumono mComHmono Hmppme HmuumE .mHHo CH HMCHOHHO mm ICOC Hmtuo UHCmmHo .Cmmuo Coaumo umHmUHmCoo .ECUUd Hmuoe UHCmmHo CONHHOE "CH Hmuuma UHCmmHo umuwHCECUU¢ mo x mm .mmHHHoua HHOm mH cH COHumHCECUUm Hmuuma UHCmmHO .mm mHnme 216 OH MH Cm Hv we Cm vm #0 NC Hm mm 00.00 HH.mb hH.Hh hm.Hm 0m.®0 05.0NH Hh.m0 0¢.Hm HO.NOH 00.mMH HN.O 0H.o OH.o ON.o Hh.o mUU.mmoU. m0 NU HU mmoo ~NU ~HO H mo umCHmuo HHwB .Ooz NIN 02mmm prHmHQ HHwB . p02 OIHw nzmmm AchuH>v CmEHom HIHH Qme0 33:: CmEHom mIHw nzomm hme UHECm lew 920mm 217 declines gradually with depth. The data of Nygard et. a1. (1952) indicate that as degradation of the Chernozem proceeds; the boundary becomes sharper, and occurs closer to the surface. The ultimate result of this progression is the abrupt A0-A2 boundary in the true Podzol soils. The zones of organic matter accumulation in all the profiles included in this study have the gradual lower boundaries typically found in true Chernozem soils. Cultivation has mixed the upper few inches of soil, and has artificially sharpened the decline in organic matter content from the A to the B horizon. The gradual decline can still be observed, however, in cultivated soils, since the zone of organic matter accumulation extends below the depth of plowing. The decline in organic matter content with depth is most gradual in the Forman soils, where highly organic A horizon material is mechanically incorporated into the B horizons by a self-mulching process. The decline is least gradual in the Barnes soils where the self mulching effect is least evident. The low organic matter content of the Ap horizon of reddish Forman profile 2-1 is due to the fact that part of the original A1 horizon has been removed by erosion and almost a third of the present Ap horizon is composed of what was originally B horizon material. 218 b. Amounts accumulated and apparent losses Considering only the six profiles sampled in connection with this study, it is readily seen that Forman profile 37-3 contains more organic matter than the other five. This is not surprising, in view of the dark colors and deep tonguing in this profile. The other five do not differ greatly in the amounts of accumulated organic matter. Profiles 37-3 and 2-1 contain almost as much organic matter in the B horizon as in the A, while in the other four profiles, it is definitely concentrated in the A horizon. The amount of organic matter in the B horizon is a function of the amount of tonguing of A horizon material into the B. The six profiles sampled in 1959 were all from culti— vated fields. Profiles SS6ND 41—5 and S53ND 11—1 occur under native grass vegetation. These profiles contain more total and accumulated organic matter than the cultivated profiles from the same area. This indicates that there have been losses of organic matter due to cultivation and the accelerated erosion associated with it. The two virgin profiles occur in areas too steep to farm, so their higher organic matter contents are certainly not due to poorer oxidation conditions. The three cultivated profiles from the Sargent County area (37-3, 41—1 and 41-2) have an average content of 3.55 percent organic carbon, or 6.11 percent organic matter in the upper 6 inches. Figuring a bulk density of 1.35 for the upper six inches, the organic matter content 219 is roughly 56 tons per acre. The upper six inches of the virgin profile, 41-5, contains 5.00 percent organic carbon, or 8.60 percent organic matter. This amounts to 79 tons of organic matter per acre or the apparent loss of 23 tons per acre, is assumed to have been due to the effects of cultivation. The two profiles developed on Cary till contain amounts of organic matter comparable to those in the cultivated soils of the study area, but less than those of the virgin soils. The organic content increases rapidly as one moves from well drained positions to adjacent areas with poorer drainage. This can be predicted on the basis of field observation since thicker and darker surface layers are present in the lower lying areas. c. Carbon-nitrogen relationships The percentages of nitrogen closely parallel those of total organic matter. The C:N ratios are very similar for equivalent horizons in the six profiles. This ratio is 12 to 13 in the A horizons, and declines to about 9 in the lower B horizons. This may indicate a difference in the composition of the organic matter in the B horizons from that in the A horizons, or it may indicate the leaching of soluble nitrogen, and its fixation lower in the profile. The similarities in C:N ratios between profiles suggests a similarity in the composition of the organic matter. The percentages of both carbon and nitrogen decline less 220 rapidly with depth in the Forman profiles than in the others. The percentages of nitrogen are higher in virgin than in cultivated profiles, but the C:N ratios are about the same. 4. Summary There is little doubt that organic matter has accumulated in these profiles. The organic matter content in cultivated areas has been depleted to a lower level than that in virgin areas. The amounts of organic matter are not greatly different in the A horizons of five of the six profiles sampled in connection with this study, but it is considerably lower in one of the reddish Forman profiles, due primarily to greater erosion losses at the site of this profile. I. Iron Content and Movement 1. Results The percentages of total iron (expressed as per cent Fe203), and of free iron oxides as extracted by two methods, are shown in Table 39 for the upper portions of three profiles. Data for the lower horizons of these profiles, and for the other three profiles, are presented in Tables 7 and 50 through 55. The data shown in Table 39 were selected to illustrate the magnitude of the differences in the amounts of iron extracted by the various procedures. The difficulties encountered in extracting free iron 222 oxides with thioglycolic acid are discussed in Chapter IV. The values given in Table 39 for the thioglycolic acid extraction were all obtained from the same run of samples, and are felt to be relatively valid. 2. Discussion a. Iron content 1) Total iron The amounts of total iron extracted from these soils was less than that reported in the literature for similar soils. There is no available data from immediate area of these soils. In general, total iron content de— creases with depth in Forman profile 37—3, and reddish Forman profile 2—1, and increases with depth in Barnes profile 50-2. The highest percentages of total iron were extracted from Barnes profile 50-2. The fine and very fine sand fractions of this profile contained the highest percentages of non-resistant, iron bearing, heavy minerals. Such minerals should represent the main source of total iron in all these profiles, although almandite, the principal garnet, also contains some iron. The ratios between the percentages of total iron and non-resistant heavy minerals of fine and very fine sand size in selected horizons from three profiles are shown in Table 40. The rather constant ratios in the Barnes and reddish Forman profiles indicate a definite relationship between fine and very fine sand size heavy mineral content, 221 HH 00 00.0 0 000.0 00.0 000 0H 00 00.0 0 00H.0 00.0 000 00 H0 00.0 0 00H.0 00.0 H0m 00 00 00.0 0 00H.0 00.0 00 0:00 mmCHmm 0H 00 00.0 0 0HH.0 00.H 000 00 00 0H.H 0H 000.0 00.H 00m 0H 00 00.H 0H 00H.0 00.H H00 00 00 00.H 0H 000.0 0H.0 00 Hu0 CmEHom 00H000m 0 00 00.0 0 000.0 00.H 000 00 H0 00.H 0H 000.0 00.H 00m 0H 00 0H.H 0H 00H.0 00.H H00 00 00 00.0 0H 000.0 00.0 Hm 00 00 00.0 0H 000.0 00.0 00 0:00 CmEHom 000005 HmsHHx as 00 .000 00 0 HH00 00 x 00 .000 00 0 HH00 00.x 00000 0 000H000 omuumuuxm HMCH MO @0500: HmEHHM OHUm UHHOO>H00HCB mm Hmuoe w mwmmmmm X mm UHom .OHCH >9 pmuumnuxm MONmm R 0Q umuomnuxm mONmm x >9 pwuomuuxm mONmm .mmHHmoum 000:0 mo mCONHHOC 0000: 0:0 mo quusou mOon COHH mmum OCm COHH H0009 .0m mHQMB 223 and total iron content in these profiles. The erratic pattern of ratios in the Forman profile indicate another source of iron, besides these heavy minerals. This profile is finer textured than the other two, and it is possible that micaceous clays contribute more of the iron, and in addition, there are probably large quantities of silt size particles of iron bearing minerals. Table 40. Ratios between percent total Fe203 and percent non-resistant heavy minerals of fine and very fine sand size in the upper horizons of three profiles. Horizon Soil and profile Ap 81 821 822 Cca Forman 37-3 6.94 11.50 7.10 7.40 10.18 Reddish Forman 2-1 4.34 3.77 3.45 2.96 Barnes 50-2 4.07 4.23 4.76 4.54 Reddish stains and concretions, presumably composed of iron oxides, were observed in the lower C horizons of all the profiles. Because of the position in which they occur, it is felt that they were present in the original material. If such forms were originally present in the original materials of the upper horizons, they could have formed an important source of total and mobile iron. 2) Free iron oxides, thioglycolic acid extraction It is assumed in this discussion, that the results obtained from the same run of samples, using the thioglycolic acid procedure, have comparative validity. The soundness 224 of this assumption is open to question. The very small amounts of iron extracted suggest that this extraction method is very selective. There is little possibility that mineral lattice iron is included. In general, the amounts of iron extracted decline with depth in the profiles, roughly paralleling the decline in organic matter content. This suggests that at least part of the iron extracted was in some way complexed with organic matter. The amounts of iron extracted are too great to consist entirely of organically held iron, especially in the 8 horizons. The ratios between the percentages of organic carbon and thioglycolic acid extracted Fe203 in the upper horizons of six profiles, are shown in Table 41. Table 41. Organic carbon/thioglycolic acid extracted Fe203 ratios in the upper horizons of six profiles. Soil series Forman Reddish Forman Barnes Profile no. 37-3 41-1 2-1 2—2 50-1 50—2 Horizon Ap 12.2 12.4 8.3 13.9 13.4 18.8 81 10.4 821 8.3 5.8 5.3 5.1 4.5 4.7 822 4.4 8.8 3.4 2.9 3.3 5.3 Cca 14.50 6.2 2.9 2.2 5.8 7.3 Although the thioglycolic acid must extract iron compounds other than those held in complex with organic matter, the amounts of iron extracted are more closely related to organic matter content than to total iron content. Very little iron was extracted from the Cca 225 horizons by this procedure, although it was designed for use in calcareous soils. 3) Free iron oxides, Kilmer method of extraction This determination was made by the Lincoln Soil Survey Laboratory. The percentages of iron oxides extracted by this method were much higher than those extracted with thioglycolic acid. The pattern of occurrence of iron oxides as extracted by this method was also quite different from that indicated by the results of the thioglycolic acid extraction, and indicated that the iron oxide content parallels clay content, rather than organic matter content, at least in the A and B horizons. Within each profile, the largest percentages of iron oxides were extracted from the 8 horizons, which also contain the highest percentages of clay. However, this relationship does not hold between profiles. For example, a higher percentage of iron oxides was extracted from the B horizon of reddish Forman profile 2—1, than from the B horizon of Forman profile 37-3, although the latter horizon has much the higher clay content, The percentages of iron extracted by this method increased with depth in the calcareous C horizons, without respect to clay content. The movement and accumulation of iron oxides, at least those of pedogenetic significance, in this part of the profile is highly unlikely. Either forms of iron other than those involved in pedogenetic movement can be extracted by this procedure, or the reddish brown 226 iron stains and concretions in the lower C horizons contain the same forms of iron as are of pedogenetic significance. The distribution of these stains and concretions is felt to be inherent from the original material, since movement in this part of the profile is unlikely. The smallest percentages of iron oxides were extracted by this method from Barnes profile 50-2, which was found to contain the most total iron of the three profiles on which this quantity was evaluated. The amount of iron oxides extracted by this procedure are more closely related to clay content than to total iron or organic matter content. 4) Iron extracted by dilute 8C1 This extraction was made only on reddish Forman profile 2-1. The results are presented in Table 7. A very small quantity of iron was extracted from the Ap horizon. This suggests that a high proportion of the iron in this horizon is in the form of organic complexes, which are not broken down by the acid treatment. 5) Comparative relationships A sample from the Ap horizon of reddish Forman profile 2-2 was extracted with dilute HCl. Analysis of the extract revealed an iron content of 0.75 ppm. of Fe203. The sample was then washed with a saturated solution of calcium carbonate to bring its pH back into the range in which the 227 thioglycolic acid procedure was designed to work. The sample was then treated according to the thioglycolic acid procedure, and the iron content of the extract determined. An additional 138 ppm. of iron (as expressed as Fe203) was extracted from this sample. This experiment indi- cated that the thioglycolic acid was capable of extracting iron from compounds unaffected by treatment with dilute HCl. In the A horizons, such compounds are probably organic complexes. Iron content was also determined on reddish Forman profile 2—l using the method of Mehra and Jackson (1960). The data in Table 7 indicate that this procedure like the thioglycolic acid procedure, extracted the highest percentage of iron oxides from the Ap horizon. The method of Kilmer (1960) is no doubt more thorough in its removal of iron oxides than the thioglycolic acid method. In fact, it may be too thorough, in that some mineral lattice iron may also be extracted. If it is assumed that only free iron oxides are extracted by this procedure, the data in Table 39 indicate that free iron oxides comprise a high proportion of the total iron in some horizons. This seems unlikely in soils containing such high proportions of unweathered iron bearing minerals such as augite and hornblende, unless some very easily weathered mineral such as limonite were originally present. 228 b. Evidence of iron movement in the profiles studied The best evidence of iron oxide movement in a profile is its occurrence in significantly greater amounts in some horizons than in others, provided that the iron oxide content of these horizons was originally the same. Each of the six profiles will be examined for such evidence of movement. 1. Profile 37-3, Forman The amounts of iron extracted by the Kilmer method indicate an accumulation in the 821 and 822 horizons, Table 39. Amounts equal to those extracted from the 8 horizons were also extracted from the lower C horizons, Table 52, where it is almost certain that no movement has occurred. If only the upper part of the profile is considered, there is a definite iron oxide ”bulge" in the 8 horizons, The amount of iron oxides extracted with thioglycolic acid declines with depth in the profile. However, a larger percentage was extracted from the 822 horizon than from the 821 or Cca horizons. Both methods indicate the presence of an accumulation in the 822 horizon. However, it is indicated in Table 13 that the original material of this horizon differed from that of the 821 or Cca horizons. Thus it is possible that the differences in iron oxide content are inherited from these original differences, and are not due to movement. 229 2. Profile 41-1, Forman The amounts of iron oxides extracted by the Kilmer method, Table 53, are very similar to those extracted from the preceding profile. Higher percentages were removed from the B horizons than from the A or Cca horizons, but equally high percentages were extracted from the lower C horizons. The thioglycolic acid extracted progressively smaller percentages with depth in the profile, Table 7. The presence of an accumulation of iron oxides in this profile is questionable. 3. Profile 2-1, reddish Forman The percentage of iron extracted from the 821 horizon by the Kilmer method is distinctly higher than that extracted from the Ap or 822 horizons. High percentages were also extracted from the lower C horizons, but these were slightly lower than those extracted from the 821 horizon. The highest percentage of iron oxides extracted by the thioglycolic acid was from the Ap horizon, Table 39. The percentage extracted from the 821 horizon was less than that extracted from either the Ap or 822 horizons, just the opposite of the results from the Kilmer method. It is indicated in Tab1e13, that the original material of the 821 horizon was mineralogically different from that of the Ap or 822 horizons. Evidently this material was 230 higher in iron compounds extractable by the Kilmer method and lower in those extractable by the thioglycolic acid, than the material above or below. t is felt that the horizon to horizon differences in iron oxide content in this profile are inherited from differences in the original materials of the several horizons, and are not due to movement and accumulation. 