\ W |le w W ”H ‘ 144 834 ITHS SOME PHYSECM. ?R$§ER?€ES GP ORGAMC SO‘LS AS RELA'fiD T'O EFFECHVE DRAWAGE Thais 'ior rho [309mg of M. S. ‘JCHEGAN STATE COLLEGE Richer? W. Graeme W54 .fHEblE This is to certifg that the thesis entitled SOME PHYSICAL PROPERTIES OF ORGANIC SOILS AS RELATED TO EFFECTIVE DRAINAGE presented by Robert Worth George has been accepted towards fulfillment of the requirements for MASTER 0’ mdeme in MMCE (ELM Major professor Date “37 181 1994 0-169 SOME PHYSICAL PROPERTIES OF ORGANIC SOILS AS RELATED TO EFFECTIVE DRAINAGE By Robert'Ws George A THESIS Submitted to the School of Graduate Studies of Miehigan State College of Agriculture and Applied Science in partial fulfillment at the requirements for the degree of MASTER OF SCIENCE Department of Soil Science 1951: lllllill‘ll‘! Tu C815 ACKNOHLEDGMENT The author is grateful to Dr. A. E. Erickson for guidance and assistance during the course of the investigation. He is also indebted to Dr. J. F. Davis for making available the resources of the Michigan State College Enck Experimental Farm for this investigation. Grateful acknowledgment is also due to many others for helpful suggestions and assistance. 331800 TABLE (F CONTENTS INTRUDUCTION............................................... REVIEW OF LITERATURE....................................... ‘Water Content and Absorbing Capacity..................... Drying Characteristics................................... Shrinking and Swelling in Relation to Porosity........... Percolation of‘later through Organic Soile............... EXPERIMENTAL PROCEDURE..................................... Physical Characteristics................................. Equipment used......................................... Preparation of the site................................ Taking and preparing the soil cores for laboratory detemination........................................ Making laboratory determination........................ 'lhter Table Studies...................................... Equipment used......................................... Preparation of the site................................ Field determination.................................... DISCUSSION JED RESUIES..................................... Physical Characteristics................................. Shrinking and swelling oharacteristioe................. Pbrmeability........................................... Pore volume and desorption oharacteristice............. Water Table Studialeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee PAGE NUT p-w N 10 11 ll 11 12 1h 1h 1h 15 15 20 21 28 O 0 C q a v g V a Q j I e e u I I C ' Q I TABLE I. II. III. V. VI. VII. VIII. I. II. IIST OF TABLES moisture Content and Bulk Density of Soil Cores from Surface Samples of Varying Moisture Condi- tions at Site "A" "' 1951eeeeeeeeeeeeeeeeeeeeeeee Moisture Content and Bulk Density of Soil Cores from Varying Depths at Site nAneeeeeeeeeeeeeeeee moisture Content and Bulk Density of Soil Cores from Varying Depths at the Three Sites Sampled for Comparison StUdieseeeeeeeeeeeeeeeeeeeeeeeeee Summary of Shrinking and Swelling Characteristics Of 8011 Cores from Site "Aneeeeeeeeeeeeeeeeeeeee Summary of Pbrmeability Showing Eben Values, Stan- dard Deviation, and Permeability Class.......... Volume of Pbres Drained at Different Moisture Tensions for Soil Cores Sampled at Varying Depths Per Cent Mbieture at Different moisture Tensions for Soil Cores Samples at Varying Depths (Oven- Dry Basil)...................................... The Measured‘flater Loss from Pore Volume Correlated with water Table StudieBOOOOOOOOOOOOOOOOOOOOO... Drainage Coefficient for Varying Crop and Soil Conditions (With and'lithcut Surface Inlets).... Calculations for Determining Tile Spacing and Depth in Relation to Organic Soil Permeability .....Drainage Coefficient of 1 Inch per 2h Hours 01' 00d.> IOPOHOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO Recommended Tile Spacing for Organic Soil in Rela- tion to Permeability and the Depth of Tile...... PAGE 15 17 18 21 23 2h 26 141 It‘lt-Iletieleaeeeoe-e-e " COIee-eeev-eegee.‘ . . 1 teens-eeeeeoeu-ee--e.-e‘..e . I, I I'D-Ileeeeoeocee.-~-e .- " I ’ ceased.ele ( - . ( . O . . o—a . .0 - . . ' v'- - .I . . .. . - . . . I‘d. . 'd". ‘...qvL'C'."‘.'.-'.‘.."'.'.OCIO'A . a O 7 -. Correlation of water table studies and pore volume dataeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee Correlation of organic soil permeability and proper tile spacing and depth for effective drainage........ SWEARYOOOOCIOOOOOOOIOOOOOOOOOCOOOOOO0.00.00.00.00...COO... LITmTURE CITEDOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOC0.0.0.000... PAGE 38 39 50 |Illl’| FIGURE 1. 5. 6. 8. 9. 10. ll. 12. LIST OF FIGURES Relationship of Per Cent Moisture and Bulk Density on Different Sites at Varying Lepths............. Volume of Pores Drained at Different Tensions of water for 0-} Inch Depth; 9-12 Inch Depth; and 18-21 InCh Depth................................. Per Cent Moisture (0.13. Basis) at Different Ten- sions of Water for 0-} Inch Depth; 9-12 Inch Depth; aDd 18-21 Inch Depth...................... Location Plan for'Water Table Studies and Core Sampled Area at Site "A" " May 1952eeeeeeeoeeeeee Draw-Down Curves at Cross-Section A May 19-27, 1952.00.00.0000000000.0.00...OOOOOOOOOOOOOOOOOOOO Draw-Down Curves at Cross-Section B May 19-27, 1952......00......00......DOOOOOOOOOOOOOOOIOOOOO. Draw-Down Curves at Cross-Section C May 21-27, 1952.00.00.000000000......OOOOOOOOOOOOOIOOOOOOOOO EastJWest Profile Showing Calculated E4W Area of Dr0p and Draw-Down Curves at Site "A" - may 19- 27’ 19520.00...OOOOOOOOOOOOOOOOOOOOOIOO0.00.00... North-South Profile Showing Calculated NhS Area of LrOp, Kay 1952eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee- Location Plan for'Water Table Studies and Core Sampled Area at Site "A" - yfirCh 1953eeeeeeeeeeee Draw-Down Curves at Cross-Section D March 21 to April 11. 