3‘1 mitte 5';er “d4 EFFECTS OF 3311. MANAGEMENT PRACTICES IN A FOREST TREE NURSERY ON SOIL PROPERTIES AND ON LOBIDLLY PINE SEBDLI NGS JACK T.MAY AN ABSTRACT Suhaitted to the School for Advanced Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OP PHILOSDPHY Department of Forestry Year 1957 ._ / / ‘4? , Approved ! loblol seeil; (f) ..'1 ‘ ' "=«;a:. ”Cf-13;? phYSica‘ Effects of Ebil Management Practices in a Forest Tree Nursery on Soil Properties and on Loblolly Pine Seedlings The effects of various soil treatments on germination of loblolly pine seed, development of seedlings, survival of out-planted seedlings, chemical content of seedlings, and soil characteristics were investigated during a three-year period. Treatments included different combinations of green manure crop and seedling rotations, methyl bromide applications, three levels of sawdust applications, and three levels of phosphorus and potassium applications. Soil samples were analyzed to ascertain the effects of treatments on soil reaction, organic matter content, cation exchange capacity, available phosphorus, available potassium, exchangeable calcium and exchangeable magnesium. Seedling characteristics were evaluated by physical measurements and chemical analyses. Methyl bromide treatments did not affect germination of seed or development of seedlings. Sawdust applications reduced seedling shoot/root ratios, lowered the soil acidity, and increased the organic matter content and the cation exchange capacity of the soil. The soil organic matter content was reduced when sawdust and green manure creps were omitted. A green manure crop in a rotation increased the percentage of plantable seedlings and the survival of out-planted stock. the I In an the 1 of tze calcim The original level of available phosphorus was not maintained by the heaviest application of phosphorus, 450 pounds of P205 per acre. In an annual seedling rotation, 160 pounds of K20 per acre maintained the level of available potassium at about 70 ppm of K. Applications of mineral fertilizers immediately prior to sowing of seed did not affect germination of seed or mortality of seedlings. When phosphorus and potassium applications were omitted, the percentage of plantable seedlings was reduced. There was a direct relationship between the phosphorus and potassium content of the plant foliage and of the soil. Loblolly pine seedlings made a heavy drain on soil calcium and.magnesium. EFFECTS OF SOIL MANAGEMENT PRACTICES IN A FOREST TREE NURSERY ON SOIL PROPERTIES AND ON LOELOLLY PINE SEEDLINGS By JACK’T.IMAY A THESIS Submitted to the School for Advanced Graduate Studies of Michigan State University of Agriculture and.Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Forestry 1957 ACKNOWLEDGERENTS This study was Sponsored by the Agricultural EXperiment Station of the Alabama Polytechnic Institute as one of its official research projects. Grateful acknowledgement is made to members of the staff for their c00peration and suggestions in the planning and execution of the study. Mr. N. D. Pearce, nursery superintendent, cooperated on the field work for the project. Professor E. Fred Schultz, Jr., biometrician for the eXperiment station, gave invaluable guidance and assistance on statistical analyses. Acknowledgement is also made to Mr. A. R. Gilmore for help with the chemical analyses; to Mr. K. W. Livingston for his critical perusal of this manuscript during its preparation, and to Mrs. Helen Sanders for doing the bulk of the typing connected with this thesis. The author is particularly grateful to Dr. T. D. Stevens, major professor, for his effective handling of all matters pertaining to the writing of this dissertation in absentia. Special recognition is given for the encouragement and assistance of the writer's wife during all phases of this study. ii T3 5 313} In. TABLE OF CONTENTS ACKNOWLEDGEMENTS . . . . . . . LIST OF LIST OF Chapter I. II. III. IV. TABLES O O I O I O I O ILLUSTRATIONS . . . . INTRODUCTION . . . . . REVIEW OP LITERATURE . Basic Considerations Effects of Nutrients on Development of Seedlings of Native SPOCAQS e e e e e e e e e e e e e e s e e e Soil.Treatments in Nurseries in Great Britain . Effects of Nutrients on Soils and Seedling Growth in the Far Eastern Countries European Investigations 8°11 RCQCtion and Plant GIOWth e e e e e e e e e Organic Matter and Nursery Soil Fertility . . . Nursery Diseases and Soil Fertility . Hycorrhisae, Soil Fertility and.Tree Nutrition . Soil Fundgants, Soil Fertility and Plant Nutrition Effects of Soil Fertility on Morphological Characteristics of Seedlings . . . . . . . . . . . Relationships Between Nutrient Availability and Physiological and Anatomical Characteristics of Seedling! e e e e e e e e e e e e e e e e e e e e Effects of Nursery Practice on Field Survival of Plant.d StOCk e e e e e e e e e e eye e e e e e e General Relationships Between Plant Nutrition and $011 PCItility e e e e e e e e e e e e e e e e e e Cbnclnsions from the Literature LOCATION AND DESCRIPTION OF EXPERIMENTAL AREA . . EXPLORATORY STUDIES . . . . . . . . . . . . . . . . . iii Page ii vi 11 23 26 39 35 86 40 42 44 46 48 51 52 70 72 75 V. VI. VII. VIII. Experimental DISIO‘ e e e e e e e e e e TrIatnIntI e e e e e e e e e a e e e e e e e e e e Plot Size, Designation and Arrangement . . . . . . DiIcuSSLOD OfirrIItNQntI e e e e e e e e e e e e e calleCtion Of 8011 Samples e e e e e e e e e e e a Laboratory Analysis of Soil Samples . . . . . . . Determination of Germination and Seed Bed Survival Measuring Morphological Features of Seedlings . . . Chemical Analysis of Samples . . . . . . . . . . . Measuring Survival of Plants . . . . . . . . . . . Statilt16d1 Analysis Of Data e a e e e e e e e e 0 EFFECTS OF TREATMENTS ON GERMINATION, MORTALITY AND NUMBERSOFPLANTABLESEEDLINGS ........... Genlinatlon e e e e e e e e e e e e e e e e e e e e Seedling Mortality after Establishment . . . . . . Percentage of Plantable Seedlings . . . . . . . . . Number of Seedlings and Number of Plantable Seedlings Pb! Square FOIt e e a e e e e e e e e e EFFECTS OF TREATMENTS ON MPHOLOGICAL CHARACTER OF ms I I I I I I I I I I I I I I I I I I I I I I I Volume of Plant Material . . . . . . . . Length and Diameter of Seedlings . . . . . . . . . Seedlings Developing Winter Buds . . . .. . . . . . fitoot and Root Weights of 1953 Seedlings . . . . . Shoot and Root Heights of 1954 Seedlings e e e e e Shoot and Root Weights of 1955 Seedlings . . . . . Comparison of Mean Weights of Oven-dry Plants . . . EFFECTS OF WMS 0N NURSERY SOILS e a e e e e e 8011 RIaCtion e e e e e e e e e e e e e e e e e a a 8011 Organic Matter a e e e e e e e e e e e e e e e Cation EXChanqe capCCity e e e e e e e e e e e e e 8011 NitrOQIn e e e e e e e e e e e e e e e e a e e 3011 Phosphor‘s a e e e e e e e e e a e e e e e e e 8011 PbtfiSSium. e e e e e e e e e e e e a e e e e e 8011 Calcium e e e e e e e e e e e e e e a e e e e 8011 MICBIILII. e e e e e e e e e e e e e e e e a e iv Page 79 79 80 81 84 06 89 91 92 93 93 94 95 95 95 97 102 104 104 105 106 106 108 108 113 114 114 117 120 127 127 181 140 146 IX. EFFECTS OF TREATMENTS ON Pm I I I I I I I I I Phosphorus in Plants Pbtassiun.in Plants Calciul.in Plants . Magnesiul.in Plants .1. FIELD SURVIVAL . . . . . 1953 Seedlings . . 1954 SIIdlI-m a e e e 1955 Seedlings . . . . 11. SUMMARY AND CONCLUSIONS sun-ary . . . Conclusions . . . . . LITERATURE CITED . . . . . . . . mnI II I I I I I I I I I CHEMICAL COMPOSITION OF Page 149 149 155 163 168 172 172 172 174 177 177 178 183 208 Tat-I 1. 10. 11, 12, 13, 14 Table 1. 3. 4. 5. 9. 10. 11. 12. 13. 14. LIST OF TABLES Particle Sise Class Distribution of the Faceville Soil b” I I I I I I I I I I I I I I I I I I I I I I I I I Se-ary of P20 and K O Fertilisation for the Period 1958-1955'IIOinaineeeeeeeeeeeeeesee Cumulative Seedbed Genination of Loblolly Pine Seed . Percentage of Seedlings Plantable, 1954 Crop . . . . . Grade 1 Loblolly Pine Seedlings from the Modified 301108,].955Cl’0p.g...oo....o.....o Plantable Seedlings for Different Densities . . . . . Mean Vole-e of Roots and Shoots of Loblolly Pine 3.0d11nqs,1n1953Cr¢p............o.o Length and Diameter of Loblolly Pine Seedlings, 1953 crop I I I I I I I I I I I I I I I I I I I I I I I I I Mean Weights and Shoot/Root Ratio for Loblolly Pine Seedlings,l9530rop............o.... Mean Oven-dry Weights for Plantable Loblolly Pine sadliw331954cr°paeeeeeeeeeeeeeeee Mean Heights of Oven-dry fleets and Roots of Loblolly PineSeedlinqs,19550rop.............. Mean Swot [Root Ratios of Oven-dried Loblolly Pine Seedlings - MfiId Series, 1955 Crop e e e e e e e a Mean Weights of Oven-dry Loblolly Pine Seedlings and MtIROOtRItLOIeeeeeeeeeeeeeeeeee MeaanValuesofSoflSamples............ vi Page 73 87 96 99 101 103 104 105 107 109 110 112 113 114 Table Page 15. Mean :13 Values, January 1954 and January 1955 Soil m1.’ I I I I I I I I I I I I I I I I I I I I I I I I 115 16. Mean pH Values for January 1956 Soil Samples . . . . . 116 17. Mean Organic Matter Content of Soil Samples for DiffIIIRt DItII e e e e e e e e e e e e e e e e e a a e 118 18. Mean Organic Matter Content of January 1954 and January 1955 ail @168 I I I I I I I I I I I I I I I I I I I 119 19. Partial Analysis of Variance for Organic Matter content. fer January 1956 Data e e e e e e e e e e e e 121 20. Mean Organic Matter Contents for the January 1956 Soil M188 I I I I I I I I I I I I I I I I I I I I I I I I 122 21. Probabilities of Differences, as Large as Those Found in the Three Year Sumary of Organic Matter Content, fianIItoala-nOIeeeeeeeeeeeeeeeeee 123 22. Mean Cation Exchange Values for Different Sampling D‘t.‘ I I I I I I I I I I I I I I I I I I I I I I I I I 123 23. “Incationhmvaluoaeeeeeeeeeeeeea 125 24. Mean Content of Available Phosphorus in Soil Samples for DiffIrent Sampling DQtII e e e e e e e e e e e e a 128 25. ban Lovel of Available Phosphorus for January 1954 and Jmndry1955$alplos................. 128 26. Mean Levels of Available Phosphorus for 1956 Soil suplIIeeeeeeeeeeeeeeeeeeeeeeee 130 27. Smary of Phosphorus Application and Utilisation or Pintioneeeeeeeseeeeeeeeeeeeeee 132 28. Mean Contents of Available Potassium for Different SamplianltOl....o......-........ 135 29. Mean Levels of Available Potassium in January 1954 8011343113108.........o...o....... 136 30. Available Potassium in January 1955 Soil Samples . . . 137 vii '1” an s... Table Page 31. Available Potassium Iaevels for the January 1956 Soil SCIPIII e e a e e e e e e e e e e e e e e e e e e e e a 139 32. Summary of Potassium Applications and Removal, 1953 Through 1955 Inclusive . . . . . . . . . . . . . . . . 141 33. Exchangeable Calcium Content of Soil Samples . . . . . 144 34. Exchangeable Magnesium Content of Soil Samples . . . . 147 35. Phosphorus Content of Loblolly Pine Needles . . . . . . 151 36. Phosphorus Content of Loblolly Pine Stems . . . . . . . 152 37. Phosphorus Content of Loblolly Pine Roots . . . . . . . 154 38. Phosphorus Content of Loblolly Seedlings and the Ratios BGtWIQn ROOtB, Stems, and Needles e e e e e e s e e e e 155 39. Potassium Content of Loblolly Pine Needles, 1954 Crop . 156 40. Potassium Content of Loblolly Pine Needles, 1955 Crop . 158 41. Potassium Content of Loblolly Pine Seedling Stems . . . 166 42. Potassium Content of Loblolly Pine Seedling Roots, 1955 Crop e e e e e e e e s e e e e s e s e e e e e e a 162 43. Potassium Content of Loblolly Pine Seedlings and Ratios Between Roots, Stems and Needles . . . . . . . . . . . 163 44. Calcium Content of Loblolly Pine Seedlings, 1954 and 1955 crop I I I I I I I I I I I I I I I I I I I I I I I 165 45. Magnesium Content of Loblolly Pine Seedlings . . . . . 170 46. Mean Survival and Height Increase for Loblolly Pine Seedlings Planted February 1954 . . . . . . . . . . . . 172 47. Survival of Loblolly Pine Seedlings Planted January 1955 I I I I I I I I I I I I I I I I I I I I I I I I I 173 48. Survival of Out-planted Loblolly Pine, 1955 Seedling Crop e e e e e e e e e e e e e e a e e e e e e a a e e 175 viii maze" Table Page 49. Monthly and Annual Precipitation and Temperature Dataformn'mmeeeeeeeeeeeeea 208 Figure 1 . 3. 4. 5. 6. 7. 9. 10. LIST OF ILLUSTRATIONS Plot Arrangement and Designation . . . . . . . . . . Total P 05 in Pounds Per Seedling CrOp, Which Was Utili , Fixed in the Soil or Lost by Erosion in Relation to the Total Amount of P205 Applied, 1953 to 1955 Inclusive e e e e e e e e e e a e e a e e e e a Total K20 in Pounds Per Seedling Crop, Which Was Utilised, Fixed in the Soil or Lost by leaching in Relation to the Total Amount of K20 Applied, 1953 to 1955 InC1n31'. e e e e e e e e e e e e e e e e e e a General View of Nursery Experimental Area . . . . . . Close View of Seedlings in an Annual Seedling Rotation That Received Like Treatments Each Year . . Close View of Seedlings in an Annual Seedling Rotation in Which the Rates of Fertilisation Had BIC“ Reduced AftIr the Second.Year e e e e e e e e a Close View of Seedlings in a Green Manure Crop - Seedling Rotation from Which Sawdust Had Been Omitted Close View of Seedlings in a Green Manure Crop - Seedling Rotation That Had Received an Application of 30 Tons of Sawdust Per Acre Prior to the Green Manure Crap s e e e e e e e e e e e e e e e e e e e e e e e One-Year-Old Seedlings from Different Rotations . . . One-Year-Old Seedlings from Annual Seedling Rotations that Received Different Kinds of Treatments . . . . . Page 82 134 143 209 210 211 212 213 214 215 CHAPTER I INTRODUCTION Loblolly pine (2.1.3113 33395 L.) grows over a larger area and under a wider variety of conditions than any of the other southern pines (Lotti, 1956). Its range extends from southern New Jersey southwestward in a broadening crescent for a distance of nearly 1500 miles to Oklahoma and.Texas. Loblolly pine is taking over many areas formerly dominated by longleaf pine (21333.231ustris Mill.) (Wahlenberg, 1946). It is one of the most valuable trees in the south, providing about one-half of the pine timber (Dorman and Sims, 1949). Loblolly pine grows to a larger size faster than any of the other southern pines. During the first twenty years or so, slash pine (Eiggg elliottii Engelmm) within its natural range may grow faster, but beyond that, and up to about 80 years, loblolly pine exceeds all other southern pines. Loblolly pine is being extensively used for reforestation in the south. Of the 438,924,000 seedlings produced in 14 southern states in 1953-54, 36 per cent were loblolly pine (Myers, 1955). The proposed increase of state and.private nurseries will expand seedling production in the southern region to nearly one and.one-ha1f billion seedlings by 1960. IBecause of its rapid.growth, its adaptability to a variety of sites and its utility for numerous uses, loblolly pine should continue -1- “CF. to rank high in reforestation. Artificial regeneration of forests has been a most important work for quite a long time in Europe. The technique and.practice in the European nurseries has reached.an amazing degree of perfection by continual improvement based on research and.experience. Before 1939, of the two billion seedlings produced annually in Germany about 70 per cent were grown in privately owned forest tree nurseries (Pein, 1953). Many of these nurseries had.been in the same family for over a hundred years. In contrast, of the 173 forest tree nurseries in the United States in 1954, 122 or 70 per cent were owned.by public agencies. Forest tree seedling production in the United States started.about the beginning of the twentieth century (Pettis, 1909; Bates and Pierce, 1913; Tillotson, 1917). In general, survival and early growth of the planted trees have been fairly satisfactory when the nursery fertility level has been high and planting has been done properly. IMortality sometimes has been relatively high during the first year when precipitation in late winter or in spring was deficient, particularly on sites which are naturally dry (Stoeckeler and Limstrom, 1950). wakeley (1935) reported that quality of planting stock affected.not only the survival of southern pine seedlings, but also their rate of growth during the first several years. He devised a grading system based on such morphological characteristics as stem height, stem.diameter, root length, and.presence or absence of fascicled.needles and winter buds. ‘Hhkeley stated that "The most conspicuous differences between grades result from.differences THE I". -3- in seedbed.environment, in age, or in both. Lowagrade seedlings result more often from overcrowding than from.any other cause. Poor soil quality, abundance of weeds, and insufficiency of water are other important factors. The most clearcut results obtained by the Southern Forest Experiment Station in its planting experiments have been those bearing on the use of various grades of planting stock. These results have been abundantly confirmed by general experience practically throughout the southern pine region.’ Later, wakeley (1948) found that grades based on morphological characteristics were not a reliable index of a plant's capability for survival and growth. ‘Wakeley states ”Beginning in 1933-34, the plant- ing of southern pines increased tremendously. At about the same time, discrepancies in the morphological grades began coming to light. One of the commonest was better survival of mediumpeised.or grade 2 plantable stock than of larger or grade 1 plantable stockf. wakeley found that, when seedlings of the same morphological grade were drawn from different nurseries and.planted together on the same site, survival was consistently high for stock from.some nurseries and consistently low for stock from other nurseries. There was a distinct tendency for one nursery to produce stock whose true grade was consistently above the average and for another nursery to produce stock whose true grade was consistently below the average, even when both nurseries received the same fertiliser and.soil management treatments. ‘Wakeley (1948) states 'Bvidently something about an individual nursery could, without showing in morphological grade, produce an internal chemical or - 4 - physiological condition in the seedlings which greatly influenced their survival". ‘Wakeley (1948) found that fertilizer experiments in a single nursery substantiated the evidence that soil conditions influence physiological grades independently of morphological grades. working with longleaf pine, he found that two fertiliser treatments signifi- cantly raised average morphological grade, but of these, one treatment significantly raised and the other significantly lowered physiological grade, as shown by subsequent survival. The variability in morphological and physiological quality of stock is not surprising when the following factors are considered: (1) variability in seedling size and nutrient requirements, (2) varia- bility in physical and chemical soil characteristics between nurseries and within nurseries, and (3) the scarcity of information regarding the fertilizer needs of a Specific nursery or a specific species. Huberman (1940a) found considerable variation in the mean dry weights of normal one-year-old nursery planting stock. The mean dry weights in grams per plant were: loblolly pine - 2.30, shortleaf pine - 2.89, slash pine - 3.97 and longleaf pine - 5.85. In general, the nutrient requirements are proportional to the yield of ash or dry weight. Thus the nutrient requirements for a longleaf pine seedling might be about 2.5 times that of a loblolly pine seedling. ‘Wilde (1936, 1946a) found that, in Wisconsin and adjoining'states, the analysis of virgin soils under productive stands of various tree species gave the closest approach to the physiological optimum of -5- growth conditions. Such data provided.not only the amount of nutrients, but the constant ratio of various constituents, which is the chief prerequisite to balanced nutrition of seedlings. Youngberg and.Austin (1954) found that Wilde's procedure was applicable to certain areas in the Pacific Northwest. The low inherent fertility of the red and yellow podzolic soils in the southern pine region has been mentioned.by several authors (Bennett, 1921; Bureau of Chemistry and Soils, 1938; Heyward.and Barnette, 1934; Logan, 1916; and wahlenberg, 1946). The soils are strongly leached, acid in reaction, and low in organic matter and plant nutrients. In much of the southern region, crop failures have so often followed the effort to grow truck crops on land.which has just been cleared that there has developed a general opinion among truck growers that new ground is not suited to the growing of many crops the first year after clearing. ‘Ware (1936), reporting on experiments at the Alabama Gulfcoast substation, stated that 'It was apparent long before maturity of the crops that those plots receiving no phosphorus would produce practically no crops, and that the almost complete absence of available phosphorus was one specific cause of crop failure on new ground even for crops to which phosphorus applications are not usually considered.necessary. Where phosphorus was applied.in adequate quantities for good.production, crop yields however were still very low except where quantities of nitrogen were appliedumuch in excess of amounts generally required.on old.ground?. ‘Ware found that the second year yields increased.two to four-fold, even though no nitrogen was added. He attributes this increase to a release of nitrogen due to -6- bacterial decomposition. May (1938) found the same response in a forest tree nursery. He reports that the poorest longleaf seedlings produced the second year of cultivation compares very favorably with the best stock produced the first year after clearing. very little information is available regarding the nutrient requirements of southern pine seedlings. The following comments expressed the sentiment of participants attending the first Southern Conference of Nursery and.Planting Specialists (W.‘W. Ashe Nursery Conference} 1937). ”Fertilisers: - not generally used in nurseries. A standard fertilizer cannot be recommended because of varying soil requirements. Each nursery must work out its own fertiliser require- ments and study them continually. Better no fertiliser than the .wrong fertiliser. Lime should be used.sparingly, if at all, in conifer nurseries'. In the thirties, most southern nurseries were using a 2-1 or a 1-1 rotation of forest trees and.green manure crops. About 300 pounds of a complete fertilizer such as 4-8-4 or 6-10-7 was applied prior to the green.manure crop. 'Wakeley (1935) stated that ”very heavy applications of almost any fertiliser may cause injury or high mortality among young southern pine seedlings, particularly of the smaller-seeded species“. Cossitt (1937) recommended a 1-1 rotation rather than 2-1 rotation for the Stuart Nursery. He reported that the 2-1 rotation depleted.the soil to such an extent that the class of stock was materially affected, resulting in an increased.percentage of culls. He expected that the depleted condition would.be corrected by a l-l rotation and.two green manure crops per year. 1H! V. 4 9 rum-v ' Nursery practice did not change materially during the period 1937 to 1949. In 1949, nurserymen were still applying from 200 to 400 pounds per acre of complete fertilizers and attempting to correct pronounced deficiencies by side dressing of any recommended fertilizer (Muller, 1949). An additional factor that complicates the soil fertility problem is the fact that the same soil management practice is being used for all Species. A species that produces twelve tons of oven-dry matter per acre each year receives the same fertilization as one that produces only six tons of oven-dry matter per acre. Nutrient requirements of individual species have been ignored. Several investigations have been concerned with the effect of certain types of nursery management on the morphological characteristics of southern pine seedlings. Huberman (1940b), May (1933), and Scarbrough and Allen (1954) have shown that the largest and best seedlings are produced at low seedbed densities. Compost applications have resulted in increased root growth and stem growth (Muntz, 1944). Andrews (1941), Auten (1945), and Rosendahl and Korstian (1945) obtained variable re- sponses for fertilizer ammendments. 'Westveld (1946) studied the reSponse of slash pine to various nutrients in Norfolk soils in Florida. He was concerned primarily with branch and needle deve10pment and with root/shoot ratios. Maki and Henry (1951) found that root rot of pine seedlings could be controlled or partly alleviated by increasing the amounts of organic matter and fertilizers. Numerous investigators in the field of Agronomy and Horticulture have recorded the effects of various soil management practices on soil IA _ 1H! fertility, and chemical composition of plants. Very few such studies have been reported, however, for forest seedling nurseries in the southern pine region. An understanding of the effects of specific soil management practices on soil nutrients and mineral uptake by seedlings is essential if the nursery objective is the production of high-quality planting stock. In 1950, exploratory studies were initiated for the purpose of testing the effects of specific soil treatments on loblolly pine seed- ling developuent. In 1953, a study was initiated for the purpose of determining how specific soil management practices affect the chemical composition of the soil and the mineral content of one-year-old seed- lings. The results of these investigations form the basis for this Pal-791'- CHAPTER II REVIEW OF LITERRTURE Basic Considerations There is an abundance of literature on the general subjects of soil:management, plant nutrition and crop yields. Rather complete re- views of literature are available on each phase of these subjects. inany of the results of general soils and.plant investigations are appli- cable in the management of forest tree seedling nurseries. Only a few of the general contributions that have a direct bearing on the present investigations need be included with the contributions that are specifi- cally associated.with the subject at hand. According to Wilde, gtflgl. (1942) general investigations of ferti- lizer influence on tree growth were initiated.about the middle of the nineteenth century. These early studies were concerned with the effects of fertilizers upon the growth of plantations and.young forest stands. Nearly every tree species that is used.extensively in reforestation has received some attention. Colby (1933) reviewed.much of the literature on mineral nutrition in conifers from.the work of Duhamel Du Mbnceau in 1775 to 1932. Colby included the recent work done by German scientists (rfibler, Bauer, Ramann, Gossner, Suchting, John, Dienes, Weidelt and Mbnshard) on seasonal absorption of nutrient salts from the soil by forest trees, both coniferous and.dicotyledonous. Layton (1948) discusses -9- -10.. variations in mineral commsition of foliage according to location on the tree, season of year, time of day, and age of tree. Rennie (1955), after investigating the uptake of nutrients by mature trees, concluded that a continuing nutrient removal in silvicultural cuttings would have an increasingly important long term effect on forest growth and the soil. Leiningen (1931) found that many of the early investigations were unreliable because a number of important conditions were overlooked or misinterpreted. In many instances, highly productive forests were found on soils with a low content of plant nutrients. A number of misconceptions developed because the fact that trees are able to utilise nutrients from a tremendous volume of soil was overlooked. Wilde (1941) reports that some of the theories advanced discounted the importance of nutrients for growth of trees, particularly seedlings. These misconceptions were carried over so far that some European nursery managers suggested that starved seedlings raised on infertile soils were especially well suited to reforestation. Many of the older Germany nurseries maintained soil fertility by using farmyard or stable manure plus some N, P, and K fertilizers. Benzian (1951) and Pain (1953) report that almost continuous crops have been grown for over 100 years. However, the importance of nursery soil fertilisation has been fully recognized only during the past few decades (Wilde, 1946a). A large number of conflicting reports from early and recent investigations have increased the complications involved in the problem of nursery soils fertilization. Wilde (1946a) partly attributed this confusion to a lack of general knowledge concerning soil chemistry and plant physiology. It has been stated that the field trial represents the ultimate test to which any other proposed method of nutritional diagnosis must be suhuitted (Goodall and Gregory, 1947). But, as a diagnostic method, the field trial is subject to a number of disadvantages, namely (1) the results cannot be used during the year in which the trial is set up, (2) its results are subject to substantial errors and (3) it makes very heavy demands upon labor. Other diagnosticlmethods that have been widely used include sand or water cultures, soil analyses, and plant analyses. The value of these diagnostic measures have been widely tested by a number of investigators. Goodall and Gregory (1947) discuss the merits of the following methods used for the diagnosis of fertilizer requiraents of plants: field trials, pot culture methods, soil analysis, plant analysis, and observation of deficiency symptoms. They give the content of nutrients in plant material for a large number of species in relation to the in- cidence of deficiency or toxicity symptoms. They reviewed thoroughly the literature devoted to agricultural and horticultural crops. Layton (1948) reviewed the advances that have been made in the study of mineral nutrition of forest trees and discussed the applications of the work to forestry practice. Effects of Nutrients on Developnent of Seedlings of Native Species Pot cultures, soil analyses, plant analyses and deficiency symptoms have been used in the United States by a number of investigators working -12- with forest seedlings. A considerable number of investigations were made by graduate stu- dents who could investigate only a small segment of a problem or by field investigators who were limited by the lack of equipment and facilities. Anderson, C. E. (1933), Argetsinger (1941), Clifford (1929), Hanan (1916) and Stoeckeler (1931) studied the effects of fertilizer on northern species. Felker (1938), Kapel (1939) and Bundling (1929) investigated the relationship between the soil reaction and seedling developnent. Andrews (1941), Forbes (1945), Lynch _e_t_g_];. (1943), McComb (1941), Rosendahl and Korstian (194$) Schomeyer (1939), Voigt (1949), and Westveld (1946) investigated nutritional and physiological characteristics of loblolly pine or other species. ‘ Clark (1916), Hansen (1923), Kopitke (1941), Larsen and Stump (1939), McIntyre and White (1930), Mitchell (1934, 1936, 1939), and Wilde (1938) have investigated the nutritional requirements of eastern white pine (39.51.! strobus L.). Clark (1916) found that eastern white pine seedlings remove a large amount of nutrients from the soil each year. On the basis of chunical analyses of white pine seedlings, he concluded that a crop of seedlings rancved 94.6 pounds of nitrogen, 31.8 pounds of phosphoric acid and 41.6 pounds of potassium per acre. Hansen (1923) found that seedlings grown without fertilizer treatments produced more dry weight than those receiving fertilizer treatments. He suggested that coniferous seedlings remove very little minerals from the soil. Mitchell (1934, 1936, 1939) made exhaustive studies of nutrient requirements of eastern white pine and Scotch pine (Pinus sylvestris L.). Growing these species in sand cultures, he determined for the soil solu- TH! .