I I I 71-18,266 OYA, Kazuhiro, 1934EVALUATION OF POTASSIUM AVAILABILITY OF FOUR MICHIGAN SOILS. Michigan State University, Ph.D., 1970 Agriculture, soil science U n iv e r s it y M ic ro film s , A XEROX C o m p a n y , A n n A rb o r, M ic h ig a n EVALUATION OF POTASSIUM AVAILABILITY OF FOUR M I C H I G A N SOI IB By Ktzuhiro Oya A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Crop and Soil Sciences 1970 PLEASE NOTE: Several pages contain colored illustrations. Filmed in the best possible way. UNIVERSITY MICROFILMS ABSTRACT EVALUATION OF POTASSIUM AVAILABILITY OF FOUR M ICHIGAN SOILS By Kazuhiro Oya Since the availability of* soil potassium is affected b y plant and soil factors, the supply of this element in four Michigan soils varying in chemical, physical and mineralogical properties was studied using wheat, sorghum and tomatoes as the indicator crops. From December, 2 of sorghum, 1968 to April, 1970 3 crops of wheat, and 1 tomato crop were grown in sequence in the greenhouse on Brookston loam, Genesee loam, Kalamazoo sandy loam, and Landes-Abscota sandy loam. The following levels of potassium were applied on all soils: 0 , 200, 400, 8 0 0 , and 1,600 pounds per acre. Applied potassium markedly affected plant yields obtained on Genesee loam, Kalamazoo sandy loam, and especially on Landes-Abscota sandy loam. Potassium concentration In the plants Increased with Increasing levels of applied potassium while the concen­ tration of plant calcium and magnesium generally decreased. These findings were verified by the application of the electron microprobe X - ray technique. Kazuhiro Oya Potassium uptake by the plants grown on all the soils was significantly affected by potassium treatments: however., plant uptake of calcium and magnesium varied with the crop end the soil. The potassium supplying p o w e r of the soils are in the following order: Brookston loam > Kalamazoo sandy loam > Landes-Abscota sandy loam > Genesee loam. Nonexchangeable potassium was retained at levels higher than the original levels, even after 5 croppings, when potassium was initially applied at the rate of 400 or more pounds of potassium per acre on Brookston loam, Genesee loam, and Landes-Abscota sandy loam, and at the rate of 1,600 pounds of potassium per acre on Kalamazoo sandy loam. Subsequent to a 13-month incubation period of the soils with various levels of applied potassium, b o t h the exchangeable and nonexchangeable potassium content of all soils increased except for that of Kalamazoo sandy loam. The alternate wetting and drying treatments resulted in the fixation of potassium in the following order: B r o o k ­ ston loam > Landes-Abscota sandy loam Kalamazoo sandy loam. > Genesee loam > The fixation or release of p o t a s ­ sium by the soils subjected to freezing and thawing was of minor importance. Of the various criteria employed for evaluating Q potassium availability -^K , A R e , exchangeable, no n e xchange­ able, and total potassium were generally most m e a n i n g f u l . Kazuhiro Oya The percentage of vermiculite and m i c a in the clay fractions of the original soils were determined as: and 27.6 for Brookston loam (1 8 .5^ clay): Genesee loam (11.5^ clay): loam (13.5^ clay): 8.3 10.0 and 18.0 for 1.7 and 18.0 for Kalamazoo sandy and 8.9 and 28.8 respectively for Landes- Abscota sandy loam (l4.8$ clay). The following clay minerals were found to predominate in the four soils studied: kaolinite* montmorillonite in Brookston loam and vermiculite-chlorite-montmorillonite inter­ stratified minerals in Genesee loam; vermiculite-chlorite interstratified minerals and kaolinite in Kalamazoo sandy loam; and vermiculite-chlorite interstratified minerals in Landes-Abscota sandy loam. The vermiculite content of the clay fractions tended to increase as soil potassium was depleted b y cropping* whereas the m i c a content tended to increase when the soils were incubated with 1*600 pounds of potassium per acre. These tendencies were most pronounced with Landes-Abscota sandy loam. This "thesis is affectionately dedicated to my wife Sachiko ii ACKNOWLEDGMENTS The author sincerely expresses his deepest a p p r e ­ ciation to Dr. J. C. Shickluna,, who as the major professor consistently guided the author to accomplish his research. He is also grateful to D r s . R. L. Carolus,, R. L. Cook, R. L. Donahue, B. D. K n ez e k and L. S. Robertson for their numerous suggestions and kind encouragement. The author thanks all other faculty members and graduate students of the Department of Crop and Soil Sciences for their warm and friendly assistance to perform his work. Special thanks are expressed to Dr. E. P. Whiteside and David Lietzke for their help in the identification and collection of the soils. Appreciation is extended to Mr. V. E. Shull of the Department of Horticulture for operation of the electron microprobe; to Messrs. M. McKenzie and J. Oaks for their help in the greenhouse and field laboratory; and to Mrs. David A. G. Green who expertly proofread the manuscript. The author's study at Michigan State University was made possible by the Ryukyuan Scholarship Program under the U. S. Department of the Army. iii TABLE OF CONTENTS INTRODUCTION Chapter I LITERATURE REVIEW ............................ A. Importance of* Potassium in Plant Metabolism . . . . . . . . . . . . . B. Potassium Absorption b y P l a n t s ......... 1. 2. 3. 4. 5. C. Dynamic Nature of Soil Potassium 1. 2. 3. D. Differential Absorption of Potassium b y Plant Species Effects of Potassium Level in Soil Effects of Other Nutrients in Soil on Potassium Availability Effects of Physical Factors in Soil on Potassium Availability Effects of Clay Mineralogy of Soil on Potassium Availability . . . Origin of Soil Potassium Factors Affecting Potassium Availability Mechanisms of Potassium Release and Fixation in the Soil Potassium Availability Measurement. 1. 2. Biological Methods Chemical Methods , . II S O I L CROPPING EXPERIMENT I N T H E GREENHOUSE EMPLOYING WHEAT* SORGHUM* AND TOMATO AS T H E INDICATOR P L A N T S ............................ 30 A. Experimental Methods and Materials 1. 2. 3. B. 3. 4. Soils Plants Plant Analysis for Potassium* Calcium* and Magnesium Plant Yields Potassium* Calcium* and Magnesium Concentrations In the Plants Potassium* Calcium* and Magnesium Uptake of the Plants Quantity of Potassium Released to the Plants from Nonexchangeable Forms CHEMICAL PROPERTIES OF T H E SOILS A. ............ 