1953eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee water Loss in Relation to Tension or Drainage Head. PfiGE 19 25 27 29 30 51 52 35 36 37 INTRODUCTION For many years a difference of opinion has existed as to the most effective methods of drainage on organic soil. This has been due to lack of information on the exact capacity needs of drainage systems, the most desirable water level to maintain, and the effect of such drainage on organic soils over a period of years. There have been only a limited number of investigations directly concerned with the physical prcperties of organic soils as related to effec- tive drainage. It was the purpose of this study to investigate the physical properties of organic soils that are related to drainage. It was intended that the correlation of such information‘would aid in deve- IOping drainage recommendations for organic soils based on their physical prcperties. The problem is of utmost importance because farmers who have drained organic soils often find a need after three to five years of having their tile lines or open ditches spaced closer together. On the other hand, they sometimes need to establish'water level con- trol dams, because of over-drainage. Any conclusions that would result in more complete and effec- tive drainage recommendations would mean a substantial savings to a muck farmer, not only in the initial drainage operations but in later crOp production and soil maintenance. REVIEW OF LITERATURE The relation of the physical prcperties of organic soils to effective farm drainage is extremely complex. The variations exhi- bited by such physical properties as shrinking and swelling, pore- sise distribution, and.water permeability are some of the problems encountered. Organic soils vary greatly throughout the United States and even within the same soil formation due to their origin and type of formation (2, h, 5, 10, 29). ‘Waksman (29) stated that, "The mecha- nical structure of peats, their colloidal properties, and other phy- sical and physio-chemical characteristics are determined and controlled by the nature of the plants from.which they have been formed, environ- mental factors, especially nature of water and temperature, and by other conditions which have contributed to their formation and decom- position". Davis (5) has classified the posts of Florida into four groups according to their variation in origin and physical properties. He classified them as follows: I/ Fibrous, great porosity; _2_/ Sedimen- tary, macerated, plastic, often colloidal, shrinks and hardens more than group-l upon drying; 2/' Granular, becomes granular after drainage and cultivation; {4/ Woody, with pieces of wood or stems abundant, ‘woody particles shrink less upon drying than other materials. The above grouping of peats according to their variation in origin and physical properties has been correlated with volume changes. Davis (5) reported that volume change in peats as related to the 3 above grouping of peats show the following variations: Group 5/ - Fibrous, Everglades saw-grass, shrank 20-25 per cent of original volume upon being air-dried. Group §/'- Sedimentary, shrank 10 per cent of original volume, and Iarabatcher, semi-aquatic, shrank 10-15 per cent when air-dried. Group é/l- Granular, Woody Gandy, shrank 30-35 per cent, and Fibrous mangrove shrank hO-5O per cent when air- dried. Group E/'-‘Woody, matted, strongly fibrous Florahome Peat shrank LO~60 per cent of original volume upon being air-dried. Hater Content and Absorbing Capacity Specifications according to water holding capacity were established by Procurement Director of the United States Treasury Department. Davis (5) reported their established Specifications as follows: Peat Moss.....................................llOO-2000 per cent Reed Peat or Sedge Peat....................... 350- 800 per cent Reed Muck or Sedge Muck....................... 100- 350 per cent Davis (5) noted that water holding capacity is difficult if not impossible to measure accurately in the laboratory. However, he added that the field water content of organic soils could be approximated by weighing uniform size samples at or near the deposit and then dry- ing these to nearly constant weight in the laboratory. Harmer (10) reported that, ”Huck water-holding capacity is several times that of a clay loam, and many times that of a sand. It is considerably greater than that of straw". He noted further that, "most muck soils as they exist in Michigan need to be drained, however, when drained they have the capacity, with proper fertili- nation to produce bountiful crops." h. Davis (5) reported, "The average condition in cultivated or nearly constantly drained peat or muck areas in the northern part of the Everglades is 67 per cent water in the upper two feet of soil, and 79 per cent water in the peat or muck below two feet depth. In fact, most of the samples of peat soils below two feet contained over 82 per cent water." The preceding, referred to per cent moisture, was computed on the volume basis. Clayton and associates (3) showed that rates of seepage verti- cally downward through Everglades peat varied from a rate of 0.3 feet per day through the top 18 inches to a rate of 27.3 feet per day through the layer from 18 to 56 inches below the surface. They found that the horizontal transmission of water was at a rate of 0.25 feet per day at a depth of 3 feet. These observations concerning water content and absorbing capacity have shown also that the t0p soil had been greatly changed by cultivation and weathering, causing it to be less permeable than were the lower undisturbed layers. Drying Characteristics Davis (5) reported that when peats are dried, their structure, and certain other characteristics are often radically modified. He noted that loss of weight was the most uniform.result of drying, and that such loss of weight was due, partially, to the biological acti- vities of organisms in the peat. Oven-drying reduced the weight of peat samples taken from above the water-table by 78 per cent, while drying reduced the weight of samples taken from below the water-table by 86 per cent. The poets in general, after drying, were reported to have a lower Specific gravity than when saturated with water. Shrinking and Swelling Phenomena in Relation to Porosity flaksman (29), reporting on investigations of peat soils in New Jersey, stated, "Swelling and shrinking of the organic colloids makes the determination of the pore volume rather difficult. The determination of the air-content of peat in a fresh condition is of much greater value than the determination of the pore volume. The degree of decomposition of peat soils is influenced by the air-content." He noted also that additional problems arise when measuring pore volume in peat soils because of the many factors that may appreciably alter its deveIOpment. The water-level of the bog, the rate of evapo- ration, condition of drainage, rainfall, as well as dry versus wet seasons, all, were found to be particularly important in regulating the growth and type of peat produced, and its physical and chemical prcperties. Lauritzen and Stewart (12) reported that the volume change ratio was equal to the change in volume of the clod that accompanies the loss of a given volume of water, divided by the volume of water lost. They noted that shrinkage which accompanied drying was depen- dent on the manner in which the moisture was associated with the soil material and the pore space in the soil mass. 