— e a. at.-- ‘E I . a i n I ,. ~— —— -~ . \ . s I C -13- tions, the region of the minima, the working region, the region of tension, and the toxic region for nitrogen, phosphorus, potassium, and calcium. He found that seedling yield measured as total dry weight was almost directly proportional to nitrogen supply up to a concentration of 300 pm. Greater concentrations of nitrogen caused a reduction in growth. Root] shoot ratio was affected adversely by increasing the nit- rogen supply. The maximum root/shoot ratio was obtained with a nitrogen supply of 50 ppm in solution whereas the maximum yield was obtained at a concentration of about 300 ppm. Corsican pine (m laricio Poir) grew to a much greater size than Scotch or eastern white pine in so- lutions of equal nitrogen supply and showed no signs of retarded growth in concentrations as high as 485 ppm of nitrogen. Mitchell (1939) found that white pine seedling yield was almost directly proportional to phosphorus concentration up to about 200 ppm in solution. Greater supplies of phosphorus were toxic to even a greater extent than equivalent excess concentrations of nitrogen. White pine seedling yield was almost linearly related to potassium concentrations up to about 100 pm. The point of maximum yield was about 150 pm. Increases in calcium supply up to about 100 pm were accompanied by yield incraaents somewhat comparable in magnitude to those obtained with equivalent amounts of potassium. Between calcium concent- rations of 100 to 350 ppm, there was but little change in seedling yield. At concentrations above 350 pm seedling yield decreased as the calcium concentration increased. Mitchell's data indicate an optimum N-PzOs-KzO ratio of approximately 2-4-1. -14- By analyzing the plant material, Mitchell obtained the internal concentration of nitrogen, phOSphorus, potassium and calcium and then determined the relationship between the soil solution concentration and the seedling concentration of these elements. He also found that needle color could be correlated with nutrient content. McIntyre and White (1930), working with a silt loam soil, found that only small additions of nitrogen (20 pounds per acre), but larger additions of phosphorus (80 pounds of P205) and potassimn (50 pounds of K20), were needed to produce good quality planting stock of eastern white pine, pitch pine (Riggs rigida Mill.) and Norway spruce [M abigs (L.) Karst.]. In some instances, the addition of calcium was necessary for best results. Wilde §£_§l, (1938, 1940, 1946a, 1955) have made exhaustive in- vestigations of the fertility standards required for Optimum production of forest tree seedlings of northern species in northern nurseries. Following the lead of Hilgard (1911), he used the results of analysis of virgin soils from sites highly productive for various species as a basis for interpreting needs of the Species for nitrogen, phosphorus, potassium and calcium. He inferred that a virgin soil on a highly productive site should be capable of producing one cr0p of seedlings. However, since nursery stock is raised at a great density and no crop residue is left in the soil, the maintenance of a satisfactory fertility level in a nursery soil requires applications of fertilizer at rates higher than is common in farming practice. Wilde concluded that for Lake States nurseries an N'PZOS'K2O ratio of 1-2-5 was Optimum for pro- duction of conifers and that the annual nitrogen requirements ranged -15.. from 20 to 45 pounds per acre, P205 requirements from 40 to 100 pounds, and K20 from 100 to 275 pounds. The optimum N-PzOs-Kzo ratio for hard- woods was 1-3-5 (Wilde and Patzer, 1940). Youngberg and Austin (1954) found that an N-PzOs-Kzo ratio of 1-2-5 was optimum for Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco.] and its associates in some sections of the Pacific Northwest. They recom- mended a standard level of 40 pounds per acre of available N, 80 pounds of available P205, 200 pounds of available K20, 2000 pounds of calcium and 450 pounds of magnesium. Wahlenberg (1930) found that on the soils in the Savenac Nursery in Montana, ponderosa pine (2.1192 ponderosa Laws.) responded best to a complete fertiliser containing a relatively large amount of nitrogen, an intermediate amount of phosphorus, and a small amount of potassium. The results obtained by Wahlenberg do not agree with results obtained by other investigators. It is very probable that the levels of available and fixed nutrient content of the soil of the Savenag nursery are quite different from the soils in other regions. Vaartaja (1954, 1955) studied the effects of soil amendnents on growth of spruce in a Canadian nursery. He found that in a nitrogen deficient soil addition of peat, forest humus, fungicidal treatments and amonium nitrate, alone or in various combinations, resulted in sig- nificant improvement in growth and colour of white spruce [£1,235 115332 (Hoench) Voss]. Applications of ammonium sulphate had little effect on growth or colour. The nutrient or fertilizer requirements of red pine (£31133 resinosa Ait.) and other northern species have been investigated by Bensend (1943), -16- Chadwick (1937, 1946), Larsen and Stump (1939), Lunt (1938), Mchb 1949), McComb and Kapel (1940, 1942), McIntyre and White (1930), Marth and.Gardner (1937),.Mitchell and Chandler (1939), Shirley and.Meuli (1939), and Wilde and Patzer (1940). Bensend (1943) observed the effect of nitrogen upon the growth and drought resistance of jack pine (BEBE! banksiana Lamb.) seedlings that were grown in sand.cultures and nursery soil. He found that the average seedling weight of jack pine was greatest at a nitrogen concentration of approximately 200 to 230 parts per million, and.from this point on the curve dropped and leveled off. The same trend was obtained.for stem weight and stem height. These trends were in agreement with those of Mitchell (1939), except that he found that the optimum nitrogen con- centration for eastern white and Scotch pine was about 300 parts per million. The weight of roots increased.up to 100 parts per million and further increase in nitrogen supply resulted in little change. The root/ shoot ratio decreased with increase in available nitrogen until a supply of 100 parts per.million was reached, after which there was little or no change. Bensend found that jack pine seedlings grown under an optimum nit- rogen supply, i.e. 200 to 250 ppm, were as drought resistant as seedlings grown in soil deficient in that element. Increase of nitrogen supply over the optimum.resu1ted.in a decrease in drought resistance. Shirley and Meuli (1939) found that the top growth and.drought re- sistance of two-year-old red pine seedlings could be reduced by an excess of nitrogen. -17- Larsen and Stump (1939) found that for most northern conifers nitrogen fertilizers stimulated top growth of seedlings and transplants while fertilizers containing phosphorus increased root development. In the nursery, complete fertilizers were more effective than fertilizers containing only one element. In contrast, in greenhouse tests addition of single elaents frequently proved more effective. Lunt (1938) grew red pine, eastern white pine, European larch (La-315 decidua 11111.), Norway spruce, white spruce, and Scotch pine on a loamy sand soil. He made chemical analyses of some of the trees and from these analyses determined the N-ons-Kzo requirauents for each species and for three ages of stock. He concluded that the annual N-PzOs-KzO requiranents of 1-0 red pins in pounds per acre were 41, 14, and 18; of 2-0 red pins, 154, 32, and 59; and of 2-1 red pine, 84, 23, and 41. The N-PzOs-IzO ratios for these three classes of stock would be 3-1-1, 11-2- 4 and 6-2-3, respectively. In general, he suggested for red pine and other conifers a ratio of 10-4-5. 0f the species studied, Scotch pine made the heaviest demands on the soil and Norway spruce the least. 11wa and Kapel (1940) and 14ch (1949) found that the response to fertilizers was governed in part by the type of soil and the species. On an acid, infertile, glacial clay exposed to erosion, black locust (Robinia Escudoacacia L.) and green ash [ Fraxinus pe_nnsy1vanica var. lancelota (Borkh.) Sarg.] made little response to fertilization with nitrogen (140 pounds per acre), but made marked response to phosphorus alone (270 pounds per acre of P) at controlled pH values ranging from 4.3 to 7.7. Black locust that received phosphorus was 24 times and green ash 3 times as heavy as trees grown in untreated soil. On a gray- -18- brown podzolic soil and.on a prairie soil, seedlings did.not respond.to nitrogen applications when the total nitrogen was in excess of about 2000 pounds per acre. Seedling response diminished as the residual soil nitrogen increased. Marth and Gardner (1937) found.that different species did not give a similar response to similar fertilizer treatments. Hebbs (1944) grew four species of pine under starvation levels of nitrogen, potassium, and phosphorus. He found.that the normal growth of seedlings was upset by nutritional unbalance. Hobbs reported that the coloration of needles was an indication of deficiency symptoms. Day and Robbins (1950) grew red spruce (21.333 £232.: Sarg.) seedlings in sand.culture and found that the colour of the needles was related to the content and concentration of the nutrient solutions. Wilde and voigt (1948) used colour of leaf tissue as an indicator of nutrient deficiencies or adverse soil conditions. MbDernott and.Pletcher (1955) found that growth and coloration of eastern redcedar (Juniperus virginiana L.) was not affected by variations in nutrient level. Fletcher and.0chrymowych (1955) report that, although opthmmm levels of most soil nutrients are now well established for most agricultural crops, relatively little is know about the nutrition require- ments of most forest trees, particularly those species that grow on a wide variety of soil conditions. The studies of Addams (1937), Aldrich and Blake (19351xMCIntyre and White (1930), and.Mitche11 (1934, 1939), indicate that seed.weight exerts an important effect on the early cumulative dry weight of several species of pine. It is certain that the distribution of weights in an -]_9- average sample of pine seeds include a range sufficient to account for large variations in the yield of one-year-old seedlings (Mitchell, 1939). The phosphorus, potassium, and calcium content of seed may be sufficiently high to provide the nutrient requirements for several months. The amount of food reserves in seeds of identical fresh weight varies not only with the seed source, but from year to year in the same sample (Youngberg, 1952). Variations in seed weight and nutrient content may account for some of the variations in seedling response due to different nutrients. Southern conifers have been studied to only a limited extent, and all of the work has been done very recently. Many of the nursery in- vestigations were concerned with the immediate effects of nitrogen, phos- phorus, and potassium applications or other practices on general plant development. They did not include soil or plant analyses. Typical of this type investigation are the studies of Allen and Maki (1955), Andrews (1941), Auten (1945), Bryan (1954), Chapman (1941), Hubenman (1940a, 1940b), Johansen (1955), Maki (1953), Maki anleenry (1951), May (1933), Rosendahl and Kbrstian (1945), Read (1934), Scarbrough and Allen (1954), Umland (1956), and wakeley (1935, 1948, 1954). Read (1934), in a lengthy discussion of nursery'management, states, "That the forest tree nursery is probably the most important unit of the entire reforestation program.‘ However, he omits any'mention of soil fertility‘maintenance. wakeley (1935) reports that in southern forest tree nurseries, largely because most of them have been laid out on a fairly good soil and have not been in existence long, the use of either soiling crops or fertilizer on a commercial scale has barely begun, and practically no systematic experiments with nursery fertilizers have been undertaken. Hay (1933) reported that fertility of an alluvial nursery soil was maintained with green manure crops. Huberman (1940a, 1940b) found that seedling development was correlated with seedling density and that dry weights of seedlings increased greatly in December. ’ Andrews (1941) found that on a sandy soil the most desirable loblolly pine planting stock was produced when both organic matter and concent- rated fertilizer containing a high phosphorus content was added. Rosen- dahl and Korstian (1945) found that nitrogen applications to loblolly pine gave a positive response to tap-root length, shoot length, average length of needles, diameter of stem at root collar, mycorrhizal abun- dance, dry weight of roots and shoots, and percentage of plantable trees. Phosphorus and potassium applications did not produce any significant response on a Congaree silt loam, except on stem diameter. Auten (1945) found that soluble inorganic fertilizers applied at seeding time had a negative effect on seed germination and reduced seedling densities. Pessin (1937) grew longleaf pine seedlings in water cultures and found that those seedlings that were supplied with all the essential mineral elasents were the most vigorous and showed the best development. Especially poor vigor was shown by the seedlings grown in solutions lacking magnesium, iron, or potassium. Leaving either phosphorus or sulphur out of the nutrient solution produced the least effect on the seedlings. Pessin (1941) grew slash pine for nine months in washed sand which received no nutrient solution. The seedlings were then treated for eight months with nutrient solutions containing ten elments. The -21- amounts of nitrogen, phosphorus, and potassium were varied. Seedling vigor was improved by increasing amounts of nitrogen. Changing phos- phorus levels produced no significant effect on dry weight, while potassium in increasing amounts decreased the dry weights. The seedlings produced the longest roots when the nitrogen supply was smallest. Addoms (1937) grew loblolly pine seedlings for eight months in a sand-peat mixture, then transferred them to a washed white quartz sand in unglased pots. The composition of solutions were varied from time to time in an attempt to determine the optimum nutrient solution for growth. Even after selecting plants on the basis of uniformity, she found that great variations in the growth of individual plants occurred with the same nutrient solutions. She found, also, that loblolly pine seedlings are capable of utilizing nitrogen in either the nitrate or the amoniun form, the former more successfully in a highly acid solution, the latter more successfully in a more nearly neutral solution. She attributed differences in root development to differences in aeration. Westveld (1946), using pot cultures and nursery soil, investigated the response of slash pins to various nutrients. He found that appli- cations of nitrogen, nitrogen plus potassium plus 20 to 25 tons per acre of colloidal phosphates or peat plus nutrients produced a marked response in seedling growth. Combinations of two or more nutrients pro- duced more favorable response than a single nutrient. Excess applications of nutrients, particularly nitrogen, depressed the growth of seedlings. The type of treatment had no significant effect on rootl shoot ratio. Maki and Henry (1951) found that root rot of southern pines was associated with low fertility. They believed that the addition of saw- dust, ammonium nitrate at the rates of 300 to 600 pounds, 20 per cent superphosphate at the rate of 3,000 pounds, and 50 per cent muriate of potash at the rate of 240 pounds per acre would sustain a production of seedlings of satisfactory size and vigor. Scarbrough and Allen (1954) grew longleaf pine seedlings on beds that had received the equivalent per acre of 4000 pounds of super- phosphate, 300 pounds of muriate of potash and 10 tons of sawdust. Nit- rogen was applied as a top dressing after seed germination. They found that seedlings from low density seedbeds grow larger and survived better than those from high density beds. Allen and Maki (1955) found that the green weight of longleaf pine seedlings and their ability to survive transplanting differ with the media in which they are raised. The mean green weight of seedlings with NPK applied was double that of those with nitrogen alone or with no fertilizer. Umland (1956) reported that with an application of 1000 pounds per acre of 10-22-12 fertilizer troughing developed toward the center of the seedbeds. With an application of 2000 pounds of 10-22-12 fertilizer, seedling heights were uniform throughout the bed. Bryan (1954) found that the colour and vigor of yellow, unthrifty loblolly pine seedlings could be improved by late season applications of nitrogen. If past fertilizing history of poor 1 spots suggest that phosphorus or potassium is lacking, the elments may be applied simultaneously with nitrogen without harm to the stock. Switzer and Nelson (1956) grew loblolly pine seedlings on a Kaufman sandy loam, alluvial phase. With three levels of nitrogen, twa levels of P205 and two levels of potassium, only nitrogen treatments affected the dry weights of seedling tops and of the whole plant. They found -23- that the phosphorus and potassium levels were adequate for a crop of pine seedlings. On the basis chemical analyses of the foliage and the soil, they concluded that a crop of one year old loblolly pine seedlings removes approximately 126 pounds of nitrogen, 20 pounds of phosphorus and 70 pounds of potassium per acre. Wakeley (1954) gives an excellent review of the literature on the subject 'Nursery Soil Management”. He states, 'Soil differences from nursery to nursery frequently make findings in one place inapplicable in “01:11.1... Soil Treatments in Nurseries in Great Britain MacDonald (1953), reporting on developnents in nursery practice in Great Britain, indicated that nursery fertility had been reduced to a critical level in the 1930's. An intensive research program was initiated about 1946. Holmes and Faulkner (1953) investigated the possibilities of improving fertility by partial sterilization of the soil by steaming or the application of formalin or other fumigants. Treatments of these types evidently modify fertility levels by modifying the population of soil micro-organisms. Many of the tests gave inconclusive results. Crowther (1950, 1951) reports that, in seedbed experiments in (which com- posts and bulky organic manures were compared with artificial ferti- lizers, markedly poorer stands of seedlings were obtained in the compost- treated beds. He attributes these results to a drought effect in a particularly dry season. Soil acidification improved growth of seedlings at m nurseries. He found that on an acid sand soil (pH ca 4.0) top dressing with ammonium sulfate had a negative effect on height growth. -24.. Some species gave a positive response to phosphorus in all four nur- series where experiments were done, while other species gave a negative response to soil treatments. Rayner and.Neilson-Jones (1946) made intensive investigations of problems associated with the growing of Scotch pine, Corsican pine, lodgepole pine (£1925 contorta Dougl.), and Maritime pine (£1.93; pinaster Ait.) in Great Britain. They concluded that the development of unhealthy and.semi-moribund.plants was a starvation phenomenon and that deficiencies could not be corrected with inorganic fertilizers. They believed that in soils poor in inorganic nitrogen the nutrient requirements of the young trees are normally met by a proper mycorrhiza development. They reported that certain types of organic material in the soil contained substances actively injurious to root growth. Better aeration following deep ploughing reduced the toxic effect, but seedlings without mycor- rhizae rooted poorly. They found that the toxic substances were of bio- logical origin and that they operate directly by inhibiting fungal growth. Enduring effects brought about in the soil by the accumulation of undecomposed humus residues and by diversion of normal degradation changes into channels leading to the formation of by-products deleterious to vascular plants lead.to the formation of an infertile soil. Other investigations at English nurseries (Rothamsted.Experilent Station Reports, 1952, 1953, 1954, 1955) have revealed that Sitka spruce [£_i_c_:_e;_a_ sitchensis (Bong.) Carr] on acid nursery sites responded to nitrogen, phosphorus and.potassium. Compost plus a complete fertiliser was not consistently superior to inorganic fertilizers alone. On the neutral or slightly acid soils of old.nurseries, sitka spruce made very -25- poor growth and did not respond to compost and fertilizers. The residues from seedbedgmnlches that contained.considerable amounts of CaC03 in the forl.of limestone or shell fragments resulted.in much poorer growth of one-year-old Sitka spruce than residues of covers free of CaCO3. Cal- careous seedbed mulches were used frequently before the autumn of 1947, when, on the recommendation of Rothamsted.Experiment Station, they were banned.in Forestry Commission nurseries. When a two year's grass ley was followed.by two successive crops of one-year-old Sitka spruce, the second.crop was much larger and more vigorous than the first crop. Formalin and chloropicrin treatments resulted in greatly increased growth and at the poor, long-established.nurseries the crops resembled those grown in the very acid, newer nurseries. In 1954, a series of experiments in which different rates of phosphorus and potassium had.been tested.over several years were concluded. Plant response showed no signs of falling off even at the highest rates of phosphorus (6 glsq. yd.) tested. A new series of experiments were designed to test higher rates of application. Rayner (1947) studied the behavior of Corsican pine following different nursery treatments. She found that different types of soil conditions resulted in different types of root systems and different species of nycorrhizae. She reported that seedlings with nonnal root systh and adequate myoorrhizal vigor carried their constitutional vigor into the forest, and.oven to poor soils of non-forest type. Edwards and Holmes (1951) reported that phosphorus fertilizer placed beneath the drills was very successful in increasing the growth of Sitka -26.. spruce one year, but the same treatment ih a previous year had given negligible results. Effects of Nutrients on Soils and Seedling Grewth in the Far Eastern Countries Loblolly pine, slash pine, Maritime pine, and Monterey pine (M radiata D. Don) have been planted in Australia and New Zealand, but unsuitability of soil and climate resulted in the failure of many of the plantations. A number of disorders including yellowing, spindle stands, resetting, and die-back developed on the poor, infertile sites. Several investigators have delved into the causes of the disorders or diseases and the possibility of developing remedial measures. Kessell and Stoate (1936, 1938) found that the sites producing healthy, vigorous trees had a significantly higher phosphorus and nitrogen content than the sites producing diseased trees. They did not find any significant difference in chemical composition of needles from healthy trees and diseased trees, except for potassium levels. Askew (1937) analysed the needles, stems and roots of Monterey pine seedlings. He found that needles were relatively rich in minerals, particularly nitrogen, and that mineral content was higher in stems than roots. As the tree aged, the calcium, phosphorus, sodium, chlorine, iron, and insoluble ash content decreased, while the nitrogen, magnesium and manganese content increased. He calculated that an acre of tw0-year-old Monterey pine seedlings absorbed the equivalent of 84 pounds of ground limestone, 84 pounds of sulphate of potash, 564 pounds of 44146 per cent triple superphosphate, and 616 pounds of sulphate of ammonia. This amounts to 33 pounds of calcium, 123 pounds U V..- -27- of nitrogen, 254 pounds of B205 and 42 pounds of K20. Young (1940a) observed that the phosphorus content of pine needles could be related to the phosphorus content of the soil when the soil was deficient in phOSphorus. When the phosphorus level was sufficient for healthy growth, the phosphorus content of the foliage tended to remain constant. YOung (1948) investigated the reSponse of loblolly pine and slash pine to phOSphate manures. He applied different rates of superphoSphate to loblolly and slash pine plantations. Stem diameter, stem height and stem volume were measured prior to the treatments in 1939 and again in 1946. Needles of each Species were ashed and analyzed for 8102, sesquioxides, P205, CaO,MgO, Na, and K20. The mean ash content of needles was 2.94 per cent for slash and 3.63 per cent for loblolly. The P205, CaO and MgO content of slash pine needles was considerably below that of loblolly pine needles, whereas the K20 content was about the same for the two Species. Young found that growth response to phosphate fertilizer either alone or in combination with other nutrients was correlated with the original soil phosphate value and the amount of P205 added. He concluded that the nutrient requirements for loblolly and slash pine differ appreciably. Kessell (1943) and Stoate (1950) believe that irregularities of growth which are not due to the attack of any known parasitic organism may be regarded as deficiency disease. Plantings in Australia were restricted to the poor soils, including the coastal sands. The fertility of some of the sands was estremely low, as indicated by -23- total phosphate content of from less than one to around 20 ppm. Phosphate and zinc have been used to correct a number of disorders in existing plantations and render possible the establishment of other plantations on poor, infertile soils hitherto considered unsuitable for afforestation with exotic conifers. No benefits occurred from the use of other recognized main plant nutrients, potash, nitrogen, or calcium, either singly or in the combinations tried. Results from fertilizer studies in the nursery were in general agreement with results from plantation studies (Queensland Dept. Agr., 1951). Slash pine seedlings were grown under different levels of nitrogen, phosphorus and potash. A marked positive response was obtained with phosphate, whereas added nitrogen depressed growth. In the nursery, soil structure was improved by applying molasses to an area that had received heavy applications of sawdust for several years. Aggregation was increased 21 to 25 per cent. Hearman (1938), Perry (1939), Smith (1943), and Young (1940a) have obtained results similar to those reported above. Since 1932, seedling production in Japan has never fallen much below half a billion a year. In 1948, about 24,000 nurseries, ranging in size from 1/50 acre to about 8 acres, were well-distributed through- out Japan (Haibach, 1949). A tremendously increased planting program was in the planning stage. Within recent years, several Japanese invest- igators have studied the nutrient requirements for tree seedlings. Ono, Shibata, and.Hoshino (1951) analyzed soil samples and found that the soils were deficient in nitrogen, phosphorus and potassium. They found that Japanese redwood or, Sugi, (Cryptomeria japonica) and Japanese cedar, -VV~ - 29 - or Hinoki, (Chamaecyparis.gb§g§a) gave a positive response to additions of nitrogen, phosphorus, potassium and calcium. They found that the sulphates of manganese, magnesium, zinc and.boron and boric acid.had little effect on seedling growth if the major nutrients were omitted. Ando (1952) analyzed the Japanese redwood seedlings for nitrogen, phosphoric acid, potash, calcium and nah content. Contents expressed as a percentage of the dry weight at the end.of one growing season were: Nitrogen 1.2 - 1.8 per cent, P205 0.3 - 6.4 per cent, K20 1.5 - 1.7 per cent, CaO 1.1 - 1.4 per cent and ash 6.0 - 6.5 per cent. For each nutrient the concentration was affectedumore by different stages of growth than by the amount of fertilizer applied. The concentration of nitrogen and calcium in the plant increased as concentrations in the soil solution increased. P205 and.KZO concentrations in plants were not influenced significantly by variations in fertilizer levels. Ando and.Hukasaku (1953) found that variations in nitrogen levels affected seedling development more than phosphorus or potassium. High levels of all three nutrients were toxic to Japanese redwood. ‘When nitrogen was applied at rates of O, 5, 10, 20, 40 and 60 grams per square meter, seedling growth increased with increasing nitrogen up to 20 grams, and then decreased. TheJmaxbmmm content of nitrogen in the seedling was found at 40 grams per square meter. It was 1.67 per cent for the whole plant, 1.83 per cent for the shoot, and 1.00 per cent for the roots. Relationships between weight and.nitrogen content suggested that the opttnml application was 20 grams per square meter. However, the percentage of nitrogen utilization was higher for the five gram applica- tion than for other rates. r PLIIIII. .rI—I..s v. -30- Goor (1953) used pot culture tests to study the influence of nitrogen and phosphorus on the growth of Japanese larch (Larix leptolepis Murr.). He found an NIP antagonism in the Japanese larch. Nitrogen applications decreased phosphorus uptake and vice versa. The growth was optimmm over a naIIOW'N/P ratio and decreased rapidly on both sides of the optimum ratio. The lower the phosphorus content of the soil solution, the more rapidly growth decreased as the supply of nitrogen increased. Sato and Muto (1951a) found that larch and Spruce seedlings could be grown in incomplete nutrient solutions for Short intervals and that the period of most efficient use of a nutrient was associated with the age and development of the seedling. European Investigations The early investigations on the mineral nutrient relations of forest trees were concerned primarily with the forest plantations and natural stands. Bauer (1912) found that every species of forest tree apparently has a different curve for mineral salt absorption throughout the year as well as a different curve for dry weight increase. Mineral absorption and dry weight increase may follow along the same path, but there is never a perfect correlation between the two. He observed that a tree may have different seasonal absorption curves for various ions. During the past century nursery soil fertility was maintained with the use of animal manures and forest litter, supplemented by liming and some additions of mineral