96 Methods and M a t e r i a l s ............................ 96 1. 2. 3. 4. B. 30 Results and D i s c u s s i o n ..........................42 1. 2. III ......... Exchangeable and Nonexchangeable Potassium Potassium Release and Fixation by Wetting and Drying Treatments Potassium Release and Fixation by Freezing and Thawing Treatments Studies of Potassium Potential and Quantity-Intensity Relationships of Potassium in Original* Cropped* and Incubated Soils Results and D i s c u s s i o n ........................ 101 1. 2. 3. 4. 5- Exchangeable and Nonexchangeable Potassium Potassium Release and Fixation by Wetting and Drying Treatments Potassium Release and Fixation b y Freezing and Thawing Treatments Quantity-Intensity Relationships of Soil Potassium in Original* Cropped* and Incubated Soils Relationships between Plant Uptake of Potassium and Various Measurements of Soil Potassium v IV PHYSICAL AND MINERALOGICAL PROPERTIES OF T H E S O I L S ..................................... 124 A. 124 Methods and Materials 1. 2. 3. B. Mechanical Analysis X-ray Diffraction Studies Cation Exchange Capacities and Total Potassium of the C l a y Fractions Results and Discussion 1. 2. 3. 4. ..................... .................. 129 Textural Designation of the Soils Active Fractions of the Soils Cation Exchange Capacities, and Kinds and Relative Amounts of Minerals Present In the Clay Fractions of the Original Soils Effects of Potassium Exhaustion and Incubation on the Clay Mineralogy of the Soils SUMMARY. 140 LIST OF REFERENCES 147 APPENDICES Appendix A. DESCRIPTIONS OF T H E S O I L S .............. B♦ C. D. E. 156 PHOTOGRAPHS OF GROWTH RESPONSE OF WHEAT, SORGHUM, AND TOMATOES TO POTASSIUM ON B R O O K S T O N L O A M ......................... 161 PHOTOGRAPHS OF GROWTH RESPONSE OF WHEAT, SORGHUM, AND TOMATOES TO POTASSIUM ON GENESEE L O A M ......................... 164 PHOTOGRAPHS OF GRO W T H R ESPONSE OF WHEAT, SORGHUM, AND TOMATOES TO POTASSIUM O N KALAMAZOO SANDY LOAM ................ 167 PHOTOGRAPHS OF GROWTH RESPONSE OF WHEAT, SORGHUM, A N D TOMATOES T O POTASSIUM ON LANDES-ABSCOTA SANDY LOAM ........... 170 vi F. RELATIONSHIPS OF POTASSIUM A CTIVITY RATIO (ARk ) TO POTASSIUM A D S O R P T I O N OR R E L E A S E (AK ) O N T H E UNCROPPED SOILS . . . 173 G. X-RAY DI F F R A C T I O N PATTERNS OF THE CLAY FRA C T I O N OF B R O O K S T O N L O A M ................ 178 H. X-RAY D I F F R ACTION PATTERNS OF THE CLAY F R A C T I O N OF GENESEE L O A M .....................183 I. X-RAY D I F F R A C T I O N PATTERNS OF T H E C LAY F RA C T I O N OF KALAMAZOO SANDY L O A M ............ 192 J. X-RAY DIFFRA C T I O N PATTERNS OF T H E CLAY F R A C T I O N OF LANDES-ABSCOTA SANDY L O A M ............................................ 197 vii LIST OF TABLES Page Table 1. 2. 3. 4. 5. Chemical analysis of the experimental soils . . . ................................... 33 Applied rates of nitrogen, phosphorus, potassium, and m a n g a n e s e .................. 36 Yields of wheat, sorghum, and tomato crops as affected b y potassium treatments on B r o okston l o a m .............................. 44 Yields of wheat, sorghum, and tomato crops as affected b y potassium treatments on Genesee loam. ......................... 44 Yields of wheat, sorghum, and tomato crops as affected b y potassium treatments on Kalamazoo sandy loam . . . . . . . . . . . 45 6 . Yields of wheat, sorghum, and tomato crops 7. 8. 9. as affected by potassium treatments on Landes-Abscota sandy loam ................... 45 Relationships between plant yields and potassium treatments on Br o o k s t o n loam, Genesee loam, Kalamazoo sandy loam, and Landes-Abscota sandy loam ................... 46 Yields of tomato plants on n e wly treated (uncropped) Brookston, Genesee, Kalamazoo, and Landes-Abscota soils .................. 51 Potassium, calcium, and magnesium c o n c e n ­ trations of plant material as affected by potassium treatments on B r o okston l o a m ......................................... 5^ viil 10. 11. 12. 13. 14. 15. 16. 17- Potassium,, calcium, and. magnesium concentrations of plant material as affected b y potassium treatments on Genesee l o a m ............................... Potassium, calcium, and magnesium concentrations of plant material as affected by potassium treatments on Kalamazoo sandy l o a m .................. .. . 56 Potassium, calcium, and magnesium concentrations of plant material as affected by potassium treatments on Landes-Abscota sandy loam ................ 57 Relationships among concentrations of potassium, calcium, and magnesium in plants grown on Brookston, Genesee, Kalamazoo, and Landes-Abscota soils 58 . . . Relationships between plant yields, and potassium, calcium, and magnesium concentrations of the plants grown on Brookston, Genesee, Kalamazoo, and Landes-Abscota soils ....................... 69 Plant uptake of potassium as affected by potassium treatments on Brookston, Genesee, Kalamazoo, and LandesAbscota s o i l s ............................... 73 Plant uptake of calcium as affected b y potassium treatments on Brookston, Genesee, Kalamazoo, and Landes-Abscota s o i l s ....................................... 75 Plant uptake of magnesium as affected by potassium treatments on Brookston, Genesee, Kalamazoo, and Landes-Abscota s o i l s ....................................... 77 1 8 . Relationships between plant yields, and potassium, calcium, and magnesium uptake of the p l a n t s ....................... 19. 55 Relationship between the potassium, calcium, and magnesium uptake of the plants . . . . ix 82 86 Potassium release to the plants from nonexchangeable forms in Brookston, Genesee, Kalamazoo, and Landes-Abscota soils ....................................... 88 Exchangeable and nonexchangeable potassium in originalj cropped, and incubated soils ....................................... 103 Ratio of exchangeable to nonexchangeable potassium in original, cropped, and incubated soils ............................ 107 Potassium release and fixation of the soils as affected b y wetting and drying . . . . no Percentage of potassium saturation for the soils* cation exchange capacity ......... in Potassium release and fixation of the soils as affected b y freezing and thawing . . . 113 Quantity-intensity relationships for original and cropped s o i l s ................ 115 Quantity-intensity relationships for incubated soils ............................ 