'Woodruff (30) stated, "Most, if not all of the phenomena of soil water relations may be accounted for by the integration of the effects of surface tension and absorption in pores of different sizes with respect to the vapor pressure of water and to the pressure of the atmosphere.” Russell (22) reported that moisture desorption curves may provide a simples method of measuring the size distribution of soil pores. "They represent the volume of those portions of the void labyrinth through which airdwater interfaces are caused to retreat by unit of increase in tension.” He found that the similarity of the curves for pores having a radii of less than 30 micronS'was con- sistently supported by curves for individual samples, and was signi- ficant. Soil with disturbed structure resulting from a bluegrass sod showed many large pores whereas soils with undisturbed structure showed only a small amount of large pores. Russell (22) concluded that airdwater interfaces must exist in a soil void if it is to drain at calculated tensions. He suggested that the size of the chan- nels by which a water-filled void was connected to other voids having airdwater interfaces determined the tension at which the void would drain. He said that the characterization of soil porosity from desorp- tion-curves promised to develop into a useful method of attacking problems of soil structure, especially as procedures are refined to improve accuracy of measurement in the important low-tension range. Lauritzen and Stewart (12) in their investigations of soil prosity concluded that, "Moisture in the soil available to plants may be governed by the relative size of the pore-space which it occupies and the size of the root hairs". Percolation of'Water Through Organic Soils 'Woodruff (30) reported that there were three pore size groups that affect water relations of the soil in different ways: ‘L/ Pores with radii of 1.5 microns or more where water will flow as a liquid from regions of high pressure to regions of low pressure. 'Water obeys the laws of rise in capillary tubes and adjusts itself rapidly to changes in moisture potential. It moves rapidly and is lost rapidly by percolation or evaporation;z 2/, Pores with effective radii of 0.2 to 1.5 microns where water will move through the soil only as a vapor, and can be removed from the soil only as a vapor. 'Water is unstable and moisture potential adjustments are slow. 'Water can be used by plants: .2/ Pores with effective radii less than 0.2 microns ‘where water may be extracted from the soil only as a vapor. ‘Water is stable and can not be drawn from the pores by plants. 'Woodruff (30) noted that the transition between pores of group .E/ and group g/bccurred at a moisture potential of pF 5.0. The transition between the pores of group g/and group é/bccurred at a moisture potential of pF h.1. He stated further that, "Average soil after saturation loses water rapidly until it attains a field capacity at pF 5.0. If soil is vegetated the moisture diffuses 8 to the roots through the vapor state, and the entire mass of soil dries to the wilting point at pF n.1, leaving water only in the pores of group 2/." The moisture potential at pF 3.0 appeared to be the upper limit on the moisture potential scale for the movement of water as a liquid. He concluded that movement of water through the soil in the liquid phase ceases when the surface of a short column of soil becomes dry. He found that it took four times as long to dry out the second inch of soil, as it did to dry out the first inch in the column. Russell (23), in his study of water-table variations in peat land, stated, ”It is necessary to determine the volume of water-filled pores at all points between the water table and the soil surface. After establishing the vertical distribution of water-bearing pores, it is a simple matter to determine how far the water-table will rise or fall in response to the addition or removal of a known amount of soil water." He suggested that if effect of drainage on water-table elevation is to be predicted, a moisture sorption curve from desorp- tion data should be used. If effect of rainfall or irrigation on water-table position is to be determined, the calculation should be made from absorption data. His method of procedure for soil sampling was to take samples in organic soil having undisturbed structure at 6-inch intervals to a depth of four feet, from each of five different sites. Desorption curves were determined then for each sample. Haines (8) noted a definite lag in the re-absorption of water into a soil after it was once dried below to per cent moisture. He termed this leg as "Hystersis". Such a lag, hystersis, existing between absorption and desorption curves, validated further the need for both absorption and desorption data if both irrigation and drainage effects are to be determined. Van Bevel and Kirkham (28) have used a field measurement of soil permeability using auger holes which gave rates of permeability in close correlation with previous laboratory tests. A serious limi- tation of this method, as the authors state, is that it requires the presence of a water table, either perched or real, which should not be too low. This means that in most locations, for mineral soils, only a few Opportunities are available for measurement each year. However, for work with organic soils where the water table is normal- ly less than four feet below the soil surface, it would seem that the method warrants consideration, especially where a large number of sites are to be studied. The existance of drawdown curves between tile lines in organic soil studied in Indiana was noted by Morris (15). Complete drainage systems with water control were shown to increase crop production and reduce the rate of subsidence of the organic soil. Slater (25) reported on the attempts made at the correlation of measureable soil physical characteristics and the prcper depth and spacing of tile. He computed the depth and spacing of tile from a tile-spacing formula that was based on soil permeability and the application of Darcy's law to the conditions of lateral flow. 10 EXPERINENTAL PROCEDURE This investigation was made to determine a possible corre- lation between the rate at which water-table levels are lowered and one or more of the physical characteristics of organic soil. The investigation consisted of two phases. One, an investigation of some of the physical characteristics of an organic soil and two, water table studies of the area. The