nutrients. Present nursery fertilization practices have been described by Aaltonen (1948), Hilf -31- (1949), Krussman (1954), Nicolaisen (1938), Olbrich (1948), Pein (1953), and Wittich (1950) . Becker-Dillingen (1937), Jessen (1938, 1939), Mfiller (1904), Schdnnamsgruber (1955), have grown various species in nutrient solutions and have described the resulting growth patterns and deficiency symptoms. Jessen (1939) reported that applications of potash fertilizers increased the yield of dry matter and the potassium content of the seedlings. Sch6nnamsgruber (1955) found a high correlation between the phos- phorus content of leaves and that of the media, though the pattern was irregular at high concentrations. The addition of other nutrients, partic- ularly magnesium, increaSed phosphorus uptake. He found that the phospho- rus requirements were not the same for all Species. Maximum dry matter was produced by pOplars and elms when the phosphorus supply was high. Beech and birch produce maximum dry weights with only medium phOSphorus supply. Black locust produced its maximum dry weight in cultures con- taining hardly any phosphorus. Sfichting (1939, 1940), using a number of soil types, found that, in general, larch, pine, and Spruce reSponded to all types of fertilizers. However, in some instances potash treatments reduced growth. The soils were deficient in nearly all nutrients. Mitscherlich (1955) proved that root and shoot growth of nursery seedlings could be increased with mineral nutrients and adequate water. He dis- counts an old Opinion that nursery stock Should be raised in a soil that is not superior to that in which the seedling will be planted. Demortier and Fouarge (1938) observed that Scotch pine seedlings re- quired much more nitrogen and phosphorus than potassium and that the seed- lings utilized ammonium nitrogen more efficiently than nitrate nitrogen. -32- Grant (1952) described the Dunemann process, in which the seedbed consists of needle litter. Water is applied frequently. The seedlings develop very extensive fibrous root systems. Nemec (1937, 1941) has studied the reSponse of many species to fertilizers. He has observed the influence of supply on uptake of nitrogen, phOSphorus, potassium, calcium, magnesium, manganese, silica, iron and aluminum. The results of his studies reveal the complexity of the interrelationships involved. Nitrogen applications increased the uptake of silicic acid by seedlings and reduced the phosphorus uptake, particularly on soils low in phoSphorus and high in silicic acid (Nemec, 1938a). Nitrates reduced and sulfate of ammonia increased the uptake of aluminum. Sulphate of ammonia increased the iron uptake by pine needles provided adequate phosphorus was present in the soil. Sul- phate of ammonia produced a greater uptake of manganese than any other form of nitrogen, particularly on soils containing the lowest amounts of exchangeable calcium. The effects of NaNSs, Ca(N03)2, and (NH4)ZSO4 on one year tranSplants was investigated. He found that the effect on growth was determined largely by the degree of acidity and the nutrient supply. In general, NaNO3 and Ca(N03)2 were more effective on very acid soils and (NH4)ZSO4 was more effective on slightly acid to neutral soils. Nemec (1937, 1938b, 1939a, 1938c) found that heavy applications of phOSphorus tended to lower nitrogen uptake on soils that were rich in nitrogen. Seedling response was more favorable to basic slag than to superphoSphate on soils that were well supplied with phosphorus and soluble nitrogen. PhOSphate fertilization did not affect the potash uptake except on potassium deficient soils, but it did increase the uptake -33- of calcium. Phosphate fertilization increased growth of pine seedlings on strongly acid soils and on soils low in lime and potash provided pot- ash was also applied. Purple discoloration of pine needles was found to be associated with a low phosphorus and calcium concentration in the soil. Generally, manuring acid soils with phosphorus resulted in a slight decrease in iron and aluminum absorption. However, he reports that the aluminum status affects iron absorption in a complicated manner. Nemec (1939b) reported that pines are chlor0phobes and recommended that chlorine free fertilizers should be used. Large applications of potassium chloride caused trees to die because of the flooding of needles and stems with chlorine ions. The effect on growth of potassium fertili- zation depended primarily on the potassium, phosphorus, and calcium supply in the soil. Manuring with potassium had a positive effect on growth only where the soil contained more than 100 mg. of P205 per Kg and about 150 mg. of CaO per 100 grams. Absorption of potassium by the needles depended, in general, on the potassium supply in the soil (Nemec, 1939c). On soils low in phosphorus, no material increase in potassium absorption by the needles resulted from increasing potassium fertilization, even on soils poorest in potassium. Absorption of phOSphorus by needles decreased with decreasing phosphorus in the soil, in both potassium fertilized and non-potassium fertilized plots. The availability of phosphorus in the soil was influenced by the amount of exchangeable calcium. Even on soils low in potassium, the phosphorus content of needles was not increased by unbalanced potassium fertilizing if the calcium content of the soil was high. -34- Absorption of nitrogen by needles depended on the relative solubility of nitrogen in the soil. However, with a favorable phosphorus supply in the soil, fertilizing with potassium increased nitrogen absorption on soils with adequate nitrogen, particularly if the soil was deficient in potassium. On soils with a relatively low nitrogen content the nitrogen uptake of needles was reduced by un- balanced fertilizing with potash. In general, absorption of calcium was dependent on the content of exchangeable calcium in the soil. Manuring with potassium fertil- izers reduced the uptake of calcium by needles in the case of soils with a good potassium supply, but considerably increased uptake of calcium on soils poor in potassium. On soils with a low phosphorus and potassium content, fertilizing with potassium gave a closer K20:Ca0 ratio in the needles. Absorption of magnesium by needles corresponded roughly to the content of exchangeable magnesium in the soil. 0n soils provided with adequate phosphorus but low in potassium, unbalanced potassium fertili- zation resulted in a slight increase in magnesium uptake by needles. Liming of acid soils increased growth of spruce seedlings and raised the calcium content of the needles (Nemec, 1938a) except on soils rich in nutrients. Liming increased the nitrogen content and lowered the phosphorus content of needles. Nemec (1941) reports that adequate fertilization of seedlings in the nursery guarantees favorable growth after planting. Goncharov (1941). Jacob (1937) and Than (1938) discuss the diffi- culties involved in arriving at optimal fertilizer ratios and conclude - 35 - that there is no optimum N-P-K ratio that is applicable to all soils and all crops. Each soil and each crop will require individual treatment. Goncharov suggested that for hardwoods an N'pZOS'KZO ratio of approximate- ly 4-8-3 might be effective. Soil Reaction and Tree Growmh Several investigators in recent years have studied the relationship between soil reaction and nutrient uptake and plant growth. Baker (1925) and Howell (1932) found that soil reaction had little effect on the seed- ling development of western yellow pine (Pinus ponderosa Laws). Within its natural range, the species was found on sites with pH ranges from about 4.5 to 9.0. Wherry (1922) reported that some eastern conifers such as longleaf pine preferred a very acid soil while other srecies such as loblolly pine and Shortleaf pine preferred a slightly acid soil. 'Wide (1934) sets forth the optimum pH range for different Species. He classi- fied tree preference according to five pH ranges, 3.7 - 4.4, 4.5 - 5.4, 5.5 - 6.8, 6.9 - 7.2, 7.3 - 8.0. He reported that, in nursery practice, the reaction of the soil influenced not only the growth of seedlings but the rate and kind of fertilizer that should be applied. He found that the most desirable reaction of a nursery soil was between pH 5.0 and pH 6.0. Greenhouse eXperiments with northern conifers indicated that a difference of 1.5 pH between nursery and planting Site was the maximum safe dif- ferential. Jacobi (1951) recommended optimum pH values for growing different hardwoods in the nursery. The overall range was 5.0 to 7.15. McComb and Karel (1942) grew black locust and green ash at four acidity levels (pH 4.3, 6.6, 6.9, and 7.7) and three fertility levels. They - 35 - found that when phosphorus was deficient, growth increased up to pH 6.9 and decreased at pH 7.7. At a high fertility level best growth was obtained at pH 4.3. The good growth at a low pH was attributed to a relatively high base saturation and apparently adequate quantities of individually important bases. Layton (1952) investigated.the effect of pH and form of nitrogen on growth of conifers. He found that a reaction between pH 4 and 5 (resulted in optimum growth of root and shoot of Sitka spruce. Nitrate nitrogen stimulated root growth more than ammonia nitrogen, whereas stem growth was.more responsive to ammonia nitrogen. Shibamoto, Takhara and.Kawana (1950) found that the optimum.pH for Japanese redwood and.Japanese red pine seedling development varied according to the source of nitrogen. The optimum pH was higher when nitrate nitrogen was used than when ammonia nitrogen was used. Stoeckeler (1949) reported that the acidity of Lake States nursery , soils was increased by repeated applications of sulphuric acid and peat. Switser and Nelson (1956) found that nitrogen treatments had a highly significant effect on soil pH. Soil acidity increased with increasing rates of nitrogen application. Organic Matter and Nursery Soil Fertility The nature and importance of organic matter in the soil has been thoroughly discussed by Baver (1948); Brauns (1952); Fraser (1955); Hopkins (1945); Jenny (1941); Joffe (1955); Lyon, Buckman, and Brady (1952); Lmts and.Chandler (1946); Martin.gt_g;, (1955); Pieters (1927); Russell and Russell (1950); Russe11.gt_gl, (1951); Waksman (1938, 1952); and'Hilde (1946a). -37- Organic matter improves water holding capacity, aeration, cation exchange capacity, and structure of some soils (Baver, 1948). Morris and Collins (1951) and Joffe (1955) report that organic matter does not improve the structure of lateritic soils. Soil fertility and productivity are closely associated with soil organic matter content. Organic matter, particularly humus, is a storehouse of important chemical elements essential for plant life, especially carbon and nitrogen, and, to less extent, calcium, phosphorus, potassium, magnesium, iron and possibly other minerals (Fraser, 1955). The amounts of organic matter in virgin soils vary so widely that it is difficult to present representative figures. Mineral surface soil may contain from only a trace to 15 or 20 per cent of organic matter (Lyon, Buckman, and Brady, 1952). Normally a very marked change occurs when a virgin soil is placed under cultivation. A lower level of organic matter is gradually established as the soil seeks equilibrium or a minimum constant below which the organic level cannot be lowered no matter what system of soil management is followed (Joffe, 1955). The addition of organic matter has a necessary role in any program of maintaining soil fertility in forest tree nurseries, particularly in the southern region of the United States. Nursery soils receive a maximum of abuse. A crop of one million seedlings per acre removes from five to fifteen tons of dry matter. No crop residues are left in the soil because even the root systems of seedlings are removed. Seedlings are lifted during the winter months when soil moisture is extremely high. Soil struc- ture is unfavorably modified. However, a favorable soil structure must be maintained so that seedlings can be removed from the Soil without injury -38- to the root system (wakeley, 1954). Intensive cultivation, high temperatures, abundant rainfall supplemented by artificial irrigation, and additions of commercial fertilizers promote biological activity and rapid decomposition of organic matter. The decomposition of organic matter is a complex process. Adequate moisture, favorable temperature, abundant nutrients, and active micro- organisms are a requisite for decomposition of organic matter. Any variation in one of these factors will modify the rate and course of decomposition of organic matter. Allison (1955); Gamble, Edwinster and Orcutt (1951); Harmsen and Van Schreven (1955); Norman and Bartholomew (1943); Phillips, Weihe, and Smith (1930); Pinck, Allison, and Gaddy (1946); Turk (1942); ‘Waksman and Hutchings (1936); waksman and Tenny (1927); and. White, Holben, and Jefferies (1949) have studied the influence of one or more factors on decomposition of organic matter. The general conclusion is that the accumulation of the lignins, which are more resistant to decomposition than other plant constituents, and the synthesis of microbial nitrogenous complexes account for the increase in soil humus by decomposition of natural organic materials. The composition of plant material will influence the rate of decomposition and the accumulation of humus. Pieters (1927) and Broadbent and Bartholomew (1948) report that it is very difficult to increase organic matter in the soil by the use of green manure crops or highly carbonaceous residues. They reported that the rate of organic matter decomposition was inversely related to the quantity applied. Mixed types of organic matter frequently decompose more quickly than single types of materials (waksman, 1952). Decomposition of stable humus can be accelerated - 39 - by the addition of fresh material (Harmsen and Van Schreven, 1955). The micro-organisms bringing about decomposition of plant and animal residues require considerable amounts of energy and nutrients as they grow and multiply. A nitrogen content of about 1.7 per cent is the minimum sufficient to supply the requirements of the micro-organisms for cell synthesis (waksman, 1952). When organic materials have a carbon/ni- trogen ratio greater than 20:1 only carbon dioxide is liberated during decomposition. All mineralized nitrogen is immediately bound in the protoplasm of the developing microbes. When large quantities of sawdust are added to the soil, nitrogen must be added in order to supply the requirements of micro-organisms and to prevent a nitrogen deficiency in seedlings. Bornebusch (1941), Brener and Wilde (1941), Holmes and Faulkner (1953), Karlsson (1945), Knight (1956), Maki and Henry (1951), Muntz (1944), Nemec (1939d), Pein (1953), Retan (1918), Wilde and Hull (1937), Wilde and Krumn (1946), Wilde and Wittenkamp (1939), and.wycoff (1956) have reported on the use and effects of organic matter in tree seedling nurser- ies. Although some conflicting results have been obtained, most investi- gators agree that the productivity of a permanent nursery is dependent upon a supply of organic matter that is used for the improvement of the physical condition of the soil, as a source of nitrogen and as a carrier of nutrients. Within recent years, sawdust, wood chips or shavings, and other forms of wood waste have received considerable attention as a possible soil conditioner and source of organic matter. The possibility of using sawdust is of extreme importance to nurserymen in the southern region. -40- Peat, straw,:manure, and other forms of organics are extremely scarce and expensive; whereas, sawdust is plentiful, accessible, and cheap. ,A com- plete review of the literature dealing with investigation of sawdust use is not within the scope of this paper. Allison and Anderson (1951) reviewed the literature dealing with the use of sawdust and summarized the results. They report that very little information is available on the comparative values of artificial manures prepared from.sawdust, straw, legumes, and other materials, but that there seems to be no reason to doubt that one material is as good as another if the content of fertilizer elements is the same. They omphasize the fact that nutrient content ratios vary for different species and that in some instances variations within a species, due to differences in soil nutrients, may be greater than the differences between species (Lunt, 1954; and Wilde, 1946) . Nursery Diseases and Soil Fertility Chloresis is probably the most common minor disease that affects coniferous seedlings (Korstian, Hartley, watts, and Hahn, 1921). Although pathologists and physiologists classify chlorosis as a disease, it is a symptom.of malnutrition. (Wakeley (1954) defines chlorosis as a yellowing of part of all of the seedling foliage resulting from the breaking down or non-formation of the normal green pigment. He attributes chlorosis to an.imuense number of climatic influences and physical, cheudcal, and micro-biological peculiarities of the soil. In southern nurseries it has been associated with deficiences and excesses of nitrogen, deficiencies of iron or magnesium, excessive lining, and heavy applications of sawdust or -41- compost. 'Wilde and Voigt (1952) report that chlorosis may be also caused by deficiences of other nutrients. Damping-off is probably the most serious disease that is found in southern pine nurseries. Hartley and Pierce (1917) define damping-off as a term commonly used to describe the disease causing the death of very young seedlings due to parasitic fungi. Davis, wright, and Hartley (1942), ‘Wakeley (1954), and wycoff (1952) attribute damping-off epidemics to a number of factors including (1) use of nitrogenous fertilizers prior to sowing; (2) presence of undecomposed organic matter in any form, particu- larly green manures; (3) high calcium content or high pH; and (4) high moisture content of the soil. Tbumey and Kbrstian (1942) suggest that the most practical and least expensive method of controlling damping-off may be the attaining by cultural methods of conditions in seed beds inimical to the rapid developnent of damping-off fungi. Root-rot of conifers has been frequently attributed to soil condi- tions. Eliason (1938) reports that repeated cropping with buckwheat on the sandy soil of a New York nursery has caused serious losses of red pine transplants due to root-rot. Root-rot of l and 2-year-old white spruce seedlings has been associated with excessive use of cover crops according to the New York Conservation Department (1951). Levisohn (1951) reports that a serious haustorial infection is frequently encountered in run-down nurseries. Stone (1948) and Maki and Henry (1951) consider fertility depletion a primary cause of root-rot at the W. W. Ashe Nursery. Kessell and Stoate (1938), Hearman (1938), Neilson-Jones (1938), and Young (1940a) found that irregularities of growth or needle disorders were associated with nutrient deficiencies. -42- Mycorrhizae, Soil Fertility, and Tree Nutrition The role of mycorrhizae on the growth of conifer seedlings has been eXplored by a number of investigators. Hatch (1937) reviewed the published data on early experiments dealing with mycorrhizae on conifers and continued investigations with pine. He concluded that mycorrhizae occurred normally only where there was a deficiency of one or more of a number of nutrient minerals. As a result of mycorrhizal formation on roots, trees growing in poor soils were able to obtain a more nearly adequate supply of mineral nutrients because of (l) the greater surface area of the infected short mycorrhizal root; (2) the greater abundance of the absorbing root ends due to the profuse branching of the mycorrhizal structure; (3) the delay in suberization of the cortex and endodermis of the infected short roots; and (4) the great extension of the fungal mycelium through the soil and the resultant increased surface for mineral absorption. Miller (1938) found that shortleaf pine seedlings would not grow in old, depleted farm soils unless mycorrhizal fungi were present. Miller contended that organic matter should be built up in depleted soil to a point approaching natural forest conditions. Otherwise, the mycorrhizal fungi have nothing to grow on after removal of pine seedlings. MCComb (1938) found that Virginia pine (Pinus virginiana Mill) seedlings ina nursery on old agricultural land, in the absence of mycorrhizal fungi, ceased growth in the middle of the first growing season as a result of insuffi- cient phosphorus nutrition. Seedlings with mycorrhizae absorbed phosphorus at a sufficient rate and developed in a normal manner. Young (1940) working with slash pine in Australia, grew seedlings A; ,K‘ "'Lr -43- in boxes in which the soils were inoculated with different Species of fungi from healthy pine stands. After one seasons growth, the mean height and mean dry weight of seedlings grown with the imported mycorrhizal fungi exceeded those of the controls. However, the increase in growth was not the same for all species of fungi employed. Bj3rkman (1940) found that the addition of nitrate nitrogen tended to decrease mycorrhizal develOpment on the roots of pine and spruce seedlings, particularly when the rates of application were high. However, a high rate of nitrate nitrogen did not completely prevent the formation of mycorrhizae. McComb and Griffith (1946) found that eastern white pine seedlings made satisfactory growth on an uninoculated soil that was fertilized heavily with phosphates. However, some mycorrhizae formed on the roots. Douglas-fir seedlings made a moderate growth response at high rates of phosphate, but mycorrhizae did not develop on the roots. They suggest that the stimulating effect of mycorrhizal fungi on conifer seedlings is due to heightened.metabolism associated with the transfer of phosphorus and growth stimulators from fungi to seedlings. Stone (1949) obtained similar results with Monterrey pine. He analyzed needles for phOSphorus content and concluded that the outstanding consequence of mycorrhizal infection was the uptake by seedlings of phOSphorus that was previously unobtainable. He attributed much of the response by pines with mycorrhizal formation to improved phosphorus nutrition. Neilson-Jones (1943) reports that under natural conditions the short roots of healthy plants are converted into mycorrhizae by association with -44- certain specific fungi. He suggests that for some soils fertility was dependent more on the degree to which the soil permitted the deve10pment of an efficient root system than it does on the abundance of available bases. He further suggests that the excessive use of manures or fertili- zers may disrupt the mycorrhizal relationship with the soil environment. Rayner and Neilson-Jones (1946) found evidence that the establishment and maintenance of correct mycorrhizal association in conifers is a requisite for normal and healthy growth on poor healthland soils. Soil Pumigants, Soil Fertility, and Plant Nutrition The problem of nursery stock production is being complicated by a rapidly increasing use of eradicants such as fungicides, insecticides and herbicides. Very little information regarding the effects of these sub- stances on soil fertility and plant nutrition is available. Martin and Aldrich (1952) found that soil fumigation treatments with DD, chloropicrin EDB, 032, and propylene oxide markedly affected the microbial population of the soil, but had little or no direct effect on soil aggregation. Martin and Ervin (1952) found that when a fumigant was applied to the soil insects and nematodes were readily killed and fungi, bacteria and related organisms were reduced in number. After fumigation the bacteria increased rapidly in number, but the fungi that became re-established represented fewer Species than were originally present. Hill (1955) used methyl bromide to control weeds, nematodes and root rot. Stunted, chlorotic seedlings develOped in patches throughout the treated beds. He concluded that the fumigant immobilized some of the nutrients in the soil. Thiegs (1955) investigated the effects of methyl -45- bromide and ethylene dibromide on nitrification. He found that methyl bromide retarded the nitrification of ammonium sulrhate for a period of four to eight weeks, depending on soil conditions such as temperature, moisture, aeration, and soil reaction as well as the rate of application of the fumigant. The inhibition period for ethylene dibromide was only about two weeks or less. He was of the Opinion that poor growth and possible injury to certain plants due to high levels of ammonia nitrogen were most likely to occur on acid soils that were low in nitrates. Voigt (1955) studied effects of fungicides, herbicides and insect- icides on the content of nutrient elements in tissue of Monterey pine seedlings. He found that the growth and nutrient accumulation by seed- lings was inhibited by several eradicating agents. The extent of phytotoxicity varied with the biocide and the rate of application. The inhibitory effects of some of the eradicants were alleviated by applications of commercial fertilizers or organic matter. Wilde and Persidsky (1956) studied the effects of biocides on the development of ectotr0phic mycorrhizae in Monterey pine seedlings. They found that the internal alterations of mycorrhizae under the influence of eradi- cants were characterized by irregularities in the Shape of the fungal mantle, restricted penetration of mycelia, and reduced development of the Hartig net. They suggested that the external modifications of the Short roots were the result of radical changes in the exudates of rhiZOSpheric organisms. They observed that the effect of eradicants varied with the nature of the chemical compounds and their rate of application. . 46 - Effects of Soil Fertility on Morphological Characteristics of Seedlings The effects on morphological characteristics of such factors as dates of sewing, irrigation, shading, type of mulch, density of seedlings, and root pruning in place have received considerable attention.(Higgins 1928, Hubenlan 1940a, 1940b, Janouch 1927, May 1933, wahlenburg 1929,'Walsh 1954). wakeley (1935) used.morphological characteristics such as stem height, stem diameter, root length, and state of bark, needle, and winter bud development as a criteria for the establishment of seedling grades. Later'Wakeley (1954) reports that the inconsistent results obtained from morphological grades make it difficult to write specific recommendations for grading southern pine nursery seedlings. Mitchell (1939) found that seedling dry weight, root/shoot ratio, bud formation, and needle color could be modified by variations in the external supply of nutrients. ‘When nitrogen supply was excessively high in proportion to phosphorus, potassium and calcima supplies, shoot deve10pment was abnormal in relation to the root deve10pment. Individual increases in the supplies of phosphorus, potassium, and calcium resulted in increases in the ratio of root weight to shoot weight. He found that the growth response of eastern white pine seedlings to increase in the supply of nitrogen, potassium, and calcium was greater than to equal increments of phosphorus. Rosendahl and Kbrstian (1945) studied the effects of fertilization of loblolly pine on root length, stem length, stem diameter, needle length, mycorrhizal abundance, and plant dry weight. They found that applications of nitrogen significantly affected each of these characteris- tics, whereas combinations of other nutrients generally did not result in .y—‘___-__r_, -47- significant positive response. iestveld (1946) found that variations in external nutrient supply resulted in variation in shoot growth, dry weight of stem and roots, and the number of branches per seedling. McDermott and Fletcher (1955) found that eastern redcedar seedlings grown in pots did not respond to fertilizer treatments. In another study, Fletcher and Ochrymowych (1955) found the growth of eastern redcedar seedlings was markedly influenced by the amount of certain available mineral elements in the soil. Fastest growth in weight and length, most foliage and branches, most extensive root system, and healthiest appearance characterized seedlings grown on rich, calcareous soil ndth a high pH (ca 7.8), a high organic matter (6.0%) and soluble phosphorus content, and adequate to high amounts of potassium and magnesium. Poorest growth of eastern redcedar seedlings was associated with a IOW'pH (ca 4.9), low organic matter content, (0.8 to 1.8%), and low amounts of calcium, potassium, and phosphorus. A high calcium content in the soil tended to promote an extensive root system and a vigorous stem with healthy foliage. Bj8rkman (1954) reports that on agricultural soils containing sufficient nutrients, Scotch pine and Norway Spruce seedlings do not ShOW’ any significant reSponse to heavy fertilizer treatments. Heiberg and White (1951), Stone (19531 and walker (1955) found that on potassium and magnesium deficient soils, fertilizer treatments resulted in a significant positive reSponse for some species. Using chemical analyses of needle tissue, they found a strong correlation between increased growth and a high content of potassium in the tissue. Growth increase was also related to a greater amount of exchangeable potassium in the soil. .548- Sate (1954) found that fertilizer treatments could be used to modify such morphological characteristics of birch as stem height, root collar diameter, volume, and air dry weight. Increasing the amounts of K2304 in the soil solution increased.the cellulose content of plants and improved the relationship between fibre length and breadth. ‘Maki (1950) reports that the development and vigor of longleaf pine seedlings can be modified by varying the supply of available nutrients in the soil. ‘Walker, Gessel, and.Haddock (1955) grew western redcedar (Thuja plicata Donn) in culture solutions, sand cultures, and soil pot cultures. They found that oven dry weights of shoots and roots and shoot heights varied with variations in mineral composition of growth media. Davis (1949) found that when loblolly pine seedlings were grownzin a calcium.deficient media the root tips were blunt and covered with a layer of dead, partially disintergrated cells. The needles were twisted, stiff, short, and the tips of many needles were dead. Relationships Between Nutrient Availability and Physiological and Anatomical Characteristics of Seedlings During recent years Bard (1945), Fletcher and.0chrymowych (1955), Lunt (1938), Mitchell (1939), Vbigt (1955), walker, Gessel, and.Haddock (1955), and others have analysed seedling foliage for mineral content. Generally, mineral content of foliage increased as mineral content of the soil solution increased from a deficient to an optimum.1evel. As the min- eral content of the soil solution increased from Optimum.to a toxic or - 49 - saturated level, the mineral content of foliage tended to remain constant or to decrease. Young (1947) reported that mycorrhizae on loblolly pine roots were capable of supplying carbohydrates obtained from cellulose to the plants through the roots. This carbohydrate supply was