4. Profile 2-2, reddish Forman The amounts of iron extracted by the Kilmer method, Table 55, indicate a slight accumulation in the 821 horizon of this profile. The amounts extracted with thioglycolic acid decline steadily with depth, Table 7. The existence of an accumulation of iron oxides in the B horizon of this profile is questionable. 5. Profile 50-1, Barnes The amount of iron extracted by the Kilmer method indicate the presence of a distinct accumulation of iron 'oxides in the 821 horizon, Table 50. A faint accumulation in this horizon is also indicated in the amounts of iron oxides extracted by the thioglycolic acid, Table 7. Although both methods of analysis indicate an accumulation in this horizon, the sand size distribution, Table 12, suggest that the original material of the 821 horizon is different from that of the Ap or 822 horizons. Thus the higher iron oxide content may be inherited from the 231 original materials, rather than due to movement and accumulation. 6. Profile 50-2, Barnes The percentages of iron oxides extracted by both methods are slightly higher in the 8 horizons than in the Ap or Cca horizons. The magnitude of this apparent accumulation, however, is so slight that no significance can be attached to it, either as a genetic, or an inherited phenomenon. c. Summary The amounts of total iron in these profiles is low, compared to most values reported in the literature. The thioglycolic acid extraction removes a very small fraction of the total iron, including some that occurs in the form of organic complexes. The Kilmer method extracts four to ten times as much iron as the thioglycolic acid method, and the amount extracted does not vary greatly within the profiles. A slight maximum is indicated in the B horizon, coincident with the maximum clay content. The minimum amounts of iron are extracted from the Cca horizons by this method. There is evidence that iron other than that held as mobile coatings is extracted by this method. The amounts of total iron and free iron oxides (as determined by either method) and their vertical distri- bution in the profile, seem more closely related to clay content, organic matter content, or depth, than to 232 soil series or area of occurrence. There is a possibility that a small quantity of iron oxides has moved from the A to the B horizon of all six profiles, but a more precise analytical measure is needed before this amount can be quantitatively evaluated. It must also be more firmly established that the several horizons all developed from original material with the same iron oxide content. The horizons in which there appear to be distinct accumulations of iron oxides, are in most cases developed from original materials texturally or mineralogically dissimilar to those of the horizons above and below, as indicated in Tables 12 and 13. Therefore, some of the horizon to horizon differences in iron oxide content are probably due to differences in the original materials, and not to movement and accumulation of iron oxides during soil development. J. Soil Reaction, Salinity, and Carbonate Content The Lincoln Soil Survey Laboratory determined pH at soil:water ratios of 1:1, 1:5, and 1:10; electrical conductivity, and calcium carbonate equivalents on the profiles collected in 1959. The results of these determinations are included in the tables of routine analyses in the Appendix. 233 1. Soil reaction The pH values in the six profiles are not greatly different. Reactions in the leached horizons range from slightly acid to mildly alkaline. The reaction in the calcareous horizons (based on the 1:1 pH values) is that of a saturated solution of calcium carbonate. The most acid sola occur in the profiles in which carbonates have been leached to the greatest depth. The pH values increase with dilution in all horizons. This is probably due to the fact that the activities of calcium and magnesium, and possibly that of sodium, increase more on dilution than that of hydrogen. 2. Soil salinity It is generally agreed that well drained soils in the study area are non—saline. The balance between down— ward moving precipitation, and upward moving capillary water is such that soluble salts are leached beyond the rooting depth of the common crops of the area. On the basis of data presented in U.S.D.A. HandboOk 60 (1953, p. 67), it appears that the salt tolerances of all common crops of the area are greater than the salt content in all six sampled profiles, except for the C22 horizon of reddish Forman profile 2-1, which has a salt content slightly greater than the tolerable limit for wheat, flax, and corn. The roots of such crops seldom extend to a depth of 49 inches, the upper boundary of this horizon. 234 3. Carbonate content Throughout this discussion, carbonate content will refer to calcium carbonate equivalent. It is realized that some of the included carbonates are those of magnesium, instead of calcium. a. Results In addition to the determination of total carbonates, the soil survey laboratory also determined the percentage of clay size carbonates in several horizons. The percentages of clay size carbonates in the total soil, and the proportion of the total carbonates in the clay, and the non-clay fractions are shown in Table 42 for those horizons on which this information is available. Table 42. Percentage of total and clay size carbonates, and percentage of carbonates in the clay vs. non— clay fractions: in selected horizons from three profiles. % % of total Profile and Horizon % total clay size carbonates in soil carbonate carbonate clay non-clay 37-3 83ca 10 1 10 90 (Forman) Cca 21 6 29 71 C2 27 6 22 78 C3 21 3 14 86 C4 18 2 ll 89 C5 16 1 6 94 2-2 Cca-cs 10 3 30 70 (reddish C21 12 2 17 83 Forman) C22 11 l 9 91 50-1 Cca 24. 9 37 63 (Barnes) C21 20 2 10 90 C22 16 l 6 94 Ccs 14 1 7 93 235 b. Discussion 1) Carbonate content of the assumed original materials (C horizons) The glacial till assumed to be the original material of all six profiles is calcareous. The carbonate content in the C horizons of the Forman soils is about double that in the C horizons of the reddish Forman soils. The car- bonate content of the C horizons of the Barnes soils is intermediate. In addition to the profiles analyzed in con— nection with this study, carbonate content had been deter— mined on several previously sampled profiles from the study area. In three such profiles which were sampled as Barnes, but are now considered to be within the range of the Forman series, the lower most C horizons sampled had carbonate contents of 19, 11, and 13 per cent. Three other profiles, sampled as Barnes, and still considered as such, had carbonate contents of l4, l6, and 18 per cent in the lower most C horizon sampled. In general, the carbonate content of the unaltered till in the study area is between 10 and 20 per cent. 2) Vertical distribution of carbonates in the profile All the profiles have non-calcareous A and 82 horizons overlying calcareous Cca and C horizons. In some cases the boundary between the calcareous and non-calcareous parts of the profile is abrupt, while in others, a transitional Bca horizon separates them. Calcareous B 236 horizons are so designated, since although they contain free carbonates, they have the texture, color, and especially the structure of 8 horizons. The 822 horizon of Barnes profile 50-2 should probably have been designated as a 83ca horizon. The redistribution of carbonates in the profiles is discussed in section K of this chapter. The 7th Approximation (1960) defines a calcic horizon as one having a carbonate content of at least 15 per cent of calcium carbonate equivalent. This carbonate content must also represent an increase of five per cent over the carbonate content of the C horizon. Five of the six profiles sampled in connection with this study have horizons that meet these requirements. However, the horizon qualifying is not, in all cases, that designated as Cca in the field. This is due to the fact that the field designations were applied primarily on the basis of the position of the horizon in the profile. In Forman profile 37-3, the horizon called C2 in the field qualifies as a calcic horizon, and in profile 41-1, also Forman, it is the Ccs, rather than the Cca horizon that qualifies as a calcic horizon. As was pointed out earlier, there were some apparent mineralogical and textural differences between the original materials of the Cca and C2 horizons in profile 37-3. It is equally likely that original differences in carbonate content were also present, and this may help to explain the difference between the field and laboratory evaluations 237 of which is the calcic horizon. The only profile without a calcic horizon is reddish Forman profile 2-2. The carbonate content is less than the required 15 per cent throughout this profile. This profile is also the deepest (24V) to free carbonates, and is developed from till with a low (11%) carbonate content. 3) Size distribution of carbonates Concretions of carbonates were found in all sand fractions of the calcareous horizons of all six profiles by the Lincoln Soil Survey Laboratory. Clay size carbonates are most abundant in the horizons designated as Cca horizons in the field, even in cases where these horizons do not contain the highest percentages of total carbonates. Clay size carbonates represent more than 25 per cent of the total carbonates in the Cca horiZons of the three profiles included in Table 42. This is in line with the findings of Redmond and McClelland (1959), who also found large amounts of clay-size carbonate in the Cca horizons. Forman profile 37-3 is the only profile on which both clay—size carbonate, and detailed mineralogical analyses data are available. A combination of the results of these two analyses indicates that probably most of the small amount of carbonates still retained in the profile after being leached from the solum are in the Cca horizon, and that the higher carbonate content in the C2 horizon is due to a difference in the carbonate content of the original material. 238 In Barnes profile 50-1, the Cca horizon has a carbonate content 8 per cent higher than that of the C22 horizon. This coincides with a difference of 8 per cent in the percentage (of the total soil) of clay size carbonate. This suggests that the accumulation in the Cca horizon is primarily, if not entirely, one of clay sized carbonate particles. The higher percentages of clay size carbonates in the Barnes profile, as compared with the Forman and reddish Forman profiles, is consistent with field and microscopic examinations. Several differences in the carbonate content of the three groups of soils have been noted. It appears that soil forming processes are working to eliminate these differences. K. Accumulations, Losses, and Redistributions in the Profile 1. Method of evaluation This section deals with the changes that have taken place in the transformation of the original materials into the present soil profiles. The processes responsible for these changes began after the deposition of the original materials, and are still operating at the present time. These processes are too slow to be measured or observed directly, thus their magnitude and direction must be inferred from indirect measurements. 239 The changes brought about by these processes are measured by means of comparisons between the altered horizons of the present solum, and material assumed to be like the original material from which these horizons developed. The validity of this evaluation rests heavily on the proper selection of the soil material selected to represent the original materials. In the profiles studied, all or part of the C horizons were selected for this purpose. The evaluations of textural and mineralogical uniformity presented in section B of this chapter, aided in this selection, but there is no sure way of determining which, if any, portions of the C horizons are identical to the original material of the sola. One can only make what seems to be the most logical, and most reasonable choice. Total quartz is used as the indicator mineral for all calculations. The assumption is made that the ratio that now exists between quartz and a mobil constituent in the assumed original material originally existed in the other horizons of the profile as well. Total quartz content is assumed to have remained constant throughout the soil development process, due to the stability of the mineral. With this assumption, it is possible to calculate the original weight of a mobil constituent in an altered horizon, by multiplying the ratio that now exists in the assumed original material between the mobil constituent and quartz, by the weight of quartz in the altered horizon. This type calculation was made for sand, silt, clay, 240 carbonates, and organic matter, in the three profiles on which carbonate—free mechanical analyses were made. The net gains and losses for the profile were obtained by adding those for its component horizons. The net gains and losses for each horizon were calculated by summing the gains and losses in the individual constituents. The changes assumed to have occurred during soil develop- ment were arrived at by comparing the original and present weights. Volume changes were calculated in two ways. One was to determine a volume per gram of quartz value for the assumed original material, and then to multiply this value by the weight of quartz in the altered horizon to get the original volume. The other method was that proposed by Barshad (1955). The original weight of the altered horizon is divided by the bulk density of the original material. The volume changes are equal to the differences between the present and original volumes. In Tables 44, 46 and 48, the volumes are expressed in cc. per sq. cm. of cross section area, which is equal to the thickness of the horizon. The quantities of clay formed, gained or lost, were calculated for each profile according to the method proposed by Barshad (1955). The amount of clay formed in each horizon is assumed to be proportional to the amount of non- clay lost from the horizon. The proportionality factor is calculated by dividing the total increase in clay content for the profile by the total loss of non-clay. This 241 factor is then multiplied times the loss in non-clay for each horizon, to arrive at the amount of clay formed in the horizon. The amount of clay formed, plus the amount originally present, minus the amount now present, gives the gain or loss in clay for the horizon. There is no provision in Barshad's method for dealing with profiles in which there have been net losses of clay, or net gains in non-clay. This led to difficulty in making the calculations on two of the profiles studied. The results of the calculations, and the sources of the information needed to make them, are presented in Table 43. 2. Data used in the calculations The data used in calculating the gains, losses, and redistributions described above are presented in Table 43. All calculations involving sand, silt, or clay, are made on the basis of data obtained from the mechanical analysis of samples in which organic matter and carbonates were destroyed. All data apply to a profile with a cross sectional area of one square centimeter. Ten items of data are provided in Table 43, for each horizon of the three profiles. These are merely designated as items 1 through 10 in the table itself, but are defined, and their sources revealed in the following list. 242 00.0H 00.0H 00.0H H0.0H 00.0 00.0H 0H.0 ..0H H0.0N 00.0H 0N.0H 00.mH 0m.OH H0.mH 0N.m .0 mH.NH H0.0H HO.NH 0H.0 00.0 00.0 m¢.m .0 ¢¢.OH NH.OH 00.0 00.0 N0.m mm.m N¢.¢ .0 m¢.m¢ m0.mm 00.Hv Nm.Om 0H.mN 00.Hm NH.mH .0 Om.¢ 00.0 00.0 m¢.0 Om.O 0m.O 00.0 .m 00.00 mv.mv 00.0¢ m0.0m 0¢.mN Hm.Nm 00.0H .0 H0.H H0.H H0.H 00.H 00.H 00.H 00.H .m 00.0N O¢.mN v0.0N 00.NN «N.0H Nm.ON O0.NH .N HH OH HH 0 0 m m .H sm0H 000 HH H0O HH moo HH 000 H 000 H H0m HH 00 H couHuom HCmEHom CmvammV HtN mHHHOHm .X0.Nm pcquoo Nunmsw mmHmEHpmm *% 000m .pCmuCOU Nuumsv umumEHumm0 NN.0 00.0H *mo.HH N0.0 00.0 0*Hm.m 00.0 mH.m 0N0.m 00.0 .OH 00.0 00.0 00.0 00.0 00.0 0O.N NH.m H0.N «m.N 0m.m .0 00.0H 0H.0H mm.HH NH.0 N0.0 H0.m 00.0 Hm.m Hm.¢ Hm.m .0 mm.0 00.0 ON.m 0H.0 00.0 @0.0 00.0 00.0 00.0 00.0 .0 0H.¢N v0.mm N0.mN NO.HN 00.MN m0.0H 00.0H H0.mH 00.HH 0N.ON .0 H0.