117 Relationships between plant uptake of potassium, and various measurements of soil potassium determined after the 2nd and 5th c r o p s ................ . . . . 121 Mechanical analysis of the soils and their textural designation ..................... 130 Cation exchange capacity of the organic matter, clay, and silt fractions of Brookston, Genesee, Kalamazoo, and Landes-Abscota soils ..................... 132 Mineralogical properties of the clay fractions of original, cropped, and incubated Brookston, Genesee, Kalamazoo, and Landes-Abscota soils ................ 134 x LIST OF FIGURES Page Figure 1, 2. Cellular detail of a 200 ]un portion of wheat stem obtained from Brookston loam receiving 400 pounds of potassium per a c r e ..................................... 62 Potassium X - ray oscillogram showing the distribution of potassium in a 200 pm portion of wheat stem obtained from B r o okston loam receiving 400 pounds of potassium per acre ................ 62 3. Calcium X - ray oscillogram showing the distribution of calcium In a 200 pm portion of wheat stem obtained from B r o okston loam receiving 400 pounds of potassium per a c r e ............................. 63 4. Magnesium X-ray oscillogram showing the distribution of magnesium in a 200 pm portion of wheat stem obtained from Brookston loam receiving 400 pounds of potassium per acre . . . . . . . . 63 Relative intensity measurements of potassium, calcium, and magnesium in a 200 pm portion of wheat stem tissue grown on Br o o k s t o n loam receiving 400 pounds of potassium per a c r e ......................................... 64 5. 6. Relative Intensity measurements of potassium, calcium, and magnesium in a 200 pm portion of wheat stem tissue grown on Genesee loam receiving 0 pounds of potassium per acre . . 64 Cellular detail of a 200 p m portion of wheat stem obtained from Genesee loam receiving 0 pounds of potassium per a c r e .................................... xi 65 8. Potassium X-ray oscillogram showing the distribution of potassium in a 200 pm portion of* wheat stem obtained from Genesee loam receiving 0 pounds of potassium per a c r e ............................................ 9* Calcium X-ray oscillogram showing the distribution of calcium in a 200 p m portion of wheat stem obtained from Genesee loam receiving 0 pounds of potassium per a c r e ............................................ 66 Magnesium X-ray oscillogram showing the distribution of calcium in a 200 pm portion of wheat stem obtained from Genesee loam receiving 0 pounds of potassium per a c r e ............................................ 66 10. 11. 12. 13. 14. Al. A2 V A3. Release of nonexchangeable potassium to the plants at various levels of potassium treatment for Brookston loam ................ . 90 Release of nonexchangeable potassium to the plants at various levels of potassium treatment for Genesee loam .................. . 91 Release of nonexchangeable potassium to the plants at various levels of potassium treatment for Kalamazoo sandy loam ......... . 92 Release of nonexchangeable potassium to the plants at various levels of potassium treatment for Landes-Abscota sandy loam . . . 93 The 2nd crop (wheat) at 40 days of growth on Brookston l o a m .............................. l6l The 4th crop (sorghum) at 48 days of growth on Brookston l o a m ................ .. l6 l The 5th crop (sorghum) at 70 days of growth on Brookston l o a m ....................... .. . 162 4. The 6 th crop (tomatoes) at 40 days of growth on Brookston loam ............................ 162 A5. Tomato plants at 40 days of growth on the uncropped soil of Brookston l o a m ......... .. . 163 a xii The 2nd crop (wheat) at 40 days of growth on Genesee loam ................................ 164 A7. The 4th crop (sorghum) at 48 days of growth on Genesee loam ................................ 164 00 The 5th crop (sorghum) at 70 days of growth on Genesee loam ................................ 165 A9- The 6th crop (tomatoes) at 4-0 days of growth on Genesee loam ................................ 165 AlO. Tomato plants at 4-0 days of growth on the uncropped soli of Genesee loam .............. 166 The 2nd crop (wheat) at 40 days of growth on Kalamazoo sandy loam ....................... 167 The 4th crop (sorghum) at 48 days of growth on Kalamazoo sandy loam ....................... 167 A13. The 5"th crop (sorghum) at 70 days of growth on Kalamazoo sandy loam ....................... 168 Al4. The 6th crop (tomatoes) at 40 days of growth on Kalamazoo sandy loam ....................... 168 A15- Tomato plants at 40 days of growth on the uncropped soil of Kalamazoo sandy loam 169 A6. < AllA12. A16. A17. A18. A19. A20. A21. . . . The 2nd crop (wheat) at 40 days of growth on Landes-Abscota sandy loam ................ 170 The 4th crop (sorghum) at 48 days of growth ................ on Landes-Abscota sandy loam 170 The 5th crop (sorghum) at 70 days of growth on Landes-Abscota sandy loam ................ 171 The 6th crop (sorghum) at 40 days of growth on Landes-Abscota sandy loam ................ 171 Tomato plants at 40 days of growth on the uncropped soil of Landes-Abscota sandy l o a m ............................................ 172 Relationship of potassium activity ratio fAR ) to potassium adsorption or release (^Ke) on Brookston l o a m ....................... 174 xiii A22. Relationship of potassium activity ratio fAR^} to potassium adsorption or release (AKe) on Genesee l o a m ............................. 175 A23* Relationship of potassium activity ratio fAR^l to potassium adsorption or release (AKe) on K a l amazoo sandy l o a m ................... 176 A2*l-. Relationship of potassium activity ratio (AR^) to potassium adsorption or release (AKe) on Landes-Abscota sandy loam . . . . . . A25. 177 X-r a y diffraction pattern of the clay fraction of B r o okston loam before cropping .............. 179 A26. X-ray diffraction pattern of the clay fraction of Br o o k s t o n loam after the 5th. crop on the 0 potassium treatment ............................ 180 A27 . X-ray diffraction pattern of the clay fraction of Br o okston loam after the 5th crop on the lj600 pound per acre potassium treatment. . . . l8 l A28. X-ray diffraction pattern of the clay fraction of Bro o k s t o n loam after a 13-month incubation period with 1^600 pounds of potassium per a c r e ........................................... 