suitable for pine nutrition and could, at least, supplement the carbohydrates supplied by photosynthetic activities. Hulde and.Voigt (1948b) found that the specific gravity of seedling stems was related to the mineral and.moisture content of the growth.media. Seedlings obtained from natural reproduction on cutover area with coarse, sandy soil showed considerably higher specific gravity of wood than seedlings produced on heavily fertilized nursery beds. They predict that weak and inelastic seedlings that have tissues of low specific gravity are liable to suffer especially severe injury by sleet, hail, and other adverse factors. ‘Wilde, Nalbandau, and Yu (1948) found that seedlings grown on a heavily fertilized soil have a significantly higher content of ash and protein and a significantly lower content of alcohol-benzene soluble substances than seedlings grown on a soil of low fertility. They suggest that the contents of ash and protein may serve as indicators of the balance of nursery-soil fertility and the desirable proportion of applied fertiliser salts. Kopitke (1941) found that potash fertilization of white-spruce, red pine, and eastern white pine promoted the accumulation of simple and invert sugars in the tissue of seedlings. It increased the content of total solids -50.. and raised the osmotic pressure and lowered the freezing point of the expressed sap. However, applications of KéO in amounts higher than 300 pounds per acre reduced.the content of soluble sugars in seedling tissue and arrested synthesis of proteins. He suggested frequent analysis of nursery soils and.timely correction of potash deficiency as a prerequisite for production of frost resistant nursery stock. Sato and Mute (1951b) found that for seedlings of several species native to Japan resistance to cold increased.with increased.amounts of potassium.in the nutrient solution. Osmotic pressure of the sap was related.directly to the concentration of potassium in the growth media. Shirley and Meuli (1939) found that drought resistance of two- year-old red pine seedlings was dependent on a favorable balance of nutrients in the soil solution. Drought resistance decreased with increase in the nitrogen supply. When the nitrogen concentration was low, an increase in available phosphorus improved.drought resistance of seedlings. Forest Service (1944) investigators reported that resistance to drought and field survival increased twenty per cent when a prOper balance between nitrogen, phosphorus, and potassium.had.been.maintained in the nursery beds during the growing season. Fertilization during the donmant season, prior to lifting, resulted in increased field survival and in increased resistance to drought. A.high, unbalanced nitrogen concentration produced seedlings with a low resistance to drought. Wilde and Voigt (1949) found that the absorption-transpiration quotient of seedlings could be controlled or modified.by varying the fertility level of the growth.media. The absorption-transpiration quotient was found to be correlated with the degree of succulence of -51- seedlings and their vulnerability to drought and frost. wakeley (1954) suggests that fertilizer treatments of the nursery soil may greatly affect the physiological quality of southern pine .nursery stock. Davis (1949), working with loblolly pine, found that certain anatomical characteristics could be modified.by varying the nutrient supply. Calcium deficient seedlings differed from those receiving 200 ppm of calcium in culture solutions in that production of primary tissues (cortex and pith) and secondary tissue (xylem) was reduced. The number and size of cells in leaf tissue were directly related to the calcium supply. Effects of Nursery Practice on Field Survival of Planted Stock The problem of satisfactorily classifying tree seedlings according to their capacities for survival and growth after planting has proved to be complex. The first seedling grades were developed in an attempt to Judge these capacities by visible characteristics, including size. Several investigators have reported that survival of planted stock was correlated with nursery management practices. Higgins (1928) reported that field survival of western yellow pine and jack pine seedlings in Nebraska was inversely proportional to the seedbed densities. ‘Wahlenberg (1929, 1930) obtained.simdlar results with ponderosa pine, western white pine (Eigugbmonticola Dougl.), and Bngelmann spruce Qgiggg_egggbmannii Parry) from the Savenac Nursery in Montana. Scarbrough and Allen (1954) and Barr (1955) found that longleaf pine seedlings grown at low densities survived better than seedlings grown at high densities. Apparently, some investigators failed to - 52 - realize that reduction in density made more nutrients available for the remaining plants. Curtis (1955); Powells (1953); Pomeroy, Green, and Burkett (1949); and wakeley (1935) reported that large, thrifty nursery stock survived ‘better than small, unthrifty stock. Chapman (1948) reported that highest survival of shortleaf pine seedlings was obtained with seedlings having a low height/diameter ratio. He found that stem.diameter was a more effective criterion of survival than stem.height. Wilde and.Voigt (1948) suggested that seedlings with stems of high Specific gravity might survive better than seedlings with stems of low specific gravity. Wilde, Wittenkapm, Stone, and Galloway (1940) and Wilde, Trenk, and Albert (1942) found that seedlings produced on highly fertile soils were better able to survive under adverse field conditions than those grown on soils of low fertility or with unbalanced fertility. Forest Service (1956) investigators found that field survival of slash pine seedlings was dependent upon the soil fertility level of the nursery seedbed. Several investigators have modified a seedling's capacity for survival by changing the water absorption rate of roots or the transpiration rate of the foliage. A review of literature in this field is not included. in this paper. General Relationships Between Plant Nutrition and Soil Fertility Opinions regarding the relative importance to plant growth of the physical and the chemical pr0perties of soil have varied considerably during different periods in the deve10pment of soil science and plant - 53 - science. This results from the existance of extreme variations in physical and chemical characteristics of soils, combined with wide variations in physical and chemical characteristics of soils, combined with wide variations in nutritive requirements of plants. Russell and Russell (1950), Shaw (1952), and Baver (1948) have discussed the physical properties of soils in relation to plant growth. Baver (1948) uses the term tilth to include all those soil conditions that determine the qualities of the soil as a suitable physical environment for plant growth. Adequate aeration, sufficient moisture, and ready infiltration of rainfall are functions of good tilth. However, a soil in good tilth is not necessarily a fertile soil. Liebig reported in 1840: “The cr0ps on a field diminish or increase in exact proportion to the diminuation or increase of the mineral substances conveyed to it in manures." Russell and Russell (1950) have reviewed the basic relationships in plant nutrition as established by Boussingault, DeSaussure, Liebig, Lawes and Gilbert, and others. Mehlich and Drake (1955), Meyer and Anderson (1952), and.Truog (1951) discuss the importance to plant growth of the essential nutritive ele- ments and the desirable regulatory elements. Truog (1938) reports that, in the modern conception of soils and plant nutrition, the soil is a three-phase medium.in which nutrients are held in various forms and degrees of availability. The basic information concerning the relationships in plant nutrition and soil fertility are as applicable to forest nursery management as to production of agricultural cr0ps. However, nursery managers and research- ers frequently have not been acquainted with some of these fundamental re- lationships. —‘ -54- Soil Reaction The reaction of the soil either affects the growth of agricultural plants and forest tree seedlings through the direct influence of H- and CH- ions and the balance of acidic and basic constituents; or it acts indirectly by affecting the physical condition of the soil, the avail- ability of nutrients, the solubility and potency of toxic compounds, and the activity of beneficial and parasitic soil organisms. The reaction of a soil determines the species that can be grown and the kind of fertiliser that should be applied (Wilde, 1946a). A low soil pH results, on the one hand, in a shortage of available calcium and sometimes phosphate, and on the other hand, in an excess of soluble aluminum, manganese, and perhaps other metallic ions. The relative A importance of these factors depends on the composition of the soil and the susceptibility of the crop to a deficiency of calcium or phosphorus or an excess of aluminum or manganese. In the hmid southeastern United States, there is a persistent and unremitting inclination tonrd intensification of soil acidity as a result of (l) leaching of metallic cations, (2) removal of basic ions by plants, and (3) reaction of certain fertilisers (Bear, Prince, and Toth, 1952; Lyon, Buchnan, and Brady, 1952; Peach, 1941; and Volk, 1956). Russell and Russell (1950) report that the harmful effects of acidity can be corrected by use of calcium carbonate, ’which raises the pH level, or by the use of a neutral calcium salt such as calcium sulphate, that has no effect on the pH of the soil. -55- Cation Bxchang Undoubtedly the most important characteristic of colloidal clay is its capacity of cation exchange (Kelley, 1948). Organic matter in the soil possesses similar colloidal prOperties. Lyon, Buckman, and Brady (1952) report that each one per cent of silicate clay content has an ex- change capacity of approximately 0.1 to 1.0 milli-equivalents per hundred grams of soil, whereas each one per cent of well hwmified organic matter in a mineral soil may have an exchange capacity in the neighborhood of 2.0 milli-equivalents per hundred grams of soil. The importance of exchange capacity to soil fertility and plant nutrition has been stressed by a name ber of workers (Lyon, Buckman, and Brady, 1952; Russell and Russell, 1950; Truog, 1951; Wilde, 1946a). In general, colloidal clay and organic colloids act as a storehouse, or bank, in which bases are preserved in a fonm available to plants, yet not easily removed.by leaching; Wilde and Iopitke (1940) report that the amount of available potassimm retained in the soil in spite of conditions favorable to leaching is directly depend- ent upon the level of the exchange capacity of the soil. Hahlich and Coleman (1952) present a comprehensive review of the relationship between the types of soil colloids and the mineral nutrition of plants. They report that there is an important general relationship between exchangeable cations in the growth media and the content of calcium, magnesium, potassium, sodium, and other cations in the plant. The ionic environment of plant roots depends to a large extent on the amounts and proportions of various colloidal acids, bases, and salts in the soil. Geraldson (1956) found that, when other factors were constant, -56- plant growth was a function of two nutritional variables, intensity and balance. Soil scientists and plant physiologists agree that the kind, amount, and rate of ion uptake by roots of plants is a complex phenomenon that may be modified by variations in the concentration and balance of one or more cations or anions. Great variations exist in the chemical composition of soils due to the extent to which the main factors of soil fonmation come into play (Lawton, 1955). The degree of availability of the nutrient elements present may vary over a wide range. The sc0pe of the field of literature devoted to the transformation of mineral elements from one degree of availability to another is too wide to cover adequately in this review. Calcium The relationships of calcium.with soil reaction, soil structure, soil micro-organisms, nutrient availability and plant reSponse have been reported by Bear (1942), Millar (1955), Russell and Russell (1950), and Thorne (1930). All investigators report that an adequate supply of lime (1) will maintain a soil reaction of approximately 6.0, (2) is beneficial in maintaining a favorable soil structure, (3) favors the more desirable soil organism, (4) affects favorably the availability and uptake of nutrient elements, and (5) promotes the growth of plants. Nitroggn Of the various plant nutrients, nitrogen probably has received the greatest amount of study, and for very good reasons. The quantity in the soil is small, while the amount withdrawn annually by crops is comparative- ly large. At tbmes soil nitrogen is lost through volatilization; at other times it is dissolved in the soil solution and lost in drainage; and at -57- other times it is held in a state of unavailability to higher plants. Its effects on plants usually are very marked and rapid. It tends primar- ily to encourage above-ground, succulent vegetative growth and to impart to the foliage a deep green color. Nitrogen is a nutrient regulator in that it governs to a considerable degree the utilization of phosphorus, potassi- um, and other elements. Insufficient quantities of nitrogen result in stunted growth, a restricted root system, and a chlorotic appearance of leaves. An excess of nitrogen will result in a harmful effect on certain craps. Bear (1942), Lyon, Buckman, and Brady (1952), Lutz and Chandler (1946), Miller (1955), Russell and.Russell (1950), Thorne (1930), waksman (1952), and others have reviewed thoroughly the nitrogen cycle and the relationship between soil nitrogen and organic matter. Because nearly all of the nitro- gen in soils is generally associated with organic matter, only very small amounts are held in readily available form, as NH4- or NO3-. The remainder falls in the moderately available or slowly available category. Harmsen and Van Schreven (1955) report that during microbial decom- ' position organic matter must contain 1.5 to 2.5 per cent nitrogen in order to guarantee good growth of microbes wdthout absorption of nitrogen from the surrounding medium. When plant residues contain more than 1.5 to 2.5 per cent nitrogen, some will be liberated.as ammonia, the actual amount depending on the original concentration of nitrogen in the residue. waksman (1952) reports that the decomposition of straw and other plant material having a high carbon/nitrogen ratio can be hastened by the addition of avail- able nitrogen and phosphorus in the form of inorganic salts. Allison (1956) -58- found that in the decomposition of organic matter, 2 to 3 per cent of the total nitrogen is released annually, supplying 20 to 50 pounds of available nitrogen per acre on poor soils and up to 100 pounds per acre on good soils. Ear-men and Van Schreven (1955) report that the liberation of mineral nit- rogen is much faster in a calcareous clay soil than in an acid sandy soil, since a slightly alkaline reaction seams to be optimal for nitrification. The problem.of nitrogen control is two-fold: (l) maintenance of an adequate supply in the soil and (2) the regulation of the turnover in such a way as to assure a ready availability at such times as needed to meet crop demands (Lyon, Buckman, and Brady, 1952). Since soils under any given climate tend to assume a normal or equilibrium nitrogen content un- der the cropping and.manuring systems in use, any attempt to raise the nitrogen content to a point materially higher than this normal will be attended by unnecessarily high losses. Allison (1955) reports that crops commonly recover only 40 to 75 per cent of the nitrogen that is added. Duortier and Fouarge (1938), Nemec (1938a), Vaartaja (1954), and ‘Wilde (1946a) report that seedlings on coniferous species have the ability to use both ammonia nitrogen and nitrate nitrogen. Definite preferences during varying stages of growth have not been conclusively determined. The effect on growth of different forms of nitrogen depends largely on the degree of soil acidity and the supply of other nutrients. Lewis (1938a, 1938b) and Tisdale (1952) reported on the utilisation of different forms of nitrogen fertilisers by different crops. In general, they found that if other factors were not lhmiting, there were no signi- ficant differences between the effects of the various nitrogen fertilisers. -59. ‘Hhen the line status of soil was maintained at an adequate level, inorganic nitrogen gave as good results as organic fertilisers supplying the same amount of nitrogen. Several factors must be considered when nitrogen fertilizers are applied. Nitrate materials, such as nitrate of soda, calcium nitrate, and calcium cyanamide, generally tend to raise the pH of the soil. Com- pounds that supply the ammonium.form of nitrogen, either directly or as a result of hydrolysis, will ultimately increase soil acidity (Collings, 1950). Peri and.Asghar (1938) found that the amount of ammonia reacting with the soil was a function of pH values. Ammonia nitrogen is most highly available to plants at pH 6.0 to 6.5, whereas the nitrate nitro- gen in.sodiul.nitrate is most readily available at pH 4.0 to 4.5. Engels (1939) found that when nitrogen concentration was increased.aaterially, it was necessary to increase phosphorus and potassium applications. He suggested.that the best general fertiliser ratio for N-P’Os-K&O, when the nutrient content of the soil was unknown, was 1:2:2. Phosphorus The function of phosphorus in the physiological activities of plants has been described.very ably by.Arnon (1953). He gives a comprehensive review’of literature on the subject. Many articles have appeared.that discuss the soil-plant relation- ships in the nutrition of phosphorus. Colwell (1944), Dean and Fried (1953), Hutton and.Robertson (1953), and welch, Hall, and Nelson (1949) report that when the soil phosphorus supply is a.limiting factor in plant growth increments of phosphate fertiliser added to the soil will result in increased yield of dry matter and fruit or seed. The rate of phosphorus -60- absorption reaches its maximum.earlier in the growth cycle than does the growth rate. Altering the phosphorus supply of a soil influences the rate and amount of phosphorus absorbed.and the phosphorus content (percentage) of crops. Dean and Fried (1953) report that an increase in the soil phOSphorus supply may result in increasing, decreasing, or leaving unchanged, the percentage of phosphorus in the plant, depending on the phosphorus level in the original soil. Hutton and Robertson (1953) grew corn on a virgin Red Bay fine sandy loam.that had 6 pounds per acre of available phosphorus. After three years of cropping, the available phOSphorus dr0pped to 1 pound per acre on untreated plots and increased to 30 pounds per acre on plots that received phOSphorus fertilization. Colwell (1944) and welch, Hall, and Nelson (1949) found that on phOSphorus deficient soils soybeans responded to applications of phOSphorus. The magnitude of yield increase was related to the level of available phOSphorus in the soil. Dean and Fried (1953) report that under conditions where an increase in soil phosphorus results in no growth changes in a plant, an increase in supply usually is accompanied by an increase in the total phOSphorus uptake by the plant and in the percentage of phOSphorus in the plant tissue. The total phosphorus content of Coastal Plain soils in the south Atlantic and Gulf States is extremely low in comparison with that in other regions of the United States. Available phosphorus may range from 1 to 15 per cent of the total phOSphorus (Parker, 1953). Analyses of nursery soils reveal that levels of available phOSphorus range from a trace on virgin soils to more than 100 parts per million on areas formerly devoted to fans crops (May and Gilmore, 1955). Since cr0ps seldom use more than 15 to 20 .61- per cent of the phosphorus applied in fertilizer, it usually requires large applications to produce maximum.yields (Pierre, 1938). Applications of excess phosphorus year after year result in the accumulation of both available and fixed phosphorus in the soil. Soils of the south Atlantic and Gulf States are acid in reaction, high in sesquioxides, and extremely variable in texture. Many articles have appeared on the retention and fixation of phosphorus in these soils. Coleman (1944a, 1944b) found that some soils have a higher capacity for phosphate fixation than others. Some of the better agricultural or nursery soils such as Orangeburg, Ruston, and Red Bay belong to the group with high fixation capabilities. anminger (1952) studied the fixation of phosphorus in a fine sandy loam in south Alabama. He found that 103 pounds of P205 per acre per year were accumulated from.a 200 pound annual application of P205. However, little or no accumulation was was reported when the rate of application was low; Dean (1941) repbrts that a 5-fold or greater increase in amount of total phosphorus has been obtained as a result of intensive use of phosphate fertilizers. At the Rothamsted Experiment Station, the content of P205 on some plots increased from.0.44 per cent in 1881 to 2.80 per cent in 1944. Karts (1953) reports that the fixation of phosphate ions to sesquioxides increased as the pH was decreased. Struthers and Sieling (1950) found that citrate and certain other organic materials inhibited the precipitation or fixation of soluble phosphate in the pH zone of 4.0 to 6.0. Later, Dalton, Russell,and Sieling (1952) found that the decomposition of organic products was highly effective in increasing the -62- , availability of fixed soil phosphate for some crOps. Black and Goring (1953) present a comprehensive review of recent literature on organic phosphorus in soils. They report that the amounts of organic phosphorus in soils are correlated positively with the amounts of organic carbon and nitrogen. The organic matter of mineral soils contains carbon, nitrogen,and phOSphorus roughly in the ratio 110:9:1 by weight. Organic phOSphorus is considered to be rather stable. However, the rate of organic phosphorus mineralization may vary appreciably during the year because of the continual changes of microbial activity in reSponse to variations in soil conditions. Phosphorus is not as soluble in water as nitrogen and potassium, and it generally is subject to only slight loss by leaching. Ensminger ‘ (1952), and Scarseth and Chandler (1938) found that losses of phosphorus by erosion could account for up to 63 per cent of the P205 applied during a long period. Losses were attributed to the removal of organic matter and clay fractions in drainage. Neller, gt gl.(1951) determined.the content of phosphorus in a lbmed and unlimed Leon fine sand with an initial pH value of 4.5. They found that when superphosphate was applied to the surface 1 to 2 inches, the phosphorus was almost completely leached out of the unlimed soil in one year. An application of one ton per acre of lime reduced leaching of phOSphorus by about 40 per cent and two tons reduced the loss by 80 per cent. They report that the pH value is a good indicator of leachability of fertilizer phosphorus in fine sandy soils, but it is not a reliable indicator in loamy sand, sandy loams, and loams. -63- Page (1953) working with Norfolk sand, found that liming tended to decrease the amount of NH4F- soluble phosphorus and total phOSphorus in the surface soil, to increase these forms in the subsoil, and to increase the acid-soluble phosphorus in both the surface and the subsoil. Truog (1953) reports that the liming of acid soils to a pH near the neutral point will increase the availability of both native phosphorus and that applied as a soluble fertilizer. Liming of acid soils to near the neutral point will reduce solubility and availability of some of the minor nutrient elements. However, a high state of general fertility can be maintained by addition of such minor elements as may be needed. I Utilization of phOSphorus by roots of plants is determined.by the degree of availability (Carter, 1951). On a Tifton sandy loam with a moderately high level of available phOSphorus, peanut plants obtained most of their phosphorus from the soil, only a relatively small amount from.fertilizer. On a Norfolk sandy loam with a low level of available phosphorus the plants secured.most of their phosphorus from the applied fertilizer. Potassium Unlike calcium, nitrogen, and phosphorus, potassium does not enter into permanent organic combinations in plants. It apparently exists only as a constituent of soluble inorganic and organic salts and bases. Although potassium is an indispensable element and cannot completely be replaced even by chemically shmilar elements, its exact role in plants is obscure (Meyer and Anderson, 1952). Potassium.appears necessary for the normal maintenance of the following processes: (1) carbohydrate -54- accumulation, (2) nitrate absorption, (3) nitrate reduction and protein synthesis, (4) cell division, (5) formation of organic acids and oils, (6) disease resistance, (7) frost resistance, (8) turgor control, and (9) photosynthesis. Lawton and Cook (1954) and Rohde (1937) have published embracive reviews of available information that deals with the role of potassium in plant growth. Potassium deficiency symptoms for many plants have been described by Lawton and Cook (1954) and others. The range of total potassium contents of soils is enormous. In the southeastern United States the soils have been thoroughly leached and are relatively low in available potassium. Yet, in one southeastern state, Marbut (1935) reported that the K20 content of the surface layer of a Durham sandy loam was 5.15 per cent, while that of a Tifton fine sandy loam was only a trace. Potassium in its simpler chemical compounds is one of the most readily soluble elements; but in the soil-plant system compounds of potassium exist with extreme differences of solubility and mobility. Potassium in the soil occurs in compounds ranging from the easily soluble salts through stages of decreasing solubility to the essential constituents of certain primary minerals from which it is released only in destruction by slow weathering of the crystal structures. Prom investigations of potassium availability in several Indiana soils Rouse and Bertramson (1950) concluded that the potassium supplying power of the soil was related to both the exchangeable and the non-exchange- able or slowly available form of potassium. Legg and Beacher (1951) - 65 - use the term potassium supplying power to designate the capacity of the soil to supply potassium to growing plants from both the exchangeable and the moderately available forms. In an examination of eight red-yellow podsolic soils in Alabama, Pearson (1950, 1952) concluded that these highly weathered and leached soils have a low rate of conversion of non-exchangeable potassium to forms available to plants. Montmorillonitic soils released fixed potassium.more readily than did kaolinitic soils. He also found a highly significant direct relationship between the original exchangeable potassium content of the soil and the total amount of potassium absorbed.by plants. When the available potassium supply is adequate, the removal rate by cr0ps is high, often 3-4 times that of phOSphorus and equal to that of nitrogen. If large quantities are present, plants tend to take up soluble potassium.far in excess of their needs. This luxury consumption of potas- sium.apparently does not increase cr0p yields to any extent. The Opinion of Seay, Attoe, and Truog (1949) that there is a definite relationship between the potassium content of a plant and that of the medium.on which it was grown has been verified by numerous investigations. However, Legg and Beacher (1952) are of the Opinion that significant crop reSponses may not be obtained by additional potassium application to soils with a potassium supplying the power of 250 ppm and a base exchange capacity above 5 milli-equivalents per 100 grams of soil. Hester and Skelton (1934) have shown that the efficiency of potassium utilization by vegetable crops varied.with soil types. A Bladen sandy loam.showed a much higher power for fixing potassium.than - 66 - either Norfolk fine sand or a Portsmouth loamy fine sand. The calculated percentages of utilization of available potassium were 38.5 from.the Bladen sandy loam, 82.8 from the Portsmouth loamy fine sand, and 84.8 from the Norfolk fine sand. More potassium was fixed in the heavier soil. COOper, Schreiner, and Brown (1938) suggest that at least 75 per cent of the plant needs should be in the form of readily available phosphorus. Frequently, the degree of saturation of the cation exchange complex by K.is small, yet the availability of the exchangeable K is relatively large. In an examination of the response of alfalfa on New Jersey soils, Bear, Prince, and.malcolm.(1945) concluded that optimum.growing conditions existed when the exchange complex was made up of 65 per cent calcium, 10 per cent magnesium, 5 per cent potassium, and 30 per cent hydrogen. The calcium: magnesium; potassium ratio was 13.5:2:l. Plant growth was not affected substantially by considerable deviation from these ratios provided the percentage saturation of an individual cation or the sum of the metal cations was not limiting. Hester (1938) reports that soil containing a high calcium content will require more potash for adequate potassium fertilization than a soil with a low calcium content. In a comparison of the response of a number of crops on a deep phase Norfolk sandy loam to potassium and magnesium additions, Page and Paden (1951) observed the following effects. Applications of potassium.