¢ H¢.0 Hm.0 00.0 00.0 0m.H 0H.O v¢.O 00.0 mm.H .m 00.0N 0H.Hv m¢.Nm 00.0N 0N.Om NH.NH 0H.0H 0H.0H NH.NH 00.HN .0 N0.H N0.H N0.H N0.H 00.H 00.H 00.H 00.H 00.H N0.H .m 00.0H Ov.mN Nm.ON 00.0H Nm.ON N0.0 0H.OH 0H.OH N0.0 0N.mH .N 0 OH 0 0 0 m w w m 0 .H EmuH mo 00 mo NO H 000 HH mm HH NNm H HNm HH Hm HH 00 H CONHHom ACmEHomv ml0m mHHHOHm .mmmCmCo HC0H03 mo COHHMHConU How mumm .mv MHQMB 243 00.0H 00.0H 00.0 00.0H 0H.0 00.HH H0.0 .0H 00.0H 00.00 00.0H 00.HH 00.0 00.0 00.0 .0 0H.0 00.0H 00.0 00.0H 0H.0 00.0 00.0 .0 H0.0 00.0 0H.0 H0.0 00.0 00.0 00.0 .0 00.00 H0.00 00.00 H0.00 00.0H 00.00 H0.0H .0 00.0 00.0 00.0 00.0H 00.H 00.0 00.0 .0 00.00 00.00 00.00 00.00 00.0H H0.00 0H.0H .0 00.H 00.H 00.H 00.H 00.H 00.H 00.H .0 00.00 00.00 00.00 00.00 00.0H 00.0H 00.0H .0 0 0H 0 0H 0 0 0 .H EmvH 0o H 00 H 00 H 000 H 000 H H00 HH 00 H couHuom AmmCHmmv Nlom mHHHOHm 244 Item no. Source or means of calculation 1. Thickness in inches measured in the field 2. Thickness in centimeters item 1 x 2.54 3. Bulk density, g./cc. from clods taken in 1958, ~ Table 34 4. Weight of horizon bulk density in g./cc. x thickness in cm. (item 2 x item 3) 5. Weight of carbonates and % organic matter plus % organic matter CaCO3 equivalent x ‘ weight of horizon. (0.m. = 0.cx 1.72) % o.c. and CaCO3 equiv. from Appendix. 6. Weight of horizon, 0.M&CO3 free basis item 4 minus item 5 7. Weight of clay, g/cc. % clay (C03 free) from 4 Table 14, x item 6 8. Weight of silt g. % silt (CO3 free) from Table 14, x item 6 9. Weight of sand 9. % sand (C03 free) from Table 14, x item 6 10. Weight of total quartz. g. % quartz (C03 and O.M. free basis) from Table 16 x item 6. exception: The carbonate-free clay content of the last three horizons in profile 37-3 (Forman) was determined directly by the Lincoln Soil Survey Laboratory. Carbonate free sand was assumed to be as in Table 12, and carbonate-free silt was determined by difference. 3. Discussion The calculations described above are made for each of the three profiles in the following section. A discussion of the major findings follows the calculations for each profile. a. Profile 37—3 (Forman) 1) Calculation and assumptions The C2 horizon of this profile was assumed to represent the original material, although Table 11 indicates 245 that the original materials of the C2 horizon had a different quartz size distribution from that of the solum. No calcareous horizon having a quartz size distribution identical with that of the solum was available for use. The sand size distribution of the C2 horizon is similar to that of the solum, so this horizon was selected as the best available. The results of the calculations are presented in Table 44a. 2) Changes in the textural constituents The calculations made assuming the C2 horizon as the original material of the entire profile indicate losses of sand and silt, and gains in clay in the B and Cca horizons. Losses of sand, silt and clay from the Ap horizon are also indicated. The net result for the profile is a loss in silt and sand, and a gain in clay. The data suggest the accumulation of clay, by either weathering or movement, to a depth greater than that to which carbonates are leached. There is an indication of a slight clay movement frOm the A to the B horizon. An alternative calculation was made, assuming the acid insoluble Cca horizon as the original material of the 81, 821, and B3 horizons, to which it is mineralogically similar: and retaining the C2 horizon as the assumed original material of the Ap and 822 horizons, to which it is mineralogically similar. The net results (Table 44b) are not greatly different from those obtained by the 246 00.0- 0H.0- 0H.0 00.0 0H.0 00.0- H0.0- 000000 00.00 00.0H 00.0H 00.0H 00.HH. 00.00 H00H0H0o 00.0 00.00 00.0H 00.0H H0.0H 00.HH 00.00 0000000 .03 000 000 .H00oe 0H.0H 00.0 00.H 00.0 00.0 00.H 00.0- 000000 00.0 0H.0 00.0 00.0 00.0 H0.0 H00H0000 00.0 00.0 00.0 00.0 00.0 00.0 00.0 0000000 00H0 00 03 H0.0- 00.0- 00.0- 00.H- 00.0- 00.0- 00.H- 000000 00.0H 00.0 00.0 00.0 0H.0 00.0H H0000H00 00.H 00.0 H0.0 00.0 H0.0 H0.0 H0.0 0000000 0H00 00 .02 00.0| 00.H- 00.0- 00.0- 00.H: 00.0- 00.H: 000000 00.0 00.0 00.0 H0.0 H0.0 00.0 H00H0000 00.0 00.0 00.0 0H.0 H0.0 00.0 00.0 0000000 0000 00 .03 00.0 H0.0 00.0 0H.0 00.0 00.0 .0 .000000 H0000 00 .03 mHHmoHQ ANHHmsw mo .0 CH 000 .00 Ho .00 000000 00 00o 0000 000 H00 H0 00 #02 CONHHO . 0 .wHHMOHQ mHHHCm 000 MO HmHkume HMCHmHHo may 00 CONHHOC NNO 000 0CHECmmm COHHMHCOHmU .0 .CmEHom .mn0m mHHHOHm .mmHm Ho .80 mHmswm 000 .00 Ho mEmHm mm Ummmwumxm 0H0 0000 .HmHmCHE HOHMOHUCH C0 00 NuHva Hmuou 0CHmC “Hmupma UHCmmuo 0C0 .mmHMCOQHmO .mmumummmm HmHCmeu Ho murmeB 0C0 .mECHo> HHOm qummHQ 0C0 H0CH0HHO Ho ComHHMQEOO .00 wHQmB 247 0m.NN m©.ml mm.o hm.ml .m\.00 00.H 000.0 mmv.o hm m.m m.¢a up 0m.m m¢.HH mm.om mm.m m©.bm wN.om mN.OI Nm.o vm.o No.m fim.m mm.© 000' (DO 00 mm.m hm.b 0H.OH mm.HI mm.ba ma.wa NH.OI mm.o mH.o NH.NI NH.N 00.0 I-lr-iN Or-l b®.~. 00.5 QH.OH H0.HI oo.mH mH.@H 0H.0 fim.o 00.0 wH.NI mH.N 00.0 m 0.0 m.vH mm wb.m om.HH flm.ma oEU mo.®l m5.hm 00.HN mm.o mm.o mm.H 0m.MI vm.m 00.0 00 .00 .0mc000 Ac0nmnmmv ..mHHO X .00 000000 A.Ho>\N0vv H0chHHO 000m0um 000500 000 .00 ~0ESH0> 000000 Hmcflmfluo 0:000Hm 000003 H0009 000000 Hmcfimfiuo 0:000Hm 000008 0000000 mo .03 0mcmsu 00000000 0000000 00000>0000 00000 no .03 248 00.0: 00.0 00.0 00.0 00.0: 00.0: 000000 m0.m 00.0 00.00 00.00 00.00 00.00 00.00 0000 0000002 000-000 00000 no .03 H000000O 00.0 00.0 00.0 00.0 00.0- 00.0: 000000 00.0 00.0 00.0 00.0 00.0 00.0 00.0 0000 . mo .03 00000000 00.0- 00.0- 00.0- 00.0- 00.0- 00.0- 000000 00.0 00.0 00.0 00.0 00.0 00.0 00.00 0000 00 .03 00000000 00.0- 00.0 00.0- 00.0- 00.0 00.0: 000000 00.0 00.0 00.0 00.0 00.0 00.0 00.0 0000 mo .03 H0000H0O 0HHMO0Q 00 A000050 mo .0\.0V 000000 00z 00 000 00mm 000 000 00 00 CONH0om 0800 0:0 000 0000003 0a0m00m. 000 000000 000 0:000 .00000000 00mm 000 ~Hmm .0H900 0030 no 0 0000 :0 00 000 00 0000000 000 0:0 mo 0000000 000500000 @000 000 00085000 000 .00000000 0>Hm 000800005 000 00% 00:0 ©000050H00 .Hm 000 mo H0000008 H0000H0o .00000000 mmm 0:0 00 0:0 mo H0000008 H0QH0H0O 0:0 00 £00000: N0 000 00085000 00000H50000 .900 0H308 249 previous calculations, but the horizon to horizon differences are more eratic, and some unlikely gains in sand are indi- cated. 3) Carbonate redistribution Carbonates have been completely removed from the upper 17 inches of this profile, and partially removed from an additional 3 inches. A total of .9.59 grams of CaCO3 equivalent have been lost from the A and B horizons (per sq. cm. of area). Of this, 5.03 grams or 52 per cent is retained as accumulations in the Cca and C2 horizons, and the remaining 4.54 grams has either been lost from the profile, or is accumulated deeper in the C horiZon. In this profile, laboratory analyses indicate a higher total carbonate content in the horizon designated C2 in the field, than in that designated Cca; but the reverse is true of clay size carbonates. The proportion of the original carbonate content still retained in this profile is inter— mediate between those in the other two profiles for which calculations were made. 4) V01ume changes Both methods of calculation indicate increases in the volumes of all horizons and in the profile as a whole. The increases calculated by means of a quartz/volume ratio are two to ten times those calculated as proposed by Barshad. Both these methods suggest that the largest relative increases in volume are in the B3 and Cca horizons. 250 The volume increases in the Cca horizon are due primarily to the deposition of carbonates. Those in the Ap horizon are due to the accumulation of organic matter, and those in the B horizons are probably due to the incorporation of A horizon material through a self mulching process. Some of the apparent increases could be due to differences in the quartz/volume ratios in the original materials of different horizons. The values calculated by the quartz/volume ratio seem illogically high in the Cca horizon of this profile, since the relative increase in volume is much greater than the relative weight change due to the accumu- lation of carbonates. 4) Clay formation, gains, and losses. These quantities were calculated according to the method proposed by Barshad (1955). In this profile, the calculations were made assuming that the C2 horizon represented the original material of the entire profile. It was calculated that 0.777 grams of clay were formed for each gram of non clay lost. This is much greater than the values calculated for the other two profiles, but is reasonably close to the values reported by Barshad. The data for this calculation is given in Table 45. This data indicate a loss of clay from the Ap horizon, and gains of the same magnitude in the remainder of the profile, particularly in the B22 horizon. The data indicate that both movement and weathering in place have occurred, carbonates. 251 the latter even in the presence of free The over—all evidence of clay movement in this pro— file can be summarized as follows. Table 45. Clay formed, gained, and lost; profile 37-3. Weight in grams Present Orig. Total clay Gain wt. of Loss of wt. Clay assuming or Horizon clay non-clay clay formed no movement loss Ap 6.1 2.68 7.01 2.27 9.1 -3.0 B1 4.7 1.53 3.49 1.30 4.7 0.0 B21 7.0 2.26 4.56 1.91 6.3 0.7 B22 7.8 2.48 4.43 2.10 6.3 1.5 B3 4.7 1.52 3.12 1.29 4.3 0.4 Cca 9.5 2.63 7.00 2.22 9.0 0.5 This profile contains the most clay of the six sampled in connection with this study. The B horizon contains the highest percentage of clay in the profile, but this percentage is not much greater than that in the Ap or Cca horizons. The B horizon contains appreciably more clay than the C horizons, especially when the comparison is made on a carbonate-free basis. The B horizon barely qualifies as an argillic horizon, as defined in the 7th Approximation. Thick, dark colored films were observed on the exteriors of peds under the binocular microscope and in the field. These coatings glistened when moistened, and were felt by several trained observers to be clay films, although 252 it was recognized that these coatings were partially composed of organic matter. The thin sections of the B horizon indicate a dense matrix that is high in clay, but which contains very few optically oriented clay films. The absence of clay films around the edges of peds in thin sections was surprising. A few very small clay films were observed, but these came nowhere near accounting for the 1 percent of the section as recommended by the 7th Approximation (as revised in late 1962) for argillic horizons. The B horizon in this profile will still be considered an argillic horizon on the basis of clay content and field observation of clay films. These are the criteria on which most profiles must be classified and should outweigh special determinations such as thin sections studies which are made on but a few profiles, and only on small fragments of these. No quartz or thin section determinations were made on nearby Forman profile 41—1. The following evaluation of the evidence of clay movement in this profile is based on field observations and routine laboratory analyses. The maximum percentage of clay in this profile occurs in the B horizon, but this percentage is not sufficiently higher than that in the Ap horizon to qualify the B horizon as an argillic horizon as defined by the 7th Approximation, although it comes close. The clay content of the B horizon includes no carbonates while that in the C horizons does. The B horizon is thus higher in.non-carbonate clay content than the C. 253 Clay films were observed on both horizontal and vertical ped faces in the B horizon, in the field and under the binocular microscope. Some clay movement has probably taken place in these two Forman profiles, but the amount involved is very small compared with the amounts inherited from the original material and formed in place. b. Profile 2-1, reddish Forman 1) Calculations and assumptions The C22 horizon of this profile was selected to represent the original material of the solum. The quartz size distribution indicates that the original materials of the solum were texturally like this horizon, but the garnet size distribution and quartz/garnet ratios in some parts of the solum are different than in the C22 horizon. This suggests the possibility of some mineralogical differences in the original materials (Table 13y. In spite of this the C22 horizon seems to be the best choice available. The results of the calculations are shown in Table 46. 2) Changes in the textural constituents These calculations indicate net losses of sand, silt, and clay from the profile. There were gains in all three in the B22 horizon, and in silt and clay in the B21 horizon. The apparent losses were greatest in the Cca horizon. This is not logical, and suggests that the 254 mm.oal oo.v| mm.~ mm.al m¢.ml mmsmco mm.mm em.om mm.mm em.am Hmsamaso mme.m me.om ea.mm ee.Hm ma.ma usmmmsm HHom HmumcHE mquOQHMUIcoc amuOH mo .uz mm.a- He.au em.o mm.o me.o- mmsmso ma.m mm.e ma.m sa.m Hmsamaso eme.o em.e mm.m mm.m m¢.e usmmmsm mmao mo .pz me.o- ee.al sm.o me.o mm.o- wmsmso ee.oa me.m ee.m Ho.e Assamese oee.o ma.m no.6 sm.m me.m usmmmsm seam mo .sz em.mn mm.e- me.o sm.~- mo.~u mmsmso mm.ma mm.m mm.es em.oa Assamese eem.a sm.ma em.oa He.ma em.m usmmmsm pcmm mo .uz He.ea as.» oe.ma ma.m assess Hence no .uz Auuumsv m\.mv maamose ea mmo moo mmm Hmm s4 mmcmno umz couflnom Hmcflmflno mm cowflmoc NNU map msHEsmmm .Eo mumswm Mom 00 no mfimnm mm commoumxm mum mumo .HSOM Ham mo amenmumfi .mcoufluos usom pmnflm map Mom soaumasonv .m .mmum mo .Hlm mHHmoum cmfiuom swappmu "HmeQHE Houmoflpcfl cm mm Npumsw Hmuou mcflmd “MonumE UHcmmHo paw smmpmsonumo .mmpmummmm Hmuzuxop mo mpcmeB paw .mEsao> HHom usmmmum 6cm Hmcflmfluo mo somHHmmEoo .mw magma 255 NH @.m om mm.mN mo.©HI m¢.H gm.©I Om\oUU H0.H vvo.o mmm.o m.o m.NN fifl Ho.b mm.ma om.NN oa.ml Ha.mv mm.bm v0.0 m©.o hm.a om.H mN.¢ mh.m hm N.m o.NH mh Mb.© Hm.m fim.ma ON.o ma.mm hv.mm ¢O.OI fim.o om.o mN.NI mN.N 00.0 m m.o m.ma ,m¢ mN.@ ¢O.va mm.om hm.ml ha.mm Hm.Nm H0.0 om.o hm.o on.MI ©5.m 00.0 NH v.a m.HH ¢¢ bw.m mm.m Oh.NH om.ml om.¢N om.ma mm.o ©m.o m©.o 0%.NI o¢.N 00.0 mm .00 .mmamno Umnmumm .HmCHmHHO mm .00 swmcmsu oflumu oESHo>\.Nuw samCHmflHo usmmmnm m85Ho> wmcmco Hmcflmfluo ucwmmum Hflom mo .uB Hmuoa mmcmno Hmcflmfluo usmmmnm umuume oacmmuo mo .uS wmcmno amasmfluo ucmmmnm mmumconnmu 256 Hm.m . Hm.o mm.au. mm.o mmsmso mme.m HH.~ me.ea mm.mm e~.ea Hmsamaso HHOm Hmumcafi mumsonnmolcos Hmuou mo .uz oa.~ we.a «N.0 ma.o mmsmso no.0 mm.o eo.e ma.m em.v Hmsamaso hmao mo .#3 He.m ms.a me.o mm.o mmsmso oss.o «6.0 em.e ee.m ma.m Hmsamaao seam mo .uz on.o mm.m hm.ml m¢.o mmsmco mem.a em.o me.e mm.ea mm.» Hasemano muflmm MO . #3 mcoufluon m umnflm ANuHmsw mo .m\.mv Nmm Hmm mfl CH mmcmco umz mmu MUD couflnom .AwHQmu wasp mo m puma CH mm mEmm or» mum munmflmB ucmmmumv .EU .Um Mom .m mm @mmmmumxm mum mumn .coufiuos Hmm map mo amaumumfi Hmcflmfluo on» no CONAHon NNU map mcflzflmumu paw .mcoufluoc mmm Ucm m¢ wzu mo Hmflumume Hmcflmflno may mm CONHHOQ moo may mo soapnom mHQSHomCHlpflom may mcHESmmm .msouflnoc Gonna umufim mgu How mCOHumasono .va magma 257 apparent losses are due to differencesin the original materials of this and the C22 horizon. Table 13 suggests that such a difference exists in terms of mineralogy, but not in terms of texture. An alternative calculation was made, in which the acid insoluble Cca horizon was assumed to represent the original material of the Ap and B22 horizons, to which it is mineralogically similar, while the C22 horizon was retained as the assumed original material of the 821 horizon, to which it is mineralogically similar. The results of this calculation are illogical, since increases in sand are indicated in the Ap and 322 horizons. 3) Redistribution of carbonates Carbonates have been completely removed from the upper 19 inches of this profile. A total of 8.44 grams of CaCO3 equivalent has been lost from the A and B horizons. Of this, 1.50 grams or 18 per cent is retained as accumulated carbonates in the Cca horizon. The remaining 6.94 grams have either been lost from the profile, or have accumulated deeper in the C horizon. A smaller proportion of the original carbonate content is retained in this profile than in the other two. This may indicate a more advanced stage of leaching in this profile. 258 4) Volume changes Both methods of calculation indicate increases in the volumes of all horizons, and in that of the profile as a whole. The pattern of increase is also similar by both methods of calculation, with the largest volume in— creases in the lower B horizon. It is likely that the apparently large volume increases in this part of the profile are due, at least in part, to differences between the quartz content and bulk density of the original material of the 322 horizon, and those of the C22 horizon. The volume increases calculated by means of the quartz/volume ratio seem illogically large, and those calculated by Barshad's method illogically small, especially in the Cca horizon, where carbonates have accumulated. The calculated volume increases in the Ap horizon are surprising, due to the erosion at the site of this profile. 