182 A 2 9 . X-ray diffraction pattern of the clay fraction of Genesee loam before cropping ................ 184 A 3 0 . X-ray diffraction pattern of the clay fraction of Genesee loam after the 5th crop on the 0 potassium treatment ............................ 186 A31. X-ray diffraction pattern of the clay fraction of Genesee loam after the 5t h crop on the lj600 p o u n d per acre potassium t r e a t m e n t ........................................... 188 A 3 2 . X-ray diffraction pattern of the clay fraction of Genesee loam after a 13-month incubation period with 1^600 pounds of potassium per acre . A 3 3 . X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam before cropping . . . . A3^. 19° 193 X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam after the 5th crop on the 0 potassium t r e a t m e n t ...................... 19^ xiv A35* X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam after the 5th crop on the Ij600 pound per acre potassium treatment ........................... . . . . . . 195 A 36. X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam after a 13-month incubation period with 1^600 pounds of potassium per a c r e ................................ 196 A37. X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam before c r o p p i n g ........................................... 198 A38. X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam after the 5th crop on the 0 potassium t r e a t m e n t ........... 199 A 39. X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam after the 5th crop on the 1 3600 pound per acre potassium treatment ............................. A40. 201 X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam after a 13month incubation period with 1^600 pounds of potassium per a c r e ............................. 202 xv INTRODUCTION A great number of research papers have been devoted to potassium fixation or release of soils. The mechanisms of potassium fixation or release are now well explained (Kardos, 1964). Soils containing m o n t m o r i l l o n i t e * illite and vermiculite are capable of fixing potassium applied to the soil as fertilizer (Bartlett and Simpson* 1964, and Welch and Scott* 1 9 6 1 ). 1 9 6 7 .J Kardos* Potassium fixed in the soil seems to become available to the plant slowly and a new equilibrium between nonexchangeable and exchangeable potassium* and exchangeable and solution potassium is established upon depletion of potassium in the soil solu­ tion (Richards and McLean* 1 9 6 1 ). Prom the soil fertility point of view* an accurate determination of available potassium is n e c essary to make effective use of soils and fertilizer. In order to discover such a measure* various methods have been employed* none of which* however* has completely satisfied soil scientists. The determination of available potassium as indicated by uptake of the plant itself should be the most accurate* but because of the time consuming nature of the method* 1 soil 2 chemical extraction methods are commonly used. Examples of chemical extractions employed for this purpose are: neutral 1 N NH4OAC (Bray, 1948), 1 N H N O 3 (Pratt and Morse, 1954), and sodium tetraphenylboron (Schulte and Corey, 1 9 6 5 )Some of the methods measure only a part of the exchangeable potassium while others may measure a portion of nonexchange­ able forms. Available potassium ranges from solution potas­ sium through exchangeable to nonexchangeable forms depending on conditions. On the other hand, an activity ratio such as aK/C/a (Ca + Mg) has been proposed as a good measure for potas­ sium availability (Matthews and Beckett, 1 9 6 2 ) for certain soils, and its usefulness has been tested to some extent (Acquaye and MacLean, 19 65 , and Beckett, 1964b). Suitability of a method for determining available potassium in a parti­ cular soil seems to be largely affected by the degree of potassium released and/or fixed by a soil. Known factors involved in the release or fixation of soil potassium are: (l) levels of potassium in the soil (DeMent at a l ., 1959); (2) absorptive power of plant species (Tisdale and Nelson, 19 6 6 ); (3) soil temperature (Weber and Caldwell, 1964); (4) soil moisture or wetting-drying condi­ tions (Bates and Scott, 1964); 1964); (5) soil pH (Page and Ganjie, (6 ) soil organic matter (Mortland, 1 9 6 1 ); (7) concen­ trations of coexisting cations such as Ca, Mg, and NHj| (Oliver and Barber, 1966, Powell and Hutcheson, 1 9 6 5 ^ and Welch and Scott, 1 9 6 1 ); (8 ) texture of the soil (Nuttall at a l ., 1967); and (9 ) types of clay mineral present in the soil (Rich and Lutz, Jr., 19 6 5 ). 3 Potassium fixing clays, such as montmorillonite, illite, and vermiculite, have been detected in Michigan soils, and release of nonexchangeable potassium from the soil has also been studied to some extent in relation to clay mineralogy (Cummings, 1 9 5 9 »and Doll et a l ., 19^5)* However, further study is considered necessary concerning the release and fixation of potassium in Michigan soils from the stand­ point of soil fertility; namely, the release and fixation of potassium in relation to fertilization, cropping, and physical, chemical and mineralogical properties of the soil. The objectives of the present thesis are to study the release and fixation of potassium in some high-potassiumfixing and low-potassium-fixing Michigan soils in relation to their physical, chemical and mineralogical properties. In order to achieve these objectives, particular emphasis was placed on the following aspects: 1. Plant yields as affected b y potassium fertili­ zation; potassium uptake of plants as related to calcium and magnesium uptake; and the effect of differential potas­ sium release and fixation of the soils on plant yield and potassium uptake. 2. Suitability of chemical methods for measuring plant available potassium and their relationship to uptake of potassium b y plants. 3. The relationships among the physical, chemical, and mineralogical properties of the soils and their ability to release and/or fix potassium. 