(a) increased the percentage of potassium.in plants, (b) decreased or had no effect on the calcium.and magnesium content of the plant, and (c) did not affect phosphorus and sodium content. Applications of magnesium (a) increased the percentage of magnesium in plants, (b) decreased or had -67- no effect on calcium, and (0) did not affect phosphorus, potassium, or sodium. Maki (1950) reported that high potassium level in soils resulted in more vigorous longleaf pine seedlings and higher survival of planted stock than did low potassium levels. Wilde (1946a) claimed that applications of feldspar and other primary minerals improved the growth of seedlings but failed to produce stock large enough to satisfy nursery standards. He suggested the supplementary use of readily soluble nutrients. Maggesium and its Relation to Other Minerals Magnesium, the only mineral constituent of the chlorophyll molecule, may be essential to photosynthesis. Meyer and Anderson (1952) report that magnesium may also act in a regulatory or catalytic capacity in the process of plant growth. The light soils of the Atlantic and Gulf Coastal Plain are generally deficient in magnesium. Magnesium-deficiency diseases of potatoes, tobacco, and cotton have been found on the Sandy Coastal Plain soils (McMurthrey and Robinson, 1938). Schreiner, Mars, and Brown (1938) con- clude that deficiency of magnesium in all probability has affected crop production more widely than that of any other secondary plant nutrient. The widespread occurrence of magnesium deficiency in some Coastal Plain soils has been due to (l) the initial low level of magnesium in virgin soils, (2) the use of commercial fertilizers made from materials contain- ing very little magnesium, (3) increased soil acidity, resulting from the heavier use of acid forming salts that facilitated the leaching of magnesium from the soil, and (4) losses resulting from cr0p removal and -68- erosion (Lyon, Buckman, and Brady, 1952). According to Johnson and‘Wear (1956), applications of magnesium to old fields in south Alabama resulted in significant increases in yields of potatoes. Increases in yield were much higher on light textured soils than on heavy textured soils. Prince, Zimmerman, and Bear (1947), working with 20 New Jersey soils, did not obtain any correlation between total magnesium content and crOp producing powers. The existance of an important general relationship between exchange- able cations in the soil and plant content of calcium, magnesium, potassium, and sodium.has been established by a number of investigators (Camp, 1947; COOper, Paden, and German, 1947; Page and Paden, 1951; Prince, Zimmerman, and Bear, 1947; Van Itallie, 1948; Zimmerman, 1947). Prince, Zimmerman, and Bear (1947) grew alfalfa on soils treated with different levels of magnesium. The response to additions of magnesium was governed in part by the ratio of magnesium to other cations in the exchange complex, particularly calcium and sodium. The most significant single factor that influenced the uptake of magnesium by alfalfa plants was the quantity of available potassium. As the supply of available potassium decreased the magnesium uptake increased. Van Itallie (1948) found it possible to cause magnesium deficiency in spite of a normal supply of magnesium in the soil by large additions of potassium and sodium. When the ratio of soil calcium to magnesium.was about 8.5:1, he found about equal amounts of the two cations in the plant. When the calcium/magnesium ratio was about equal, he found.more than three times as much magnesium as calcium in the plant. According to Zimmerman -59- (1947), absorption of magnesium by plants usually bears a straight line relationship to exchangeable magnesium/potassium ratios in the soil. Soil Structure The mainenance of favorable structure in cultivated soils is just as important to the nursery manager as is the maintenance of a balanced nutrient supply. Baver (1948), Shaw (1952), and Russell and Russell (1950) have discussed the relationships between the physical properties of the soil and plant growth. Martin, gt_§l, (1955) concluded that the ideal soil from the physical point of view is one in which the smaller mechanical fractions, sand, silt, and clay, are bound together in water stable aggregates, forming a granular or crumb structure. According to Page (1951) only when a favorable soil structure exists can the greatest advantage be gained by the liberal use of fertilizers. Van Daren and Klingebeil (1951) report that when adequate nutrient fertility levels are maintained water and air become the limiting factors affecting plant growth and yields. In a preceeding section, it was reported that in nursery operations seedlings have to be lifted when the soils are wet. A loose, friable condition must be maintained in order that roots can be removed from the soil without damage. In sands or loamy sands, the single grains should be combined into stable aggregates. In heavier soils, the large clods should be broken down into favorably sized aggregates. Clay and organic substances, plus iron, aluminum and silicon oxides, and hydrated oxides, play an important part in stabilizing aggregates. A -70- general discussion of these factors are beyond the province of this review; However, they must be given full consideration in any soil management plan. Conclusions from the Literature 1. The nutritional requirements of most tree Species have not been determined. For the few Species that have been investigated conflicting results frequently have been obtained. 2. In a majority of the investigations the results of treatments have been measured on the basis of their effects on morphological characteristics. 3. The diversities in soils within any one region have either not been recognized or accepted. The general assumption has been that for all soils the same response will be obtained from similar treat- ments. 4. The immediate and residual effects of additions of mineral fertilizers and organic substances used in connection with the production of southern pine seedlings have not been determined. 5. Chemical analyses of soils and foliage have been used in only a few of the studies on southern pine seedlings. Frequently, the studies were for only one year. Variations between years may be greater than the variations within a year. 6. Specific morphological characteristics of seedlings can be deve10ped with rather widely varying prOportions of mineral elements in the soil. variations in the proportions of mineral elements in the soil can result in a change of physiological characteristics of seedlings without a corresponding change in morphological features. -71- 7. Additions of fertilizer and organic materials that will result in favorable responses in one soil type may result in negative responses in another soil type. CHAPTER III LOCATION AND DESCRIPTION OF EXPERIMENTAL AREA Auburn Nursery The Auburn nursery is located approximately 7 miles southeast of the town of Auburn, in Lee County. It is in the transition zone between the Upper Coastal Plain region and the Piedmont region of Alabama, at a latitude of 32 degrees and 34 minutes north and a longitude of 80 degrees and.25 minutes west. The nursery, consisting of 25 acres, is on a gentle east slope. The soils are Faceville sandy loam.and.Magnolia sandy loam. The area has been in crop or pasture for approximately 100 years. The cropping and fertilizing history prior to 1949 is not available, but it is known that lime had been applied at periodic intervals. At the time of purchase in 1949 the west portion was in alfalfa and.the east portion in corn. The pH values of four samples taken in September 1949, were 6.0, 6.5, 7.0, and 8.0. ‘The average p31 value of nine topsoil samples taken in February 1953, was 5.92, with a high of 6.2 and a low of 5.85. The average pH of the subsoil was 5.2. well water used for irrigation tested as follows: Total solids in solution 85 ppm 1pH is the negative exponent of the hydrogen ion concentration and is not subject to mathematical average. When pH values are wdthin a narrow range, mathematical averages are often used. -72- -73.. Loss on ignition (includes chemically combined.OOz and organic matter) 50 ppm Chlorine Trace pH 5.0 Approximately one acre of the Paceville sandy loam.was designated as an experimental area. Mechanical analysis according to the method of Bouyoucos (1936) indicated particle size class distributions as shown in Table 1. TABLE l.--Particle size class distribution of the Faceville soil type . Textural Horizon Depth Sand Silt Clay Classification Inches Per cent Per cent Per cent Topsoil lo-1o 74 16 10 sandy loam subsoil 10-20 59 22 19 sandy loam Alfalfa was turned under in January, 1950, and the first nursery seedbeds were prepared in March, 1950. Seedling crops have been grown on part of the experimental area annually since 1950. North Auburn Experimental Area The North Auburn experimental area used for out-plantings is located.three miles north of Auburn on the gently rolling sandy loams of the Piedmont uplands and terraces. The planting site is a Cecil sandy loam, eroded.phase, which has a moderately stiff, red sandy clay or clay subsoil that is exposed in spots. -74- Autauga County Experimental Area The Autauga County experimental area used for out-planting is located nine miles northwest of Prattville in the sand hill section of the Upper Coastal Plain region. The planting site is a Lakeland (Norfolk) fine sand, deep phase. The original forest vegetation, consisting of longleaf pine and various species of scrub oak (Quercus marilandica Muenchh., Q. stellata Wangenh. and Q. falcata Michx.), was removed many years ago. The planting site was once in cultivation, but later was allowed to revert to grass and scattered trees. Broomsedge (Andropogon spp.) predominated. Climate The climate can be characterized as generally hot and.moist, but it definitely has continental properties. The average number of frost-free days at Auburn is 237 (Hocker, 1955). Temperatures are mostly hot in summer and.cool in winter. There are intermittent warm days during the winter months. The annual precipitation is generally high and moderately well distributed, but extreme variations in annual rainfall have occurred.within the past few years. There is a tendency toward.heavier precipitation in the winter and summer months and decidely lighter rainfall in the spring and fall. Precipitation and temperature data for Auburn are presented in the appendix. CHAPTER IV EXPLORATORY STUDIES Comparison of Stock Produced by Different Nurseries Loblolly pine seed collected in the vicinity of Auburn in the fall of 1949 were sown in nurseries in Alabama, Mississippi, Arkansas, and.Texas in the spring of 1950. In February and March, 1951, seed- lings from each nursery were out-planted at the North Auburn experimen- tal area. Seedlings from all nurseries were graded and planted accord- ing to the same specifications. Nitrogen, potassium and phosphorus content of needles and of nursery soil samples were determdned with the Spurway Simplex 3011- Testing Kit (Spurway and Lawton, 1949; Cook and Milldr, 1949). values were expressed in terms of high, medium, and low mineral levels. Nitro- gen content of needles was very low. Phosphorus and potassium content ranged from.medium to high. Nitrogen, phosphorus and potassium content of soils were low. Average survival for the five lots of seedlings was 60.6 per cent, with a range of 35 to 78 per cent. The results supported wakeley's (1948) findings that different nurseries or the same nursery may produce seedlings that are alike morphologically but have different capacities for survival. -75.. IV! -76- Methyl-Bromide Study-1950 Dieter and Coulter (1949) reported that methyl bromide had effectively controlled nematodes, fungi, weeds and grasses. Maki and.Henry (1951) found that methyl bromide was very effective in controlling root rot at the W. W. Ashe Nursery. Cossitt (1950) reported that methyl bromide depressed growth and deve10pment of southern pine seedlings. In order to test the effectiveness and toxicity of methyl bromide, the fumigant was applied to seed beds three weeks prior to sowing of slash pine seed. Rates of application were 1, 2, and 4 pounds of methyl bromide per 100 square feet. More plants and more plantable seedlings were produced on the non-treated plots than on the treated plots. Production decreased as the rate of application increased. The data were not analyzed statistically to determine if differences were significant. Almost complete weed control was obtained for a year with all methyl bromide treatments. However, the 1 pound rate was apparently as effective as the 2 and 4 pound rates in the control of nut grass and other grasses or weeds. Sawdust Study-1951 Sawdust was applied to an area that had been in loblolly pine in 1950. Rates of application were the equivalent of 10 and 20 tons of oven-dried sawdust per acre. Mineral fertilizers were applied at the following rates per acre: Nitrogen - 100 pounds; P20 - 250 5 pounds; and K20 - 125 pounds. Sawdust and fertilizers were mixed -77- into the tOp 6 inches of the soil using a Seaman-tiller. Additional nitrogen was applied as a top dressing during the growing season to all plots. Mean seedling density was lower in plots that received the 20 ton application, but the seedlings were larger and more vigorous. Root and stem development were exceptionally good for both treatments. Study of Mineral Fertilizer and Sawdust Treatments-1952 Six different levels of mineral fertilization, including a zero level, were tested in combination with three levels of sawdust application and two levels of methyl bromide treatment. Fertilizers and sawdust were mixed with the soil with a disc plow and a tiller. Measurements included seedling density, percentage of plantable seedlings, stem.length, stem diameter, root length, and bud develop- ment. variation between seedlings within a sub-plot was extremely high, apparently due to an uneven mixture of sawdust and fertilizers with the soil. In the statistical analysis, the only significant differences were between the fertilized and the non-fertilized plots. There were no significant differences from the effects of methyl bromide, saw- dust, or fertilizer treatments. Seedlings on the non-fertilized plots were small in size and were very poorly develOped. Only on plots that received methyl bromide did.most of the seedlings develop fascicled needles. At the suggestion of Doctor George W. Snedecor, visiting Professor of Biometry at Alabama Polytechnic Institute, the 1952 study was discontinued, and a new experiment was designed for an adjacent area . CHAPTER v PROCEDURE-MAIN EXPERIMENT Experimental Design The exploratory studies indicated that sawdust and.mineral ferti- lizers could be applied immediately prior to sowing of loblolly pine seed without adverse effect and that seedlings could be produced suc- cessfully for three consecutive years on the same area. However, the individual and combined effects on the soil of applications of sawdust, applications of mineral fertilizer, and production of seed- lings were not determined. Therefore, in 1953, an experiment was designed to test the effect of applications of sawdust and mineral fertilizers on plant growth and certain soil characteristics. Rota- tions were introduced as another variable. Chemical treatment with methyl bromide constituted a fourth variable. The experiment was put on an area that had been in seedling production for three years and had received a uniform.treatment. The experimental design was a randdmized block, split plot structure with rotations and chemical treatments applied to main plots and with treatments of fertilizer and sawdust superimposed in sub-plots (Cochran and Cox, 1950). Each of the six blocks or replica- tions contained six rotation - methyl bromide combinations, upon which were superimposed nine fertilizer-sawdust treatments. - 79 - .....,; ud-I a.. i.e. -80- Treatments Rotations 1. Annual seedling production. 2. One year in a green manure crop alternating with two years of seedlings. 3. One year in a green manure crop alternating with one year of seedlings. legumes (soybeans or cow peas) were used for a green manure crop. Seed were sown in April, following the application of sawdust and fertilizers. The crop was cut and partially turned under before the seed matured in the fall. The remaining material was turned under prior to seed bed preparation in the following spring. Chemical Treatments 1. No methyl bromide. 2. Methyl bromide. Methyl bromide was applied at the rate of one pound per 100 square feet. Fertilizer Treatments 1. 150 pounds P205 per acre and 80 pounds of K20 per acre. 2- 300 pounds P205 per acre and 160 pounds of K20 per acre. 3. 450 pounds P205 per acre and 240 pounds of K20 per acre. For the annual seedling rotation applications of P205 and K20 were made each year. For the green manure crop-seedling rotations, additions of P205 and K20 were made only in the years the green -81- manure cr0p was planted. An initial application of 100 pounds of nitrogen per acre was made annually prior to establishment of the seedling or the green manure crop. Additional nitrogen was applied as needed in order to produce seedlings of plantable size. Basic fertilizer materials were concentrated superphOSphate, muriate of potash, and ammonium nitrate. Sawdust Treatments 1. No sawdust. 2. 15 tons of pine sawdust per acre, oven-dry-weight basis. 3. 30 tons of pine sawdust per acre, oven-dry-weight basis. Plot Size,Designation and Arrangement Each main plot is 4 feet wide by 72 feet long and is assigned a number to designate its position in the block and the rotation- chemical treatment (Figure l). The disignation for each of the six.main plots is as follows: R1 Reg. - Annual seedling production, no methyl bromide. R2 Reg. - Green manure crop alternating with two years of seedlings, no methyl bromide. R3 Reg. - Green manure crop alternating with one year of seedlings, no methyl bromide. R1 Mod. - Annual seedling production and.methyl bromide. R2 Mod. - Green manure crop alternating with two years of seedlings with methyl bromide soil treatment prior to seedling crop. -82- .coawocofimoo one acosoocewwe Hoamuu.a .oam Aooasoum Hesse: ozv eowwom Heasoom u .oom noofisonm Hhseozv eofiwom commemoz a .ooz ousosmeona ansoswm woefiaauwom a mm ocooog H> n38 > n38 3 ~38 swans oozmm scene emanates Heoahamnamonaaenaee mamas 3sz oozes newness a-nmmmmmmonmmme-samm oozes moose oozes nausea» mnosremuomnaemsumnma moans moans 3sz ”assess omammnaneooeukmnamma 82mm ._ Indexes moans ameonam seasonaoaueemaamooma eases oozes mamas mnanuem ooenmnumamaasaesmoma oozes #8sz seeds Hauawlna menmaumnausnermaoema 8sz scene domes enamimnu aa-memnoameeamauaea mamas mamas oozes sens-”on «ovammoonnaammeammma mamas mamas cease -o«msnm osmuaenmneoaflmaanmma sodium eases momma woodman anaeMumonHomansoeamm mamas . swede Seam Pecan-n snows-«nmmmuoeanmamm HHH Moon HH woon H Moon a! 1.1.: s v O y . - a” ‘ .ewn - . ‘s q I! '3 .‘l. ‘ ,IIA ‘ ' 1 D ._.-.-..a~ , , , ' . . "’1 . . 5.1101 lI' . I: sie‘”: .. . ugiu'. A i ‘ ~~ 4 13'. O. “ P .5.“ i)? q ‘5'.“ Es DK .u'g, I I i a . ' ‘ , K . ”3'3: -83- R3 Mod. - Green manure crop alternating with one year of seedling with methyl bromide soil treatment prior to seedling crop. Each main plot is divided into 9 sub-plots 4 feet wide by 8 feet long. Each sub-plot is assigned a number to indicate its position in the main plot and the fertilizer-sawdust treatment. The designation for each of the nine sub-plots is as follows: FS-l: FS-2: FS-3: FS-4: FS-5: FS-6: FS-7: FS-8: FS-Q: 150 pounds of P205 per acre, 80 pounds of K20 per acre, no sawdust. 300 pounds of P205 per acre, acre, 450 pounds of no sawdust. P205 per acre, acre, no sawdust. 150 pounds of acre, 15 tons 300 pounds of acre, 15 tons 450 pounds of acre, 15 tons 150 pounds of acre, 30 tons 300 pounds of acre, 30 tons 450 pounds of acre, 30 tons P205 of sawdust per per acre, P205 per acre, of sawdust per P205 per acre, of sawdust per P205 per acre, of sawdust per P205 per acre, of sawdust per P205 per acre, of sawdust per 160 pounds of K20 per 240 pounds of K20 per 80 pounds of K20 per acre. 160 pounds of K20 per acre. 240 pounds of K20 per acre. 80 pounds of K20 per acre. 160 pounds of K20 per acre. 240 pounds of K20 per acre 0 11‘. =. We 50‘ , n, L}. .15 .b. in: Estatx Estafil Um: “that: The ; - 34 - Discussion of Treatments The experiment was designed to cover a six year period so that the longest rotation could be completed twice. This report covers a three year period, i.e. from 1953 through 1955. Rota- tions for the three year period were: 1953 1954 1955 Rotation 1 Seedlings Seedlings Seedlings Rotation 2 Green Manure Seedlings Seedlings Crop Rotation 3 Green Manure Seedlings Green Manure Crop Cr0p In the discussion symbols for seedlings and green manure crops will be S and GMC, respectively. Methyl bromide treatments were included as a protection against damping-off losses. Losses did not materialize, and methyl bromide had little effect on soil nutrient availability or on plant develop- ment. Therefore, this treatment was discontinued after the second year. In the discussion plots that did not receive methyl bromide treatment are designated as the 'Regular' series. Plots that did receive methyl bromide treatments are designated as the ”Modified" series. The abbreviations 'Reg' and "Mod" refer to the Regular series and the Modified series respectively. The rates for phosphorus and potassium.were selected in an ar- bitrary manner. Data provided bnyuberman (1940a) and Stone (1948) indicated that a crop of loblolly pine seedlings would remove about 37 pounds of P 0 62 pounds of K20 and 142 pounds of nitrogen each 2 5' year. Assuming a recovery rate of 20 per cent for phOSphorus, 60 - 35 - per cent for potassium and 50 per cent for nitrogen, fertilizer requirements would be 185 pounds P 102 pounds K20 and 284 pounds 2 5' of nitrogen. The review of literature indicated that previous studies started with low rates of application of phosphorus and potassium. For this study, the writer decided to bracket the calculated require- ments in two treatments and use a much higher rate for the third treatment. The 1952 exploratory study showed that nitrogen was essential for growth of pine seedlings, but that the working range of nitrogen availability was quite wide. Since the levels of ammonia nitrogen and nitrate nitrogen in the soil are changing continuously and lob- lolly pine seedlings may use either form, the writer decided to make a single application of ammonium.nitrate prior to each crop and then apply additional nitrogen as needed to produce seedlings of plantable size. The experiment was designed so that treatments could be modified or eliminated during the course of the study. Results of two years study showed that the selected fertilizer levels were adequate to pro- duce a crop of seedlings and possibly maintain the level of soil fer- tility. Therefore, the range of fertilization levels was expanded by modification of treatments on half of the plots after the second year, before the 1955 crop was planted. Reduced fertilizer treatments were applied to the plots that had received methyl bromide treatments. Original and new rates of applica- tion are as follows: ‘I A... “J I: .l‘. e up.» '- e ,' 7 O. as . 4.. 1. ee.~ . \“ -86- Original Rate - Regular Series New Rate - Modified Series 150 pounds P205 and 80 pounds No P205 and no K20 per acre. K20 per acre. 300 pounds P205 and 160 pounds 75 pounds P205 and 40 pounds K20 per acre. K20 per acre. 450 pounds P205 and 240 pounds 150 pounds P205 and 80 pounds K20 per acre. K20 per acre. Some plots in the Modified series received the same treatment as some plots in the Regular series. However, plots that received like treatments in 1955 did not receive like treatments in 1953 or 1954. Consequently, the cumulative effects of first and second year treatments were sometimes quite different for the two series. Applica- tions of P205 and K20 fertilization are summarized in Table 2. The number of fertilizer treatments increased from three in the original design to six after some treatments were reduced. In the discussion, fertilizer treatment Number 1 represents the lowest rate of application and consecutive numbers represent progressively higher rates of annual application. Boundaries of each sub-plot were re-established from a permanent marker prior to treatments. ‘Alleys between seed beds were plowed out with a middle buster. After sawdust and fertilizers were applied to each sub-plot, the material and soil were mixed by spading. Methyl bromide was applied under polyethylene covers about 5 to 10 days prior to sowing. Collection of Soil Samples Prior to treatments in 1953, a top soil sample was collected . i-ehvmu NIH-Jhiv... [all ‘(IIi‘l‘l'll‘lliill‘l‘ I , Ad..‘u-.uafl..lv,w.H. Hath H4 v fihs'vfl ' . I i . I1 \) I ( )H,[(. I A ....I-v...en..ll1 elem" - 87 - cam own as can can as m «was as“ ass as can can as m ”was H 53323...» cam com com com cow was one a censuses moNa Hence one so” one one me o new mean a o o o o o m «was one can own one can own use some n one can and one son one N censuses scum sauce 0 o o o o o m mean 0 o o o o o m «man owe can one owe can one use ”was N omen com one once was can A censuses mo~a Hence one can one one me o m ”was one can ems one so» one m «sea one can one one can one m some a codeoNaHasHom mama o m a a N H mono Henasz a. H HQ 500 CO H O 0 H00 a .m H a n .m.e nofie_z mo sass » sodeauom eeucoawcoua noeaafiwwem Aeuos won season use o>emsnoan .mmma-nmmn season was was soaseueflnuuom can use moss «0 swuesam--.~ mamas J i 1".) .e. iii ........ MUGCH I i i...- COflU ”floaflN .voon and moon on among acasouannouav ass. was eosnooon no one o .v .uooauomnn Housnaouooo moonom awesome sea son no and N .H monogamous Hosanousooo .ovsom sovoveoz uses oov own ooa own ooN oo o censuses one vanes ova ooH oo oo ov o ozo mood o o o o o o m voov ova ooH oo ovo ooH oo use noon o ovo ooH oo ovo ooH oo o ooaoauom cum Hence o o o o o o m mood o o o o o o m voon ovo oov oo ovo oov oo use noon N ooh oov ovo ooo oom ooH H sovnosom com Hence ova oon oo oo ov o m moon o o v o o - no.6 uoflasz no u we ado a on H a madame sovevooz no on no.» monounom caveman-sown. woe-annou- leoooasoooo--.~ mamas .c u‘ :0 n, .g.' .Iew. .IIQ‘ Iona: ‘0‘ (A, 'n-u \. D ‘m ‘. .‘ f H l.‘ 4 A 'u .U -89- from each main plot. A one pint composite sample of the top 9 inches2 was obtained by taking one sub-sample from each sub-plot. In January-February following lifting of seedlings, a soil sample was collected from each sub-plot. Similar samples were taken following the 1953, 1954, and 1955 seedling and green manure crops. Laboratory Analysis of Soil Samples 1953 1es After they were air dry, the composite samples were rolled and screened through a 2 millimeter sieve. The material less than 2 millbmeters in size was used for mechanical analysis and for chemical analysis. All analyses were made in duplicate. Mechanical analysis was made according to the method of Bouyoucos (1936). Soil reaction was measured on a Coleman pH meter according to the general method of Piper (1950) and the specific directions of Russell (1950). Soil organic matter was determined by the wet combustion method as outlined by Peach, Alexander, Dean, and Reed (1947). This method consists basically of oxidizing carbon in the soil with potassium dichromate and titrating the excess by reducing with ferrous sulfate. Percentage of carbon was converted to percentage of organic matter by the conventional 1.724 factor. 2In the nursery, the soil is plowed and disked to a depth of 9 or 10 inches. It is standard procedure to sample the plow layer. !‘JM-m I l gets:- £,..n .. v u: - u Jude ) v 0 I ‘F a, -‘ UV I Q - "z-w .pe-ub. '1 .. rm ‘. ‘se . "“sev I x vow t -.‘ . "I ' «t. "fle. a e..r‘ . \ ;. ‘s u“ ."‘; -90- Total nitrogen in the soil was determined by the Kjeldahl method as given by the Association of Official Agricultural Chemists (1950). Cation exchange capacity was determined by the method outlined by Russell (1950). Ten-gram samples were leached with 250 milliliters ammonium acetate. Excess ammonium.acetate was removed with methyl alcohol. Ammonia on the exchange position was replaced with magnesium from magnesium oxide. Ammonia was distilled by a steam distillation apparatus. Available phosphorus, available potassium, and exchangeable calcium.were determined according to a procedure used by the 8011 Testing Laboratory of the Alabama Extension Service. The extract- ing solution for phosphorous and potassium was a mixture of approxi- mately 0.05 N_HCL and 0.025 N_HZSO For phoSphorus determination 4. an ammonium.molydate-ammonium.vandate mixture was added to a vial of extract and transmission per cent was read on a Cenco photometer. Potassium was determined with a Perkins Elmer flame photometer. Calcium was extracted with a solution of ammonium acetate and deter- mined according to the same procedure used for potassium. All analy- ses in 1953, other than for phosphorus, calcium, and potassium were made in the Soils Laboratory of the Forestry Department, Alabama Polytechnic Institute. 1954, 1955, and 1956 Samples Soil samples were oven dried at 105°C. to a constant weight, then rolled and screened through a 2 millimeter sieve. '.\,-i \‘I... 3. ' "I... "-fk 3;. I I‘ hoav sen '. . «a ow... L C 7......‘4 e s V. . :4 an“ .. ‘ . 1"~?~ \r \ I. h \. - 1;: “ M. d‘ :...: be .‘ o ., . “k;ia ‘m \. - 91 - Soil reaction, organic matter content, and exchange capacity were determined as described above. For determinations of calcium, potassium, and magnesium, leachate solutions from the determination of exchange capacity were run on a Beckman Model DU flame photometer (Fieldes 33 31., 1951) . Soil phOSphorus was determined by means of a weak acid extraction according to the Truog (1930) method. Determination of Germination and Seed Bed Survival A stand density of approximately 35 seedlings per square foot was desired. The sowing rate was computed on the basis of seed viability, number of seed per pound, and predicted mortality during the growing season. Eight drills, Spaced 6 inches apart, were sown lengthwise of the seed beds. Except for a control drill, seed were machine sown. Although the rate of sowing by machine usually is uniform and accurate, some drills occasionally put out more seed than others. In order to elbminate any variation in number of seed for the control drill, seeds were counted and then sown by hand. Germination counts were made in the segment of the drill in which the counted seed were sown. Counts were made at weekly intervals after the first seed had genminated. Dead seedlings were removed and the cause of death noted if it could be determined. Germination counts were continued for four weeks, or until germination practically ceased. Cumulative germination was computed for each sub-plot. Seedling mortality was followed by seedling counts made periodically until the end of the growing season. L.- meo- .13 n" I a . -.Ed 1 . A‘J-‘I- . ‘l ‘ b‘. . u. . . ' e \ | n I e . .. . - 1 - .. s 5 -92- During the second year, germination and survival counts were also node in a machine sown drill. Results for the counted seed and the machine drilled seed were so nearly alike that counting of seed was eliminated in the third year. Measuring Morphological Features of Seedlings At the time of lifting in December or January, seedlings from 1 or 2 drills were counted and classified as plantable or non-plantable (wakeley, 1954). Group samples containing 25 or more seedlings were select- ed at random for measurements and testing. The number of seedlings in a sample was determined according to a procedure later described by Schultz (1955). For the 1953 seedlings, the following measurements were obtained: Stem.1ength Stem.diameter at ground line Root length Green weight of shoot Green weight of root Oven dry weight of shoot Oven dry weight of root Vblume of root Volume of shoot Presence or absence of terminal bud Immediately after sampling, stem length and diameter and root length were measured. Soil was washed from the plants, and surface water was allowed to evaporate. Then the plants were cut at the ground line, and the tops and the roots were weighed. Volumes were determined by O“. 