5) Clay formation, gains and losses These quantities were calculated as proposed by Barshad (1955). They were made under the assumption that the C22 horizon represents the original material for the entire profile. If the first four horizons are considered, it is impossible to calculate a proportionality factor between the clay formed and the non—clay lost, since there has been a net loss of both clay and non-clay. If only the first three horizons are considered, the calculated 259 proportionality factor is 0.089 grams of clay formed, per gram of non-clay lost. This is much lower than the factor calculated for Forman profile 37—3, and the values given by Barshad, but it is similar to that calculated for Barnes profile 50—2. The data obtained in this calculation are shown in Table 47. Table 47. Clay formed, gained, and lost in the A and B horizons of reddish Forman profile 2-1. Weight in grams Orig. Total Clay Gain Present Loss of wt. Clay assuming or Horizon wt. clay non-clay clay formed no movement loss Ap 4.42 2.67 5.17 0.24 5.41 0.99 B21 8.35 2.04 8.13 0.18 8.31 0.04 B22 5.82 -1.63 4.93 0.00 4.93 0.89 This data indicates that about a fifth of the clay originally present in the A horizon has moved into the B horizon, most of it to the lower part. There is, however, an apparent gain in non—clay, as well as in clay, in the B22 horizon, and this suggests that the apparent increase in clay content in this horizon is due to a difference in the original materials of this horizon and the C22 horizon. The over-all evidence for and against clay movement in this profile may be summarized as follows. The B horizon of this profile contains a distinct maximum of clay content. The B:A clay ratio is sufficiently 260 high that the B horizon qualifies as an argillic horizon on the basis of the mechanical analyses made by the Lincoln Soil Survey Laboratory. It does not qualify if the B:A clay ratio is based on the analyses of the acid treated samples. The clay content of the B horizon in this profile is lower than those in the Forman soils. The increase in clay content from the Ap to the B21 horizon is compensated for by a decrease in sand content, especially fine sand. There is a possibility that the original material of the Ap and B21 horizons differed in clay content. If this is the case, the apparent textural B horizon is actually a stratification phenomenon. Thick continuous clay films were observed on the vertical ped faces in the B horizon in the field. Small patches of thin clay films were observed on the horizontal ped faces. Organic coatings did not obscure the clay films in this profile, and the coatings were positively identified as clay films by several experienced observers. On the basis of field observation, it was certain that clay move- ment had occurred. The thin sections from this profile did not show the clay films observed in the field. Thin section studies reveal that there were more of the small clay films in the interiors of the peds in B horizons of this profile than in those from the B horizons of the other two profiles. Thin sections and quartz determinations were not made on reddish Forman profile 2-2, which was sampled as a 261 duplicateto the above profile, 2—1. The following evaluation of clay movement on this profile is based on field observation, and routine laboratory analyses. This profile has a high (1.31) ratio between the clay contents of the B21 and Ap horizons. The increase in clay content from the Ap to the B21 horizon is compensated for by a decrease in silt content. The sand size distributions of the Ap and B21 horizons (Table 12) are different. This suggests that the difference in clay content may be inherent from differences in the clay content of the original material, and not due to clay movement. In the field, thin patchy clay films were observed on both the vertical and horizontal ped faces in the B horizons. It was felt that the clay movement in this profile was slight. Field and laboratory observations both indicate that most of the differences between the clay contents of the A and B horizons in this profile are inherent from differences in the original materials. c. Profile 50-2 (Barnes) 1) Calculations and assumptions The C4 horizon was assumed to represent the original material in this profile. The quartz size distributions, and quartz/garnet ratios indicate that this horizon is similar to the original material of the solum. The garnet size distribution suggests that there may be some difference between this horizon and the original materials 262 of the B22 and Cca horizons, but it seems the best choice considering all the available information. Only the first four horizons are considered in making the calculations for this profile. This eliminates any apparent gains or losses that are due to stratification in the C horizon. The data for the calculation and the calculated changes are presented in Table 48. 2) Changes in the textural constituents The calculations made assuming the C4 horizon as the original material of the entire profile (Table 48a) indicate a large loss of sand, a small loss of silt, and a small gain of clay in the profile. In this profile, gains and losses in the sand fraction were calculated separately for the shale plus chert fragments, and for the remainder of the sand. In the profile as a whole, shale plus chert makes up about 35 per cent of the sand, but accounts for about 60 per cent of the calculated loss of sand. This seems logical in View of the composition and physical properties of the shale and chert fragments. Both the B21 and B22 horizons have gained in clay content. The calculated gain is much greater than the calculated loss of clay from the Ap horizon, suggesting that the increase is due more to weathering in place than to illuviation. An alternative calculation was made (Table 48b) in which the C2 horizon was assumed to represent the 263 mm.m No.0: HH.H mm.m mm.ou mmsmso mm.e ee.m me.m ~m.m Hmsamaso es.e sm.e ma.e em.e em.m usmmmae swan .uz ma.mu no.0- 60.6- mm.~u Hm.o mmsmso me.ma ms.e mm.oa em.m Assamese em.o ms.ma ma.e mo.m mm.e usmmmsm seam .sz eo.am- Hm.mu em.mu Ho.eu oe.mu mmsmso mo.o~ me.m mm.ea mm.m Hasemaso mm.a mm.aa mm.e no.0 me.e usmmmsm teem asses .uz mm.m- ee.m- mm.au ma.mu om.o- mmsmso as.ma 00.6 No.0a em.m Assamese mm.o em.» Hm.e me.m so.m usmmmsm pcmm mamzmlcoc .uz as.aau ao.m- ee.su me.e- oe.m- mmsmso mm.s ee.m ee.m me.m Hmsamaso om.o Hm.e em.s me.a mo.s ssmmmse pawn mamcm .uz ee.sa ms.s mm.as Hm.e assess Hmuou .uz maflmoum EH A.Nuw .m\.mv moo mmm Hmm mm mmcmso umz v0 cowfluom .mmum mo .50 mumsvm mom .00 Ho mfimum mm commoumxm mum mumn .mmpmconumo mHHwoum mnflucm mo amanmpma Hmcflmflno mm coufluoc v0 mcHEDmmm cofipmasuamo .m .muom maamosm monumm “HmnmcHE HoumoHUCH cm mm Munmsv Hmpou mean: “umupme Uflcmmuo new .mmemummom amHprmu mo mpcmflmz Hosamfluo paw ucmmmHm mo conflummfioo .mfl magma 264 ma ®.m ©HI ¢.VHI Nv.mml mm.H mm.©I mm.ml .m\.oo 0H.N «a m.m h.mN VI ¢.HI m.Hm ha.¢t mm.b¢ mH.m¢ mH.o 0H.0 mN.o mm.¢ ¢H.h NH.NH om.ml HH.OV Hm.om m.OI O.MH ma! m.NI m.mH hm.¢l ho.mm ow.ma mH.o mo.o mm.o 0H.NI m¢.m mm.H mN.NI wm.ma mN.hH me m.m m.HH HMI o.ml m.mN m.hH mm.HHI om.mm Hm.©N wm.o mo.o N¢.o hh.ml Pb.m 00.0 mm.ml m¢.Nm mm.mm N.0 m.NH mHI N.NI m.¢a mm.e- ea.mm ma.ea mm.o mo.o wm.o ¢M.MI 6m.m 00.0 wm.ml mh.ma HN.@H wm .UU mmcmnu pmnmumm .HMCHmHHO we .00 mmcmco OHUMH .Ho> \.Nuw .HMCHmHHO ucwmmnm mEsHo> wmcmnu Hmsamaso gammmum Haom Hmuou mo .uz mmcmco HmchHHO ucmmmum Hmuumfi Uflcmmuo m0 .pz mmcmno Hmcflmfluo ucmmmHm mmumconumo mo .uB mmcmzu (HmchHHO ucmmmum HHom Hmnmsflfi mumsonnmolcos Hmuou mo .uB 265 em.mmu ~m.oau mo.m- em.mu em.~u mmemso ms.m mm.~ ~6.Hs m~.om me.mm ms.ma Hmsamaao HHOm HmymayE myMQOQHMUIaoa Hmyoy .y3 ea.m em.o- mm.H em.m mm.on mmsmso ee.o we.o mo.» me.m me.m mm.m assamaao mmHU .yz we.au mm.o «N.0 mm.~n Hm.o mmsmso em.o mm.o oa.ma om.m mm.oa em.m Hmsymaao yaam .uz mm.emu em.oau mm.eu He.eu oe.mu wmsmso mm.a mm.a ee.~m mm.oa mm.ea mm.m assamaso . esmm anyou .yz eH.HH- Hm.mu m~.mu ma.~u om.on mmsmso mm.o em.o mm.ma ee.e me.oa em.m assamaao mommm OHMSmIEOC its ee.mau mm.eu mm.~u me.e- oe.m- mmsmsu om.o mm.o em.m sa.e em.m mv.m Hmsamaso 02mm OHMSm .93 A.Nye .m\mv maamose as so No moo mum Hmm em mmamao ymz aouflyom .mHme mHay mo m yymm CH am>ym mmoay mm mEmm may mum myamHmB yammmym .mCONHHoa Hmm cam ma may mo Hmyymymfi Hmcymyyo meSmmm may mm aouflyoa mo may cam .maouflyoa moo paw mmm may mo Hmfiymymfi Hmaflmayo may mm aouflyoa NU may madammmm aoyymasoamu .amw magma 266 original material of the B22 and Cca horizons, to which it is more similar in respect to garnet size distribution than is the C4 horizon. The C4 horizon was assumed to represent the original material of the Ap and B21 horizons, to which it is similar with respect to garnet size distribution. The results of this calculation indicate values for the loss in silt and gain in clay comparable to those obtained in the previous calculation, but the calculated loss in sand is considerably greater. 3) Carbonate redistribution The upper 11 inches of this profile have been com- pletely leached of carbonates, and an additional four inches is partially leached. A total of 11.27 grams of CaC03 equivalent have been lost from the A and B horizons (per square cm. of area); 4.98 grams, or 44 percent of this loss, is retained as an accumulation in the Cca horizon. The remaining 6.28 grams have either been lost from the profile, or have accumulated lower in the C horizon. A larger proportion of the original carbonates remain in this profile than in the other two, and this may indicate that this profile is in an earlier stage of leaching. 4) VOlume changes The volume changes calculated by means of the quartz/ volume ratios indicate a net decrease in the volume of the profile as a whole, and especially in the Ap and B21 horizons. This is in contrast to the rather large increases 267 in volume calculated for the other two profiles. The calculations made using Barshad's method indicate increases in volume, of similar magnitude to those calculated, in the other two profiles. The changes calculated by both methods may be partially due to differences in the quartz content and bulk density of the original materials. 5) Clay formation, gains, and losses These calculations were made as proposed by Barshad (1955), using the data in Table 48a. Similar results are obtained when the data in Table 48b are used. The proportionality factor between clay formed and non- clay lost in the profile was calculated to be 0.107 g. of clay formed per gram of non-clay lost. This value is much lower than those reported by Barshad, and that calculated for Forman profile 37-3. It is comparable to the value calculated for reddish Forman profile 2-1. The calculated formation, gains, and losses of clay in the profile are shown in Table 49. The over-all evidence of clay movement in this profile can be summarized as follows. Both the B21 and B22 horizons contain enough higher percentages of clay than the Ap horizon to qualify as argillic horizons on the basis of B:A clay ratios. The sand size distributions, and silt content of the Ap and 321 horizons suggest the possibility that the original materials of these two horizons were different 268 texturally. If this is the case, the B21 horizon may not be a true argillic horizon. Table 49. Formation, gains, and losses of clay in the first four horizons of profile 50-2 (Barnes). Weight in grams Total clay Gain Present Loss in Clay Orig. Horizon clay non-clay formed clay assuming or no movement loss Ap 3.27 2.29 0.25' 3.52 3.77 -0.50 821 7.87 8.94 0.96 5.49 6.45 2.49 822 4.78 3.40 0.36 3.67 4.03 -o.75 Cca 6.81 ' 8.58 0.92 7.53 8.45 —l.64 Moderately thick clay films were noted on the vertical ped faces from the B horizon, and patches of thinner clay films on the horizontal ped faces, both in the field and under the binocular microscope. Only a few small patches of optically oriented clay films were observed in the thin sections, and these were in the interiors, rather than on the exteriors of the peds. The profile contains consider- ably more clay than originally, if it is assumed that the present C horizons are identical to the original material of the solum. However, the high silt content of the B21 horizon, where much of the apparent gain is concentrated, indicates that the original material of this horizon may have had a different clay content than the present C horizons. Less complete analyses were made on Barnes profile 269 50—1, and the following evaluation of clay movement in this profile is based on field observation and routine laboratory analyses. The profile as a whole is rather coarse textured, but there is a definite increase in clay content from the A to the B horizon. The B:A clay ratio is sufficiently high that the profile has an argillic horizon as defined by the 7th Approximation. The sand size distributions in the Ap and B21 horizons are different (Table 12) suggesting that the difference in clay content may be due in part to stratification of the original materials. Moderately thick clay films were observed on the vertical ped faces from the B horizons, but none were observed on the horizontal faces. This prevents the B horizon from qualifying as an argillic horizon, as presently defined. The amount of clay moved from the A to the B horizon in these Barnes profiles is small when compared to the amounts weathered in place or inherited from the original materials. The apparent textural B horizons are likely the result of stratification in the original materials. This stratification is considerably more evident than was thought at the time ofsampling, and when the sites were selected. 270 d. Summary The methods used in the calculations of gains and losses were designed for use in cases where it could be safely assumed that the original material of the altered horizons was like one of the existing lower horizons. Such an assumption cannot be made regarding the profiles used in this study, even though they were selected for showing a minimum of stratification. If these profiles are stratified, and the results indicate that they are, it is almost certain that all our so-called non—stratified till soils are somewhat stratified, or at least hetero— geneous. This seems to be at least a partial cause of the apparent argillic horizons in some of the profiles. Stratification was not considered in the field, and for this reason several strata may have been wrongly designated as argillic horizons. It would seem more practical to relax the genetic requirements of argillic horizons, and to base their recognition on a mere increase in clay content in the B horizon, regardless of its origin. This criterion can be carried to the field and used in routine soil mapping. An assumption of Barshadfs (1955) method of calculating gains, losses, and transfers of clay in the profile, is that a high percentage of the non-clay apparently lost from the profile is converted to clay. The calculations made indicate that this is not the case in two of the three profiles. Some non-clay particles 271 probably dissolved, and the weathering productsremoved in solution. Carbonates were not considered in making these calculations, but had they been, the calculated ratio of clay formed to non-clay lost would have been even lower. This type calculation would have limited value if carbonates were included in the mechanical analysis data, as they are in the data released by the soil survey laboratories. It is likely that chert fragments weather to relatively stable particles of silt rather than clay size. This should be reflected by gains in silt, which are not evident. Hewever, the losses of silt are very small (7 per cent) compared with the losses in sand (36 per cent) suggesting that the silt supply is being added to almost as rapidly as it is being depleted by further weathering to clay. CHAPTER VI SUMMARY A. Comparison of the Original Materials 1. General nature and stratification The six profiles sampled in connection with this study were believed to be developed from non-stratified glacial till, similar to their present C horizons. Labor- atory analyses indicated more stratification in these materials than had been expected on the basis of field observations but in spite of this there are few abrupt changes within the C horizons. It is doubtful that any till plain soils are completely without stratification. Clay and carbonate contents usually decline with depth within the unleached portion of the profile. The amount of stratification was felt to be sufficiently little that all or part of the C horizons of these profiles could be assumed to represent the original material from which their sola have developed. 2. Color The C horizons or original material of the six profiles are indistinguishable on the basis of color alone. The base color in all six cases is light olive 272 273 brown, (2.5Y5/4, moist). There are minor (1 Munsell unit) deviations in some sub—horizons, but a portion of the C horizon of each profile has this base color. Reddish iron stains and light colored carbonate streaks are also present in all the C horizons. 3. Texture The original materials of the Forman profiles con- tain higher percentages of silt and clay than those of the other four profiles. This is most evident in the upper portions of the sampled C horizons, since the clay content declines more with depth in the unleached portion of the Forman profiles than in the other four profiles. The C horizons of the Barnes and reddish Forman soils are very similar in texture, although those of the Barnes contain somewhat more silt. These textural differences are in agreement with the thin section studies and bulk density determinations. 