4 4. The effect of potassium fertilization and cropp on the clay mineralogy., cation exchange capacity* and p o t a s ­ sium supplying power of the soils under investigation. CHAPTER X LITERATURE REVIEW A, Importance of Potassium in Plant Metabolism Potassium is one of the major plant nutrients * however, the role of potassium in the plant is still not fully under­ stood. The accumulation of knowledge indicates that potassium plays catalytic roles In the plant rather than becoming an integral part of plant components. For example, the enzyme systems related to starch synthesis from glucose, protein synthesis from various amino acids, and nucleic acid and nucleotide metabolisms are regarded as affected by the potas­ sium ion (Evans and Soger, 1 9 6 6 ). Furthermore, potassium helps promote turgor, and regulates permeability of cell walls and activities of various mineral elements as well as neutralizing physiologically important organic acids (Evans and Soger, 1966,and Lav/ton and Cook, 195^)* Plants with an inadequate supply of potassium may show poor fruit or seed formation, yellowing of the leaves, poor growth, and low resistance to coldness and drought (Tisdale and Nelson, 1966). Explanations of the disturbance in carbohydrate and nitrogen metabolism relative to potassium nutrition are probably that: (1) potassium deficiency results in 5 6 Inactivation of such enzymes as pyruvic acid kinase which is involved in the formation of energy-charged adenosine t ri­ phosphate (ATP) in the glycolic pathway (The insufficient energy reduces nitrogen assimilation which requires a large amount of energy from the outside.); (2 ) accumulation of soluble nitrogen compounds results from Insufficient energy necessary to synthesize proteins which is caused by inacti­ vation of cytochromeoxidase in the cytochrome system with de ­ ficient potassium (Fairley and Kilgour, 1 9 6 6 ). The respiration rate of some plants, Increases when potassium is deficient. such as rice, However, this increase in respiration Is useless as far as plant metabolism is con­ cerned since the cytochrome system is disturbed by the absence of potassium (Fujiwara, 1964). B. Potassium Absorption by Plants It is not appropriate to generalize concerning the potassium content of plants because the ability of potassium absorption differs among plant species; moreover, It is affected by soil conditions, the level of exchangeable or available potassium, the amount of other nutrients, soil moisture, aeration, soil temperature, soil pH, and the quantity and kLnd of clay minerals. 1. Differential Absorption of Potassium by Plant Species Differential absorption of potassium by various plant species was demonstrated by Newton (1 9 2 8 ), and Drake and Scarseth (1939)* 7 Newton (1 9 2 8 ) grew s u n f l o w e r s 3 beans, barley, wheat, peas and corn for 56 days In a water culture which contained 185 ppm. of potassium, and analyzed the plant tops. The potassium contents of these plants varied from the lowest 3 .9^ with corn to the highest 6 .92^ with barley. He also grew sunflower, beans, wheat and barley in a soil which co n ­ tained 1 .5^ potassium and found that the p o t assium contents ranged from 1 .1$)^ with beans to 4 . 16$ with wheat. Drake and Scarseth (1939) carried out an experiment with a. Crosby silt loam in which they grew 13 different crops such as spring wheat, spinach, carrots, oats, barley, Sudangrass, timothy, sugar beets, Turkish tobacco, alfalfa, sweet clover, buckwheat and salvia to near maturity. T he soil received constant amounts of nitrogen and phosphorus but no potassium. When no potassium was applied on the soil, in '■hich exchangeable soil KgO was 267 mg. per pot, potash u p ­ take varied from less than 100 mg. with spinach to nearly 800 mg. KgO with timothy. Several explanations have been advanced to explain the differential ability of plants to absorb potassium. Lewis and Eisenmenger (19^ 8 ) from their experimental results interpreted that the plants in lower orders of evolution utilized more potassium than the plants in higher orders. Other explanations are concerned with the physiological requirement and cation exchange capacity p r o ­ perties of the plant root. There appear to be definite differences in potassium and calcium contents of legumi­ nous crops such as alfalfa, red clover, sweet clover and 8 soybean and monocotyledon plants such as oats and corn as studied by Beeson (ig4l). The monocots absorbed more p o tas­ sium than leguminous crops but less calcium. 2. Effects of Potassium Level in Soil Plants may utilize more potassium when the available soil level of potassium is high. DeMent, et a l . (1959) re“ ported that oats absorbed the largest amount of potassium (47-3 mg. for the l4-day growth period) from the quartz sand-soil mixture which received the highest amount of p o t a s ­ sium (120 mg. potassium per 200 gm . of soil); whereas the oat plant grown without any addition of potassium absorbed only 10.8 mg. Jaworske and B a r b e r (1959) showed the relationship between potassium uptake of the plant and exchangeable soil potassium. An experiment by Oya (1 9 6 5 ) with kaolinitic Hawaiian latosols showed the potassium contents of peanut leaves in­ creased with additions of potassium up to 800 pounds per acre at lower calcium treatments. The process of nutrient uptake and transport of potas­ sium in the plant against a concentration gradient requires energy (Fried and Broesha.rt3 1 9 6 7 ). This gradient between the plant and the soil solution will be lower for a soil high in potassium than for a soil low in this element. Conse­ quently, if plants use the same amount of energy for p o t a s ­ sium uptake in soils with different levels of available potassium, a plant would absorb potassium more easily from a soil rich in potassium than from a soil poor in potassium. 3. a. Effects of Other Nutrients in Soil on Potassium Availability Nitrogen A review by Lawton and Cook (195*0 showed there are some instances when applications of nitrogenous fertilizers alone or nitrogen coupled with phosphorus fertilizers de ­ creased the potassium concentration of crops and subsequently resulted in potassium deficiency. However, such an unfavor­ able effect must b e explained b y the phenomenon of vegetative expansion of the crops by the applied fertilizers. The addi­ tion of nitrogen brings about vigorous growth of crops and plant absorbed potassium is diluted thus lowering the p o t a s ­ sium concentration. Potassium deficiency results unless the potassium supply of the soil is sufficient to meet the rapid growth of the p l a n t s . In general, with a sufficient supply of potassium, the addition of nitrogen promotes a rather favorable effect on the potassium uptake by plants due to Its stimulative effect on plant Nitrogen two forms: growth as shown by Hallock, et al. (1959)* in the soil is available