investigation proper was carried out at the Michigan State College Huck Experimental Farm. The organic soil at this location, (Site 'A“), is classified as Houghton Duck and is well decomposed in the surface with a high percentage of raw-fibrous organic material below approximately nine inches depth. It is a medium acid soil with a pH ranging from 5.7 to 6.he The land has been crapped intensively for the past twelve years with truck crops. The drainage conditions are good with tile spaced 60 feet apart at a depth of approximately 2%-to 3 feet, with open ditches along the north, east, and‘west bound- daries to carry both surface and underground water. The outlet is fair with a low-lift drainage pump installed to facillitate drainage under conditions of high water tables. Three additional sites were sampled to compare the physical characteristics measured at Site "A". These additional sites were as follows: Site "B" - Robert George nick Farm, Arcadia, Michigan (Mania- tee County); drained and cropped since l9h8. This is a well decompo- sed organic soil underlain with marl at four to five feet. Pump drainage is used exclusively. 11 Site "c" - Alfred Thompson Muck Farm, Evert, Michigan (Osceola, County); drained and cropped for the past ten years with considerable drainage problems at the present time. Site "D" - Ieonard Bontekoe Duck Farm, Marion, Michigan (Osce- ola County); drained and cropped since l9h7'with supplemental drain- age added in 1951. This organic soil is quite compact with a high content of raw undecomposed organic material. At a depth of 12 to 18 inches below the surface there is a h-to 6 inch layer of very comp pact soil which is high in silt. Seepage and springs have constituted a problem in this area. Physical Characteristics Equipment used. Soil samples were taken with a core sampler. Soil cores two inches high and three inches in diameter with a volume of 192 cc. were taken. Preparation of the site. Sampling was done at varying mois- ture conditions at the surface and at different levels through the soil profile. A minimum of not less than ten replicates were taken for each different level (horizon) and surface moisture condition. The different levels below the surface were sampled where texture, structure, size of visible pores, or stage of decomposition indicated probable differences in drainage characteristics. This significant variation'was determined by the author to be at approximately nine inch intervals down through.the profile to the water table level. A pit was dug to expose each respective layer to be sampled below the surface. Each level was sampled separately to insure that 12 no core included any part of two different layers. A.minimum.hori- sontal interval of eight inches was maintained between the cores taken from the same pit in order to prevent disturbing the soil of adjacent cores. Taking and preparing the soil cores for laboratory determina- tion. In taking the soil core sample, the sampler was used as dis- cussed by Neal (17). The soil core was then taken into the labora- tory, weighed, and prepared for further determinations. A filter paper disc was placed on the bottom of each core. The bottom of the core cylinder was then covered with a piece of mediumdweight cheese cloth and secured with a rubber band. The soil core was then weighed again to determine the added weight, and placed in a saturation pan. Each core was covered to prevent drying out of the surface, and allowed to saturate for approximately 12 hours. Making laboratory determinations. As suggested by Ohfleal (ll), the saturated soil cores were weighed and further prepared for per- meability studies by placing an additional core cylinder on top of each soil core and securing it with masking tape. The assembled cylinders were then placed on a heavy screen with one-half inch openings over a draining pan. A filter paper disc was then placed on top of each soil core and 100 ml. of water was added to each assembled core. The time of the initial application was recorded and a head of water slightly more than one-half inch was maintained over the soil core for a period of one hour, recording the amount of water added. 13 At the end of the one hour period each core was checked after water was added to equal the initial head of water. The rate at which the organic soils would drain under different tensions was determined by placing the cores on a tension table and permitting them to drain for a period of 12 hours at drainage tensions of 10 cm, 20 cm, ho cm, 60 cm, and 80 cm. The soil cores'were weighed after being subjected to drainage at each of the above tensions to measure the amount of water lost at the different drainage tensions. Swelling capacity was determined by placing the saturated soil cores in a displacement pan‘where the volume of the saturated soil plus the core was measured by the cubic centimeters of'water displaced. (The volume of the core cylinder was measured after the soil was oven-dried.) To conclude the moisture determinations the soil cores were placed in the oven and allowed to dry at a temperature of 105°(:_ Fahrenheit for a minimum.of £8 hours, and weighed. The volume of the oven-dried soil was then determined by adding sieved sand to the core until the core was filled to its capacity of 192 cc. All data were then summarized for each soil core to determine such physical characteristics as Bulk Density; Per cent moisture (oven-dry basis); Per cent Moisture (volume basis); Per cent Swel- ling; Per cent Shrinking; Permeability; Pore Volume distribution as measured in volume of water lost at tensions of 10, 20, Lo, 60, and 80 cm. of water, and the Per cent Moisture at these different drainage tensions. 1h Water Table Stud ies Equipment used. Thirty downspout pipes, five feet long and three inches in diameter, were used for test wells in addition to the few wooden wells already installed at Site "A". Preparation of the site. Holes were dug approximately four and one-half feet deep at each test well location, and the downSpout pipes were set vertically in the holes approximately four feet deep with the bottom of the test well below the water table level. Field determinations. Each well was measured periodically to determine the depth of the water table from the top of the test well. Measurements were made for each appreciable water table vari- ation. Readings were first made with gravitational drainage only, then the gate at the drainage outlet was closed and the drainage pump was used. The period of time which the pump operated was recorded, and well readings were made until the outlet ditch, or sump, was prac- tically dry. The water level in the outlet ditch was measured at each reading of the test wells. The relative elevation of each test well (top), the-depth of the tile, and each reference point used for measuring water table levels was determined. Elevations were then calculated for the measured water table level at each reading and summarized. 