4. Mineralogy The kinds of minerals in the C horizons of the three profiles on which mineralogical analyses were made are similar. All minerals present in significant amounts were present in all three profiles. The C horizons of all three profiles contain 30 to 40 per cent quartz, a considerable proportion of which occurs in the non-sand fraction. The percentage of quartz varies more within the 274 C horizon of one profile than among the C horizons of the three profiles. The C horizons of the Barnes profile contain double the percentage of heavy minerals in the very fine and fine sand fractions as compared to the other two profiles. The composition of the heavy mineral fraction in the three profiles is very similar, with pyroxenes and amphiboles the dominant species in all horizons. Garnet is the only resistant heavy mineral present in appreciable amounts. 5. Carbonate content The C horizons of all six profiles are calcareous, but the percentage of carbonates in those of the reddish Forman profiles is less than in those of the other four profiles. Carbonate content declines gradually with depth within the C horizons sampled, indicating a diffuse lower boundary to the zone of carbonate accumulation. 6. Shale and chert content The original materials of the Barnes profiles con- tain large amounts of shale and chert due to the proximity of the sampled profiles to the shale outcrops of the Pembina escarpment. There are large areas of the Barnes soils where the original material is much lower in shale and chert content. The original material of the Forman profiles has a moderate shale and chert content, while that of the reddish Forman profiles contains very little shale and chert of coarse sand or gravel size. 275 7. Overall characterization of the original materials The original materials of the Forman, reddish Forman, and Barnes profiles studied are distinct, and may be briefly characterized as follows. The Forman profiles are developed from till that is: light olive brown, loam to clay loam, very dense, strongly to moderately calcareous, and moderately shaley. The reddish Forman profiles are developed from till that is: light olive brown, loam, moderately dense, moderately calcareous, and low in shale content. The Barnes profiles are developed from till that is: lightolive brown, loam, relatively loose, moderately to strongly calcareous, and very high in shale content. It has not been determined whether these differences in the original materials are due to local variations in the nature of the till deposited during a single glacial advance, or whether the profiles are developed from tills deposited by different glacial advances. The differences are not sufficiently great to suggest that any of the till is of pre-Mankato age. B. Comparison of the Developed Profiles 1. Textural profile development The presence or absence of argillic, or textural B, horizons as defined in the 7th Approximation, does not serve to distinguish the three series (or phases) with 276 which this study has dealt. The B horizons of the Forman soils are higher in clay content than those of the other two series, but this content of clay represents only a small increase over that in the A horizons, which are also fine textured in the Forman soils. As a rule, all three series have finer textured B horizons. These are the combined result of illuviation, weathering in place, and clay inherited from the original materials. Most of the clay in the B horizons is inherited from the original materials, and there is evidence that in some cases these original materials contained more clay than those of the A or Cca horizons. 2. Organic matter accumulation The total organic matter content is highest in the Forman soils, intermediate in the Barnes soils, and lowest in the reddish Forman soils. The high organic matter content of the Forman soils is due to the self-mulching effect, which causes some of the organic material to be preserved below the surface, where it is not subject to loss by erosion. The reason for the low organic matter content in the reddish Forman soils has not been determined, but it is probably related to the favorable oxidizing and accelerated erosion conditions which seem to prevail in the area of their occurrence. 277 3. Carbonate redistribution There is a definite layer of carbonate accumulation in five of the six profiles, although the lower boundaries of these layers are often quite diffuse. In the Forman soils there are few fine pores. The carbonates are deposited in the few large pores, where in cross section they appear as lime concentrations, or occasionally as concretions. In the Barnes soils there are numerous fine pores in which the carbonates are deposited, and this results in a more uni- formly distributed appearance of the carbonates when viewed in cross section. These two conditions are very distinct in the field. The reddish Forman soils exhibit a condition intermediate between these patterns, but is closer to that in the Forman soils than to that in the Barnes. The depth to which carbonates are leached is inversely related to the carbonate content of the original material, and is greatest in the reddish Forman soils, where the assumed original materials are least calcareous. 4. Movement of iron oxides The amount and distribution of iron oxides is very similar in the six profiles. Both differ considerably more when determined on the same profile by different methods, .than when determined on different profiles by the same method. The thioglycolic acid extraction indicates very low iron oxide contents that decline with depth. The Kilmer extraction indicates much higher iron oxide contents, which parallel clay content. 278 C. Probable Soil Genesis 1. General considerations The forces which have acted to transform the original glacial till into the present soil profiles are still acting, and can be expected to produce further changes in the morphology of these profiles. The past action of these forces are summarized in the following section, and speculations are made as to the type of future changes that can be expected as these forces continue to operate. Two processes that have, without question, occurred in all the profiles are the accumulation of organic matter and the redistribution of carbonates. Both these processes began shortly after the withdrawal of the glacier. The accumulation of organic matter has been interrupted by the cultivation of these soils. Additions of organic matter still occur, but are different in kind and amount from those made under natural conditions. The leaching of carbonates is still in progress, and will continue until an equilibrium is reached between downward leaching and upward movement from the calcium saturated ground water. This will not occur for a long time in well drained profiles, since the water table is at considerable depth during most of the year. 2. Genesis of the individual profiles Only the three profiles studied in the greatest detail are included in this discussion. 279 a. Profile 37-3 (Forman) The high clay content and densely packed matrix of the original material has had an appreciable effect on the development of this profile. On drying, large cracks are produced due to the reduction of volume of the expanding lattice clays. The repeated opening of these cracks along the same planes is responsible for the strong development of the prismatic structure. Downward moving water tends to follow the planes of weakness between the peds, rather than penetrating the dense ped interiors. This is a deterrent to leaching of the ped interiors, and carbonates are present at the depth of only 17 inches, although organic coatings and clay films are present to greater depths, having been carried there by the water moving down the cracks. The cracking in the B horizon also contributes to the high organic matter content of the profile. Granular A horizon material falls into these cracks, and the organic matter it contains is protected from surface erosion losses. There has been some weathering in this profile. Shale particles of sand size are essentially absent from the upper horizons of the profile to a depth of 17 inches, but are quite abundant below this depth. The relative concentration of resistant minerals of sand size in the upper horizons indicates that small amounts of the less resistant mineral species have been removed, or at least reduced to smaller particles, by weathering. The indications 280 of weathering are slight, and are concentrated in the upper part of the B horizons, where the temperature and moisture conditions favorable to weathering are most prevalent. The textural B horizon in this profile is the combined result of clay movement, weathering in place, and possibly stratification. The calculations made in Chapter V indicate that clay has been removed from the A horizon and deposited in the B horizon. These calculations are probably valid for this profile. The most likely direction for the future development of this profile will be toward a Gray wooded type profile; as organic matter is depleted, bases are replaced by hydrogen, and clay continues to move downward in the profile. All these can be expected to proceed very slowly because of the fine texture of the soil material. The high clay content of the soil material suggests the alternative possibility of the development of a clay- pan Planosol type of profile. If the removal of weathering products were retarded by the filling of the inter-ped cracks, the normal rate of clay formation and movement could produce a clay pan. The formation of a pan is not likely if the cracks remain open, and organic matter continues to be mechanically incorporated into the B horizon. 281 b. Profile 2—l (reddish Forman) The solum of this profile developed from till that contained lower percentages of carbonates, shale, and heavy minerals than that forming the original material of the sola of the other two profiles. The lower carbonate content resulted in a less alkaline soil environment, in which weathering could be expected to proceed more rapidly. On the other hand, the low shale and heavy mineral content reduce the amount of easily weatherable coarse fragments. Development of the present profile has included the leaching of carbonates to a depth of 19 inches, and the apparent development of a definite textural B horizon. There has been a small amount of clay movement from the A to the B horizon, but there are strong indications that the apparent accumulations of clay and iron oxides in the B21 horizon are due to differences between the original material of this horizon and those above and below. The intensity of the alkaline environment has been lessened in the upper two horizons of this profile by the replacement of some calcium and magnesium on the exchange complex by hydrogen ions. The pH values in these horizons are much lower than those deeper in the profile. There are indications that quartz grains have been reduced in size in the upper part of the profile, although the overall mineralogical composition is relatively uniform with depth. The relatively low proportion of coarse fragments of easily weathered minerals extends into the 282 unleached portion of the profile, indicating that any differences in mineralogical composition predated the development of the present profile. The amount of organic matter is relatively low in this profile. This is due to accelerated erosion losses, and to favorable oxidizing conditions at this site. The most probable course of future profile develop- ment is toward a Gray Wooded type profile. The substratum is fairly porous, does not restrict the passage of water, and permits the leaching of carbaiates and bases; the amounts of which were relatively low in this profile to begin with. An A2 horizon can be expected to develop between the Ap and B21 horizons. However, if erosion losses continue at the present rate, it may never be observed, since the base of the plow layer will move down the profile at a fasterrate than the depth of leaching. c. Profile 50—2 (Barnes) This profile is still in the early stages of development, but this development is proceeding rather rapidly. Carbonates are leached only to a depth of 11 inches, but a distinct textural B horizon has apparently developed, and resistant minerals are weakly concentrated in the upper part of the profile. Shale is weathering very rapidly, with less than half the amount assumed to have been present in the original material now present in the Ap and B21 horizons. The reduction in shale content 283 is accompanied by increases in silt and clay content. The shale and non—resistant heavy minerals originally present in the upper part of this profile have been broken down under alkaline conditions. The original material contained large quantities of carbonates, heavy minerals, and shale. The presence of large numbers of easily weathered coarse fragments partially explains the rapid development of the textural B horizon. The amount of Bt development due to clay movement is small compared with that due to weathering in place. More intense B horizon development can be expected, since shale and easily weathered minerals are still abundant. There is also a possibility that the B horizons developed from materials higher in clay content than the original materials of the A and C horizons. A large quantity of organic matter has accumulated on the surface. The self-mulching phenomena noted in the Forman profile is absent here, resulting in the concentra- tion of most of the organic matter in the Ap horizon. The most probable future development of this profile is toward a Gray Wooded soil. Clay and silt content will increase substantially as shale and chert fragments continue to weather, and there is a possibility that a clay pan may develop. The leaching of carbonates will continue, but a very long time will be required for the complete removal of the large amounts present. 284 D. Soil Classification 1. Classification under the present system (1938 Yearbook as modified in 1949) All the soils involved in this study are, without question, Chernozems. The Barnes and Forman soils were felt to be different series at the time this study was undertaken in 1958. This thinking has persisted, and Forman was correlated as a separate series in Sargent County in 1961. The main decision yet to be made is what to do with the reddish Forman soils. Should they be included with the Forman soils, with the Barnes soils, or recognized as a separate series? Texturally, these soils are more similar to the Barnes soils than to the Forman soils, but mineralogically they are more similar to the‘Forman than to the Barnes. They are distinct in carbonate content, reaction, color, and shale content. In view of the uses made of these soils, texture should be given more weight than the other properties because of its direct influence on the moisture holding capacity. For this reason, the reddish Forman soils could be considered a phase of the Barnes series. The several differences in the soil profile, including the solum, suggest that if these soils can be consistently separated in mapping, they should be recognized as a separate series. 285 2. Classification under the proposed system (7th Approximation) a. Order All six profiles have been placed in order 5, the Mollisols. Mollisols must have mollic epipedons. The Ap horizons of Barnes profile 50—2, and Forman profiles 37-3 and 41—1 qualify as mollic epipedons without question, meeting all requirements for such a diagnostic surface horizon. The Ap horizons of the other three profiles con- tain sufficient organic carbon, and are dark enough in color to qualify as mollic epipedons, but fail to comprise the necessary one third of the solum, which a mollic epipedon should. However, if these profiles were plowed to a depth equal to one third the thickness of the solum, (l to 2_ inches deeper than at present) the resulting plow layers would still be sufficiently dark, and contain enough organic carbon to qualify as mollic epipedons. Separations at this level should certainly not be made on the basis of an inch or two difference in plowing depth: so all six profiles have been classified as Mollisols. b. Suborder All six profiles have been placed in suborder 5.4, the Borolls. The cool climatic conditions and good drainage conditions under which these profiles developed seem to fit the specifications of this suborder very closely. 