14“. v .n‘ -93- measuring displacement of xylene by the samples in a graduate cylinder. Tops and roots were oven dried at 105°C to a constant moisture content and then reweighed. Chemical Analysis of Samples Sample seedlings from each sub-plot were oven dried at 105°C. In 1953, the whole plants were ground in a‘Wiley mill to go through a lamillimeter screen and then stored in glass jars for subsequent chemical analysis. In 1954 and 1955, the plants were separated into three components, needles, stems, and roots; and each component was ground and analyzed separately. An ash solution was prepared frum 2 grams of each sample by the dry ashing procedure given by Piper (1950). Calcium, potassium, and magnesium concentrations were determined by burning the ash solutions in a Beckman Model DH flame photometer and by comparing light intensities at specified wave lengths with intensities from standard solutions. PhoSphorus in the ash solutions was determined according to the method of the Association of Official Agricultural Chemists (1950). Measuring Survival of Plants For testing effects of nursery treatments on field survival, randomly selected seedlings from all sub-plots that received the same treatment were mixed to form a composite sample representing each treatment. In January, 1954, four replicate plantings of seedlings from each treatment were established at the North Auburn experimental area. -94.. Seedling heights were measured immediately after planting. Survival counts were made in May. Height and survival data were obtained in November. Seedlings from the 1954 and 1955 crop were out-planted at the North Auburn experimental area and at the Autauga County experimental area in January 1955 and December 1955, respectively. Survival counts were made during the spring and fall following planting. Statistical Analysis of Data Data taken in 1953, 1954, 1955, and 1956 were subjected to analyses of variance (Snedecor, 1946) in order to determine the significance of the annual and cummulative changes following treat- ments. Many of the analyses produced significant first and second order interactions. Some of the significant interactions were due to treatment, others due to chance arrangements of the data. As a result of the nature of the experiment and type of eXperi- mental design, some replications of treatments developed other than the standard block replication. For example, rotations two and three received similar treatments until 1955. Therefore, one would expect similar results for these two rotations in 1953 and 1954. CHAPTER VI EFFECTS OF TREATMENTS ON GERMINATION, MORTALITY AND NUMBERS OF PLANTABLE SEEDLINGS Germination Sowing dates for the three-year period were: 1953 April 28 1954 April 12 1955 April 4 Mean cumulative germination per cents for each year are presented in Table 3. For 1953 and 1954, treatments did not affect germination of seed. In the analysis of the 1955 data, fertilizer treatments for the Regular series were highly significant. Germination was reduced on the plots that had received the heavy fertilizer applications for three consecu- tive years. It is possible that the cumulative effects of heavy fertilization might have resulted in an injury to the radicle, thereby preventing establishment of a seedling. Failure of germination or establishment due to a heavy concentration of mineral salts has been reported.by wakeley (1954) and others. Seedling Mortality After Establishment Seedling counts were repeated at intervals after germination until stem growth had ceased in late fall or early winter. Mortality for the growing season, expressed as a percentage of the cumulative -95.. 13".) ' . .0. a. '- . I. 9". 9 l o"! .v i k I.." -96.. germination was computed. TABLE 3.--Cumulative seedbed germination of loblolly pine seed Year and Treatment Mean Germination LSDa cv° Per cent 1953 All treatments 48.9 NSb 13.1 1954 All treatments 36.9 NS 15.9 1955 Modified series All treatments 65.8 NS 18.3 1955 Regular series 5.7 17.9 Fertilizer treatment 1 71.5 Fertilizer treatment 2 69.5 Fertilizer treatment 3 60.8 1955 Combined.Modified and Regular series 66.6 aLeast significant difference (5 per cent level). In this paper, the term.'highly significant” refers to significance at the one per cent level. The term ”significant” refers to significance at the 5 per cent level, but failing to attain the one per cent level. bNon-significant. cCoefficient of variation - per cent. Mean mortality percentages by years were: 1953 11.3 per cent 1954 23.0 per cent 1955 9.0 per cent In the statistical analysis, sawdust effects were highly signifi- cant in 1953. Other treatment effects were non-significant. Sawdust means for 1953 were: ““1 —-— \jC' " L H“? I) 14’". '4 (‘h m, t c "A A.- ... d".- ..I ; n}. A "v 3 RE ‘- E E“ 9- «v... ‘5 33 is [3‘1“ -97.. No sawdust 9.9 per cent mortality 15 tons sawdust per acre 9.4 per cent mortality 30 tons sawdust per acre 16.6 per cent mortality Least significant difference (5 per cent level) 3.5 Coefficient of variation - per cent 8.4 If the 30 tons of sawdust per acre were not mixed thoroughly with the soil, some mortality could be expected due to unfavorable moisture conditions. Since no significant effects were obtained by the 30 ton per acre application in 1954 and 1955, it can be assumed that the 1953 effects were due to improper application or to variations in sampling. The factors causing mortality in 1953 and 1954 were not recorded. However, top damping-off and white grubs were major sources of loss. These losses were more or less evenly distributed over the area and were not influenced by treatments. Percentage of Plantable Seedlings Treatments did not result in any significant differences in percentages of plantable seedlings. The mean percentage of plantable trees was 59.7. The coefficient of variation was 20.8 per cent. 1952. Seedlings from the control drill and seedlings from an equal area in another drill in each sub-plot were graded. The two sets of data were analyzed separately and then combined in one analysis. In the analysis of data, rotation effects were significant for the control drills and.highly significant for the other drill. Differences due to sawdust and fertilizer were significant for the non-control drill. , 3 13:9 0. ...'. f‘ F." 4 L. m; ] o ..«n a - ~vo-ooil o - ‘ 5 Q. h fiia éH ‘ - Q '3" " ' h..'\' I -98- However, when data for the two drills were combined, rotation effects were highly significant and sawdust effects were significant (Table 4). A green manure crop followed.by seedlings resulted in a higher percentage of plantable trees than an annual seedling rotation. An increase in the rate of fertilization resulted in an increase in the percentage of plantable seedlings. An application of 450 pounds of P205 and 240 pounds of K20 per acre was significantly superior to an application of 150 pounds of P205 and 80 pounds of K20 per acre. 1255 Data for the Regular series and the Modified series were analyzed separately, and then combined in one analysis. In the combined analysis, rotation by fertilizer interaction effects were almost significant. The mean percentage of plantable seedlings was 86.06. The coefficient of variation was 40.0 per cent. There were no significant differences due to treatments for the Regular series. For the Modified series, rotation and fertilizers created signifi- cant interaction effects, wdth fertilizers creating differences in the annual seedling rotation but not in the other rotations. Mean values for fertilizer treatments for Rotation 1, Modified series, were: Fertilization in 1955 Plantable seedlings 1. None 83.78 per cent 2. 75 lbs. of P205 and 40 lbs. of K20 per acre 87.89 per cent 3. 150 lbs. of P205 and 80 lbs. of K20 per acre 87.28 per cent Least significant difference for fertilizer means for the same rotation (5 per cent aar- ufl no i .H. «AH IIJAUHAW 56“ 1nd area-7&0 NAN '—- r1- rwiunv: C502 unflfid. don‘t—0H; :09: I I a 0 IA— ‘30... drain-Alina ‘ n. 1 End innit ,u-uniu. via-AIVI- .- 1 1 HA;- nai yo r-nuv'\v n. . a s \ n \ I I e e o 0 ~ Lava - lira ' .d. uh -5 Iv-.H..~u ae.ee «a.ee o~.ee anon non neon on .n ee.me ao.oe ee.ea once was neon ma .N mz 3.: 3.2. 3.: 0:02 .H S. A no. v S. A oueaesem ob.mm 0.0m mm.mu ones sea 0 nuance can use mo a menace one .e ae.ea m.ae aN.ee once won ONM messed owa .eeu none nausea can .N oe.aa on.ea ae.ae once .8 can 858 ea can mean menace one .A . we.n mo.v_ mo.v oanv oenmnnnaewea 9 Ad ~m.me mm.oa ma.me awesome Heroes. .N aa.ee «N.ea me.ne «wagons Hugues oz .H amz OH.v OH.v omrA naeoaaeeo ea.oe H».Ha ao.ae m-uzw .n use .N ma.me mo.ee e~.ee are .H «n.» Ho.v. moo.v_ mo.v. neoaeenom suaflanenonm aces. euuaanenonm an»: weeaenenoua can: 093 DHBGEHGOHH. uaauua casuasoo Hauha Houusoousoz Hanna Howuaou mono «.an 6.3353 confides. mo 33:023ou 39a. . .. . I‘ll .\. r I .AuudquVN .l..r.z iuifilflajuflil u¢ce=~u~vvhhfi I I V O ...... u .7y-e. n I! no 0 u r u ........ a ...-...c. .or.,.. ..o.-o~.u. o e t x.‘.-. .e..n. .Qouo ostocou homo - 100 - .ysdonasofinusozn .Aaoboa usoo nod mg cosmHoMMflo assofimwdoam ymuoqc 0.0 n.HH m.oa psoo wen : :ofiusanu> mo usofiOfimmooo m.wu om.mh oa.wu nanosecony Has use: huaafindnowm use: hufiafinsnohm ssoz huaafinsnonm sees nmA s mucosusoua 32.5 35880 H33 €380.82 Hague Houysoo 33582.... See I," Q 5V4 D_‘ . ,v-rh l gate' 5 ’cu‘ . I-IAv ." . ,0 . ‘ u. 'v'. H .. Q N.‘ CE I: -... t“! - 101 - Plantable seedlings were graded into Grades 1 and 2 (Wakeley, 1954) and percentages for each grade were computed. The mean percentage of Grade 1 seedlings was 13.0. For the Regular series, treatments did not affect the percentages of Grade 1 seedlings. Interaction effects of rotations with sawdust were highly significant for the Modified series. Percentages of Grade 1 seedlings for Rotation l and sawdust treatments in this series are presented in Table 5. TABLE 5.--Grade l loblolly pine seedlings from the Modified series, 1955 crop (in per cent of total trees) Rotations Sawdust Treatments 1. S-S-S 2. GMC-S-S 1. None 13.78 15.28 2. 15 tons per acre per year for Rotation l and 15 tons in 1953 for Rotation 2 13.83 16.00 3. 30 tons per acre per year for Rotation l and 30 tons in 1953 for Rotation 2 6.72 23.33 Least significant difference for sawdust means for the same rotation (5 per cent level) - 4.82 Treatments of 30 tons of sawdust per acre produced significantly :more Grade 1 seedlings under Rotation 2 than other treatments, and significantly less Grade 1 seedlings under Rotation 1 than other treat- ments. - 102 - Fertilizer effects were not significant. However, the smallest percentages of Grade 1 seedlings were produced on plots that received the lightest fertilizer applications. Number of Seedlings and Number of Plantable Seedlings Per Square Foot For the 1954 seedling crop, five analyses of covariance were made for five of the nine fertilizer-sawdust treatments. These treat- ment combinations were: Sawdust l Sawdust 3 Sawdust 2 Sawdust l - Sawdust 3 Fertilizer Fertilizer Fertilizer Fertilizer Fertilizer “QNHH I The covariance of Y, per cent of plantable trees, with X, number of seedlings per square foot, was computed for each of the above treatments. In some analyses there were no indications of a linear relationship between total number of plants and.percentages of plantable trees. A.mm1tiple regression was computed for each treatment with.X2, 2 the second independent variable, equal to X Another multiple 1 I regression was computed using the sums of the five regressions. The prediction equations for the six regressions are: Fertilizer 1 - Sawdust 1 Y = 85.4 - .104ax - .0002733x2 l Fertilizer 2 - Sawdust 3 Y . 90.3 - .4426X1 + .003112x2 Fertilizer 2 - Sawdust 2 Y 88.7 - .1055):1 - .0005352x? 105.7 - .6811X1 + .003939x2 2 Fertilizer 3 Sawdust 1 Y Fertilizer 3 Sawdust 3 Y I 72.6 - .4201X1 - .004512X Total regression Y'= 35.0 - .0505x1 - .000552x2 - 103 - None of the multiple regressions seemed to account for a large puoportion of variability and they were of different shapes. However, there was close agreement among the computed number of plantable seed- lings for stand densities up to 50 seedlings per square foot. Above this level, wide differences were obtained (Table 6). TABLE 6.--Plantable seedlings for different densities (number per square foot) Fertilizer - Sawdust Treatments Seedling Density All Fl-Sl F1-S3 F2-82 F3-Sl F3-S3 Treatments 0 0 0 0 0 0 0 10 8.3 8.3 8.6 9.4 7.9 8.4 20 16.2 15.5 16.7 17.0 16.4 16.3 30 23.4 22.5 24.1 23.7 24.5 23.4 40 30.1 29.9 30.7 30.6 30.9 30.4 50 36.0 38.6 36.4 38.5 34.8 36.2 For the existing fertility levels, it appears that there is no strong relationship between percentage of plantable seedlings and number of seedlings per square foot for densities below 50 seedlings per square foot. ‘x. .‘ I‘l‘J. --3 533'; .2: 355:: I’l ~illt ‘ .1. 5.. I.“ \ Matt“ 0 9‘" can // \ east . ER VII EFFECTS OF TREATMENTS ON MORPHOLOGICAL CHARACTER OF PLANTS Velume of Plant Material Some volume measurements and shoot/root ratios for seedlings from the 1953 crop are presented in Table 7. TABLE 7.--Mean volume of roots and shoots of loblolly pine seedlings, 1953 crop Vblume Treatment Sh:::{§°°t Shoot Roots Cubic Cubic centimeters centimeters No sawdust 91.1 35.8 2.61 15 tons sawdust per acre 74.7 33.3 2.23 30 tons sawdust per acre 74.1 34.3 2.17 Mean - all treatments 80.0 34.5 2.33 LSD3 11.1 NSb 0.19 Coefficient of variation - per cent 29.3 25.0 17.1 aLeast significant difference (5 per cent level). bNon-significant. - 104 - ”fl,“ '2 n : - 105 - Sawdust treatment effects were highly significant for shoot volumes and for shoot/root ratio. Sawdust treatments may have effected shoot volume by reducing the amount of available nitrogen, thereby retarding shoot development. Root volumes were not affected by treat- ments. A more favorable shoot/root ratio was obtained as a result of sawdust treatments. Length and Diameter of Seedlings Data on stem length, stem diameter and root lengths were obtained for the 1953 seedlings. A summary of length and diameter measurements are presented in Table 8. TABLE 8.--Length and diameter of loblolly pine seedlings, 1953 crop Treatment ifiiiha Diiézierd Stgfégizgeter Liigiha Trees No sawdust 6.68 .115 .1418 7.91 15 tons sawdust per acre 5.68 .104 .1400 7.83 30 tons sawdust per acre 5.85 ,fiL109 .1392 8.17 jMean all treatments 6.07 .109 .1403 . 7.97 LSD° .40 NSd NSd NSd Coefficient of vari- ation - per cent 13.9 12.6 9.1 8.5 aBased on seedlings from the total population. hBased.on seedlings from the plantable population. 9Least significant difference (5 per cent level). dNon-significant. w ‘51: . ; "a: eas- I‘-\". i I.“ v .I ' pi n.- .'euu v“ DOV! , hn- .. u e l - bukni f.) ‘8 ' r] :1 the :5 ». . ~ "‘Ie-m . s ffim. .. , a“: itte ea‘ - 106 '- Applications of sawdust resulted in a significant reduction of stem.length and.a slight but non-significant reduction in the diameters of plantable seedlings. It may be assumed that the level of available nitrogen was reduced.by sawdust treatments resulting in a corresponding reduction of stem growth. Other treatment effects were non-significant. Seedlings Developing Winter Buds Treatments did not have a significant effect on the development of terminal buds. An average of 64.25 per cent of the plants from the total population developed buds. On the basis of plantable seedlings only, the percentage might be higher. Small or slender loblolly pine seedlings frequently do not form a bud during the first year in the seedbeds. Shoot and Root Weights of 1953 Seedlings Green weights and oven-dry weights for the 1953 seedlings are summarized in Table 9. The only highly significant differences were in the effects of different sawdust treatments on green and dry weights of stems. The analysis indicated that the sawdust and chemical inter- action effects were significant for green weight of stems. For sub- plots that received.methyl bromide, green weights decreased with increasing rates of sawdust application. The same pattern developed for oven-dry weights, but the differences were non-significant. The heaviest rates of fertilization produced greater green and dry weights than the lighter rates, but the differences were not significant. The shoot/root ratios for oven-dry weights were computed. Only sawdust effects were significant (Table 9). .Aao>oa usoo won my oosouomMfio esso«Mfisown “moods e.eH a.a~ e.o~ s.om n.am uses sou - assesses» mo neosoauuoou on.“ H«.o me.o em.o so.“ assesseess Hue see: - an.o no.0 oa.o we.“ seasons assess oz - ee.o mo.a oo.a as.“ seasons Hesse: eascfisoso oH.o «H.o oe.o some sn.~ ~e.o ee.o ee.o we.“ osoe sou use» on .o as.“ an.o oo.H no.0 om.~ ouoe use easy we .N es.n ee.o no.H HH.H «o.e osoz .H . umoosom MW 1. - ne.o eo.H so.H em.~ ouoo use can season . can one acme soon one .e - oe.o so.o ee.o em.~ ouoe use 0 season cos see moNa season can .N . H«.o oa.o no.9 so.“ once sea cum season om one mesa season one .H sesasusuou nacho naoww macaw masww mason knou=o>o hhousobo sooww hhpusobo sooww cease nauseoona soouasooem .uoos we assess euoose no Leases none nmma .uosfiaoomu ones aaaoasoa new ofiueu uoou\poosu one avenge: see2.:.m mamaa - 108 - Shoot and Root Weights of 1954 Seedlings In 1954 and 1955, the only morphological measurements obtained were oven-dry shoot and root weights of plantable trees. In 1954, treatments did not have any significant effects on the oven-dry weights of shoots or roots. However, the analysis indicated that the effects of chemical treatments on the shoot/root ratio were highly significant. Higher shoot/root ratios were obtained following the use of methyl bromide. A summary of treatment means for 1954 data is presented in Table 10. Shoot and Root Weights of 1955 Seedlings ‘Egights of oven-dry shoots Data for the Regular series and for the Modified series were analyzed separately and then combined in a single analysis. In the Regular series, the interaction of rotation with sawdust was highly significant. For the annual seedling rotation, the oven-dry weight of shoots decreased with increasing rates of sawdust. When a green manure crop appeared in the rotation, oven-dry weights of shoots in- creased with increasing rates of sawdust (Table 11). In the Modified series, sawdust and rotation by sawdust inter- action effects were highly significant. The pattern for the annual seedling rotation.was similar to the annual seedling rotation in the Regular series, that is, oven-dry weights decreased with increasing rates of sawdust (Table 11). Fertilizer treatment effects were not°significant. However, ‘when oven-dry weights of seedlings from the annual seedling rotation r——- I v‘ lKS-v" lb! i» s ‘5 L. :' ‘ ‘..s -’ .Jt Treat 1" Me dist-II. — TABLE 10.--Mean oven-dry weights for plantable loblolly pine seedlings, 1954 crop Seedling Shoot/Root Treatment Shoots Roots Ratio Grams Grams Chemicals No methyl bromide 1.534 0.638 2.439 Methyl bromide 1.632 0.6 3 2.617 150* NSb NS .113 Rotations 1. S-S 1.561 0.636 2.477 2. and 3. GMC-S 1.595 0.628 2.553 Sawdustc 1. None 1.584 0.629 2.551 2. 15 tons per acre 1.588 0.627 2.549 3. 30 tons per acre 1.578 0.636 2.484 Fertilizerso 1. 150 pounds P205 and 80 pounds K20 per acre 1.552 0.621 2.515 2. 300 pounds P205 and 160 pounds K20 per acre 1.616 0.641 2.536 3. 450 pounds P205 and 240 pounds K20 per acre 1.582 0.631 2.533 Mean all treatments 1.583 0.631 2.528 Coefficient of variation - per cent 24.2 25-4 12.5 SLeast significant difference (5 per cent level). bNon-significant. cRotation 2 did not receive sawdust, P205 or K20 in 1954. E g 11.5.. .i _ - 110 - TABLE ll.--Mean weights of oven-dry shoots and roots of loblolly pine seedlings, 1955 crop (in grams) Modified Series Regular Series Treatments Rotations Rotations 1.3-3-3 Leno-SS“ 1.S.s-s 2.340-333 Sawdustb 1. None 2.064 2.002 2.022 1.875 2. 15 tons per acre 1.602 1.854 1.869 1.959 3. 30 tons per acre 1.399 2.009 1.620 2.022 LSDc Two sawdust means for the same rotation 0.224 0.214 sass Sawdustb 1. None 0.497 0.474 0.501 0.493 2. 15 tons per acre .414 .424 .460 .504 3. 30 tons per acre .398 .442 .455 .488 LSDo Two sawdust means for the same rotation 0.020 NSd aRotation 2 did not receive P205 or K20 fertilizer in 1954 and 1955. bSawdust was not applied to Rotation 2 in 1954 and 1955. cLeast significant difference (5 per cent level). dNon-significant. - 111 - are plotted over total fertilizers, there is apparently a relationship between oven-dry weight and cumulative amount of fertilizer applied, with oven-dry weights increasing with increased fertilizer applications. Heights of oven-dry roots For the Modified series, sawdust treatment effects were highly significant. On the annual seedling rotation, the oven-dry weights of roots decreased with increasing rates of sawdust. This same re- lationship occurred for the Regular series, but the differences were not significant (Table 11). When a green manure crop appeared in the rotation, the same trend developed for the Modified series but not the Regular series. Fertilizer treatment effects were not significant. However, when oven-dry weights of seedlings for the annual seedling rotation are plotted over total fertilizer, there is apparently a relationship between oven-dry weight and cumulative amount of fertilizer applied, with oven-dry weights increasing with increased fertilizer applications. Shootjroot ratig_ Shoot/root ratios for oven-dry weights were computed. This measurement is sometimes more reliable and.more sensitive to treatments than weights of shoots or roots. For the Regular series, treatment effects were not significant. For the Modified series, rotation and fertilizer effects were significant and the interaction effects of rotations with sawdust were highly significant. Mean shoot/root ratios are presented in Table 12 s ‘112- TABLE 12.--Mean shoot/root ratios of oven-dried loblolly pine seed- lings - Modified series, 1955 crop Rotations Treatments 1. S-S-S 2. Guess" Sawdust 1. None 4.232 4.260 2. 15 tons per acre 3.880 4.398 3. 30 tons per acre 3.465 4.639 Fertilizer 1. None 3.575 4.384 2. 75 pounds P205 and 40 pounds K20 per acre 3.918 4.349 3. 150 pounds P205 and 80 pounds K20 per acre 4.084 4.564 LSDb between two sawdust or fertilizer means for the same rotation 0.364 0.364 aRotation 2 did not receive sawdust, P205 or K20 in 1954 and 1955- bLeast significant difference (5 per cent level). Table 12 shows that for the annual seedling rotation, shoot] root ratios decreased with increasing rates of sawdust and increased with increasing rates of fertilizer. When a green manure crop'was in- cluded in the rotation, the shoot/root ratio increased.with increasing rates of sawdust. Fertilizer treatment effects were non-significant for Rotation 2. - 113 - Comparison of Mean weights of Oven-Dry Plants The trend for three consecutive years was toward heavier plants and higher shoot/root ratios (Table 13). Root weights remained fairly constant, while weights of shoots increased each year. TABLE l3.--Mean weights of oven-dry loblolly pine seedlings and shoot/root ratios Year Plant component 1953a 1954b 1955b Erase 252.1112 92223 Shoot 0.975 1.583 1.858 Roots 0.410 0.631 0.463 Entire Plant 1.185 2.234 2.321 Shoot/root ratio 2.378 2.509 4.013 aPlantable trees and culls. bOnly plantable trees. CHAPTER VIII EFFECTS OF TREATMENTS ON NURSERY SOILS Soil Reaction Mean pH values for different sampling dates are presented in Table 140 TABLE l4.--Mean pH values of soil samples Sampling Date Mean pH Value C.V'.a March 1953 6.36 12.0 January 1954 5.57 4.5 January 1955 5.45 3.3 January 1956 5.30 3.8 0‘Coefficient of variation - per cent. Rotations 2 and 3 received the same treatments in 1953 and in 1954. The statistical analysis for the January 1954 data did not produce any significant differences. However, the annual seedling rotation and sawdust treatments indicated a possible downward trend in pH values (Table 15). In the analysis of the January 1955 data, the interaction of sawdust with rotations was highly significant, as were differences due to sawdust treatments (Table 15). Rotation differences were significant. - 114 - - 115 - The data revealed that sawdust treatments created differences in the annual seedling rotation but not in the other rotation. TABLE lS.--Mean pH values, January 1954 and January 1955 soil samples Sawdust Rotations Treatments a Mean 1. 3-3 2. and 3. GMC-S January 1954 1. None 5.45 5.64 5.61 2. 15 tons per acre 5.44 5.62 5.56 3. 30 tons per acre 5.49 5.55 5.53 January 1955 1. None 5.43 5.54 5.50 2. 15 tons per acre 5.29 5.51 5.44 3. 30 tons per acre 5.20 5.50 5.40 Mean 5.31 5.52 5.45 LSDb 1955 rotation means 0.211 b 1955 sawdust means 0.049 LSDb 1955 two rotation means for the same level of sawdust 0.326 LSD 1955 two sawdust means for the same rotation 0.084 aRotation 2 and 3 did not receive sawdust treatments in 1954. bLeast significant difference (5 per cent level). In the statistical analysis of January 1956 data, pH value for the Regular series and the Modified series were analyzed separately. Rotations, sawdust and interactions of rotations with sawdust affected pH values, but the effects were not the same for the two series (Table 16). For the Modified series, sawdust treatment effects were highly significant and the interactions of sawdust with rotations were significant. For the Regular series rotation effects were highly {I IIDIIII ‘AI3 I .0 I Iii-alli- I ll.‘ -‘tl. III- 'II IIO\CIInJ§ ‘Q‘. .I‘v ‘Q“3 em emez IWem shag OUH50W DHEEQE .svsv mama husacsh wow nucmucoo umyudfi cacsouo you unsound» no nanhadds Hauuuumuu.ma mqmsa - 122 - .Aaoboa ucoo won my oocmnomwfip unmoflMHmmHm ammoqo efimmd flH #mfigwm OFHwOGH #05 mug n fiOHflflHOfi .mmma so «was as sooozoo ossooow moo ado N oouuouomo mmH.o Hoboa unspzmm case may we mamas aowumuou 038 coma mma. cofiymuon meow oz“ How mcmoe umdvzmm 038 09mg Hao.o ooooa ooauooom ooma oHH.o .aooa «oaozom ones do.“ mm.H om.H mu.“ coo: mn.~ m~.N mo.N mu.m once you snow on .m so.N so.~ mw.H om.w owes Hod mcow ma .N um.a mm.a H5.H mo.a ocoz .H pooosom onzw-m-ozo .o om-m-ozw .« m-m-m .H zoos nucoayoous oceansvom fiasco Hod cam madness Haas mama hhssash onw Ham mucoucoo weaves oflcmmuo csoZuu.on mAmEH I 1‘1]!!! » I 1.1-P.1- - 123 - TMBLE 21.--Probabilities of differences, as large as those found in the three year summary of organic matter content, being due to chance Probability Level Source of Difference Regular Series Modified Series Rotations < .025 < .005 Sawdust < .005 < .005 Rotation x sawdust interaction ‘<.005 <.005 Years <.30 <.05 Years x rotation interaction ‘<.05 <.005 Sawdust 1 years interaction <.005 <.005 Sawdust x rotation x years interaction < .005 < .005 TABLE 22.--Mean cation exchange values for different sampling dates Cation Exchange C.V.a Sampling Date Capacity m.e. per 100 grams March 1953 3.66 20.1b January 1954 3.95 9.9 January 1955 3.76 10.9 January 1956 4.12 9.2 aCoefficient of variation - per cent. bBased on samples from 36 main plots. -124- In the statistical analyses, all significant differences were due to rotations, sawdust or the interaction of sawdust with rotations. For the January 1954 data, rotations and sawdust treatments produced differences that were highly significant and the interaction effects of rotations with sawdust were significant (Table 23). For the January 1955 data, differences due to sawdust treatments were highly significant. Rotation effects and the interaction effects of rotations and sawdust were significant at the 10 per cent level (Table 23). The patterns established by the 1954 and 1955 data was sub- stantiated by the 1956 data. Analyses were computed for each series and the data were combined in a single analysis. Rotation and sawdust treatment effects were highly significant. The interaction effects of sawdust with rotations were highly significant for the Regular series and significant for the Modified series (Table 23). The data reveal that increases in the rates of sawdust applica- tions resulted in increases in cation exchange capacity. Green manure crops, without sawdust, resulted in significant increases in the level of cation exchange capacity values, but the levels decreased when seedling crops followed green manure crops. Fertilizer effects were not significant but greater exchange capacity was found.at the higher fertilizer rates than at the lower fertilizer rates. In a previous section, it was reported that a combination of sawdust and a green manure crop increased the organic content of the - 125 - ma.e NH.¢ om.” om.e whom “we meow ma .N as.” we.m om.» Hm.” maoz .H monEdm mmma hwedcuh we.» mm.” on.» om.n new: em.” om.» as.» mfi.¢ ones you snow on .m we.” we.” mm.” mm.» once was meow ma .N mm.m Hm.” an.” no.” osoz 2“ mmdmsum mmma assuage mm.” ma.e eo.« mo.” ago: mo.v H~.¢ m~.¢ so.» mean Hos use“ on .n Hm.» na.« mm.» «a.» can. Hos use“ ma .N «m.n No.« om.” Hm.n oaoz .H uoaaeom «mad message 5m: noeséove.” «Rodeo. N warm.” 33586 233.30% nudge»). Aeadhu 00H Hon easeddbaavo|aaawa adv uofiaub 00:0:OK0 :ofiwoo GOOZII.0N mdmsfi .Aaobea uaeo won my eonowowmfip vaeo«Mfi:U«e neeeAQ .33 EB 33 5 E638 3:83 a eoflflom .83 5 ~33.» 3582 a aofiflom .33 v.3 32 5 32a 28: n v5 N 203305 2.10 233 «26.23 32 no? omwoo enema :o«¥d#0h mmmd nfimd - e w o: 0 28s pages: 33 ham: 1 O . 00H 0 9308 #mdgfim «mod Ann..— mfls 23a 8338 33 new; Nfiov wo.¢ mm.n nnov dam: H¢o¢ mwod mH.# mh.v OHOQ Hem acoy on .m an»: $56-96.» um-m-o§.~ mime; uuaofiuoue p.536 escaveuom Avossducoovnu.nn NAmEH - 127 - soil. Baver (1930) stated that 30 to 60 per cent of the exchange complex of surface soils is due to organic matter. McGeorge (1931) found that the exchange capacity increased as organic matter or humus passed through various stages of decomposition; i.e., as the particle size decreased and the surface area increased. He found that a humus colloid has a seven times greater exchange capacity per unit of weight than a clay colloid. Soil Nitrogen Total nitrogen content of the March 1953 soil samples from.the main plots averaged 0.0434 per cent. Because of the known close rela- tionship between soil organic matter and total nitrogen and the fact that rates of nitrogen application were different each year, nitrogen determinations were omitted from the study. Soil Phosphorus The mean levels of available phosphorus for different sampling dates are presented in Table 24. Analysis of variance for the January 1954 phosphorus data indi- cated highly significant differences due to fertilizers and significant differences due to chemicals, sawdust and interactions of sawdust with fertilizers (Table 25). For the January 1955 phosphorus data, fertilizer treatment effects were highly significant and interaction effects of fertilizer with rotations were significant (Table 25). Increases in rates of P505 fertilization resulted in increases in the level of available phosphorus in the soil, but the amount of increase was greater for an annual g 15?: \\ TABLE 24.--Mean content of available phosphorus in soil samples for different sampling dates Sampling Date ghgipifiizs C.V.a Parts per million Per cent March 1953 131.1 32.65b January 1954 100.0 15.9 January 1955 89.2 18.1 January 1956 62.1 19.5 11Coefficient of variation. bBased on samples from 12 main plots. TABLE 25.--Mean level of available phosphorus for January 1954 and January 1955 samples Year Treatments a 1954 LSD 1955 LSD Parts per Parts per million million Chemical 14.4 Nsb 1. No methyl bromide 109.0 88.1 2. Methyl bromide 91.2 90.2 Sawdust 4.2 NS 1. None 103.1 90.7 2. 15 tons per acre 100.1 88.1 3. 30 tons per acre 97.0 88.7 Fertilizer‘ 4.2 13.4 1. 150 pounds P205 per acre 89.0 79.1 2. 300 pounds P205 per acre 103.3 89.1 3. 450 pounds P205 per acre 107.8 99.3 & aLeast significant difference (5 per cent level). bNon-significant. ,u .9... 