15 DISCUSSION AND RESULTS Physical Characteristics The physical characteristics of the organic soil such as per cent moisture (oven-dry basis and volume basis) and bulk density were determined for Site "A", first, by taking surface samples, wet- ting soil, allowing a day or so for equilibrium, and resampling at seemingly different moisture conditions. The mean values for each sampling are shown in Table I. It is noted that the five different samplings, ten replicates each, showed definite variation in moisture content, however, did not appear consistent with the variation in bulk density. This was probably due to the fact that sufficient time had not elapsed for equilibrium with the swelling characteristic of the soil. TABLE I MOISTURE CONTENT AND BULK DENSITY w SOIL cones FROM SURFACE SAMPLES or VARYING MOISTURE CONDITIONS AT SITE "1" - 1951 1/ Date of Per cent Per cent Bulk core Moisture Moisture Density Sampling (oven-dry basis) (volume basis) (grams per cc) July 21. 230 55.8 .215 July 25 273 69.2 .257 July 26 258 65.14 .256 August 16 238 ohm .262 .L/ .kverage of 10 replicates for each date. 16 Studies of surface samples with varying degrees of moisture gave no appreciable correlation between per cent moisture and bulk density. However, when these moisture characteristics were compared with core samples taken at 0-3 inch, 9-12 inch, and 18-21 inch depths there was a definite correlation between per cent moisture and bulk density. Data on moisture content and bulk density of soil cores from varying depths at Site ”A" are shown in Table II. Comparable data for Sites "B”, "C", and "D" are shown in Table 111. It was noted that there was a constant increase in per cent moisture with depth and a decrease in bulk density on all of the sites except Site "D" which was explained by the existance of a more compact layer at the 18-21 inch depth which caused a higher bulk denSity and lower moisture content. 'When organic soil came to equilibrium there appeared to be throughout the profile a uniform.correlation between moisture content and bulk density. As shown in Figure 1, when moisture was decreased there‘was an accompanying increase in bulk density. Dehydration of organic soil is apparently closely correlated to an increase in bulk density. Likewise, in all samples of the sub-surface layers at a depth of 18-21 inches there was observed a lower bulk density accom- panied by a higher per cent moisture. Figure 1 shows a consistent moisture-bulk density curve for three of the four sites. TABLE II MOISTURE CONTENT AND BUIK DENSITY OF SOIL cams FROM VARYING DEPTHS AT SITE "A" 1/ October 12, 1951 Depth of Per cent Per cent Bulk core sample Moisture Moisture Density (inches) (oven-dry basis) (volume basis) (grams per cc) 0'3 351 62 .6 . 178 9-12 577 66.9 .177 18-21 L179 81.5 .169 27-50 1498 83 . 8 . 168 October 30, 1951 0-3 229 55.9 .2115 9-12 319 68.3 .2114 18-21 511 80.9 .158 (go-ripacted) 191 68.1; .557 March 13, 1953 0-3 275 70. l .255 18-21 553 86.14 .156 3/ Average of 10 replicates for each sampling. 18 TABLE III MOISTURE CONTENT AND BULK DENSITY CF SOIL COREB FROM VARYING DEPTHS AT THE THREE SITES SAEIIED FOR COMPARISON STUDIES SITE "B" - August 18, 1951 Depth of Per cent Per cent Bulk core sample Moisture moisture Density (inches) (oven-dry basis) (volume basis) (grams per cc) 0-3 158.6* 58.6* .566* 18-21 h57.h. 76.8 .178 SITE "c" - August 19, 1951 0'3 277 06* 7803* 0283* 18-21 b55.8 85.7 .185 SITE ”D" - December 1951 0-5 169 62.h. .569 9-12 196 66.7 .5ho 18-21 168 61.h .ho6 * As is the case in the other tables these data are averages of the results from.10 cores. The others in this table are averages from 5 cores. 19 00h. . .wnpmoo moahueb pa oopfla pncaommHv no zpamneo Mann one enspudofi vqeoaom mo mazunodpeaem .H ouswdm «on nuKbEEQ \x .2.ch 33% com. can. con. QQ\. ’ , I ’ '. I. ‘ B ----§.\ut.. up: 0 -- --$\.s.wl q 111 nVflKUbss “10 ---------- Q eta [cell-II. 0 ”fix” . .. a 3.3: 3.2% 8.5 1. l.. I... 5&7? MFG. .ccx O‘N o c § '3 e3 Pen-an 1‘ M0 is 2‘“ re (a van-dry basis) cog 20 Shrinking and swelling characteristics. Samples were taken at Site "A" and measurements made to determine the per cent shrink- age of the soil upon being oven-dried. The surface samples, 0-3 inch depth, showed less shrinkage than did the lower depth samples. This was to be expected because of the higher moisture content of the 9-12 and 18-21 inch samples and the accompanying lower oven- dried weights. Table IV shows the average of 10 replicates and the standard deviation of the mean for each level sampled. The swelling characteristics of the soil were calculated by measuring the increase in volume of the core sample upon saturation. The surface samples, 0-3 inch depth, showed considerably higher swel- ling characteristics, especially in the area with the compacted sur- face. Table IV also gives the mean per cent swelling at different depths. It is evident that the swelling data were less reliable than 'were the shrinkage data, except for the compacted 0-3 inch cores. This is indicated by the smaller values for per cent swelling and the resulting higher standard deviations from the mean. Shrinkage and swelling characteristics of organic soil are reported to be an important factor in the effectiveness-of drainage systems, because of their affect upon the permeability of the soil. Uhland and O'Neal (2h) have observed a significant decrease in per- meability attributed to shrinkage and swelling. 