286 c. Great group Here the six profiles must be divided, if the rules are followed explicitly. Forman profile 41-1 does not have an argillic horizon and therefore is placed in great group 5.42, the Haplaborolls. The other five profiles contain argillic horizons, on the basis of B:A clay ratios, and are classified as great group 5.43, the Argiborolls. The logic of the separation of the two Forman profiles at this level is questionable. The 1.20 B:A clay ratio divides the soils recognized as Forman in the field. Some profiles have B:A clay ratios just over 1.20, others just below. Both Forman profiles considered here have B:C clay ratios over 1.20. For this reason, the rules will be violated slightly, and all six profiles will be considered Argiborolls. It has not, however, been shown conclusively that the apparent textural B horizons in any of the profiles are due primarily to illuviation. d. Subgroup The Barnes and reddish Forman soils are tentatively classified as Haplig Argiborolls, while the Forman soils are classified as Vertic Argiborolls. e. Family Names at the family level are not fixed at this writing. The following names are used very tentatively. The Forman profiles will be classified as Fine Loamy Soils 287 with layer lattice mineralogy. The other four profiles will be classified as Fine Loamy Soils with mixed mineralogy. f. Series The Fbrman soils must be considered separate series from the Barnes, since the two have been separated at the family level. The reddish Forman soils are also separated from the Forman at the family level, but if they are to be separated from the Barnes it must be at the series level. g. Comments Judgment must be used in classifying soils according to this system, in spite of the great detail in which the limits of the classes in each category are set forth. Once a separation between soils is made at a high level, these soils cannot be recombined at a lower level, regardless of their similarities. Therefore, it is desirable to make the higher level separations on a regional, rather than an individual profile basis. If the 1.20 B:A clay ratio is used as the primary criterion of classification, the boundary between the Haplaborolls and Argiborolls does not coincide with observable profile differences or with mapable geographic areas. The proper classification of these soils depends upon the mode of origin of the textural B horizons. In the field, it was felt that these horizons had developed through illuviation, in which case the Argiboroll designation 288 is correct. Later calculations and analyses indicate that the amount of illuvial clay in the B horizons is small compared with the amounts inherited from the original material, or formed in place. In this case, the soils possess cambic, rather than argillic horizons, and should be classified as Haplaborolls. While the laboratory investi— gations were morethorough, the field evaluation cannot be disregarded, since this is the basis on which most soils must be classified. In the opinion of the author, the presence of the textural B horizons is of more practical significance than their mode of origin, and for this reason the soils are classified as Argiborolls. The six profiles should not be separated at the great group level. E.‘ Practical Applications The study was not designed for the purpose of solving practical problems in the use and management of the soils involved. The morphologic differences discussed in this thesis will be overshadowed by the effects of minor climatic differences in the utilization of these soils. This will be true for many centuries to come, in spite of the fact that the soil forming processes are continually acting to intensify the profile differences. The forerunners of Chernozem degradation have been observed in these profiles, but this will not noticeably affect crop yields for several centuries. The differences in the physical condition of the 289 Barnes and Forman soils are of sufficient magnitude to be of practical significance. While this was known before this study was undertaken, it has been possible here to provide a more quantitative definition of these differences. It has been noted that organic matter is being depleted rapidly, and this could be of some concern in the foreseeable future. The study is of most practical value to those concerned with the classification of the soils. It involved a large amount of correlation of detailed laboratory studies with routine field observations. The former are essential, especially in View of the criteria used in the proposed system, for the proper classification of soils. These determinations can be made on only a very small percentage of the profiles to be classified. The bulk of the classification must rest on field observations. The value of a study such as this, in which the two are tied together, lies in the fact that quantitative reference points are established among the soils to be classified, and in the verification of field observations by more accurate techniques. In this study, existing techniques were applied to a new group of soils with varying degrees of success. It was the first detailed mineralogical analysis of the soils of this region, and as such, has contributed to the knowledge of the morphology, genesis, and classification of these soils. 290 The agricultural utilization of these soils will not, and should not, be changed on the basis of the findings of this study. F. Needs for Further Research 1. Clay studies This research has shown that definite finer textured B horizons develop in well drained Chernozem soils prior to the stage commonly known as degradation. The nature of this B horizon, and the processes responsible for its formation are still uncertain. A study should be undertaken to determine more accurately the nature of the clay fraction of this horizon, and to determine the processes by which clays are capable of moving under alkaline conditions. Clay films should be analyzed separately from the remainder of the peds, in an attempt to determine why they are not optically oriented in thin section. It is possible that these films will be found to be composed of a clay-organic complex with erratic optical properties. 2. Shrinking and swelling The magnitudes of the forces developed by the shrinking and swelling of the B horizons, particularly those of the Forman soils, should be evaluated quantitatively. In this study the occurrence of the shrinking and swelling has been inferred from other soil properties, rather than measured, or even observed directly. 291 It would be desirable if a device were designed to measure the pressures produced when adjacent peds come in contact on swelling. A study of the changes in ped volumes with changes in moisture content would in itself be beneficial in evaluating the physical behavior of these soils. 3. Iron movement Before the movement of iron compounds can be accurately evaluated, it must be determined what forms of iron are extracted by the various extracting agents. It must then be determined which of these iron compounds are capable of movement, and if these are distinct from forms that do not move. The movement of iron and iron-organic matter complexes should be studied under alkaline conditions, possibly in an artificial medium in which other forms of iron are not present. 4. Geologic correlation Time relationships among the profiles studied can be evaluated only if the original materials are correlated to known advances of the glacier. This correlation could be made by using radio carbon dating, or through correlating the mineralogy and mechanical composition with those of previously dated deposits. 292 5. Organic matter analysis The composition of the organic fractions of the A and B horizons should be determined, and compared within and among profiles. The presence of minute bits of resistant plant tissue from times past, such as phytoliths, may provide clues to differences in the natural vegetation that existed several thousand years ago. Radioactive carbon dating in the profile may aid in establishing time relationships among the organic materials in various parts of the profile. 6. Drainage studies Studies similar to this one could be made at each drainage position in the landscape. Comparisons among the results of these studies could then be used to evaluate the effect of natural drainage on mineral weathering. 7. Productivity Crop yield information should be obtained on areas of each of the soils studied, under defined systems of management. This would indicate whether or hot the observed soil profile differences are of enough significance to warrant their use as criteria of classification, and if so, at what level. 293 8. Shale and chert weathering The composition and weathering products of the shale and chert particles in these profiles should be studied further. More of these fragments can be expected to weather to silt or clay size in the future. Therefore, the resulting products could have an appreciable influence on the future soil profile development, and perhaps on soil fertility and productivity. Shale and chert should be treated separately in future analysis. All the proposed research would be interesting, and would add to the knowledge of the soils of the area. With the exception of yield studies however, this is not the type of research that will net anyone any financial return in the foreseeable future, and therefore it is apt to have a low priority. Most of the proposed research is more specialized than this study has been. It is the hope of this author that anyone pursuing any of these highly specialized problems does not lose sight of where his work fits into the broader problem of the proper classification and understanding of the soils of the area. CHAPTER VII CONCLUSIONS AND SPECULATIONS Most of the present morphologic differences among the Barnes, reddish Forman and Forman soils exist because of differences in the original materials from which the soils developed. Sufficient time has not elapsed for the effects of common climate and vegetation to even out the differences inherited from the original materials. The differences between the Barnes and reddish Forman soils will probably disappear as the forces of climate and vegetation continue to act. The reddish Forman is in a more advanced stage of development, but the Barnes is developing at a rapid rate because of the abundance of easily weatherable minerals. Both Soils will proceed to a degraded Chernozem type profile, and forest enroachment will not be prerequisite to this transformation. Further development to the Gray Wooded soils will probably require forest vegetation. The Forman soils, or at least the finer part of the series, is enough different from the others, that it is doubtful whether the differences can ever be overcome by the forces of climate and vegetation. The fine textures and dense packing of the original materials of the Forman 294 295 soils have introduced the self—mulching effect in these soils. It is entirely possible that the Forman soils will eventually develop into clay pan Planosols. The following changes have occurred since the beginning of soil development from the original materials. 1. 2. Large quantities of organic matter have accumulated. Carbonates have been leached to depths of l to 2 feet, and soluble salts to even greater depth. Small amounts of silicate clays have been removed from the A horizons and deposited in the B horizons. The illuvial horizons are obvious, but the eluvial horizons are masked by dark color and the effects of cultivation. Montmorilldnite is the dominant clay material in all horizons. The less resistant heavy minerals have begun to weather from the upper parts of the profiles. The weathering is most intense in the upper part of the B horizons. Shale has weathered from the upper horizons, and has broken down directly from particles of gravel size to particles of silt and clay size. Some clay has been formed in place, with clay formation greatest in the upper part of the B horizons. There has probably been a slight movement of iron oxides from the A to the B horizons, but this is not known for certain. 296 The present stage of weathering in these profiles is not as advanced as that thought by most workers to represent the transition from the true to the degraded Chernozems. The Barnes and Forman soils are separated at the family level on the basis of their mineralogy, according to the 7th Approximation system of classification. For the purposes of mapping, they should be split at least at the series level. The separation should be regional rather than local. Texture of the C horizons, structure develop- ment, depth of organic matter incorporation, and the nature of the carbonate accumulation are the best criteria for separating the two series in the field. The reddish Forman soils should be included in the Barnes series if they are not to be separated as different mapping units. It is felt that they will be distinct enough to be separated in mapping, in which case they should be recognized at the series level. LITERATURE CITED Alexander, L. T., Hendricks, S. B., and Nelson, R. A. 1939. Minerals present in soil colloids, II. Estimation in some representative soils. Soil Sci. 48:273-279. Adlaway, W. H., and Rhoades, H. F. 1951. 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Sci. Soc. Amer. Proc. 16:123—129. Olson, R. V. 1947. Iron solubility in soils as affected by pH and free iron oxide content. Soil Sci. Soc. Amer. Proc. 12:153-157. Paddick, M. E. 1948. A simple colorimetric test for iron in alkaline soils. Soil Sci. Soc. Amer. Proc. 13:197-201. Pawluk, S., and Bentley, C. F. 1956. Exchangeable cation characteristics of some West-Central Alberta Soils. Peech, M., Alexander, L. T., Dean, L. A., and Reed. J. F. 1947. Methods of Soil Analysis for Soil Fertility Investigations. U.S.D.A. Circular 757. Pettijohn, F. J. 1941. Persistence of heavy minerals and geologic age. Journ. of Geol. 49:610-625. . 1957. Sedimentary Rocks. 2nd Edition. Harper & Bros., N.Y. 301 Pollack, S. S., Whiteside, E. P., and Van Farrowe, D. E. 1954. X-ray diffraction of common silica minerals and possible applications to studies of soil genesis. Soil Sci. Soc. Amer. Proc. 18:268-272. Raeside, J. D. 1959. Stability of index minerals in soils, with particular reference to quartz, zircon, and garnet. Jour. Sed. Petr. 29:493-502. Rankama, K. and Sahama, T. C. 1949. Geochemistry. Univ. of Chicago Press. Redmond, C. E., and McClelland, J. E. 1959. The occurrence and distribution of lime in Calcium Carbonate Solonchak and associated soils of Eastern North Dakota. Soil Sci. Soc. Amer. Proc. 23:61-65. Robertson, J. A. 1961. The characteristics of different genetic soil types in the Newdale soil association of Manitoba. Can. Jour. Soil Sci. 41:124—133. Rogers, A. F., and Kerr, P. F. 1933. Thin Section Mineralogy. McGraw-Hill, N.Y. & London. Ruhe, R. V., and Scholtes, W. H. 1956. Ages and development of soil landscapes in relation to climatic and vegetation changes in Iowa. Soil Sci. Soc. Amer. Proc. 20:264-273. St. Arnaud, R. J. 1961. The pedogenesis of a BlaCk-Gray Wooded sequence of soils in Saskatchewan,Canada. Unpub. Ph.D. Thesis, Michigan State Univ., E. Lansing, Michigan. Soil Survey Staff, U.S. Dept. of Agriculture. 1951. Soil Survey Manual. U.S.D.A. Handbodk No. 18. U.S. Govt. Printing Office, Washington, D.C. . 1960. Soil Classification, a Comprehensive System. 7th Approximation. U.S. Govt. Printing Office, Washington,D.C. Starkey, R. L., and Halvorson, H. O. 1927. Studies on the transformations of iron in nature, II: Concerning the importance of micro-organisms in the solution and precipitation of iron. Soil Sci. 24:381-402. Stephen, I. 1959. Some aspects of soil mineralogy. Report, Rothamstead Expt. Sta. 1958. pp. 205-213. 302 Stobbe, P. C., and Wright, J. R. 1959. Modern concepts in the genesis of Podzols. Soil Sci. Soc. Amer. Proc. 23:161-164. Taylor, F. R. 1960. Changes in number and size of North Dakota farms. Bimonthly Bulletin, 21—7:l6-18. Thorp, J., Williams, B. H., and Watkins, W. I. 1949. Soil Zones of the Great Plains, Kansas to Canada. Soil Sci. Soc. Amer. Proc. 13:438—445. U.S. Dept. of Agriculture. 1941. Climate and Man. Yearbook of Agriculture, 1941. pp. 1049-1054. . 1954. Diagnosis and Improvement of Saline and Alkali Soils. Agriculture Handbook No. 60. U.S. Govt. Printing Office, Washington, D.C. . 1938. Soils and Men. Yearbook of Agriculture 1938. Webber, L. R., and Shives, J. A. 1953. The identification of clay minerals in some Ontario soils. Soil Sci. Soc. Amer. Proc. 17:96-99. Westin, F. C. 1953. Solonetz soils of Eastern South Dakota, their properties and genesis. Soil Sci. Soc. Amer. Proc. 17:287-293. Wilding, L. P., and Westin, F. C. 1961. Characterization of the Sinai soils. Soil Sci. Soc. Amer. Proc. 25:380-384. APPENDIX Results of Analyses by Soil Survey Laboratory SCS, USDA Lincoln, Nebraska and Detailed Soil Profile Descriptions by the Author Color names from ?The ISCC-NBS Method of Designating colors and a Dictionary of Color Names,? U.S. Nat'l. Bur. Standards Circ. 553, 1955. All other designations are as proposed in the ?Soil Survey Manual.? 304 o.NH H.¢m 0.0m my m w m.o HH.o u.m m.m m.h m.ma m.¢m o.am my 0 N m.o Ha.o N.0 o.m m.m «.ma m.mm H.mm om m N 0.0 ma.o H.m @.m H.m m.ma «.mm o.mm mm o H m.o m ovo.o om.o m.m h.m N.m ¢.¢H ¢.mm m.Hm m o m.o m omo.o mm.o m.m m.h ©.h m.HH 0.0m m.wm w o H.H 0H Hmo.o va.o m.h m.h H.h O.MH ¢.wm o.hm m.o N.0 my Nam.o mm.m o.m v.5 m.h X R R X .UOmgw X x 80 awe x 0H.H mus Hus .mOEya .mOEya .mOEyd HHOm yamym moa monm Z\O amm coaymo ma m\a oH\H.mooa\.ms u>asmm [gasses cosy uosyaz oasmmao ESmQ>O mOUmo oaxom mmnm yfl>yy Iosoaoo Hmo IHHyUmHm y m m.mm o.Nm m.om m.mm mm.m mm.ma ma.o mm.b mm.¢ moo oolam H m o.¢m m.am N.Hm m.mm mm.m mn.my mm.© ma.h mh.m NNO Hmlhm a v m.mm 0.0N m.mm h.mm mm.m mm.0y am.m mm.h mh.m HNO emumm H0 m v.vm H.mm n.5m h.mm mm.m mm.m m©.v mm.m mm.w mou mmlhy a .ye o.NN w.¢m o.mm 0.0m Mm.mamo.