7.. EN. «I . - 129 - seedling rotation than for a green manure crop-seedling rotation. For the January 1956 phosphorus data, separate analyses were made for the Regular series and the Modified series. Fertilizer treat- ment effects were highly significant for each series. Rotation effects and interaction effects of rotations with fertilizers were significant for the Regular series (Table 26). The data reveal that P205 treatments are more effective in main- taining the level of available phosphorus in an annual seedling rotation than in a rotation in which a green manure crop alternates with two years of seedlings. A rotation in which a green manure crop alternates with one year of seedlings and the annual seedling rotation produced.similar results (Table 26). Sawdust treatment effects were not significant but the phosphorus content was lower for the 30 ton per acre application than for 15 tons per acre or for no sawdust. In considering phosphorus values for a three year period, another variable, time, was added. Phosphorus values for three sets of data (January 1954, January 1955 and January 1956) were combined for each series. In the statistical analysis, years and fertilizer treatment effects were highly significant for each series. Sawdust effects and rotation by sawdust interaction effects were highly significant for the Modified series. The available phosphorus in the January, 1956, samples should be equal to the available phosphorus present in March, 1953, plus the phosphorus added in 1953, 1954, and 1955, minus that used by the plant ‘lll‘i’Il IIIKI‘.‘ Ix tiniei(\ - 130 - .Aae>ea usoo Hod m. oosewemmwp pancamwsufiu «usage .mmma was ”mad as ussmavoauu some ucpfimoou n aofisuyomn .haso nmma ea nusmsueeuu mon.po>«ooeu « scaveuome m.ea enema sofiueuon moanom weasoom cam; n.« eases unspzwe magnum Heasoem sang a.« names sneeze» nowuom.uo«Mfiuoz coma «.em «.05 m.em m.eo sums o.na o.ma ¢.mm H.Nm one. has mesa nuance cow .m o.mm m.ee e.mm c.5o once was mean season can .m m.em m.eo a.a« a.nm anon you news season and .« eoawom weammum s.mm m.es o.mm m.Ho acme a.mo «.ma m.em m.~a anon Hon moan season and .» n.ao m.em 5.5m ”.mo once Hon mon season as .N ”.me m.em H.m¢ ».e« eaoz .H nausea assesses goo nozw-m-ozo » om-m-ozo.~ m-m-m.a .ysmauuona z secuuozom Houaaeeuom “sowaafls non owned say noddeeu Hwoe mmma Mom usuozdnond saneaaepe mo cached asezuu.mn mqmaa - 131 - or fixed in unavailable form or lost through erosion. These values are summarized in Table 27. The amounts of available P205 that were removed from the soil or fixed in unavailable form were plotted over total cumulative applications for the three year period (Figure 2). Data reveal that phosphorus utilization, fixation or loss through erosion increased with increased rates of application. The most efficient utilization of phosphorus was obtained.with rotation 2. It was unfortunate that reserve or total phosphorus determinations were not made each year. Ensminger (1950) found that levels of availa- ble phosphorus tended to reach equilibrium for a given rate of applica- tion, whereas unavailable phosphorus tended to increase. In a continuation of this study, an equilibrium should.be obtained for each rate of application. Where phosphorus is omitted, the level of available phosphorus should approach zero. For these soils, the present rates of phosphorus application are not sufficient to maintain a constant level of available phosphorus. Soil Potassium Mean levels of available potassium for different sampling dates are presented in Table 28. Available potassium levels are summarized in Table 29 for January 1954 soil samples. In the analysis of variance, rotations, sawdust and fertilizer treatment effects were highly significant. Increases in rates of sawdust and.K20 fertilizer resulted in increases in available potassium. Inter- action effects were not significant. - 132 - Han man as“ own man no“ coho seed spoon Hon ago» a“ women we undead a5 flees mon .m. thl wal nmml Huh- 5mm: mum: an I N + Hg dado Ho quA o# OBN Ohm mam Hmm man man Hook thnw Mo fine 05 we asoycoc mean one: .m owe can one one so» am” season use» cones assess vanes some .N Now Now Now Now Now Now dammfi¢00ua 0% Hagen flamenco mONm use: .H cofivcuom mafiapmom I wcfiapmom I mouo chasm: cacao mNm man we“ «me man was sows seed upmoe nod 30» a“ powmm Ho nude—HQ .3 Uses no A .m whmdl omHHI mom- meHI hum: «mm- Am I N + AV dado Ho anon .v man «an hwm man 00» mam Ndofi flhwnv mo.Uao 05. we useuboo mend sec: .0 omnH Dom om¢ omoa mum con VOAHOQ Much cause saunas eases moum .« Now Now Now Now now Now G¥GQE#UOH¥ Ou mafia essence mONm 532 .H sequence unseemmm unease o m ¢ 0 N H eoflnom Hudsoem eefiwem Usage: nacho..— nen 3.33m eucofieeua ucwfigvuem Reece Hen opened :3 :93in no 233.333: use #8300393 ushognnoga mo hhcafismuu.bn mdmga .owoe “on amazon 3H ..... mom an: amide» uoad flea NH How ucoucoo some can .. .. u .. . .. .. done as: Epsom wed 30m 5 pow: no agenda 3 poms mean .m . “w oeHH new use- cam- was- new- A” - N + He sees no smog .e 1. «on man He“ was man am“ new» sense «o . Use «c «season mon use: .m com com com cos new one eozuoa use» money unease eases meme .N wow wow Now Now New Now seamsueoeu on Mona “daemon mon 5mm: 2m soflpeuom mono one—sex somuw I meageem .. mono cusses qeouo m m w n N H mousse “sesame . mousse eminence news»; Hmswaessom nesofiuowa umwfiflnom 3353:0311: mama. . 952505 mmma 3 83 defines mend we unease ~33 23 cu sot—each 5 seasons 3 use." no 30» 23 5 pear“ 6333: a!» :03: down osqgwom use evened 3" mean Heuoané .0; 05259: 33:33 once and mean evened Hopes oo: 82 coca com com cow con P _ _ _ - p _ none ewssea nacho a 0:25.33 1 engage» no he; pcooom seeaeueu e loo” . 4. 05.230» 2352 o 3 1 . o m u con * o o e r 8e 0 1 com doze buupees red peach: 902d [1340; . LP'LI‘ .7 ,— '1 «I 7‘ -4 'e - I" - 135 - TABLE 28.--Mean contents of available potassium for different sampling dates Sampling Date Available Potassium c.v."‘1 Parts_per million Per cent March 1953 52.9 24.61:) January 1954 95.1 4 14.0 January 1955 71.9 14.9 January 1956 78.7 14.7 aCoefficient of variation. bBased on samples from 12 main plots. The mean levels of available potassium were reduced during the 1954 growing season. Rotations 2 and 3 were in seedlings but they did not receive K20 fertilization. Table 30 gives the mean levels of available potassium in the January 1955 samples. The statistical analysis indicated highly significant differences due to sawdust, fertilizers and interactions of fertilizers with rotations. More potassium was available on sub-plots that received sawdust and.K20 fertilizer than on non-treated plots, with available potassium.increasing with increasing rates of sawdust and.KiO fertili- zation. Fertilizers and rotations created highly significant interaction effects, with fertilizers creating differences in the annual seedling rotation but not in the other rotations. A fertilizer treatment of 240 pounds of KiO per acre on the annual seedling rotation resulted in a level of available potassium almost equal to the mean level of the ...\ Iii-.11.:lll I elill ‘an1il \illlI-uIII- al- .-.IIIIIIII.|AIII -n...‘-I.i)l ‘..I II-ll\lnl~ neuiui-Q ‘.|\uu.‘ .§.~.~fl\~ . . I . . I 1 .- . I . . .. ‘ I. . . I . . 1 . . . I O O I I I I . . I . . e _ . . ‘ . .. _ . r a h n O I I I 1 l.isl,..1,1r. .- . FY A - 136 - .pocwnacc me m use N nsofiueaow Mom evegn .Aaobea acme wed my eocou0MMfip useOaMfison «moods o.va usoc wen u scauofiwe> mo ysmficfimmeoo N.m segueuow case new needs ewewqaeewom 93¢ unmq a.» edema sofiuevou 09mg o.n mecca unopzee snag H.mm n.am m.ea «.mm a was N .H .aoaauuom .aaoz H.Hoa a.aoa «.OOH m.em some a.ao~ m.eaa m.eoe H.aoa one. sea owe season can .0 n.noa m.eoa N.noH o.Noa .Hoa use cam season omH .N m.Ha o.am m.em «.mm one. was OHM season on .H nwono ounce: modem 1 u use N cofiueaom c.0m m.mm a.nm a.aa same n.aa N.ma m.ea ”.mm .uoa Hos can season can .0 H.am o.mm H.aw m.am case was one season owe .N a.aa a.ma m.ea n.na anus use cam season as .H .Hoawflwusaa .maaaeaam - H aoauauom once Hod once wed ecoz .H :soz msou on .0 ago“ ma .N muceeueoua uucofiueowa unspzmm Asoaaafia wed «when new seamen» dice vmma huesceh a“ scammeuOQ caneafiepe mo naObea coax-u.mu mqmmH III.I I I I IIII ”I'Ai D... ll..- oe i v lilielaull‘l I I Q!!! Ale-1.... - \A I.'IIIIl-. II ‘ IIIIII OUI\I\InIIII '-.§Ir!~ I 'i)’\l. llaul.whuu-:\.I. 1. 1 - ... .11.. . ..u.. v... . I I I n.. .. .... 4.. -.;.. .. . . . . I. 1. .. o .. . ... I I I e . I I I I I I I l I O I 1 I I I l I Q I I I I I I I I I I I I . I I I I I 1: 1 .. .... . .... .. . u.. . . . I I I - 137 - .ssse eosnnaoo .AHoboa usoo non my coconommao waccnmnnonn umeogn .emma an munoeaeonu noananunom no unspsce o>nooon won one 0 one N un0nnenome om.m ncnyepon made new names newnannnom 038 nnmA os.« asoas noannnunoo ess sosezew news m.Hh m.mm m.mb aeoz m.es v.Hb o.mm once non ONM messed oeu .n m.ws 5.05 H.os once non ONM modded oma .« o.mo m.eo a.no onoo non can aesson as .n noannnonon o.mh o.mu m.m> once non anon on .n 5.Hu m.mo «.ms once nod econ ma .N H.mm m.ww $.05 Odoz .H pudpsem sm-o2e .n ess .N m-m .n coax mucosueena unenuenom AsOnHHfiE non owned any ”cameos anew mmma unacceh an sensuouoa canoanc>¢t|.on mqmga - 138 - January 1954 samples (Tables 29 and 30). In the statistical analysis of the January 1956 data, potassium values for the Regular series and the Modified series were analyzed separately. In each analysis, rotation, sawdust and fertilizer effects were highly significant and interaction effects of sawdust with rotation were significant. Potassium values for the January 1956 samples are presented in Table 31. Data reveal that a wide range in levels of available potassium can be created by various treatments or combinations of treatments. For the annual seedling rotation, annual applications of fertilizer and saws dust have maintained a fairly constant level, based on levels of previous years (52.8 ppm in 1953, 92.2 ppm in 1954, 75.9 ppm in 1955, and 62.2 ppm in 1956). When a green manure crop alternated with two years of seedlings, the potassium level decreased following each seedling crop (52.8 ppm in 1953, 94.8 ppm in 1954, 69.9 ppm in 1955 and 45.3 ppm in 1956). .A green manure crop alternating with one year of seedlings produced higher levels of available potassium than other rotations. Potassium levels increased following the green manure crop and decreased during the seedling crop (52.9 ppm in 1953, 98.3 ppm in 1954, 69.9 ppm in 1955 and 128.6 ppm in 1956). By considering potassium values for three sampling dates, another variable, time, was introduced in the analysis. In the statistical analysis combining January 1954, January 1955, and January 1956 data, rotation, sawdust, fertilizer, year effects, interaction effects of rotations with years, and interaction effects of fertilizers by rotations .unoo nod u zenvonnob mo unoncnmmoooo .Adoboa ucoo nod my ooconommwp unocnmnnono nooogp .oonnom ponmnpoz one cu m one .5 .a munoenoonu one nonnom noasoom one on hands o one .m .e munoauoonn nownannnomo .vmma an unannounaddo noananvnom no unspsoo obnooon uoc_pnp o canuouomn .mmma no emma an onOnnooando nounannnom no unspsoo o>nooon #0:.pnp u nofinouomo 5.va oonnoo oonmnpozno.>.o m.en manna» nonsooe o.>.o «.5 monnoo ponMjpca nn memos noufiannnom no unspsoo oza_pamA o.m oonnoo noasoon an enema nounannnom no poopsoo oze.pamq v.o oonnoo ponMfich a onooalncnnouom 69mg 5.wa eonnoo noasoon . memos sonaoaom UQMA «.5HH a.me m.mm m.mmH m.m¢ «.mm coo: . on m.mHH 5.m¢ 5.Nm ”.mea c.5e o.m5 n no 0 m“ m.eaa m.ev m.mm w.owa m.mw «.H5 « no m . m.NHH o.~¢ 5.Hm m.nma m.~v H.mm A no w oenosnannnom m.5HH «.me m.em «.Hea o.mv ¢.m5 once nod anon on .n «.nnn m.ee o.nm «.ean «.«e m.eo .nos non soon on .N m.eaa m.ee m.wv m.ema H.m¢ m.5m onoz .H unspsom Anzwumuozw.n omamuozw.n mumam.a AuzwnMnozw.n omumnuzw.m mumum.H nonnom ponmnpcz eonnem neasoom “cospoona onenneaom Azanaaea non owned any ooadaco anon mama hnossoh oau new oaoboa.asnooeuon oanoawobflcu.an mAmEH I. y.’ E. \tflflg by years were highly significant. The fertilizer with years interaction effects were highly significant for the Modified series. The inter- action effects of fertilizers with rotation were significant for the Regular series. Theoretically, the level of available potassium in the 1956 soil samples should equal the original potassium in the soil plus the added potassium minus the potassium that was used.by the plant, fixed in the soil or lost through leaching. These values are summarized in Table 32. The average removal, fixation, or loss per seedling crop was computed for Rotations l and 2. The scatter diagram in Figure 3 indi- cates a linear relationship between the total KiO applications and the amounts removed, fixed or lost per seedling crop. The amount of K20 that is used, fixed or lost increases with the accumulated rates of KgO fertilization. Soil Calcium No calcium was added to the sub-plots as a part of the fertili- zation program. The mean exchangeable calcium content of 12 main plot samples collected in March 1953 was 355 parts per ndllion. The coefficient of variation was 27.0 per cent. Values for these samples were low in relation to mean values collected at later dates. The extraction method used for the March 1953 samples was different from the method used for the 1954, 1955, and 1956 samples. Mean exchangeable calcium contents for the January 1954, January .1955 and January 1956 samples are presented in Table 33. In the statistical analysis, rotation effects were significant for the January 1954 samples. Sawdust effects were significant for the January 1955 one mm 3 one 5» a... _ none 3:33 non manncooa an need no .Hnoo one an pow n .ounoaa 5n_poos O .m «mm: 55H: «oar 5mm: e5au «can an n a + Hy need no mmOA .e mad oaa noa oaa ”Ha moa neo5_pnnnn no one no unovnoo emu coo: .n can ooa om ova cod om pennon noon oonas osnnse eoeeo can .n 5NH 5NH 5NH 5NH 5NH 5NH nanosecone on nannd unounoo owu moo: .H cannonomloanapoom n unnapoom a monv onsnoz noonm onm men on men can an nono sonneooa non onneoooa 5Q need no .nnoa one an eoxnn .onsenn an eoas can .m . mmmn one- mmmu 5mm: can: mean Am a N + A. snow no mmoq .« Mu mwa H5~ «ma oma 5~H «NH noon pnnnu mo 1 pno no unounoo ONM cooz .n . 0N5 owe ovm can own own UOnnoQ noo5 oonen oannse eoees own .n 5NH 5~H 5NH 5NH 5~H 5NH ounoEnoonu on nannn usonnoo ONM coax .H nOnnouom wnnapoom Hoscnm o w v n N H monnom noasoom sonnom eonnneoz oaoboq noananunom nanosecona nounanunom “once non apnoea new obnncaonn mmma soconnu mama .Hoboaon one onOnuoOnHodo asnooonOQ no knoaasmus.nn mAmEH (I I'll} h 6. «II. .onoo nod Season 5NH mos ooHdamu noHd anus NH non nconnoo Gnu noofi ones mono onanooo non mongoooH .3 oon no .HnOo can an . poNHm .mnnnoHQ n3 flood ONM .m mm one- son- ao+ own- as. so. A» - a + no anso no smog .e 1 won an» Hun mmN mmm H5N nook UHEn "no 6:0 . no ncondoo ONM .302 .n one an” son one com os eonnon noon oonsn osnnse eoees can .n 5NH 5NH 5NH 5NH 5NH 5NH undoanoonn on nannn nnonnoo ONM coo: .H connonom mono onsnoz coono Qangoom .. mono oncsoz coonw o m e n N H oonnom noHpoom oonnom ponmnpoz oHoboA nouannnom oncosnoonm. non: nnnom ll Aeossnnsooo--.nn mummy .cbauuaoaa mama cu anon .vofiaaad emu «0 uaaoau Houou an» cu nauuunou aw oauwouod 5A umoa uo Haom map =« vegan .voaqauua my: gvfing.aouo oauavooo non oufiaon :« o M Houoau.n .oflm 25.32: ”3782 82.. En oau ouaaon H33. 005 com com oov can con oou P F . b _ _ b ¢ 0 noun ounces guano a OcasoHHOM x oucqavooa mo Mao» vacuum acuuuuou o Nx 1 on ozfiavmom Hos::<_ o g o 3 M x . r. OOH o m o I on” o . . I con 0 doxo buttpoos 10d pOAomaz oz} {910; - 144 - TABLE 33.--Bxchangeable calcium content of soil samples (in parts per million) Date of Sampling Treatments January January January 1955 1954 1955 Modified Regular Series Series Rotations 1. 3-8-8 480 506 438 414 2. GMC-S-S 560 539 394 410 3. GMC-S-GMC 588 556 470 487 2. and 3. (MC-3a 574 547 - - Sawdustb 1. None 528 515 396 410 2. 15 tons per acre 546 533 434 438 3. 30 tons per acre 553 552 472 464 Mean 543 533 434 437 Coefficient of vari- ation - per cent 14.5 16.4 , 19.7 16.1 1.31)‘2 1954 rotation means 64 151)" 1955 sawdust means 23 1.31)" 1956 sawdust means Modified series 27 LSDc 1956 sawdust means Regular series 32 aRotation 2 and.3 were alike in 1954 and 1955. bSawdnst was applied.annua11y to the annual seedling rotation and with the green.manure crop on other rotations. °Least significant difference (5 per cent level). ‘.'-'- - 145 - data and highly significant for the January 1956 data. Rotation effects for the 1955 and 1956 samples and sawdust effects for the 1954 samples were not quite significant. By considering exchangeable calcium values for three sampling dates, another variable, years, was introduced into the analysis. ‘When values for January 1954, January 1955, and January 1956 were combined in an analysis of variance, sawdust treatment effects were highly significant for the Regular and.Modified series. For the Regular series, rotation effects and the interaction effects of sawdust with years were highly significant. Year effects and sawdust by rotation by year inter- action effects were significant. For the Modified series, year effects were highly significant. Data reveal that the effects of a green manure crop on exchangeable calcium is not consistent from one year to the next (Table 33). Exchangeable calcium increased on rotations 2 and 3 following a green manure crop in 1953. Exchangeable calcium decreased on rotation 3 following a green manure crop in 1955. Exchangeable calcium decreased when seedling crops were in the rotation, except for the 1953 seedling crop on Rotation 1. Levels of exchangeable calcium were consistently higher on plots that received sawdust treatments than on plots from which sawdust was ‘withheld. It would seem therefore, that when calciumpcontaining fertilizers and sawdust were omitted, the levels of exchangeable calcium would decrease under a continuous cropping of seedlings or under a system of alternating seedlings with green manure crops. - 146 - Sbil Magnesium No magnesium was added to the seedbeds as a part of the fertili- zer program. Determinations of exchangeable magnesium were not made for the March 1953 samples, but were made for the January 1954, January 1955, and January 1956 samples. Exchangeable magnesimm values are presented in Table 34. In the statistical analysis of the January 1954 data, rotation effects and the interaction effects of fertilizers with chemicals were highly significant. The level of exchangeable magnesium was signifi- cantly higher for the rotations containing a green manure crop than for the annual seedling rotation (Table 34). For the methyl bromide treat- ment, Modified series, increasing the rate of fertilization resulted in decreasing levels of exchangeable magnesium. When no methyl bromide was applied, the exchangeable magnesium.content increased with increasing rates of fertilization. Sawdust treatment effects were not quite significant for the January 1954 samples. In the statistical analysis of January 1955 data, sawdust effects and the interaction effects of sawdust with chemicals were highly significant. Rotation effects and sawdust by rotation by chemical interaction effects were significant. Exchangeable magnesium decreased in 1954, but the magnesium levels were higher for rotations that con- tained a green manure crop than for the annual seedling rotation. An increase in the rate of sawdust application produced an increase in the levels of exchangeable magnesium, with the rate of increase being greater on methyl bromide treated plots than on plots without methyl bromide treatments. - 147 - TABLE 34.--Exchangeab1e magnesium.content of soil samples (in parts per million) Date of Sampling Treatments January 1956 January January 1954 1955 Modified Regular Series Series Rotations 1. S-S-S 52.3 48.6 41.8 38.8 2. GMC-S-S 62.5 55.5 40.3 38.7 3. GMC-S-GMC 62.3 54.9 51.5 53.4 2. and 3. Gus-sa 62.4 55.2 - - Sawdust 1. Noneb 56.5 48.2 37.7 39.6 2. 15 tons per acre 60.7 53.4 44.9 43.3 3. 30 tons per acre 59.8 57.4 50.9 48.0 Mean 59.0 53.0 44.5 43.6 Coefficient of vari- ation-per cent 37.5 19.2 22.0 18.6 LSD° 1954 rotation means 5 9 LSD° 1955 rotation means 7 0 Lsn° 1956 rotation means - Regular series 4 5 LSD° 1956 rotation means - Modified series 0 o LSD° 1955 sawdust means 2 7 LSD° 1956 sawdust means - Regular series 3 7 LSD° 1956 sawdust means - Modified series 3.1 aRotations 2 and 3 were alike in 1954 and 1955. bSawdust was applied annually to the annual seedling rotation and with green manure crops on other rotations. cLeast significant difference (5 per cent level). - 148 - In the statistical analysis of the January 1956 data, one analysis was made for the Regular series and another for the Modified series. Sawdust effects were highly significant for each series. Rotation effects were highly significant for the Regular series and significant for the Modified series. Sawdust treatments resulted.in more exchangeable magnesium. The mean exchangeable magnesium content decreased during 1955, and the amount of the decrease was significantly greater for a seedling crop than for a green manure crop. By considering magnesium values for three sampling dates, another variable, time, was introduced into the analysis. Exchangeable magnesium values for January 1954, January 1955, and January 1956 were combined for each series. Rotation and year effects were highly significant for each series. For the Regular series, sawdust effects were significant and the interaction effects of sawdust with years were highly signifi- cant. For the Modified series sawdust effects and the interaction effects of sawdust with years were highly significant. Data reveal that the mean values for exchangeable magnesium decreased each year (Table 34). The rate of annual decrease was retarded by the use of sawdust or a green manure crop. It may be assumed that exchangeable magnesium will continue to decrease unless a magnesium- containing fertilizer is used. CHAPTER IX EFFECTS OF TREATMENTS ON CHEMICAL COMPOSITION OF PLANTS Phosphorus in Plants 1953 - Entire Plant For the 1953 seedling crop, the sample consisted of the whole plant. In the statistical analysis, differences in phosphorus contents of needles attributable to sawdust appeared to be highly significant. Other treatment effects were non-significant. Phosphorus means for sawdust treatments were: Treatment Phosphorus content No sawdust 1425 ppm 15 tons per acre sawdust 1665 ppm 30 tons per acre sawdust 1527 ppm Mean all treatments 1539 ppm Least significant difference (5 per cent level) 135 Coefficient of variation - per cent 18.56 The apparent superiority of 15 tons sawdust per acre over no sawdust or 30 tons per acre cannot be satisfactorily explained. This difference may be due to chance. 1954 and 1955 Needles In the statistical analysis, fertilizer treatment effects were - 149 - -150- significant for the 1954 data and highly significant for the 1955 data. Increases in rates of P205 fertilization resulted in increased phosphorus content of needles (Table 35). Fertilizer treatments 2 and 3 in Rotation 1, Modified series, has received more P205 fertilization over a three year period than fertilizer treatment 6, Regular series (Table 2). Apparently some residual effects of P205 fertilization were carried over from one year to the next. The inclusion of a green manure crop in a rotation did not have any significant effect on phOSphorus content of needles. 1954 and 1955 Stems In the statistical analysis, fertilizer treatment effects were significant for the 1954 data. Increases in rates of P205 fertiliza- tion resulted in increased phosphorus content of stems (Table 36). Based on analysis of 1955 data, it appeared that treatments of the Modified series were not significant. Rotation and fertilizer treatment effects appeared to be highly significant, and sawdust and interaction effects of sawdust with rotation appeared to be significant for the Regular series (Table 36). However, when.mean values of sub- plots were plotted, it was found that much of the variation was of a random nature rather than being due to treatments. The data reveal that phosphorus content of stems is higher for an annual seedling rotation than for the second seedling crop following a green manure crop. -151- TABLE 35.--Phosphorus content of loblolly pine needles (in parts per million) Rotations Treatments Mean 1.3-3-3 2.6MC-S-Sa 1954 Seedlings Fertilizer 1. 150 pounds P205 per acre 1451 1418 1429 2. 300 pounds P205 per acre 1492 1456 1468 3. 450 pounds P205 per acre 1511 1462 1478 Mean 1485 1445 1459 1955 Seedlings Esziilises. Modified Series 1. No P205 1461 1492 1477 2. 75 pounds P 0 per acre 1538 1513 1525 3. 150 pounds 3285 per acre 1615 1560 1587 Regular Series 4. 150 pounds P205 per acre 1452 1486 1468 5. 300 pounds P205 per acre 1557 1542 1549 6. 450 pounds P205 per acre 1650 1589 1620 Mean 1545 1530 1538 tan: 1954 fertilizer means 36 LSD 1955 fertilizer means in same rotation - Modified series 62 LSDb 1955 fertilizer means in same rotation - Regular series 86 aRotations 2 and 3 were combined in the 1954 analysis. Rotation 2 did not receive P205 fertilization in 1954. Rotation 3 was not in seedlings in 1955. bLeast significant difference (5 per cent level). - 152 - TABLE 36.--Phosphorus content of loblolly pine stems (in parts per nullion) Rotations Treatments Mean 1.3-3-3 2.Guc.s.sa 1954 Seedlings Fertilizers 1. 150 pounds P205 per acre 1674 1707 1696 2. 300 pounds P205 per acre 1634 1736 1702 3. 450 pounds P205 per acre 1804 1788 1793 Mean 1761 1744 1730 _§55 Seedlimgg Fertilizers Modified Series 1. No P 0 1648 1460 1554 2. 75 pounds P205 per acre 1736 1525 1631 3. 150 pounds P205 per acre 1783 1515 1649 Mean 1722 1500 1611 Regular Series 4. 150 pounds P205 per acre 1513 1329 1421 5. 300 pounds P205 per acre 1611 1435 1523 6. 450 pounds P205 per acre 1768 1437 1603 Mean 1631 1400 1516 Mean - Modified and Regular Series 1676 1450 1563 LSDb 1954 fertilizer means 1955 rotation means - Regular series 1955 rotation means for combined.Modified and Regular series 142 1955 fertilizer means for same rotation - Regular series 124 c.v.° 1954 9.7 C.V.c 1955 13.4 aRotations 2 and 3 were combined in 1954. Rotation 3 did not receive P 05 fertilization in 1954. Rotation 2 did not receive P205 fertiliza ion in 1954 or 1955. Rotation 3 was not in seedlings in 1955. bLeast significant difference (5 per cent level). 0Coefficient of variation - per cent. (Ellllilnl. - 153 - 1954 and 1955 Roots In the statistical analysis of 1954 data, fertilizer effects on phosphorus content of roots appeared highly significant and sawdust effects appeared significant. Increases in rates of P205 fertilization treatments resulted in increased phosphorus in roots (Table 37). A similar pattern was revealed by the 1955 data. In a statistical analysis of data for the Regular series, rotation, sawdust, fertilizer and sawdust by rotation interaction effects appeared highly significant. The interaction effects of fertilizer with rotations appeared signifi- cant. In the Modified series, rotation effects appeared significant and the interaction effect of sawdust with rotations appeared highly significant. When mean values of sub-plots were plotted, it was found that much of the variation was of a random nature rather than being due to treatments. (Table 37) Table 37 shows that annual seedling rotations with annual applications of P205 will result in a higher phosphorus content in roots than a rotation in which seedlings follow a green manure crop for one and two years without benefit of additional P205 fertilization. In Rotation 1, 1944, and Regular series, Rotation 1, 1955, phosphorus content of roots increased with increasing rates of sawdust. These differences are likely due to chance rather than real differences between treatments. Phosphorus Ratios Between Roots, Stems and Needles In 1954, Rotation 1 had received two applications of P205, whereas Rotations 2 and 3 had received only 1 application. In 1955, the Regular - 154 - TABLE 37.--Phosphorus content of loblolly pine roots (in parts per million) Rotations Treatments Mean 1.3-3-3 2.GMC-s-s° 1954 Seedliggg Fertilizer 1. 150 pounds P205 per acre 1247 1243 1244 2. 300 pounds P205 per acre 1391 1228 1282 3. 400 pounds P205 per acre 1488 1307 1367 Mean 1375 1259 1298 1955 Seedlings Fertilizer Modified Series 1. No P205 1947 1489 1718 2. 75 pounds P205 per acre 2001 1579 1790 3. 150 pounds P205 per acre 1995 1557 1776 Mean 1981 1544 1762 Regular Series 4. 150 pounds P205 per acre 1764 1443 1603 5. 300 pounds P205 per acre 1852 1485 1668 6. 450 pounds P205 per acre 2100 1476 1787 Mean 1905 1468 1686 Mean - Modified and Regular Series 1943 1505 1724 LSD:b 1954 fertilizer means 56 1955 rotation means - Modified series 432 1955 rotation means - Regular series 389 LSDb 1955 fertilizer means for same rotation - Regular series 159 aRotations 2 and 3 are combined in the 1954 analysis. They did not receive P 05 fertilization treatments in 1954. Rotation 3 was not in seedlings in 1955. bLeast significant difference (5 per cent level). - 155 - series had received full fertilizer treatments and the Modified series had received reduced fertilizer applications. Table 38 gives the phosphorus content and ratios between plant components. TABLE 38.--Phosphorus content of loblolly seedlings and the ratios between roots, stems and needles Year and Phosphorus Content Phosphorus Treatment Ratio Roots Stems Needles Roots/Stems/Needles Partsgper Parts_per Parts per million million million 1954 Seedlings Rotation 1 1375 1704 1485 1.00:1.24:1.08 Rotation 2 and 3.(combined) 1259 1744 1445 1.00:1.38:1.15 1955 Seedlings Modified series 1762 1611 1530 1.00:0.91:0.87 Regular series 1686 1516 1546 1.00:0.90:0.92 Potassium in Plants 1953 - Entire Plants For the 1953 seedling crop, the sample consisted of the whole ‘plant. In the statistical analysis, there were apparently no differential effects of chemical or fertilizer treatments on the potassium content of the plant. Sawdust effects alone were highly significant. Sawdust means for 1953 data were: Treatment Potassium content No sawdust 5535 ppm 15 tons per acre 5834 ppm - 156 - 30 tons per acre 5075 ppm Mean for all data 5481 ppm Least significant difference (5 per cent level) 389 Coefficient of variation - per cent 15.0 Differences in potassium content between seedlings grown with no sawdust and with 15 tons of sawdust per acre were not significant. An application of 30 tons of sawdust per acre produced a significant reduction in either potassium uptake or potassium accumulation by the seedlings. 1954 Needles Needles, stems and roots of seedlings from the 1954 and 1955 crops were analyzed separately. Potassium content of 1954 seedling needles are presented in Table 39. TMBLE 39.--Potassium content of loblolly pine needles - 1954 crop (in parts per million) Rotations T tm t Nean tea 6“ s 1. S-3 2. and 3. ems-3a 1 Chemicals 1. No methyl bromide 5318 4774 4955 2. Methyl bromide 4843 4411 4555 Sawdust 1. None 5383 4586 4852 2. 15 tons per acre 5065 4600 4755 3. 