to plants mainly in ammonium nitrogen and nitrate nitrogen. Studies have been carried out concerning the effect of ammonium rather than the nitrate on potassium absorption by plants. The ammonium ion (NH^) seems to have little direct effect on the potassium uptake of the plant but has remarkable indirect 10 effect in soils particularly where potassium fixing clay minerals are dominant (Welch and Scott, 1 9 6 1 , Macleod and Carson, 1 9 6 6 , and Bartlett and Simpson, 1 9 6 7 )- Macleod and Carson (1 9 6 6 ) u s ing the hydroponic culture technique grew three species of grass at three levels of ammonium and two levels of potassium (5° 2 50 ppm.); 12, 50, and 75$ of the applied 250 ppm. nitrogen was in the NHj form. The potassium concentrations of timothy, orchard- grass, and bromegrass were about 3-5$ irrespective of the ammonium levels in the culture containing 50 ppm. of potassium. Bartlett and Simpson (1 9 6 7 ) studied the effect of ammo­ nium addition on potassium uptake of a plant in a potassiumfixing soil. They found that the addition of ammonium nitrogen, after potassium was equilibrated with the soil for two weeks, did not indicate any apparent effect on the p o t a s ­ sium uptake of corn seedlings; whereas the equilibration of ammonium with the soil before the potassium addition showed an increase in the potassium absorption by the seedlings. An ammonium application prior to a potassium application to the soil containing clays that fix both ammonium and p o t a s ­ sium may have brought about the occupancy of potassium fixing sites by the ammonium ions, and left the potassium unfixed. The consequent result is an efficient use of potassium by the plant. It has been shown that plants absorb potassium in both exchangeable and nonexchangeable forms. However, ammonium ions b l ock the release of nonexchangeable potassium from the clay fraction to the plant (Welch and Scott, 1 9 6 1 ). 11 Further information concerning potassium fixation will be reviewed in the section, "Mechanisms of Potassium Release and Fixation in the Soil", below. b. Phosphorus Readily available soil phosphorus exists in the forms 2 of such anions as H 2P0 4 , HFO4 (Kardos, 1964). - 3 and less abundantly as PO^ - Because of its anionic nature, phosphorus does not exhibit the cation exchange phenomena as does p o t a s ­ sium. Consequently, there seems to be no direct effect of phosphorus on the release of potassium from the exchange complex of the soil; but indirectly, phosphorus promotes plant growth and absorption of potassium as well as other nutrients as mentioned b y Lawton and Cook. (195^-)* Gillinghan (1 9 6 6 ) studied potassium uptake in connec­ tion with nitrogen and phosphorus additions using the Neubauer rye seedling method with soils of Vancouver Island, British Columbia. His data appeared to show that phosphorus had a favorable effect on the potassium uptake of the rye seed­ lings, and his conclusion was "it was an illustration of Liebig’s Lav/ of the Minimum." c. Calcium and Magnesium The level of calcium and magnesium has a definite effect on the potassium accumulation of plants. relationships among potassium, v/ell understood, Although calcium and magnesium are not antagonistic relationships have been ob­ served among these elements. 12 In a study carried out by Burkhart and Collins (19^1) with the peanut plant, in water culture, a large application of potassium increased the uptake of potassium by the plant but markedly decreased the uptake of calcium and magnesium, and vice versa. Oya (1 9 6 5 ) also found an antagonistic relationship between calcium and potassium uptake of the peanut plant grown on kaolinitic soils. However, the same relationship was not demonstrated clearly on a montmorillonitic soil. Omar and Kobbia (1 9 6 6 ) reported that the increase of soil magnesium led to a marked decrease in the potassium content of the plant whereas the magnesium content in the plant increased only slightly. In general the antagonistic relationships among potas­ sium, calcium and magnesium are clearly demonstrated with the use of water or sand culture, but rather insufficiently with soils. The reason is based on the factors controlling nutrient availability. include: Factors that are to be considered (1 ) mechanisms of contact exchange, (2 ) the effec­ tive concentration of ions in the growing medium, and (3 ) the renewal rate of nutrients in the growlng medium (Tisdale and Nelson, 1 966). Contact exchange of nutrients between plant roots and soil colloids takes place in the soil but not in the v/ater and sand cultures. The renewal rate of the nutrients in the soil Is governed by much more complex conditions than that of water and sand cultures where colloidal particles of clays are 13 not involved- Consequently the phenomena observed for the relationships among potassium, calcium and m a g nesium are simpler for the sand and water cultures than for soils. Among soils themselves, kaolinitic clays have larger size and lower negative charges than montmorillonitic c l a y s , and therefore fewer interactions with these cations. The d i f ­ ferent nature of the clay minerals apparently affects plant uptake of potassium, d. calcium and magnesium. Sodium and B o r o n According to the review b y Lav/ton and C o o k (195^0 rela­ tive to the effects of sodium and boron on plant absorption of potassium, it is not clear whether sodium affects the u p ­ take of this element, although sodium may partially substitute for potassium in certain crops. These workers suggested that the application of boron to tomato plants and orange trees increased the potassium absorption b y the plants. 