¢a m¢.m mo.m we.y mmm balmy Hum .HB H.ma N.5m m.om b.mm m.m N.my ¢.oa m.h m.y Hmm malm H .ye @.om ©.Hm N.¢N ¢.mm @.m w.ma 0.0 N.0 m.¢ Ga mlo Noo.o No.0 Noo.o mo.o 0H.0 mm.o -mo.o -m.o moo.ov -mo.o lea.o umm.o um.o m.oua H1m mmmyo pawn pawn pamm pawn pawn aouyyom mmaoay Hmysyxme NA xmyo yaym maflm maym Esflomz mmymoo mmymoo aymmn mym> mym> Ayamo ymmv A.EE EHV soaysaflyymflp mNHm maoflyymm .mxmmyamz saaooaflq .>H0ymyoama >m>y5m Hyom may >9 UmaHEHmymp mm .Hlom maywoym mmaymm you mmmmamam xyoymyoan mayysom .om magma 305 mmoomu .yoaoo mymaoaymu mmmme o.mv o.Nm N.0 o.m N.0 m.ma OH v.0 N.N H.o n.0H ¢.mN m.¢H N.hv N.0 o.oa dd v.0 5.N N.0 m.ma m.0N H.my ¢.hv H.o H.> m m.o m.a N.0 5.NH N.NN m.¢a m.n¢ H.o o.m m m.o m.o N.0 h.oa h.mN m.¢a o.Nm H.o N.H N m.o m.o ¢.N muHH m.oa ¢.ma m.m¢ N.0 0.0 m.o H.o ¢.N 0.0H m.oa ¢.ON 0.0m «.0 «.0 N.H H.o ¢.N H.h H.mN N.0N ymyya Hmm myamym>flsvmyaayfi aflom .mooa Hmm myamam>y5vmyaaye a e m a osoemz scayma now so com x 62 .62 x 62 m ms 60 Nyaommmo laymm I I I .aoxm mmamaoxm ym aoaymo mysymfloz mHQSHom yomyyxm aoflymysymm maoflymo maamyomyyxm 306 Soil Type: Barnes loam (Chernozem) Area: Western Walsh County, North Dakota Location: 200 ft. W, 50 ft. S of NE cor. Sect. 31, Twp. 158N, Rg. 58W. Vegetation: Grain stubble Parent Material: Glacial till Physiography: 2/3 way up a knoll on 4% undulating till plain Drainage: Well drained Relief: 6 ft. Slope: 4%, southwest Erosion: Slight Sample No.: S-59-ND-50-1 Soil Profile: LSL# 11964 Ap O-SV Loam; brownish gray (lOYR 4/1, dry) to brownish black (lOYR 2/1, moist); weak coarse subangular blocky structure, breaking to weak fine crumbs: slightly hard, friable, slightly sticky and slightly plastic; noncalcareous, abrupt smooth boundary. 11965 821 5-129 Clay loam, moderate yellowish brown (lOYR 5/3, dry to 10YR 4/3, moist) with tongues of light brownish gray (lOYR 5/1, dry) to brownish gray (lOYR 4/1, moist) Al; moderate to strong medium prismatic structure, breaking to strong fine and medium angular blocks: very hard, firm, sticky and slightly plastic; non-calcareous; moder- ately thidk to thick clay films on ped surfaces: clear irregular boundary. 11966 B22 12—179 Clay loam: light olive brown (2.5Y 6/2, dry) to moderate olive brown, (2.5Y 4.5/2, moist): moderate medium prismatic structure breaking to moderate medium subangular blocks; very hard, friable, sticky and slightly plastic: patches of thin clay films on ped surfaces: noncalcareous, but weakly calcareous around pebbles: clear wavy boundary. Soil Profile: 11967 Cca 11968 C21 11969 C22 11970 Ccs l7-29fi 29-379 37-519 51-609 307 Silt loam: yellowish gray (2.5Y 8/2, dry) to between grayish yellow and light olive brown (2.5Y 6.5/2, moist); weak coarse prismatic structure, breaking to moderate coarse subangular blocks: hard, friable, slightly sticky and plastic: strongly calcareous with the lime disseminated throughout the soil mass: gradual boundary. Clay loam; light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with common, medium distinct light gray (N8/0, dry) to yellowish gray (2.5Y 7/2, moist) concentrations of lime and common fine prominent reddish brown mottlings: very weak coarse prismatic structure, breaking to moderate, thick plates, which in turn break to moderate very fine subangular blocks: hard, friable, sticky and plastic: moderately calcar- eous: gradual boundary. Loam; yellowish gray (2.5Y 7/2, dry) to light olive brown, (2.5Y 5/4, moist) with common fine distinct light gray (N 8/0, dry. 2.5Y 8/2, moist) concen- trations of lime and common fine distinct reddish brown mottlings; moderate thick platy structure, breaking to weak fine subangular blocks: hard, friable, slightly sticky and slightly plastic; weakly calcareous: gradual boundary. Loam; yellowish gray (2.5Y 7/2, dry) to light olive brown (2.5Y 5/4, moist) with a few coarse distinct light gray (N 8/0, dry) to yellowish gray (2.5Y 8/2, moist) lime and gypsum concen- trations, and common medium prominent reddish brown mottlings: moderate thick platy structure breaking to weak thin plates which break to weak very fine subangular blocks: hard, friable, slightly sticky and slightly plastic: weakly calcareous. 308 H.mH 0.0m N.om w my o.m o.H NH.o h.m v.m m.w H.m N.my H.¢N av ma 0.0 5.0 NH.o m.m o.m H.m m.HH N.NN m.mN HN m.m v.0 mN.o H.m m.m N.m m.NH o.vN m.Nm mN m.o m.o m mmo.o w¢.o N.m m.m m.m o.¢H h.MN m.mN h 0.0 m.o m mmo.o ah.o m.m m.m m.b N.ma h.¢N m.Nm HW m.o m.o m moa.o No.0 o.m v.5 m.h m.NH m.MN o.hm H w.o 0.0 N mmN.o ma.m o.m m.h 0.5 x X X X X x .oOmmo is EU ymm Z\O amm aoaymu oyua mud .nosya .nntue .nOEya Haom steam nostaaaas amONmm Ionyaz oasmmao ma m\H oa\a .mooa\.0e I>asem mos x om sosH EDmQ>O moomo Nyy>fly mmym IUSCQOU Hmo maoflmame mHSymyoS Iayyomam ymyymz mycmmyo mm a h m.mN ¢.om «.ON N.Nm mn.m mv.ma mm.o mm.h mn.m do ooIov a m m.ma m.mm 0.0H m.mm mo.Na mo.ma mm.b ma.m mm.¢ mu odlmm a e m.om 6.0m o.mm m.mm no.6 6m.ma 6m.m mo.e 6m.e mo mmuem so he H.mm 6.6m H.Hm «.mm 6m.e mm.oa mm.s mn.m 6m.e moo emuma Ho\a he m.Hm m.mm m.em m.mm mm.m we.ma mm.m mm.e me.m mmm mHIHH Hm I N.mH ¢.mN m.om m.Nm m.m ©.my m.m m.m o.N HNm HHIm H I ¢.ma H.mm m.ON h.mm o.oa h.¢y H.h m.m m.m ma mIo Noo.o No.0 Noo.o V Noo.o mo.o 0H.0 mN.o INO.O IN.o Imo.o IOH.O ImN.o Im.o m.OIH HhN mmmao N A mmao yaym team namm pcmm pamm pamm sonyyoa mmaoaH Hmysyxme maam maflm Esypmz mmymoo mmymoo hym> . Nym> Ayamo ymmv A.EE EHV aoaysayyymyn mNym maoyyymm Hyom may Na pmaHEymymp mm .mxmmyamz .NIom maymoym mmanmm Mom mmmwamam Nyoymyoama mayysom .caooayq .wyoymyoama >m>ysm .Hm mHQmB 309 mmoumo .Hoaoo mymaoaymu mumyem ¢.@v HmH N.H v.¢ e o m.mN HH d o m N H o ¢.mH N.Hm h.¢H n.mm H.©m h.o N.¢ N.0 0.0N 0H m.o o.N H.o ¢.NH m.0N ¢.HH. H.mv H.o m.NH 0H m.o m.H H.o m.mH o.NN m.mH m.>¢ H.o m.m @ m.o H.H H.o m.NH o.NN b.¢H N.Nm N.0 0.0 N 0.0 m.o N.0 m.0H b.0N m.mH h.mm N.0 0.0 H 5.0 N.0 N.H m.OH o.mH m.NN m.m¢ 0.0 m.o H v N.H H.o N.N m.m v.0N N.¢N K HmyHH Hmm myamHm>stmHHHHE X HHom .mOOH Hmm myamHm>H5UmHHHHE U¢OJEH .mz MyHommmo soayma wow IHo moom x 62 .soxm m 62 m m: 6o mmsmsoxm IDymm I COHymu ym mysymHoE mHasHom yomyyxm coHyMHSymm mcoHymo mHamyomyyxm 310 Soil Type: Barnes loam (Chernozem) Date: 8/26/59 Described by C. E. Redmond Area: Western Walsh Co., North Dakota Location: 280 ft. E, 200 ft. N of SW cor. Sect. 27, Twp 157N, Rg. 58W. Vegetation: Wheat Parent Material: Glacial till Physiography: 2/3 way up knoll on 4% undulating till plain Relief: 12-15 ft. Drainage: Well drained Slope: 4%, South Erosion: Slight Sample No.: S-59-ND—50—2 Soil Profile: LSL# 11971 Ap 0-59 Loam, brownish gray, (lOYR 4/1, dry) to brownish black (lOYR 2/1, moist): moderate medium subangular bloCky structure, breaking to weak fine crumbs: slightly hard, friable, slightly sticky and slightly plastic: noncalcareous: abrupt smooth boundary. 11972 B21 5—11? Clay loam: light grayish broWn, (lOYR 5/2, dry) to grayish brown (lOYR 4/2, moist) with tongues of brownish gray (lOYR 4/1, dry to lOYR 3/1, moist): moderate medium prismatic structure breaking to moderate fine and medium subangular blocks: very hard, friable, sticky and plastic: clay films not visible because of coatings formed by the dark tongues of A1 horizon: noncalcareous: clear wavy boundary. 11973 B22 11-159 Clay loam: light olive brown (2.5Y 5/2, dry) to moderate olive brown (2.5Y 3/2, moist): moderate coarse prismatic structure, breaking to moderate coarse subangular blocks: very hard, friable, sticky and plastic: discontinuous thin clay films on ped surfaces: noncalcareous, but weakly calcareous around lime coated pebbles: clear irregular boundary. Soil Profile: 11974 Cca 15-27" 11975 C2 27—339 11976 C3 33-469 11977 C4 46-609 311 Silt loam: yellowish gray (2.5Y 7/2, dry) to light olive brown (2.5Y 6/3, moist) with a few medium prominent reddish brown mottlings: weak coarse prismatic structure breaking to weak medium subangular blocks: hard, friable, sticky and plastic: strongly calcareous With the lime disseminated throughout the soil mass: gradual boundary. Loam: grayish yellow (2.5Y 7/3, dry) to light olive brown, (2.5Y 5/3, moist) with common medium distinct light gray (N 8/0, dry) to medium gray (N 6/0, moist) concentrations of lime and a few medium prominent brownish orange (2.5YR 5/8, dry) to strong brown (2,5YR 4/6, moist) mottlings: weak coarse prismatic structure, breaking to weak coarse plates which break to moderate, fine angular blocks: hard friable, sticky and slightly plastic: moderately calcareous: gradual boundary. Loam, yellowish gray (2.5Y 7/2, dry) to light olive brown, (2.5Y 6/3, moist) with a few fine prominent reddish brown mottlings: moderate medium platy structure, breaking to weak fine subangular blocks: hard, friable, slightly sticky and slightly plastic: weakly to moderately calcareous: gradual boundary. Loam: light olive brown (2.5Y 6/2, ,. dry. to. 2.5Y 5/4, moist) with a few medium distinct light gray (N 8/0, dry) to yellowish gray (2.5Y 7/2, moist) concentrations of lime and a few very fine reddish brown mottlings: moderate medium platy structure, breaking to moderate, fine subangular blocks: hard, friable, slightly sticky and slightly plastic: weakly calcareous. 312 o.NH m.mm m.om H v mH o.m H.H 6H.o 6.6 m.a o.m o.NH o.em m.Hm H v mH m.» o.H 6H.o n.m m.m H.m ¢.mH e.nN o.Nm H Hm m.o m.o om.o m.m o.m H.m H.mH m.mN m.Nm H 5N m.m m.o mN.o m.m ©.m H.m m.mH h.vN N.Hm HN m.N m.o m Hoo.o om.o m.m ©.m o.m v.mH w.mN o.mm m CH 5.0 o.H m emo.o hm.o o.m ¢.m o.N N.5H m.om m.©m H m.o N.H 0H OHH.o wo.H v.5 o.N N.h m.oH 5.0N h.Hm H ¢.o H.H OH mmH.o hm.H o.b 0.5 m.o m.mH o.hN ¢.Nm H ¢.o m.o NH wNN.o hb.N m.© 5.0 m.© m.mH H.5N ¢.mm H v.0 0.0 MH NmN.o Nb.m 5.0 0.0 ¢.® s. s. s. a. .6626 s. a. H.H EU Hmm Z\O amm COQHMU OHHH muH .mOEya .mOEya .mOEya HHom yamHm manHHHHZ Xmonm onyHZ UHammHO mH m\H oH\H .mOOH\.08 I>Hsom oH x om soaH Eammmu mOOmO m NyH>Hy mmym IyUSUaoo Hmo mconamB mysymHoE IHHyomHm Hmyymz mHam&HO mm H OH N.mm b.0N h.MN m.m¢ mH.m om.m mm.m mo.¢ mo.N mo ooImm HHm .HB 5.5m 5.0N 0.0N m.mm mm.o mm.© mm.N we.N mo.H do mmlmw Ho .HB m.mm m.mN m.mN m.m¢ m>.> mm.b m©.N mH.m mH.H mo memm H0 .HB m.mm H.mN m.om m.mv mo.b mm.h mm.N mm.m mb.N NO mMImN Hm I ¢.Nm ¢.¢N 0.6m ¢.m¢ mm.h MN.h m©.N mm.N mo.H moo mNION Hm I .o.mN m.¢N N.0m o.Nw mm.© MN.b mm.N mm.N m¢.H memm ONIhH o I m.oN m.NN m.H¢ m.mm v.0 H.h o.N b.N H.H NNm hHImH Ho\o I e.mm m.om H.oe m.em s.e m.m H.m e.m 6.0 Hmm mHIm HU I m.mN N.©N m.mm m.o¢ .m.m m.h m.N m.N b.H Hm mlm Hm I o.mN H.mN o.¢m h.Hv m.h m.m m.m H.m m.H ma mIo Noo.o No.0 Noo.o V Noo.o mo.o 0H.0 mN.o mmmHO INo.o IN.o Imo.o IQH.o ImN.o Im.o m.OIH HLN Hessyxme m A NmHo oHHm osmm osmm osmm 666m osmm maHm maHm EoHpmz mmymoo mmymoo CONHHOE mmaoaH Nym> Nym> aymma Aycmo Hmmv A.EE aHv COHySQHHymHQ mNHm mHoHyymm .mammyamz .aHooaHH .myoymyoamH >m>y5m HHom may >3 pmcHEHmymp mm .mInm mHHmoym amEHom How mmmmHmam NHOyMHOQMH maHysom .Nm mHamB 313 mmoumo .Hmaou mymaonymo momyam o.Nm vOH m.OH m.m v.0 w.o¢ NH «.0 o.¢ H.o m.mH m.mH v.6H N.mm H.wm m.m N.v m.o m.mm MH v.0 H.¢ H.o ¢.hH m.mH m.mH m.©m o.Nh m.o m.o N.0 o.Hm NH m.o m.m H.o N.mH o.hH m.mH N.¢m o.mh m.v h.m Ndo N.¢N OH N.0 o.m H.o m.bH N.HN 0.0H w.em H.o o.m o m.o @.H H.o w.NH N.¢N o.mH o.mm N.0 o.m o m.o @.H H.o N.HH o.mN m.NN 0.6m N.o e.e H e.o m.o e.~ e.mH e.eH m.m~ H.om N.0 v.0 H N.0 N.0 m.m m.HH H.mH m.mN m.Ho N.0 m.o H m.o N.0 N.m m.m ¢.mH «.mN m.nm v.0 m.o H v m.H H.o H.n m.m o.Hm o.m~ x a oaoemz HmyHH Hmm myamHm>HsvaHHHE .mz HHOm .mOOH Hmm myamHm>HDmeHHHE NyHommmo a0Hymy wow IHO moum & m2 .aoxm & 02 m m2 mo mmamaoxm Isymm aoHymo ym mysywHoz mHQDHom yomyyxm COHymysymm mcoHymo mHamyomyyxm 314 Soil Type: Forman (silt loam (Chermozem) Date: August 22, 1959. Described by C. E. Redmond Area: Southern Ransom County,North Dakota Location: 310 ft. N, 165 ft. W of SE Cor. Sec. 18, TWp. 133N, Rg. 55W. Vegetation: Millet Parent Material: Glacial till Physiography: 4% undulating till plain: on slope to a shallow drainageway. Relife: 6 ft. Drainage: Well drained Slope: 3%, Northwest Erosion: Slight Sample No.: S-59-ND-37-3 Note: There is a great deal of tongueing in this profile. Approximately 50% of the B21 and 20% of the B22 are composed of tongues of A material. These tongues retain the dark color of the A, but have structure similar to that of the surrounding B material. The maximum depth of tongue'ing is 22 inches. Soil Profile: LSL# 11932 Ap 0—6" Silt loam: brownish gray (lOYR 3/1, dry) to brownish black (lOYR 2/1, moist): weak medium subangular blocky structure, breaking to weak fine crumbs: hard, friable, slightly sticky and plastic: noncalcareous: abrupt smooth boundary. 11933 Bl 6-99 Clay loam: dark grayish, yellowish, brown, (lOYR 3/2, dry to lOYR 2/2, moist) with thick tongues of brownish gray (lOYR 3/1, dry) to brownish black (lOYR 2/1, moist): strong medium and coarse blocky structure: very hard, firm, very sticky and plastic: non— calcareous: clear broken boundary. 11934 B21 9—139 Clay loam: grayish yellowish brown (lOYR 5/2, dry) to dark grayish yellowish brown (lOYR 3/2, moiSt) with tongues of brownish gray (lOYR 3/1, dry) to brownish black (lOYR 2/1, moist): strong medium prismatic structure breaking to strong very fine angular blocks: very hard, firm, very sticky and plastic: non- calcareous: thick clay films on ped surfaces; diffuse. boundary. Soil Profile: 11935 B22 13-17" 11936 B3ca 17-20” 11937 Cca 11938 C2 20-289 28-35" 315 Clay loam: moderate olive brown and light olive brown (2.5Y 4/2 and 5/2, dry) to moderate and dark olive brown, (2.5Y 3/2 and 4/2, moist) with tongues of brownish gray, (lOYR 3/1, dry) to brownish black, (lOYR 2/1, moist): strong medium prismatic structure, breaking to strong fine angular blocks: very hard, firm, sticky and plastic: continuous moderate and patchy thick clay films on ped surfaces: non-calcareous, but containing small rounded pebbles which have lime coatings: clear irregular boundary. Clay loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/3, moist) with common, fine distinct light gray (N 8/0, dry) to faint yellowish gray (2.5Y 7/2, moist) lime concentrations: moderate medium prismatic structure, breaking to moderate medium blocks: hard, friable, sticky and slightly plastic: thin clay films on ped surfaces: weakly calcareous, becoming moderately calcareous with depth: clear wavy boundary. Silt loam: yellowish gray (2.5Y 7/2, dry) to light olive brown, (2.5Y 5/4, moist): weak coarse prismatic structure, breaking to weak fine blocks: hard, friable, slightly sticky and plastic: patchy light clay films on vertical ped surfaces; strongly calcareous with the lime segregated into distinct white blotches; gradual boundary. Loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with common medium faint yellowish gray (2.5Y 8/2, dry) to light olive brown (2.5Y 6/2, moist) mottlings: weak medium platy structure breaking to weak very fine blocks: very hard, friable, slightly sticky and slightly plastic: moderately calcareous: gradual boundary. Soil Profile: 11939 C3 11940 C4 11941 C 35—43" 43-53" 53-609 316 Loam: lightolive brown (2.5Y 6/2, dry to 2.5Y 5/3, moist) with common, medium, very faint yellowish gray (2.5Y 7/2, dry) and a few very fine prominent reddish brown mottlings: weak thin platy structure, breaking to weak fine blocks: hard, friable, slightly sticky and plastic: weakly calcareous, gradual boundary. Clay loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with a few fine prominent reddish brown, and common medium distinct light gray, (N 7/10, dry), yellowish gray (2.5Y 7/2, moist) mottlings: moderate medium platy structure, breaking to moderate fine blocks: hard, friable, sticky and plastic: weakly calcareous: gradual boundary. Loam, light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with common coarse faint light gray (N 7/10) to medium gray, (N 6/0, moist), and a few fine prominent reddish brown mottlings: weak medium platy structure, breaking to moderate fine blocks: friable, slightly sticky and slightly plastic: weakly calcareous. This horizon contains some gypsum, and some unidentified black specks. 317 N.OH b.wH b.vN NH ON ¢.m H.H OH.O m.m m.m m.h m.m m.mH ¢.mN v MN O.m O.H ON.O h.m m.m N.N ¢.OH N.NN m.Hm. m Om m.h mJO vN.O O.m ¢.m m.b m.m H.NH H.ON N «N 0.0 m.O NN.O m.m m.m O.m n.n; m.eH m.H~ H v mm o.N 5.0 om.o m.m m.m ~.m h.m m.hH O.mN vN m.O m.O m Hm0.0 O¢.O O.m m.m N.m N.¢H N.mN m.mm H 0.0 H.H m NNH.O .mH.H m.m N.m h.h h.MH O.¢N H.ON H m.O O.H OH H¢H.O m¢.H m.> m.b ¢.h m.¢H m.mN ¢.Nm H 0.0 m.O MH vhN.O h¢.m 0.5 m.h N.5 a a a a .663 6 a a H.H EU Hmm Z\U amm aoaymo OHuH muH .mOEya .moaya .moEya HHom yamHm manHHHHE Xmonm onsz UHammHO mH m\H OH\H .meoH\.oa I>Hsom mOH x om .eonH Eammho mOUmU NyH>Hy mmym Iospaoo Hmo mCOHmamB mysymHoz IHHyumHm ymyymz oHammyo mm H m O.¢N m.mm O.¢N m.Hv 5.0 O.HH O.m N.m H.N mo OOIOm H v O.mN ¢.mm m.¢N h.©¢ b.m m.m O.m O.m mo.H mu OmIHw HHm\Hon m 0.0m m.mN ¢.hN O.mm wh.m mo.v me.H mm.H mm.O moo HwImm H0 v m.MN m.mN m.bN N.Nm m¢.m mv.NH mo.m m0.0 mm.N m0 MMION HU m m.HN m.hN >.hN b.mm mm.m m¢.mH MN.O mm.O mb.m NU ONIeN H0 I N.mN m.bN ¢.Hm N.Om mH.m mm.HH mh.¢ mo.m mm.m moo ONImH Hm I N.MN m.mN H.Om b.0m O.m O.HH m.m m.m O.H NNm OHIO Ho .HB H.ON m.Om m.mm O.mm O.m ¢.HH m.¢ N.¢ N.N HNm mIm Ho .HB 5.NN o.NN b.mN 5.5m O.m m.HH «.6 m.