30 tons per acre 4792 4593 4659 Mean 5080 4593 4755 LSDb Chemical and rotation means 396 LSDb Two sawdust means for same rotation 354 aRotations 2 and 3 received the same treatments in 1953 and 1954. They were in a green manure crop in 1953 and in a seedling crop in 1954. bLeast significant difference (5 per cent level). - 157 - Chemical and rotation treatment effects and the interaction effects of sawdust with chemicals, sawdust with rotations and sawdust with fertilizers were significant. Methyl bromide treatments reduced the potassium content of needles. A green manure crop, preceeding seedlings in a rotation, resulted in a lower potassium level than an annual seedling rotation. When methyl bromide was included in the treatments, potassium in needles decreased with increasing rates of sawdust. When methyl bmomide was omitted, sawdust treatment effects were not significant. For the annual seedling rotation, the potassium level decreased with increasing rates of sawdust. When a green manure crop was included in the rotation, sawdust treatments did not produce any significant differences. 1955 Needles Data for 1955 needles were analyzed separately for the Regular series and the Modified series. Potassium content of needles are presented in Table 40. For the Regular series,rotation and fertilizer effects were highly significant and the interactions of fertilizers with rotations were significant. For the Modified series only fertilizer effects were significant. Rotation 1, under annual cropping, has received annual appli- cations of potassium.fertilizer. The Modified series and the Regular series received like fertilizer treatments in 1953 and 1954, that is, treatment pairs 1 and 4, 2 and 5, and 3 and 6. Therefore, fertilizer treatments 2 and 3 in the Modified series had received.more potassium (Ill. . lsislgl. .11.}. 1 - 158 - TABLE 40.--Potassium content of loblolly pine needles, 1955 crop (in parts per million) Rotations Treatments Mean 1. S-S-S 2. GMC-S-Sa Modified Series Fertilizer 1. None 5227 5439 5333 2. 40 pounds K20 per acre 5591 5477 5534 3. 80 pounds K20 per acre 5872 5534 5703 Mean 5563 5484 5523 Regular Series Fertiliserb 4. 80 pounds 0 per acre 5585 5346 5465 5. 160 pounds 20 per acre 6341 5578 5959 6. 240 pounds K20 per acre 6532 5638 6085 Mean 6153 5520 5837 LSDc Fertilizer means - Modified series 253 LSD° Fertilizer means - Regular series 264 LSD° Two fertilizer means for same rotation - Modified series 358 LSD° Two fertilizer means for same rotation - Regular series 375 LSD° Two rotation means - Regular series 458 0.7.“1 Modified series 9.7 c.v.d Regular series 9.6 1954. aRotation 2 did not receive fertilizer treatments in 1954 or 1955. bFertilizer rate for rotation l and 2 in 1953 and for rotation 1 in °Least significant difference (5 per cent level). dCoefficient of variation - per cent. - 159 - over the three year period than treatment 4 in the Regular series. The values given in Table 40 indicate that some residual effects were carried over from year to year. Annual applications of 160 and 240 pounds per acre of K20, with the annual seedling crop rotation, resulted in the highest concentration of potassium in needles. When means for three years are compared, it appears that factors other than rates of K20 fertilization may affect uptake or accumulation of potassium by needles. Means by years were: 1953 seedlings (entire plant) 5481 ppm 1954 seedlings - needles only 4755 ppm 1955 seedlings - needles only Modified series 5523 ppn Regular series 5837 ppm 1954 and 1955 Stems In the analysis of 1954 data Rotations 2 and 3 were combined. Rotation effects were significant. The potassium content of stems was higher for a seedling crop that followed a green manure crop than for one that followed another seedling crop (Table 41). The statistical analysis of data for the 1955 stems indicated that fertilizer effects on potassium content of stems were highly significant for the Modified series and significant for the Regular series. Fertilizer treatments 2 and.3, Modified series 1955, had received more K20 fertilization over a three year period than treat- ment 4, Regular series. Apparently some residual effects of potassimn fertilization were carried over from one year to the next. Rotation 2 did not receive K§O fertilization in 1954 or 1955. The potassium content of the stems decreased.when a seedling crop - 160 - TABLE 41.--Potassium content of loblolly pine seedling stems (in parts per million) Rotations Treatments Mean 1. 3.3.3 2. GMC-S-Sa 1954 Seedlings Fertilizerb 1. 80 pounds 0 per acre 6991 8193 7792 2. 160 pounds 0 per acre 6922 8340 7867 3. 240 pounds 20 per acre 7372 8392 8052 Mean 7095 8308 7903 1955 Seedlings Fertilizerb Modified Series" 1. No 0 5227 5536 5381 2. 40 pounds xgo per acre 5894 6163 6029 3. 80 pounds K20 per acre 6188 6217 6202 Regular Seriesc 4. 80 pounds 0 per acre 5760 5387 5574 5. 160 pounds 20 per acre 5878 5719- 5798 6. 240 pounds K20 per acre 6221 5853 6037 Mean - Modified and Regular Series 5861 5813 5837 LSDd 1954 rotation means 703 1.3139l 1955 two fertilizer means for same rotation - Modified series 421 LSD 1955 two fertilizer means for same rotation - Regular series 416 £1Rotations 2 and 3 are combined for 1954. Rotation 3 was not in seedlings in 1955. bRotation 2 did not receive fertilizer treatments in 1954 or 1955. °The two series received similar fertilizer treatments in 1953 and 1954. dLeast significant difference (5 per cent level). - 161 - followed a seedling crop without benefit of additional fertilization. 1954 and 1955 Roots In 1954, there were no significant effects of treatments on potassium content of seedling roots. The range was 2925 ppm.to 6275 ppm, with a mean of 4411 ppm. The coefficient of variation was 8.4 per cent. There was considerable variation within treatments. It is difficult to remove completely all soil particles from.the roots. Therefore, determination of mineral content of whole roots are subject to considerable experimental error. Fertilizer effects in 1955 were highly significant for each of the series. The interaction effects of fertilizers with rotations were significant for the Regular series. Mean potassium contents of roots according to fertilizer and.rotation treatments are presented in Table 42. Fertilizer treatments 2 and.3 in Rotation 1, Modified series, had received more K20 fertilization over a three year period than treatment 4, Regular series. (Table 2) Apparently some residual effects of K20 fertilization were carried over from one year to another. There is no logical explanation for the pattern observed for fertilizer treatment 6, Rotation 2 (Table 42). In general, data reveal that potassium content of roots increases with increasing rates of K¢O fertilization. Potassium.Ratios Between RootsL_Stems and.Needles Table 43 gives the mean potassium levels for roots, stems and needles, and the RISIN ratios. .Aaopoa uses won my eosouommflo usooflMH:an uncoqo .omma an a :ofiueyou How one ”mad ca N one H scapeuou new open Honflaeuuom any we: manage. .mmma Ho mama cw scaveuwawuuom ONM 0>Hooon yo: poo N acayeyome Hon seamen Hoaooom u scaucuon case may now eases Hoeaafiyuem 09mg own nuance oofimfiooz n cofiyeuou case any new asses Honaaavuom 09mg some some seem seem memo seen some case nod emu season can .o some «new oaoo .aco and 0N mosses con .o seem . seen some case and o mosses as .e Ammmd u Honaawahom - 162 - mownom Meammmm some mean some case and can messed on .e one» name some case and can cocoon as .N seen one» mean can oz .H some - nonessenom seesaw ooeeecom sm-m-omw .a m-e-m .H coax eusoaueeha eoofiueaom / “goddamn hen named one done mama .eaoou condense esfim.haaoanoa mo «sousoo saneuepomua.«v mamsH (Eli!) ii . . 1:1 3......) - 163 - TABLE 43.--Potassium.content of loblolly pine seedlings and ratios between roots, stems and needles Year and Phosphorus Content Phosphorus Ratio T tm rea ent Roots Stems Needles Roots/StemslNeedles Parts per Parts per Parts per ndllion million million 1954 Seedlings Rotation 1 4125 7095 5080 1.00:1.72:1.23 Rotations 2 and 3 4554 8308 4593 1.00:1.82:1.01 .All treatments 4411 7903 4755 1.00:1.79:1.08 1955 Seedlings Modified series 5645 5871 5524 1.00:1.03:0.98 Regular series 5737 5803 5837 1.00:1.02:1.02 All treatments 5691 5837 5680 1.00:1.03:1.00 Table 43 reveals that levels of potassium concentration in plantsmay vary from one year to another and that the ratios between roots, stems and needles may not be constant. Calcium in Plants Calcium was not included.as a treatment. However, some of the treatments that were applied.had.significant effects on the calcium content of seedlings. l§_3 Entire Plant The only significant difference in calcium.content of the entire seedUing'was due to sawdust treatments. Means for sawdust treatments were: - 164 - Treatment Calcium content No sawdust 1585 ppm 15 tons sawdust per acre 1586 ppm 30 tons sawdust per acre 1488 ppm Mean - all treatments 1553 ppm Least significant difference (5 per cent level) 83 Coefficient of variation - per cent 11.4 Sawdust applied at a rate of 30 tons per acre reduced calcium concentration in the plant. 1954 and 1955 Needles In the statistical analysis of data on the 1954 seedlings, differences due to rotation and sawdust treatments were highly significant. .A green manure crop in the rotation increased the concentration of calcium in needles (Table 44). It is possible that a green manure crop may be very effective in maintaining a high level of available calcium, perhaps by converting relatively unavailable calcium to a form that is readily taken up by pine seedlings. Calcium concentration in needles decreased as the rate of sawdust application increased. For the 1955 data, rotation and sawdust effects were highly significant and rotation by sawdust interactions were significant for the Modified series. For the Regular series, all treatment effects were non-significant. Rotation, sawdust, and rotation by sawdust interaction effects barely missed significance. When mean values of sub-plots were plotted, it was found that much of the variation was due to chance rather than being due to treatments. Calcium content of needles declined from 1954 to 1955 (Table 44). -165- or» «av awn on» can «an «no man no» easesueeuu and euoom one anon new «so need was coda «ona «mm coax mam u u com 3 u HNHA coma Hon euoe nod moon on .n moo - - Hoe - - goes ”one moo case was soon on .« mum . a do» u s mafia aona anon econ .H «esosem .mmmfim owed coma wood «and ones awed Haas one" mean sea: omna fiend coma Anna mmoa ooaa woos esan wood euoe won econ on .o moon noon bond amen mama «NHH omen anon coma once nod econ ma .« onwa «and man” nmna mood Head noun wen" «man one: .H uesosem eeaooez use: nmuMnozw mumum use: anmuuzw mumfm « a u a least emuuxw mfm eeauem Menacem eequem courage: o .u n a Melanoma .eoeoeeom omen escauevom vmaa Illl .I (1" I'll) . “90‘2”le Ha eta and; flown mama «3:. god .ubflfinfioon Sudan AHHOHQOH “no HGOHflOO §«0chlc.v# ans—v - 166 - .Aaoboa peso won my oesoHOMMfio vccOHMflsofie “usage ewmmH fiH NHfiOEUOHH “mugged“ O>HOOOH PO—u fig N GOfl¥U¥O~f .omma ca mucosuoony aososom o>aooou «os_ofio hose .vwma :« oceanaoo ones.» one N escayeuomo an no moa no no am now on «ma oofihom Hoasoom a mason soausuon mmma oomA oases compouou omma 09mg epoom moanom oceanooz i noses sofiyouon mmma 09mg mecca wannabe emma onmq mecca cofiuouon vmma camA esoym magnum condom .. mecca madman on: some soeaom coaeeooz .. cases 5338 32 some .53 sneeze. 33 some .58. 5338 33 some oedpooz .Ivlnlr I ‘ll - 167 - Although no covariance or regression was computed to measure the relationship of soil and plant calcium content, it is reasonable that such a relationship should.exist and be positive in nature. The level of available calcium, expressed.as calcium carbonate, decreased from 2665 pounds per acre in January 1955 to 2177 pounds per acre in January 1956. 1954 and 1955 Stems The same treatments affected calcium content in stems as in needles. In the analysis of data for the 1954 seedlings, rotation and sawdust effects were highly significant. A green manure crop in the rotation increased the concentration of calcium in stems. Calcium content decreased as the rate of sawdust increased (Table 44). In the statistical analysis of data for the 1955 seedlings, ’ differences due to rotation effects were highly significant. The residual effect of the green manure crop extended over the second.year of seedlings, with the green manure crop increasing the calcium con- tent of stems. 1954 and 1955 Roots Rotation effects on calcium.content of roots were highly significant in 1954, and for the Regular series in 1955. A green manure crop in a rotation increased.the calcium content of roots for two consecutive years following the green manure crop (Table 44). Calcium Ratios Between RootngStems and Needles Calcium concentration in roots, stems and needles decreased from - 168 - 1954 to 1955. Means and ratios are: Year Calcium content and ratios Roots Stems Needles 1954 means in ppm 472 1160 2131 Ratio 1.00 : 2.46 : 4.51 1955 means in ppm 370 906 1374 Ratio 1.00 : 2.45 : 3.71 RelationshipiBetween the Level of Available Calcium in the Soil and Calcium.Concentration in Plants A decrease in the level of available calcium in the soil was associated with a decrease in the concentration in the plant. The levels of available calcium in soils and calcium content of plants are: calcium.content 1954 1955 Soil 533 ppm 435 ppm Plant Roots 472 pm 370 ppm Stems 1160 ppm 906 ppm Needles 2131 ppm 1374 pm Magnesium.in Plants Magnesium was not included as a treatment. However, some of the treatments that were applied had significant effects on the magnesium content of seedlings. 1953 - Entire Plant Sawdust effects on magnesium content were highly significant. Means for sawdust treatments were: Treatment Magnesium.content No sawdust 1007 ppm 15 tons sawdust per acre 1036 ppm 30 tons sawdust per acre 939 ppm Mean all treatments 992 ppm - 169 - Least significant dufference (5 per cent level) 66 Coefficient of variation - per cent 14.1 Applications of 30 tons of sawdust per acre resulted in signifi- cantly lower magnesium concentrations than did no sawdust or 15 tons of sawdust per acre. 1954 Needles, Stems and Roots The pattern of results was similar for roots, stems and needles, although the degree of significance was not the same for all variables. Sawdust treatment effects were significant for roots but not for stems or needles. Applications of 30 tons of sawdust per acre resulted in significantly lower magnesium concentrations in roots than did no sawa dust or 15 tons of sawdust per acre (Table 45). Chemical treatment effects were highly significant for roots, significant for needles, and nearly significant for stems. The magnesium content of roots, needles and stems was reduced when methyl bromide was applied to seedbeds prior to a seedling crop. Since methyl bromide treatments did not significantly affect the concentra- tions of phosphorus, potassium or calcium in plants, there is no logical reason why it should affect magnesium concentrations. Differences due to rotation effects were highly significant for needles, stems and roots. Higher magnesium concentrations occurred on rotations that included a green manure crop than on the annual seedling rotation (Table 45). 1955 NeedlengStems and Roots The Modified and Regular series were analyzed both separately and - 170 - TABLE 45.--Magnesium content of loblolly pine seedlings (in parts per million) Plant Component Treatment Roots LSD“ Stems LSD“ Needles L31)El 1954 Seedlings Rotations 30 73 33 1. S-S 964 955 784 2. and 3. GMC-S 1127 1163 891 Chemicals 21 NS° 26 1. No methyl bromide 1140 1127 881 2. Methyl bromide 1006 1060 830 Sawdustb 18 113" NS" 1. None 1082 1094 862 2. 15 tons per acre 1085 1095 859 3. 30 tons per acre 1051 1093 846 Mean all treatments 1073 1094 855 Coefficient of vari- ation-per cent 6.3 6.8 7.9 1955 Seedlimgg Rotations Modified Series 101 113° 113° 1. 3-3-3 1117 916 1002 2. GMC-S-S 1008 998 1048 Regular Series 113° 113° 113° 1. S-S-S 1148 930 1063 2. GMC-S-S 1132 :1962 #1098 Mean all treatments 1101 977 1053 Coefficient of vari- ation-per cent 12.5 12.8 12.4 _; * “Least significant difference (5 per cent level). hOne sawdust treatment was applied to each seedling crop. SNon-significant. - 171 - in combination. Rotation effects on roots in the Modified series were significant. The magnesium content of roots was higher for the annual seedling rotation than for a rotation that included a green manure crop (Table 45). This variation was probably of a random nature rather than being due to treatment since the effects were opposite to those produced in 1954. Mggnesium.Ratio Between Roots, Stems and.Needles Magnesium.content did not vary appreciably between roots, stems and needles. Mean levels and ratios for 1954 and 1955 were: Year Magnesium content and ratios Roots Stems Needles 1954 means in ppm 1073 1094 885 Ratio 1.00 = 1.02 : 0.82 1955 means in ppm 1101 977 1053 Ratio 1.00 : 0.89 : 0.96 Although the level of available magnesium.in the soil decreased from 368 to 309 pounds per acre of magnesium carbonate between January 1955 and January 1956, there was no marked decrease in magnesium concentration of the plant. CHAPTER X FIELD SURVIVAL 1953 Seedlings Nursery treatments had no significant effects on field survival and initial growth of 4320 seedlings that were out-planted on the North Auburn experimental area in February, 1954. Mean values for survival and height growth are presented in Table 46. TABLE 46.--Mean survival and height increase for loblolly pine seed- lings planted February 1954 Date of , a Height 3 Measurement Survlval C'V' Increase C'V' Per cent Per cent Feet Per cent biay 1954 4e]. - " November 1954 12.6 0.51 23.6 October 1955 12.9 2.24 17.4 “Coefficient of variation. Calendar year 1954 was very unfavorable for seedling survival. Rainfall recorded for the year was only 28.44 inches, 24.35 inches below'average. 1954 Seedlings Seedlings from the 1954 crop were out-planted in January, 1955. - 172 - - 173 - A total of 5184 seedlings were planted on the North Auburn experimental area and 5076 seedlings were planted on the Autauga County experimental area. Height growth measurements were obtained for plants on the North Auburn experimental area. All dead seedlings were dug and carefully examined to determine the cause of death if possible. On the North Auburn experimental area pales weevil attacked seed- lings on an area that had been cleared recently of pine saplings. Mortality was rather heavy in one locality. On the Autauga County experimental area, white grub damage was rather heavy. The planting site occupied an abandoned field or pasture, and the grub population in the soil was rather heavy. A small percentage of dead stock was found to be planted with U- roots. Survival of planted stock was not affected by nursery treat- ments. Mean survival for the two areas is presented in Table 47. TABLE 47.-~Surviva1 of loblolly pine seedlings planted January 1955 Coefficient of Plantation Mean Survival Variation Per cent Per cent Actual survival North Auburn 93.00 6.95 Autaugaville 56.82 27.4 Adjusted survivala North Auburn 98.79 3.00 Autaugaville 93.93 9.8 a‘Excludes losses attributed to pales weevil, white grubs, and improper planting. - 174 - The statistical analysis indicated that rotation and chemical treatment effects on height growth were highly significant for the North Auburn planting. Mean value by treatments were: Treatments One-year height m No methyl bromide 0.687 feet Methyl bromide 0.775 feet Rotation l - S-S 0.688 feet Rotations 2 and 3 - GMC-S 0.753 feet iean all treatments 0.731 Least significant difference (5 per cent level) 0.051 Coefficient of variation - per cent 15.5 Growth was not measured at the Autauga plantation. 1955 Seedlings A total of 4,320 seedlings were out-planted at each location in 1955. Although the degree of significance differed for some treatments, the survival patterns were similar on the two sites. A summary is given in Table 48. Rotation effects on spring survival were statisti- cally significant for the Modified series on the North Auburn experi- mental area and for the Regular series on the Autauga County experimental area. Series effects were highly significant at Autauga. For October survival, rotation effects were highly significant for both series at North Auburn and significant for the Regular series at Autauga. Data in Table 48 reveal clearly that, under the conditions of this study, a green manure crop in the rotation had a significant positive effect on survival of out-planted seedlings. The cause of this effect is not - 175 - TABLE 48.--Survival of out-planted loblolly pine, 1955 seedling crop (in per cent) North Auburn Autauga County Experimental Experimental Treatment Area Area Means LSDa Means LSDa May Survival Rotations Modified Series 2.28 usb 1. S-S-S 95.28 81.14 2. GMC-S-S 97.60 83.68 Regular Series NSb 4.04 l. S-S-S 95.20 86.39 2. GMC-S-S 95.29 91.20 Means - Modified and Regular Series 95.84 85.60 Coefficient of variation - per cent 5.1 10.0 October Survival Rotations Modified Series 3.08 usb 1. 3.3.3 87.22 76.72 2. GMC-S-S 92.13 78.96 Mean 89.68 77.84 Regular Series 3.08 4.72 l. S-S-S 88.34 79.29 2. GMC-S-S 92.04 88.05 Means 90.19 83.67 Means - Modified and Regular Series 89.93 80.76 Coefficient of variation - per cent 7.2 12.6 ¥ h “Least significant difference (5 per cent level). bNon-significant. - 176 - clearly understood. It was shown that a green manure crop tends to maintain or increase the amount of available calcium and.magnesium.in the soil. It is possible that the nutrient ratio within the plant was affected favorably by conditions that resulted from the green manure crop. Although fertilizer effects were not significant, survival of seedlings from the Regular series was consistently higher than that of the Modified series. This difference was highly significant for planting on the dry sandy site on the Autauga County experimental area. Finding a way to insure high field survival is the final objective in most phases of nursery research. In this study, nursery treatments did not significantly affect field survival of the 1953 seedlings. Rotation effects on seedlings were significant in 1954 and 1955. A continuation of the study should produce a wider range between treat- ment means, and the effects of treatments on survival should be more pronounced. CHAPTER XI SUMMARY AND CONCLUSION Summary The effects of various soil treatments on germination of loblolly pine seed, development of seedlings, survival of out-planted seedlings, chemical content of seedlings and on soil characteristics were investigated during a three-year period. Treatments included (1) three rotations that included different combinations of green manure crops and seedlings, (2) methyl bromide, (3) three levels of sawdust and (4) three levels of phosphorus and potassium. Soil samples were collected.before initial treatments were made and thereafter annually in January from each of the 324 subuplots. All samples were subjected to chemical and physical analysis in the laboratory to ascertain the effects of the treatments on soil reaction, organic matter content, cation exchange capacity, available phosphorus, available potassium, exchangeable calcium and exchangeable magnesium. Data on seed germination, seedling mortality in the seedbed and percentages of plantable seedlings was Obtained during the growing season. Representative samples of seedlings were selected at the time of lifting. Seedling characteristics were detenmined by measurements and chemical contents. Field survival was determined.by out-planting of other seedlings. - 177 - - 178 - Soil and plant data were statistically analyzed, using the analysis of variance technique. Many of the results were positive in nature. In other instances, conflicting results were obtained from one year to another. The significant differences due to treatment effects increased when the range of fertilization was expanded in the third year. Conclusions From this study, it can be stated tentatively that loblolly pine seedlings can be grown annually on the same area for a period of several years provided sufficient quantities of nitrogen, phOSphorus and potassium are applied. Inclusion of a green manure crop in a rotation had some effects on the soil and seedlings. A leguminous green manure cr0p tended to maintain the pH level of the soil, whereas soil acidity was increased as a result of the annual seedling rotation. A green manure crop alternating with a crop of seedlings resulted in an increased level of available potassium. The level increased preportionately with the rate of potassium fertilization. When a green manure crop alternated with two consecutive seedling crops and potassium fertilizer was not applied to the second seedling crop, there was a marked decrease in the level of available potassium during the second year. Available magnesium in the soil was increased when a green manure cr0p was included in the rotation. The potassium content of loblolly pine needles, the magnesium content of stems and needles, and the calcium content of roots, stems, - 179 - and.needles were higher for the rotation in which a green manure crop alternated with one year of seedlings than for other rotations. The percentage of plantable seedlings and the field survival of out-planted stock was higher for seedlings from the rotations that included a green manure crop than for the annual seedling rotation. Methyl bromide treatments did not affect germination of seed or survival and growth of seedlings. The effects of methyl bromide treatments on the availability of mdneral nutrients was not consistent from one year to another. Some soil properties were changed by the use of sawdust alone or by the interaction of sawdust and a green manure crop. Soil acidity increased with increasing rates of sawdust applied annually. Yet, the levels of available potassium, calcium and.magnesium increased with increasing rates of sawdust. Organic matter content was maintained at a nearly constant level by the annual application of fifteen tons of sawdust per acre, by fifteen tons of sawdust per acre in the rotation of a green manure crop with one year of seedlings, or by thirty tons of sawdust per acre in the rotation of a green manure crop with two years of seedlings. Organic matter content was increased.by annual applications of thirty tons of sawdust per acre or by thirty tons of sawdust in the rotation of a green manure crop with one year of seedlings. The exchange capacity of the soil increased with increasing rates of sawdust. An application of fifteen tons of sawdust per acre and a green manure crop alternating with one year of seedlings resulted in an increase approximately equal to that obtained.with two consecutive - 180 - applications of sawdust. Applications of thirty tons of sawdust per acre did not affect germination of seed or mortality of seedlings. However, the percentages of Grade 1 seedlings were reduced by the application of thirty tons of sawdust per year in the annual seedling rotation, but increased when thirty ton applications of sawdust per acre were included with a green manure crop. An annual application of sawdust resulted in reductions of shoot volume, stem length, stem diameter, and green and oven-dry shoot weights. Shoot/root ratios, based both on volume and on weight, were reduced with increasing rates of sawdust. When a rotation con- tained a green manure crop, applications of sawdust resulted in an increase in weights of oven-dry shoots. Mineral fertilizers can be applied to the seedbed area before preparation of seedbeds. Annual applications of 300 pounds of P205, 160 pounds of K20, and 100 pounds of nitrogen per acre did not reduce germination of seed. However, residual effects of annual fertilization over a period of several years may affect genmination of seed. After three annual applications of 450 pounds of P205 and 240 pounds of K20 per acre, there was a reduction in germination. Fertilizer treatments did not affect mortality of seedlings in the seedbeds. There were no significant differences in the percentages of plantable seedlings for different fertilizer rates within the range of 150 pounds of P205 plus 80 pounds of K20 and 450 pounds of P205 plus - 181 - 240 pounds of K 0 per acre. When applications of P20 and K 0 were 2 5 2 emitted the percentage of plantable seedlings was reduced, even though rates of nitrogen remain unchanged. The original level of available phOSphorus in the soil was not maintained by the heaviest rate of P205 fertilization, 450 pounds of P205 per acre. There was an annual decrease in the mean level of available phosphorus, and a correspondingly greater decrease with smaller rates of phosphorus fertilization. .A relatively stable level of available potassium was maintained ‘when 160 pounds of K20 were applied with each seedling crop. Decreasing rates of potassium fertilization resulted in decreasing levels of available potassium. In an annual seedling rotation the phosphorus and potassium content of stems, needles, and roots increased with increasing rates of phosphorus and potassium fertilization. Loblolly pine seedlings made a heavy demand on calcium and magnesium in the soil. For each seedling crop there was a decrease in the levels of exchangeable calcium.and.magnesium, but the rate of decrease was reduced.when sawdust or green manure crops were included in the treatment. It is expected that pronounced phosphorus, potassium, calcium, and magnesium deficiencies will develop in seedlings if these elements are not included in fertilizer or organic matter applications. It should.be possible to find a relationship between visible deficiency symptoms and mineral levels in the plant tissue and in the soil solution. LITERATURE CITED LITERATURE CITED AALTONEN, V. T. 1948. Boden und Weld. Berlin: Paul Parey. ADDOMS, RUTH M. 1937. Nutritional studies of loblolly pine. Plant Physiol. 12(1): 199-205. ALDRICH-BLAKE, R. N. 1935. A note on the influence of seed weight on plant weight. Forestry 9: 54-57. ALLEN, R. M. and MAKI, T. E. 1955. Response of longleaf pine seedlings to soils and fertilizers. Soil Sci. 79(5): 359-362. ALLISON, P. E. 1955. The enigma of soil nitrogen balance sheets. In Advances in Agronomy VII. New York: Academic Press Inc. , and ANDERSON, M. S. 1951. The use of sawdust for mulches and soil improvement. U. S. Dept. of Agr. Circ. 891. ANDERSON, CLARENCE E. 1933. The effect of commercial fertilizers upon white pine seedling stock. Unpublished Master's thesis, Iowa State College Library. ANDERSON, C. H. 1934. Root development in seedlings of Norway pine, balsam fir and white spruce with relation to the texture and.moisture of sand soils. Unpublished Master's thesis, Univ. of Wisconsin Library. ANDO, A. 1952. The effect of fertilizers on the nutrient content of Sugi. (Cryptomeria japonica seedlings). Tokyo Univ. For. Bul. 43: 91-100. (Forestry Abstracts l4) and Hukasaku, T. 1953. The effect on the growth of Sugi (Cryptomeria japonica) one-year seedlings of increasing applications of fertilizers. Tokyo Univ. For. Bul. 44: 15-22. (Forestry Abstracts 15) ANDREWS, L. K. 1941. Effects of certain soil treatments on the develop- ment of loblolly pine nursery stock. Jour. Forestry 39: 918-921. ARGETSINGER, LYLE M. 1941. Chemical fertilizer treatments of Norway pine transplants in the University of Michigan Nursery. 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