4. a. Effects of Physical Factors in Soil on Potassium Availability Soil Moisture Soil moisture is closely related to plant absorption of potassium as reported by Mederski and Stackhouse (i9 6 0 ). Plant nutrients in the soil may reach the plant root by: (l) root extension, (2) mass flow, and (3 ) diffusion. the speed of the root extension is a constant, If the mass flow and diffusion control degrees of contact b y the plant with 14 nutrients. The supply of potassium to the plant root is mostly a diffusion controlled process; unlike calcium^ m a g ­ nesium and nitrogen which are supplied adequately b y mass flow (Barber at a l ., 1 9 6 3 , and. Oliver and Barber, 1 9 6 6 ). The relative rate of diffusion of potassium is expected to become greater with an increase in soil moisture (Barber, 1964). Potassium uptake m a y be impeded by a discontinuity of the v/ater film around the soil particles which intercepts the diffusion, and also b y a high water stress in a soil of low moisture which depresses the root activity. In the expe­ riment of Mederski and Stackhouse (i9 6 0 ), potassium uptake by corn seedlings up to l6fo. (2 5 -day old) increased with soil moisture The soil was found to contain 25 and 6 .5^* m o i s t ­ ure at 1/3 and 15 atmospheres, respectively. At moisture levels higher than 16^, plant absorption of potassium seemed to be affected by levels of soil aeration which served as a limiting condition of root respiration for the best p o t a s ­ sium uptake. b. Soil Aeration Vlamis and Davis (1944) and Lav/ton (1945) demonstrated the effect of aeration on the uptake of potassium b y plants. In the water culture experiment, increased with aeration. accumulation of potassium Tomato and barley were found to require more aeration than rice in the root medium. The corn plants grown by Lawton in potassium-rich soils showed p o t a s ­ sium deficiency when the soils were either compacted or too wet. 15 Soil aeration seems to have specific effects on the potassium uptake of the plant. I f the aeration is inade­ quate, root respiration (which is a process to decompose car­ bohydrate through pyruvate to carbon dioxide and water) is disturbed and creates less energy thus resulting in the p r o ­ duction of ethyl alcohol. The accumulation of ethyl alcohol In the plant sap was very marked when soil aeration was res­ tricted according to Pulton and Erickson (1964). Since potassium absorption is an energy requiring process, less potassium is absorbed under conditions of poor aeration. Furthermore, potassium is involved in pyruvate oxidase and cytochrome oxidase (Evans and Sorger, Fujiwara, 1 9 6 6 , and 1964), which lowers the energy output when I n suf­ ficient potassium is supplied. absorption, Soil aeration, potassium and energy produced b y the plant root are closely related. c. Soil Temperature The plant seems to absorb more potassium as the soil temperature rises. According to Worl e y et a l . (19^3)^ excised roots of Sudangrass, peas, more potassium from 0.005 the and soybeans absorbed N KC1 solution when the solution temperature was raised from 5° to 2 ^ ° C . W e ber and Caldwell (ig64) showed that the sorghum plant absorbed more potassium y- o o as the soil temperature was raised from 60 to 9° F. The effect of temperature on potassium uptake was greater in a Floyd silty clay loam than In a M i l a c a sandy loam when 16 potassium was applied. Since the release of C02 b y the excised root of Worley et al. 5° to 25°C* (1 9 6 3 ) increased linearly from although there were variations above 25°C* soil temperature* potassium uptake* and respiration of the plant are related. 5. Effects of Clay Mineralogy of Soil on Potassium Availability Clay minerals such as illite* montmorillonite and vermiculite are known to fix potassium (Kardos* 1964). Soils containing these clay minerals may fix potassium applied as fertilizer and permit the plant to absorb only a fraction of it. Therefore* plants growing in a soil containing potassium- fixing minerals in quantity may take up less potassium in a short time when the soil is less saturated with potassium. Plants growing in such a potassium-fixing soil may* however, absorb more potassium than in other soils for a long period of time* because the potassium in the fixed state and in primary minerals (such as micas) becomes available slowly as potassium equilibrium moves to balance potassium absorbed by the plant. C. Dynamic Mature of Soil Potassium 1. Origin of Soil Potassium Soil potassium originates mainly from feldspars and micas which occur chiefly in igneous rocks. crust is composed of 95^ igneous rock* stone and 0.25^ limestone* The e a r t h ’s shale* 0.75^5 sand­ of which K 2 0 contents are 3-13* 17 3.24, 1.32 and 0.33 percent, respectively (Clark and Washington, 1924). Soil is formed from parent materials, b y the action of physical disintegration, chemical reaction and mineralogical changes under the influence of climate, drainage, and activity of life over varying periods of time. Soils vary in their potassium content from place to place because soil forming processes occur in differing i n ­ tensity. An important phase in soil formation and weathering is the formation of secondary clay minerals. The secondary clay minerals include 2 :1 , 2 :2 , and 1:1 type crystalline minerals and amorphous materials. Illite, vermiculite and montmorillonite are typical of 2:1 type clay, type clay and kaolinite 1:1 type clay. chlorite 2:2 In general clay mineral weathering proceeds from 2:1 and 2:2 types to 1:1 and ultimately to gibbsite, an aluminum oxide A1(0H)^ (Jackson, 1964). Important clay minerals concerned with soil potassium are the 2:1 type clays which may hold potassium with their high cation exchange capacity, and among which illite and vermiculite carry potassium as their chemical component like the micas which are primary minerals. Since feldspars (potassium carrying primary minerals) easily weather and do not remain in an active soil fraction clay, micas and 2:1 type clay minerals (especially illite and vermiculite) are considered to be the primary source of soil potassium. The potassium contents of most agricultural 18 soils (0 to 6 inches in depth) in the United States range from 1 to 2 % expressed as K 2 0 (Jackson, 2. 1964). Factors Af f e c t i n g Potassium Availa b i l i t y Potassium availability in the soil would b e best determined b y potassium accumulation of the plant as the result of the integral condition of soil and other environ­ mental factors. Soil potassium is generally divided into three broad categories: difficult, moderate and easily available. The first group includes potassium present in the lattice of biotite, illite and vermiculite; the second group includes fixed potassium in the interlayer of potassium fixing clays such as illite, vermiculite aid montmorillonite; and the last group includes exchangeable and water soluble potassium. Since these three groups of potassium are present in equili­ brium in the soil, the rate of potassium change from d i f f i ­ cultly to easily available form or vice versa u pon depletion or supply of easily available potassium determines the soil potassium availability. Soil factors that affect the rate and direction of soil potassium equilibrium are: moisture, freezing and thawing, organic matter, soil pH, and comple­ mentary cations particularly in connection with potassium fixing c l a y s . 