¢ m.m ma mIO NO0.0 N0.0 NO0.0 v NO0.0 m0.0 OH.O mN.O INO.O IN.O ImO.O IOH.O ImN.O Im.O m.OIH HrN nano N A mmHo oHHm 666m 666m osmm seem teem HmHSyxmB maHm maHm EDHUmE mmymoo mmymou aotuom mmaoaH hym> mym> aymmn Aycmo Hmmv A.EE aHv aoHyDQHyymHQ mNHm mHoHyymm .mxmmyflmz .CHOUCHH .NHOymyoamH >m>y5m HHOm may Na OmaHEHmymp mm .HIHv mHHmoym amEHom How mmmemcm myoymyoamH maHysom .mm mHamB 318 Nmoomv .yoaoo mymaoaymo momym.m m.me mMH m H o m o o m.mm m m.o m.m H.o ¢.NH m.Hm n.HH e.ov mmH m.H o.N v.0 m.~m n m.o ¢.m H.o o.eH ¢.em o.NH e.Hm omH o.H o.m m.o m.em m m.o m.m H.o. «.mH m.mm m.mH m.m¢ o.Hm o.H m.m m.o «.mH m m.o n.H H.o m.HH m.m~ m.HH H.He N.0 o.n a N.0 m.o H.o c.6H m.om O.HH H.ev H.o H.H H m.o N.0 H.o H.m m.- H.4H m.¢m «.6 6.0 (H n.o N.0 e.o m.m n.mm m.mm m.em N.0 «.0 H W m.o H.o e.m m.a m.mH «.mm o.mm m.o 4.0 H m.H H.o ~.m 6.6 0.6m o.mm e x x . omo m2 ymyHH ymm myamHm>qumHHHHE .mz HHom mOOH Hmm myamHm>HsvaHHHE myHommmU sOHyma mom IHo moor M 62 .soxm x 62 m o: no mmsmsoxm ISymm COHymo ym GHDUamHOZ mHQSHOm UHUMHIIHXG COH#MH5#MW mCOHHMU @HQMUUMHflxm - so“ \ ' .I I I \ A U 319 Soil Type: Forman silt loam (Chernozem) Date: August 26, 1959. Described by C. E. Redmond Area: No. Sargent County, North Dakota Vegetation: Millet Parent Material: Glacial till Physiography: Knoll on 4% undulating till plain Relief: 8 ft. . Drainage: Well drained Slope: 4%, southwest Erosion: Slight Sample No.: S—59-ND-4l-l Soil Profile: LSL# 11942 Ap 0-59 Silt loam: brownish gray (lOYR 3/1, dry) to brownish black (lOYR 2/1, moist): weak coarse and medium subangular blocky structure: hard, friable, slightly sticky and slightly plastic: noncalcareous: abrupt smooth boundary. 11943 B21 5-99 Clay loam: grayish yellowish brown (lOYR 5/2, dry to lOYR 4/2, moist) with tongues of brownish gray (lOYR 4/1, dry to lOYR 3/1, moist): strong, coarse prismatic structure, breaking to strong fine angular blocks: very hard, firm, sticky and slightly plastic: noncalcareous: continuous moderate and discontinuous thick clay films on ped surfaces: diffuse. boundary. 11944 B22 9-13" Clay loam: light olive brown, (2.5Y 5/2, dry) to grayish yellowish brown (lOYR 4/2, moist), with tongues of medium gray (lOYR 5/1, dry) to brownish gray (lOYR 3/1, moist): strong medium prismatic structure, breaking to strong fine angular blocks: very hard, firm, sticky and plastic: noncalcareous, but becoming weakly calcareous with depth and containing a few rounded calcareous pebbles: continuous moderate with patches of thick clay films on ped surfaces: clear wavy boundary. ‘. Note: 11945 11946 11947 320 A discontinuous B3ca, 1-3 inches thidk, occurs in- termittently around the pit. It has clay loam texture, moderate medium prismatic structure, breaking to moderate medium angular blocks, and is weakly to moderately calcareous. Cca C2 C3 13-24" 24-299 29-33" Silt loam: lightolive brown and yellowish gray (2.5Y 6/2 and 7/2, dry) to light olive brown (2.5Y 5/2 and 6/2, moist) with common medium and fine distinct light yellowish brown (lOYR 6/4, dry) to grayish yellowish brown (lOYR 5/3, moist), and a few medium prominent reddish brown mottlings, and with common medium distinct light gray (N 7/0, dry) to medium gray (N 6/0, moist) lime con- centrations: moderate medium prismatic structure breaking to moderate medium and fine subangular blocks: very hard, friable, slightly stiCky and plastic: strongly calcareous with the lime segregated into distinct white blotches: gradual boundary. Loam: light olive brown (2.5Y 6/3, dry to 2.5Y 5/4, moist) with a few fine prominent dark orange yellow (7.5YR 6/8, dry) to light brown (7.5YR 5/6, moist) mottlings, and common, medium distinct light gray, (N 8/0, dry to yellowish gray (2.5Y 7/2, moist) lime concentrations: moderate medium prismatic structure, breaking to moderate medium subangular blocks: very hard, friable, slightly sticky and slightly plastic: moderately clacareous: clear wavy boundary. Clay loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with a few fine prominent light brown (5YR 5/6, dry) to strong brown (5YR 4/6, moist) mottlings, and many medium and coarse faint light gray (N 7/0, dry) to medium gray (N 6/0, moist) and common medium distinct light gray (N 8/0, dry to N 7/0, moist) lime concentrations: weak' medium platy structure breaking to weak fine subangular blocks: very hard, friable, sticky and plastic: moderately calcareous: gradual boundary. Soil Profile: 11948 Ccs 11949 C5 11950 C6 33-41" 41-50" 50—609 321 Clay loam, yellowish gray and light olive brown (2.5Y 8/2 and 6/3, dry) to light olive brown, (2.5Y 5/2, and 5/4, moist) with common fine distinct strong yellowish brown, (lOYR 5/6, dry) to moderate yellowish brown (lOYR 4/4, moist) and a few medium prominent brownish orange (5YR 5/8, dry) to strong brown (YR 4/8, moist) mottlings: weak thick platy structure, breaking to weak fine subangular blocks: very hard, friable, sticky and plastic: weakly calcareous, many gypsum crystals: gradual boundary. Silt loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with many coarse distinct yellowish gray (2.5Y 7/2, dry) to faint light olive brown, (2.5Y 5/2, moist) and common medium faint light yellowish brown, (lOYR 6/4, dry) to moderate yellowish brown (lOYR 5/4, moist) mottlings: moderate medium platy structure breaking to moderate very fine angular blocks: very hard, friable, sticky and plastic: weakly calcareous, gradual boundary. Clay loam: light olive brown, (2.5Y 6/3, dry to 2.5Y 5/4, moist) with common, medium distinct strong yellowish brown (lOYR 5/6, dry) to moderate yellowish brown (lOYR 4/4, moist) mottlings, and many coarse distinct light gray, (N 7/0, dry) to medium gray (N 5/0, moist) lime and gypsum concentrations: moderate thick platy structure breaking to moderate fine angular blocks: hard, friable, sticky and slightly plastic: weakly calcareous. 322 m 0 0.0H m.0N m 0 O. O.H 0H.0 0.0 v.m O.m 5.0 0.0H m.hN H V HH b. O.H 0H.0 m.m O.m H.w 0.0 m.mH m.bN OH wH h. w.0 mN.O m.m ¢.m 0.m m.m ¢.hH m.mN 0H m. m.0 0 mm0.0 dm.0 H.m m.m m.m N.OH b.0N m.mN H d. H.H 0 050.0 db.0 0.5 m.h ¢.b m.HH O.HN N.Hm H v. va OH HOH.O N0.H m.b 0.0 5.0 m.0 b.mH m.hN H 0. O.H NH mmH.0 HN.N 0.5 m.0 m.0 s. a s. a s s .mOEy< .mOEyd .mOEya HHom yamHm .UomN.@ o o HuH mH m\H OH\H .000H\.mE I>Hsvm EU ymm Z\O amm aonymo OHuH mnH Edmm>0 COMO manHHHHZ Xmonm onsz UHammHo OH x 0m aoyH m hyH>Hy mmHm IUDpaoo Hmo mCOHmamB mysymHoz IHHyomHm Hmyymz UHammyo mm H .HB m.ON m.mm H.NN m.0m mO.MH mm.0H mN.m m0.¢ mH.N NNU OOIO¢ H .HB 0.0N H.Om N.NN N.5m mo.NH we.mH mN.m mh.¢ mv.N HNO memm H m m.0N h.mm N.mN m.0m m0.HH mv.wH wh.¢ m0.¢ mN.m moo mmImN H\Ho .HE m.0N m.¢m N.5N H.mm m¢.HH m¢.¢H mn.¢ mm.v m0.N moO mNImH H I m.bH b.0m ¢.mN N.Hm H.MH v.0H 0.m H.m 5.N NNm OHImH Ho .HB N.OH m.mm 0.NN 0.0N 0.NH m.0H 0.m 0.v o.N HNm MHIm H .HB 0.0H 0.0m N.NN N.Om 0.NH m.mH v.0 m.m h.m ma mIO N00.0 No.0 NO0.0 V NO0.0 m0.0 0H.0 mN.O INO.O IN.O Im0.0 IOH.O ImN.0 Im.0 m.OIH HIN mmmHU N A NMHO yHHm pamm pamm pamm pamm Ucmm aotuom mmaoaH HMHSyxmB maHm maHm EsHme mmymoo mmymoo aymmm >Hm> Nym> Ayamo HmmVA.EE CH0 COHySQHHymHQ mNHm mHUHyHmm may Na UmaHEHmymp mm .mxmmyamz .aHomaHH .myoymyoamH >m>ysm HHom .HIN mHHyoym cmEHom amepmH Mom mmmNHmam NyoymyoamH maHysom .wm mHQMB 323 .m 0 oumo .Hoaoo mymaoaymo momyem mysymHoz mHQSHOm yomyyxm COHyMHSymm —-_- ‘\\ q 5“ A A up .— -4- ——- ..... MCOHHMU GHQMHUmHHNW .. Avid I-.. O.m¢ HmH ¢.m N.5 0.0 0.00 0H 0.0 v.m H.O m.MH H.mm H.mH H.Om N.m0 v.N 4.0 m.0 m.mm 0H ,¢.0 H.m H.O O.HH m.ON O.MH w.0¢ HOH 0.N m.m 0.0 N.ON 0 m.0 ¢.N H.0 O.MH 0.Nm m.mH N.Ov N.0 m.m m «.0 m.0 H.O m.HH 5.0N 0.mH 0.m¢ N.0 0.0 H m.0 N.0 O.H 0.0H m.m 0.mH N.m¢ N.0 ¢.O H W 0.0 H.O H.m O.m b.0H b.0H O.¢v m.0 «.0 H 0.0 H.0 O.m N.0 N.NH N.ON o ymyHH ymm myamHm>HJUmHHHHE X HHom .OOOH Hmm mycmHm>HSUmHHHHE umefimz a mz NyHommmu soHymn mom IHo moom s 62 .soxm & 62 m ms to mmsmsoxm ISymm I I aO.Hymo ym 324 Soil Type: Formanl loam, reddish variant (Chernozem) Date: 8-26-59 Described by C. E. Redmond Area: SouthwesternBarnes County, North Dakota Location: 80 ft. N, 135 ft. W of E quarter cor., Sec. 5, Twp. 137N, Rg. 60W. Vegetation: Grain stubble Parent Material: Glacial till Physiography: Gently undulating till plain, with 8-10 ft. relief and 4% slopes. Site is midway up the side of a ridge 10 feet high. Well drained soils occupy an abnormally large share of the landscape, compared to other till plain areas of comparable topography and relief. Relief: 8—10 ft. Drainage: Well drained Slope: Area 4%: Erosion: Moderate ' 5% SE at Stoniness: Common small pebbles throughout site the profile. Large stones rare. Sample No.: S-59-ND-2-l Soil Profile: LSL# 11951 Ap 0-5" Loam, brownish gray, (lOYR 4/1, dry) to brownish black (lOYR 2/1, moist): weak coarse subangular blocky structure: breaking to weak, medium crumbs: hard, friable, slightly sticky and slightly plastic: noncalcareous: abrupt smooth boundary. (Approximately 30% of the volume of this horizon is composed of B horizon material which has been mixed with the A in plowing. This material has the color and texture of the material in the B21 horizon. 11952 B21 5—13? Clay loam: grayish yellowish brown, (lOYR 5/3, dry) to moderate yellowish brown, (lOYR 4/3, moist): strong medium prismatic structure, breaking to strong fine and medium angular blocks: hard, firm, sticky and slightly plastic: noncalcareous: patches of thin to moder- ately thick clay films on ped surfaces: clear irregular boundary. (Thin tongues of brownish black (lOYR 2/1, moist) A1 horizon extend down between the prisms, making up 10 to 15% of the velume of the horizon. The colors in this horizon have a hue slightly redder than lOYR. This is especially true near the top of the horizon. Tentative series: not correlated. Soil Profile: 11953 B22 13-19'' 11954 Cca 19-282 11955 Ccs 28-399 11956 C21 39-49r 325 Clay loam: light olive brown, (2.5Y 5/3, dry) to moderate olive brown (2.5Y 4/3, moist): strong coarse prismatic structure, breaking to strong coarse angular blocks: very hard, firm, sticky and slightly plastic: noncalcareous: continuous thin and discontinuous moderate clay films on ped surfaces: clear, irregular boundary. (The colors of this horizon have a hue slightly redder than 2.5Y). Clay loam: light olive brown (2.5Y 6/2, dry) to moderate olive brown (2.5Y 4/4, moist) with many coarse, prominent, white lime and gypsum concentrations, and a few, fine, prominent reddish brown mottlings: moderate coarse prismatic structure, breaking to moderate, medium angular blocks: very hard, friable, sticky and slightly plastic: moderately calcareous, but strongly calcareous in and around lime concentrations: patches of thin clay films on vertical ped surfaces: gradual wavy boundary. Clay loam: light olive brown (2.5Y 6/2, dry) to moderate olive brown (2.5Y 4/4, moist) with many coarse, prominent, white clusters of gypsum crystals, and a few, fine prominent, reddish brown mottlings: weak coarse prismatic structure, breaking to weak thin plates, which break to moderate, very fine subangular blocks: very hard, friable, sticky and slightly plastic: moderately calcareous: gradual boundary, (Gypsum crystals occur in clusters up to one inch in diameter.) Clay loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with common, fine, prominent, strong yellowish brown (7.5YR 5/6, dry) to moderate brown (7.5YR 4/4, moist) mottlings, and a few, fine, prominent . white threads of gypsum: weak, very coarse prismatic structure, breaking to moderate medium plates, which break to weak, fine subangular blocks: very hard, friable, sticky and slightly plastic: weakly calcareous: gradual boundary. Soil Profile: 11957 C22 49-60" 326 Loam: light olive brown (2.5Y 6/2, dry) to moderate olive brown, (2.5Y 4/3, moist) with common, medium, prominent strong brown and brownish orange (5YR 4/6 and 5/6, dry) to moderate brown (5YR 3/4 and 4/4, moist) mottlings, and common, medium, prominent, white clusters of gypsum crystals: very weak, very coarse prismatic structure, breaking to moderate, thick plates which break to moderate fine subangular blocks:' hard, friable, slightly sticky and slightly plastic: weakly calcareous. 327 N.0 H.OH m.mN H W HH m.h O.H 0H.0 0.0 0.m H.m m.0 0.0H 0.0N H NH N.0 O.H 0H.0 0.0 O.m N.0 0.0 O.«H m.0H m OH m.« w.0 «N.0 «.m m.m 0.5 N.0 h.MH N.OH H «.0 0.0 0 h«0.0 m«.O m.h m.h H.h 0.0 H.OH o.NN H «.0 H.H HH 000.0 Nm.0 N.5 N.0 0.0 0.0H O.HN O.«m H 0.0 m.0 MH mmN.0 0«.m H.h 0.0 0.0 \ \ \ \ .UomN @ 2M0 aoammu HHH 50 “mm m « 2\o 6HuH mnH .mOEya .mOEya .mosya HHom yamHm manHHHHE N.0 mm onsz UHammyo mH m\H 0H\H .000H\.6E I>Hsem 0H x om soaH ESmQNO mOUmU m wa>Hy mmym Iospcou Hmo mconamy myoymHoE IHyyomHm ymyyme 0Hammyo mm H h 0.0H m.hm «.HN m.«m mo.MH m0.0H no.0 mm.m mm.N NNO OOImm H 0 h.mH 0.0m m.mm 0.mm mO.NH mm.0H mm.m mm.m mm.N HNU mmImm H .HB 0.mH 0.«m 0.«N m.Hm mO.HH mOKH 00.0 m0.m mH.m moImoO mMI«N Hum .ye 0.mH m.«m 0.mN 0.0N 0.NH 0.0H 0.0 0.0 m.N NNm «NI«H Hum .HB 0.«H 0.Nm 0.0N m.0N N.HH N.OH N.0 0.0 O.m HNm «HIm H .HB m.0H 0.0m N.HN 0.0m N.OH 0.«H 0.0 0.m m.m ma mIO «00.0 «0.0 «00.0 v «00.0 60.0 0H.0 m«.0 INO.O IN.O Im0.0 IOH.O ImN.0 Im.0 m.OIH HrN mmmHO N A NMHO yHHm pamm pamm pamm pamm pamm aotuom mmaocH Hmysyxme maHm maHm EsHme mmymou mmumoo aymma mym> mym> Ayamo Hmmv A.EE CH0 aoHyDQHyymHQ mNHm mHoHyumm .mxmmyamz .aHooaHH shyoyMHOQMH >m>ysm HHOm may Na UmcHEHmymp mm .NIN mHHyoym dmeyom amepmy How mmmNHmam NHOyMHOQMH maHysom .mm mHamB 328 mmoomo .Hoaou mymaonymo momyem b.«« m.00 «.«H « « m 0 0.0m «H «.0 «.m H.O 5.NH N.OH N.MH H.m« 0.«h 0.0H H.m m.0 0.0N mH «.0 H.m H.O N.OH O.HN m.mH 0.0m m.m0 N.H m.0 «.0 N.OH m m.0 0.0 H.0 0.0 m.mN H.OH «.mm N.0 0.0 H «.0 H.0 h.H 0.0 0.« m.NH 0.0« N.0 m.0 N m.0 m.0 H.m m.h. «.h N.mH m.Hm O.H m.0 H V O.H H.0 O.« 0.m «.mH 5.0N X ymyHH ymm myamHm>stmHHHHE .ma HHom .mOOH ymm myamHm>HsUmHHHHE NyMMmMMM soHymn mom IHo moom M 62 Iroxm s 62 m as so mmsmsoxm Isymm I COHymo ym mysymHoz mHasHow yomyyxm COHymysymm mCOHymo mHamyomyyxm 329 Soil Type: Formanl loam, reddish variant (Chernozem) Date: August 26, 1959. Described by C. E. Redmond Area: Southwestern Barnes County, North Dakota Location: 1100 ft. E, 145 ft. N of SW Cor Sec. 9, Mo 138NI Rg. 60W. Vegetation: Grain stubble Parent Material: Glacial till Physiography: 4% undulating till plain with 6 ft. relief. Site is on gentle slope. Area contains more well drained soils than one wouldeaxpect on this landscape. Relief: 6 ft. Drainage: Well drained Slope: Area, 4%. 3% North at site Erosion: Slight Stoniness: Common to many throughout the profile. Sample No.: S—59—ND-2-2 Soil Profile: LSL# 11958 Ap 0-59 Loam, brownish gray (lOYR 4/1, dry) to brownish black (lOYR 2/1, moist): weak fine and medium subangular blocky structure, breaking to weak, fine crumbs: hard, friable, slightly sticky and slightly plastic: noncalcareous: abrupt smooth boundary. (A small amount of B21 material was incorporated in the Ap by plowing.) 11959 B21 5-14" Clay loam: light brown, (7.5YR 5/3, dry) grading with depth to grayish yellowish brown (lOYR 5/3, dry) grayish brown, (7.5YR 4/2, moist grading with depth to moderate yellowish brown (lOYR 4/3, moist): strong medium prismatic structure, breaking to strong fine angular blocks: very hard, firm, sticky and slightly plastic: noncalcareous: discontinuous thin clay films on ped surfaces: clear wavy boundary. 11960 B22 14-249 Clay loam: light olive brown (2.5Y 5/2, dry) becoming yellowish gray (2.5Y 7/2, dry) when rubbed, to moderate olive brown, (2.5Y 4/2, moist), with a few, fine distinct strong yellowish brown (lOYR 5/6, dry) to dark yellowish brown mottlings: strong medium prismatic structure, breaking to strong medium and fine angular blocks: very hard, firm, sticky and slightly plastic: noncalcareous: continuous moderate clay films on ped surfaces: lTentative series: not correlated. Profile: 11961 Cca cs 24—38" 11962 C21 38-53” 11963 C22 53—60? Note: 330 clear, very irregular boundary. (Colors in this horizon have a hue slightly redder than 2.5Y). ' Clay loam: light olive brown (2.5Y 6/2, dry to 2.5Y 5/4, moist) with many, coarse, distinct light gray (N 8/0, dry) to yellowish gray (2.5Y 8/2, moist) concentrations of gypsum and lime, and a few, fine prominent reddish brown mottlings: moderate coarse and very coarse prismatic structure, breaking to moderate, medium subangular blocks: very hard, firm, sticky and slightly plastic: moderately calcareous, very high in gypsum: gradual boundary. Loam: light olive brown, (2.5Y 6/3, dry to 2.5Y 5/4, moist) with a few, medium, prominent moderate orange (5YR 6/8, dry) to light brown (5YR 5/6, moist) mottlings: weak coarse prismatic structure, breaking to moderate thidk plates which break into moderate fine subangular blocks: very hard, friable, slightly sticky and slightly plastic: weakly calcareous, gradual boundary. Loam: between light olive brown and yellowish gray (2.5Y 6.5/2, dry) to be- tween light olive brown and moderate olive brown, (2.5Y 4.5/4, moist) with common, fine distinct yellowish red mottlings: moderate, medium platy structure, breaking to moderate fine subangular blocks: very hard, friable, sticky and slightly plastic: weakly calcareous. The depth to lime varied from 20 to 30 inches around the pit. horizon, In the deeper areas, a noncalcareous B3 similar to the B22 in color and structure occurs betWeen the B22 and Ccs.