21 TABLE IV SUMMARY OF SHRINKING AND SWELLING CHARACTERISTICS OF SOIL cones FROM SITE "A" Depth of Shrinking Swelling core sample Per cent Standard Per cent Standard (inches) shrinking deviation swelling deviation 1/ of the mean 1/ of the mean 0-5 113.0 / 0.52 12.5 )1 0.95 9-12 80.8 r’ 0.66 11.5 / 0.67 18-21 77.5 r’ 0.81 7.1+ .1 0.19 0-3 ---- ---- 16.9 .1 0.90 (compacted) L/ Average of 10 replicates for each sampling. Permeability. Percolation rates were measured through the soil cores in inches per hour. The permeability data, mean values and standard deviations, are summarized in Table'V. A noticeable varia- tion was recorded for Site "A" - October 30, 1951 with increasing depth. The percolation rate through the soil cores from the compacted area, 0-3 inch depth, was 0.50h inches per hour. The results of the Site "A” - March 13, 1953 measurements, however, Showed less varia- tion throughout the profile. Site "D", where a slow permeability class for the 18-21 inch depth was expected, showed only a slight decrease in percolation rate from the surface samples. The perco— lation rates from the measurements recorded would appear to place organic soil, largely, in the permeability classof rapid (5.0 to 10.0 22 inches per hour). These measurements are within the range of the vertical water transmission reported for the Everglades by Clayton (3). He reported that the surface, upon being cultivated and sub- ject to weathering, became less capable of transmitting water down- ward. This, however, was not the case with the soil cores measured in this investigation except in the case of the heavily compacted area, 0-3 inch depth, which did Show a decided decrease in ability to transmit water downward. Pore volume and desorption characteristics. Soil cores for two samplings at Site "A" were saturated and placed on a tension table for the measurement of the water lost or volume of pores drained at different drainage tensions. Table VI shows the volume of pores drained at the tensions of 10 cm, 20 cm, ho cm, 60 cm, and 80 cm of water as well as the volume of pores or water lost from saturation to field condition and oven-dry. The volume of pores drained at low tensions, 10 cm and 20 cm, was relatively lower than at the higher tensions. The volume of pores drained at a given drainage tension appeared to increase with the depth of sampling. Figure 2 shows the volume of pores drained at different tensions in relation to depth of the sampled area. The per cent moisture of the soil cores at saturation, field condition, and at the different drainage tensions are recorded in Table VII. In Figure 3 the per cent of moisture at different tensions are graphically shown in relation to depth of the sampled area. It is believed that the variations between the measurements for Site "A" TABLE V SITE "A” - October 50, 1951 SUI'F'ARY OF PERMEABILITY SEWING MEAN VALUES, STANDARD DEVIATION, AND PERMEABILITY CLASS Depth Mean Standard Permeability of Percolation Deviation class core rate L/ of the sample " mean (Inches) (Inches/hour) (Per cent) 0-5 12.08 /ro.h6 Very Rapid 9-12 7.22 / 0.115 Rapid 18-21 5.51 r’ 0.15 Moderately ‘ Slow 0-5 0.5oh / 0.009 Slow (compacted) ‘ SITE "A" - march 15, 1955 0-5 9.27 / 0.1411 Rapid 9-12 6.b5 /'0.bh Rapid 18-21 7.89 , 0.57 Rapid SITE ”D” - December 1951 0-3 7e5 / 0.81 Rapid 9-12 7e8 / 0.28 Rapid 18-21 7.5 /'0.29 Rapid L/ Averages of 10 replicates except for Site "D" " 'where 5 replicates were used. 2/ Permeability 61.1.... from Uhland and O'Neal (27) -' for percolation rates in inches per hour through saturated undisturbed cores under é-inch head of'water. 23 TABLE VI VOLUME OF PJRES DRAINED AT DIFFERENT MOISTURE TENSIONS FOR SOIL CJRES SAMPLED AT VARYING DEPTHS SITE "A" - October 50, 1951 Tension Volume of Pores Drained at Varying De the or head (mean Values in Cubic Centimeters L/ of '- water 0-3' 9-12" 18-21" 0-3” (Compacted) 10 cm 21e0 22s} 2107 16.7 20 cm 25.h. 25.5 26.7 20.5 ’40 cm Me; aheé 37c]. 26e2 60 cm 50.1 59.7 no.9 50.5 80 cm 65.0 58a? 5505 19.8 Field- 67.2 h9.6 28.0 58.9 Condition Oven-Dry 1711.7 181.7 185.5 170.2 SITE "A" - March 13, 1953 10 cm. 8.8 1h.2 12.2 20 cm. 1h.5 19.6 17.9 ho cm 17.8 25.9 25.5 60 0m 20e2 26e0 28e1 80 cm 25.h. 29.7 52.6 F10 1d- lleh 23 02 11402 Condition Oven-Dry 1h6.1 180.0 180.0 .5/ .kverages of 10 replicates. -mx- .. . Ir .! 'Y;_h“_" Ii" *- ‘9 *3sz' “11-1" wrv‘" ' ’ ‘2'» 4-” “.4 :. ' C 3' all 'a' '8. a...“ ‘ . Lhu-invvfi-fi “Air—2:"; ' 1":— Figure 2e 75/78/00 (am) so 3 3‘ 8‘ S 3‘ 8‘ 8‘ 3° ‘ U r 1 7 0-3 inc/c a’epf/I .- ". . 2 1”; I’Ii S 1’ ’ I I , .’ a / X] I I l -” an. A- (95/ ...... sire A4953. :3 {“0 :3 in 7? 73 Volume offers: drained (cc) ?-/2 inc/3 depfé 81‘}: A-IVJ’ ------ / p Sift A-I953 fa staff; 4/10) its (‘7) 73 3’? Volume offers: O’raillea’ (ca) /d’-'Z/ inc/t G’s/c 2‘}: 51'}: 24-1957 -----_ 81"}: A‘l95'3 _1 4-1: L I‘ A ; 1+ IO 20 39 ya :0 60 70 do Vo/ame offers: o’n/‘no’ (ac) Volume of pores drained at different tensions of water for 0-3 inch depth; 9-12 inch depth; and 18-21 inch depth. TABLE VII PER CENT MOISTURE AT DIFFERENT MOISTURE TENSIJNS F08 soIL CORES SANPLED AT VARYING DEPTHS (OVEN-DRY BASIS) SITE "A" - October 30, 1951 Tension Per cent Moisture at Va ing Depths or head (OVen-Dry Basig) L/ of " water 0-5“ 9-12" 18—21" 0-5" (Compacted) 10 cm 528 586 551 22h 20 cm 518 577 516 218 LC cm 279 556 h82 210 60 cm 267 5&5 h68 20h 80 cm 238 297 h2l 176 Field- 229 519 511 191 Condition Saturation 575 h59 602 2h8 SITE "1" - march 15. 1953 10 cm 280 5&7 559 20 cm 269 529 5h0 b0 cm 262 515 515 60 cm 257 508 506 80 cm 2&6 #96 b9l Field- 275 517 553 Condition Saturation 299 59h 600 T L/ kverage of 10 replicates. Fins/an fem.) 72/7 aria/7 (Cm) RflJ/‘Ofl (can) do 719L 60' 5'0- 4’0- 30 .. ZO- lav do~ 70 - 60- 6'0 ya. .50 20* IOL 0 Mb Figure 3e 0 [3'0 ’ cm A-Ma': 0-3 focé (Ye/01% 27 SH: 5495/ Jifc A-l953 maid—v“ C. .,-o' L 9:50 5:? 6377 fires/t 1’ Ma 49/205: (0 var day basis) 9-/2 2;ch a’e/of/l 51+: A-mv---" \ Site .4495: \, | \ \ \ J \ ““l I. A L ‘7 2:0 3:0 1‘6’0 J’J’o 75-0 fire (It 2‘ ”a 1': far: (Oren- d7 54 :I'J ) /€'2/ far/I O’e/o f7! Jife A #957 - ----- l 1.. 2:0 332: Are en? Max‘s fare (area-00’ basis) 650 Per cent moisture (o.d. basis) at different tensions of water for 0-5 inch depth; 9-12 inch depth; and 18-21 inch depth. 28 on October 30, 1951 and march 13, 1953 were largely due to swelling differences caused by different moisture contents. Also, the sur- face cores from Site "A" - March 13, 1953 may have been low in volume of pores drained, partially because there was still evidence of fro- zen soil at the time of the sampling at that level. ‘Water Table Studies Test wells were measured periodically to determine the draw down of the water table within a given period of time, and to approx- imate the total amount of water removed. A location plan Showing the test well placement and the core sampled areas is shown in Figure h for Site ”A" - May 1952. The test wells were placed to obtain water table readings directly over the tile line and at distances of 3 feet, 10 feet, and 30 feet from the tile. The location plan of the various cross- sections for Site "A" - may 1952 is shown in Figure be The draw down curves for cross—sections A, B, and C are shown in Figures 5, 6, and 7 resPectively. The water table was lowered during the period of Thy 19th to Hwy 26th by gravity drainage. The water table was lowered further during the period of May 26th to May 27th by supplemental pump drainage. Figure 6 shows the draw-down characteristics at cross section B, between three tile lines, and quite definitely brings out the fact that no appreciable draw-down curve existed in the drainage of the orga- nic soil except within three feet of the tile line. This is in agreement 29 .mmmn has I :4: 03m pa eons cadence once one concave cane». hope:- no.“ mean qcaveooA .J onowfih 0%“ 0M” O N!) _ QNNNN \N WE _ _ ueux. 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S 2.3? ”11.01111 1111.....111. 11 1 1 1 111 .11111 11 1.1.. . 106% M1“! 9. 2.321s 1.11.1an unun“Hun"HHUHH11111111L111.1.1.111. 11 1 1 1 11 1.111 111 1HHHHHH.\..H M1313 <30? 11.11.111.111 11 1 11. 111111111 1111.17.11! 111111111 . 11111111 .111 «I. . ofim "0:03. 2.0x. 030x 30:0} 20.5.3va . 5&0 ‘Q‘s‘Kb )l‘/\‘\\"11 111 III/>0 L 0.02 h.§°\ .30 En: N..\ .3 «3 § .3 mi .3 .w\\ Ex fix .3 .3 . 0 .3x \\ 2s 1.5K 3 .S 8‘ -£I¢va tion in feet- 38 apparent after 6 hours of pump drainage. It'wae concluded that the pump capacity of flow‘was not being fully realized due to lack of sufficient reservoir capacity above the pump. Correlation of'water table studies and pore volume data. The loss of water at the various moisture tensions of 10, 20. Lo. 60, and 80 centimeters, measured in the laboratory, was compared with an equivalent drainage head for the field water table studies. In Figure 12 the water loss is shown in relation to tension in centi- meters of'water or the drainage head equivalent in inches from the 'water table. In computing the amount of water being removed from the orga- nic soil at Site "A" in a 2h-hour period of time the actual tension or drainage head in inches was taken from the recorded water table elevations. Figure 6 shows the varying water table elevations result- ing from drainage at test well numbers 23, 2h, 25, 29, 30, and 31. The average depth of the water table from the ground elevation for these six test wells was recorded as follows: why 19th - 1.15 feet or 13 7/8 inches May 21st - 1.23 feet or 1h.3/h inches may 22nd - 1.3h.rcct or 16 1/8 inches Hby 25th - 1.38 feet or 16 5/6 inches any 26th - 1.5h feet or 18 1/3 inches (12:00 A.M.) Nay 26th - 1.56 feet or 18 3/h inches (0.00 P. M.) may 27th - 1.69 feet or 20 l/h-inches. 39 The effect of lowering the water table on the water loss at the measured drainage head is shown by the data reported in Table VIII. During periods of gravity drainage, Kay 19 to may 26, water was removed at a rate of 0.11 acre inches per 2h hours. Measurements of the cross sectional area of flow at the outlet were made, however, the approxi- mated velocity of flow was not considered accurate enough to estimate total discharge from the area for comparison with the computed rate of loss of water per acre inch. The water table was lowered b-fi/h inches during the six day period of gravity drainage. During the period of pump drainage the computed water loss was at a rate of 0.b2 acre inches per 2h-hours to lower the water table 1 7/8 inches in 2b hours. The capacity of the drainage pump was rated at 975 gallons per minute with a 3 foot head. This is equivalent to a water removal rate of 0.86 acre inches per 2h hours. There is a discrepancy between the measured rate of 0.h2 acre inches per 2h hours and the capacity rating of the pump of 0.86 acre inches per eb-hours. This difference was attributed to the lack of adequate supply of water in the reservoir ditch above the pump to allow for the discharge of ‘water at the full capacity of the pum . Also, a certain amount of seepage from the surrounding area was noted at test well numbers 358. 36. and b0. Correlation of organic soil permeability and prcper tile spac- ing and depth for effective drainage. The measured permeability rates previously discussed and shown in Table V, were used in conjunction with Slater's (25) formula for computing tile Spacing and depth. A drainage coefficient of one inch of water removed in 2h hours was 132 80 ’ I,. /. // x / ' 0'3 flick Jeff/I l,;/ J 30 — —- —— we I'ncé def/.4 ,f/ ° 4 o’ M f/ 70 . ......... l8-2/ mc 3,0 /,/ 1 23 4’ /; 1 26 /" 60 ' .lz ‘ 2y? I 1 \ 1 5 ‘1‘. I f 1 22“ ' x 1 I 1' 4: 35.01 I, '1‘ 1 20 c ' ‘s e 1 ,1 s / 1 J 111 s .2 l 1' f g. I Q 40 , e/ e’ 1 l‘ x ‘12 / 1' 91 I, ~ 11 / 1 a K / I, ‘ [4 U xi / I, S .‘0 / I, \' 3 50» 1 12 1 s ’ 1' ' / 1” ‘0 x J m 3 / 1” 20 1 30” 8 3. I, c 1' s / ' ‘ 5‘ I I” q ’0» [7'0 1 If 1 [’7 lily 1 2 7' -. - 4"“;7 a 0 IO 20 37) 90 3’3 641 ~Wa fer less (grams) — Figure 12. Water loss in relation to tension or drainage head. 111 TABLE VIII THE MEASURED WATER Loss FROM PORE VOLUME CORRELATED'WITB'WATER TABLE STUDIES .1/ Rby 19 to may 26 (lhh hours) Depth Drainage head 2/' ‘Water loss as of " result of core Before After lowering sample 'water table (inches) (inches) (inches) (grams per core) 0 13 7/8 - 18 1/2 5.5 9 h 7/8 - 9 1/2 5.0 18 0 -~ 1/2 11.0 Total water loss - 21.5 grams per core - 0.67 acre inches in lhh hours and rate of water loss - 0.11 acre inches per 2h-hours. Nhy 26 to may 27 (2h hours) o 18 1/é - 20 1/h. 1.0 9 9 1/8 - 11 1/h. 2.5 ‘ 18 1/2 - 2 1/h. 10.0 Total water loss - 13.5 grams per core — 0.h2 acre inches in 2h hours and rate of'water loss - O.h2 acre inches per an hours. 1/ later loss is converted to acre inches by -' multiplying the water loss, grams per core, by the factor of 0.031. 2/' Drainage head is determined by converting -' moisture tension, centimeters, to inches from depth of core sample to measured water table. 142 used to afford adequate drainage for truck crops on organic soil. Table IX shows the recommended drainage coefficient for varying crops and soil conditions. The calculations for determining tile Spacing and depth in relation to organic soil permeability are shown in Table X. The use of the tile Spacing formula for the removal of one inch of water in 2h-hours gave fairly close results to the measured removal of‘water at Site "A", in that a 65 to 88 foot spacing of the tile at a 3 foot depth was required for effective drainage. The tile spacings calculated from measured permeability rates using Slater's (25) for- mula were closely related to the general recommendations now being used. In an effort to correlate permeability and drainage for orga- nic soil, Table XI was developed. This table gives the approximate tile spacing and depth in organic soiIS'where crops are to be grown. The drainage coefficient of 3/h inch per 2h hours is designed for field crops on organic soil. and the drainage coefficient of l to 1 1/2 inches per 2h hours for truck craps. Refer to Table IX. It is possible that the use of the tile depth and Spacing for- mula (25) in conjunction with extensive field measurements of organic soil permeability (28) could be used to group organic soils in Michigan as to their permeability class and drainage needs. If this could be accomplished, a close correlation of current drainage recommendations and the physical characteristic, permeability, would be established for organic soils. TABLE IX DRAINAGE COEFFICIENT FOR VARYING CROP AND SOIL CONDITIONS LI/ (WITH AND WITHOUT SURFACE INIE‘I‘S) Soil Permeability Without 2/ With 3/ Surface in13ts Surface inlets Field Truck Field Truck Crops Crops Crops Crops Mineral soils 1/ 3/8" 3/h" 3/14” 1%" Feats a. Mucks 5/11" 1 to 1%" 3/141? 7%" E0 II N 1/ For mineral soils with sandy or otherwise per- mable subsoils the drainage coefficient may be reduced approximately l/I-L". 2/'Figure only the area to be tiled as the drainage area. It is understood that surface water is removed by field ditches or water-courses. 3/’Use entire contributing watershed as the drain- _ age area. h/'From.USDA Soil Conservation Service, Engineering '- Handbook, Upper Mississippi; (Region III), Mil- waukee,'Wisconsin (1952). TABLE.X (continued) CALCULATIONS FOR DETERMINING TILE SPACING AND rem IN RELATIJN T0 ORGANIC soIL PERIEABI LITY. . . . .LRAINAGE c JERFICIRNT 08 1 INCH PER 2h HJURS 0R 0.011 I.P.H. Site "D" - December 1951 0-5" depth ... 7.5 i.p.h. permeability 9'12" depth eee 7e8 lepehe permeability 18-21" depth ... 7.3 i.p.h. permeability Tile to be at a depth of 3 feet, so the assumed barrier will be at 5 feet or 2 feet below the tile in Slater's (25) Formula. a e 2 feet 52 : b-x P (b2 - a2) b e h feet v P . 0.50 i.p.h. : h x 7.30 (16 - h) v I 0.0h 1epehe 0.6“ (Tile Spacing) s = 911 feet Site "A" - October 30, 1951 ... with compacted _ surface 0'3“ depth eee OeSOh 1epehe Permoabillty 9'12" depth eee 7e22 iepehe permflability 18-21’ depth ... 3.51 i.p.h. permeability Tile are at a depth of 3 feet, so the assumed barrier will be at 5 feet or 2 feet below the tile in Slater's (25) formula. a : 2 feet 82 I h x P (b2 - a2) b = h feet v P = OeSOh 1epehe = b-x Oefiph (16 - h) v = 0.011 i.p.h. 0.0a (Tile Spacing)S¢ 2h.2 feet TABLE1XI RECJXI'JDED TILE SPACING FOR ORGANIC SOIL IN RELATION TO PERMEABILITY AID TEE DEPTH 3F TILE Permeability Tile Spacing, in feet, when tile (inches is at varying depths per Depth Depth Depth hour) of of of 3 feet h feet 5 feet Drainage Coefficient of 3/h inches per 2h hours, (0.031 inches per hour) 0.05 9 12 15 0.2 18 20 30 0.8 36 50 60 2.5 65 85 105 5.0 90 120 150 10.0 125 170 210 Drainage coefficient of 1 inch per 2h hours, (0.0h inches per hour) 0.05 7 10 13 0.2 15 21 26 0.8 31 LI 51' 2-5 55 72 90 5.0 77 102 126 10.0 110 105 178 Drainage coefficient of 1% inch er 2h hours, (0.062 inches per hour) 0.05 6 8 10 0.2 13 17 20 0.8 25 32 hI 2.5 115 5 75 5-0 63 P 103 10.0 90 120 1b6 SUMMARY The purpose of this investigation was to study the drainage ability of organic soils as characterized by their physical prcperties. The investigation proper was carried out on Houghton muck at the Michigan State College muck EXperimental Farm, with three addi- tional sites investigated for comparison of physical prcperties. Core samples were taken at varying moisture conditions and also at nine-inch intervals down to the water table. The samples were analyzed for moisture content, bulk density, shrinking and swell- ing, permeability, and volume of pores drained at varying moisture tensions. A second phase of the investigation, water table studies, 'was carried out to determine the nature and amount of draw down of the water table. Test wells were used to measure the variation in the water level. ‘Water table studies were correlated with the volume of pores drained at varying moisture tensions to determine the amount of water removed per acre inch associated with a measured lowering of the water table. Permeability data were correlated with drainage recommendations for depth and spacing of tile, using a formula based on Darcy's me for lateral flow. The following observations were made: Studies of surface samples at varying moisture conditions resulted in a variation in moisture content from 230 to 250 per cent 119 (oven-dry basis), and an accompanying variation in bulk density from..2h3 to .270 grams per cubic centimeter. There was, however, no correlation between per cent moisture and bulk density. ‘Where samples were taken at 0;} inch, 9-12 inch, and 18-21 inch depths there was a definite correlation between per cent mois- ture and bulk density. Dehydration of organic soil was closely correlated with an increase in bulk density. Consistent moisture-density curves were observed where per cent moisture and bulk density were correlated at varying depths in the soil profile. Shrinking varied from h3.0 per cent in the surface samples to 80.8 per cent in those from the 9-12 inch depth. Swelling varied from 7.11 per cent at the 18-21 inch depth to a high of 16.9 per cent in the field compacted surface samples. Permeability was measureable within an allowable standard deviation with all samples in the rapid class (5.0 to 10.0 inches per hour) except for the compacted surface samples and those from the 18-21 inch depth. The volume of pores drained increased with depth at a given moisture tension. Pore volume data, using moisture tensions of 10, 20, ho. 60, and 80 centimeters, correlated directly with drainage. The water table studies confirmed the relatively rapid movement of water through organic soil, and the results were in agree- ment with permeability data and the measured volumes of pores drained. The non-existance of draw down curves except within three feet 50 of the tile line was attributed to the following factors: the ina- dequacy of the outlet for efficient gravity or pump drainage, seep- age from the surrounding area, and rapid permeability. The computed water removal by pump drainage, using pore volume data, was at a rate of 0.b2 acre inches per 2h hours to lower the water table 1 7/8 inches. The pump capacity rating was 0.86 acre inches per 2h hours. The inadequate capacity of the reservoir ditch above the drainage pump and seepage from the surrounding area are reflected in the variation between actual water removal and calculated pump capacity. The use of Slater's (25) formula to correlate organic soil per- meability and drainage recommendations for prcper depth and Spacing of tile showed conclusively that drainage recommendations can be based on the physical properties of the soil. (1) (2) (5) (h) (5) (6) (7) (8) (9) (10) (11) (12) LITERATURE CITED Bear, F. E., Soil and Fertilizers, "The water and air in soils", Third Edi-€1.51!) FB'IUIe I959. Baver, L. D., Soil Physics, "Soil structure", Second Edition: 126'197 e e Clayton, B. 8., J. R. Neller, and R. V. 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