19 a. Soil pH In acid soil, potassium equilibrium is prevented from fixation because difficulty replaceable cations including H, Fe* and A 1 block potassium absorption sites of illite and vermiculite (Stanford* 19^7 j and Page and Ganjie* 1964). b. Soil Moisture Level Reitemeir ^et al. (1948) and Khanna and Datta (1 9 6 8 ) reported that soils release nonexchangeable potassium in the moist condition. On the other hand Attoe (19^7) found potas­ sium fixation to occur to some extent by keeping Miami silt loam and Spencer silt loam in a moist condition. Seemingly* these reports are in conflict* however* the results are well explained by clay mineralogy and potassium equilibrium in soil. In the experiment of Reitemeir et^ al. (1948)* exchange­ able potassium was removed initially then the soil was kept in a moist condition. Consequently nonexchangeable potassium should have been released from the soil to attain the equi­ librium. Potassium fixation was nil when no potassium was added to the soils studied by Attoe (1947)* This phenomenon would be explained in the same manner as above. Potassium fixation in a moist condition is peculiar to the soils con­ taining vermiculite in which the interspace collapses even at low saturation with potassium in a moist state (Dennis and Ellis* 1 9 6 2 ). Potassium release from nonexchangeable forms was re­ ported upon drying soils by Stanford (1947)j Luebs et al. 20 (195^) and Bates (1 9 6 2 ), whereas Stanford (1947) obtained potassium fixation in drying some of his soils. Experiments with repetition of wetting and drying soil affected fixation of potassium according to V olk (1934) * and Powell and Hutcheson (1 9 6 5 )* Potassium is released in drying soil by surface t e n ­ sion of water which curls up the fracture on the surface of micaceous minerals and releases potassium (Raman and Jackson, 1 965). Potassium fixation was caused b y the contraction of montmorillonite interlayer space (Kardos, 1964). Under field condit i o n s , such drastic drying as em­ ployed in the laboratory seldom occurs except at the very surface of the soil, and release or fixation of potassium should take place only slowly. c. Freezing and Thawing Repetitions of freezing and thawing soils tended to increase exchangeable potassium. Among clays, montmorillonite and Putnam clay (a mixture of illite and montmorillonite), released potassium but illite fixed it (Pine jet a l ., 1940). Potassium release b y repetition of freezing and thawing was almost the same in quantity with that of samples kept in a moist condition when extraction was repeated during the t r eat­ ment (Reitmeir et a l ., 1948). d. Organic Matter Addition of organic matter to soil reduced the p o t a s ­ sium release upon drying (Bates, 1 9 6 2 * and Bates and Scott, 21 1964), because organic matter reduced the surface tension of water. Mortland (1 9 61 ) reported that aniline hydrochloride and 2,4-diaminephenol dihydrochloride prevented potassium absorption of vermiculite by inhibiting collapsibility of the vermiculite interspace upon potassium intake. e. Complementary Cations Because of the similarity in their ionic size, ammo­ nium and potassium ions compete for clay surface of p o tas­ sium fixing sites. The ionic sizes of potassium and ammo> hlum are 1.33 and 1.43 in radius respectively and hydrated sizes 5.3 and 5.4 A as cited by Bertramson (1955)* According to Page and Baver (cited by Kardos, 1964), potassium and ammonium fixation b y Miami colloidal clay was almost the same v/hen the clay was saturated with the res­ pective cations. When ammonium ion was abundant, potassium release from nonexchangeable form was blocked (Welch and Scott, 1 961) and v/hen ammonium was applied before potassium to the soil, potassium fixation was prevented (Bartlett and Simpson, 1 967). Calcium and magnesium, the most abundant cations in soil, also have some connection with potassium fixation or release. Powell and Hutcheson (19 6 5 ) reported that liming soils of micaceous mineralogy increased release of n o nex­ changeable potassium and prevented soils from fixing it. Their suggestion was that the calcium ion opened edges of clay mineral packet, because the calcium ion was smaller in 22 hydrated size than potassium, i.e., the hydrated ion of* cal­ cium is 5.0 8 in radius as cited b y Bertramson easily penetrated into interstice of* clays, previously trapped potassium, (1955)* and thus releasing and preventing entrappment of potassium by hindering potassium entrance into the interspace. If simplified, the adsorption or replaceability of cations on clays is expected to follow the same order as the lyotropic series (Wiklander, 1964). There are, however, variations in the order of cation adsorption b y soil. instance, For vermiculite favorably adsorbed ma g n e s i u m to calcium when magnesium saturation exceeded about 35^ (Peterson, 1 9 6 5 )* 3. Mechanisms of Potassium Release and Fixation in the Soil Potassium is released mainly from po t a s s i u m bearing minerals such as feldspars, micas, and illite, and to a minor extent from vermiculite in the weathering process. feldspars, Since including potassium-rich orthoclase and microcline, are less resistant to weathering, micas and illite are more important sources of potassium in the clay fraction (Jackson, 1964), which is considered to b e an active constituent of the soil because of its greater specific surface accompanied by physicochemical activeness. Upon weathering micas change through illite, vermiculite to montmorillonite b y releasing potassium. The weathering action includes; (l) actions of loosening mica interlayers b y the penetration of hydrated cations and by the scroll of weathered m i c a surface by the 23 surface -tension of water caused by drying the soil; and (2 ) reduction of electric charges b y oxidation of the ferric ion in the octahedral layer and b y proton addition of an hydronium ion to octahedrally charged oxygen (Jackson, 1964). When potassium is continuously removed from the surrounding solution, m i c a releases a quantity of potassium as demons­ trated in the experiment by Ellis and Mortland (1959)Potassium fixation m a y be explained b y the "lattice hole" theory and intensity of negative charge in the inter­ layer surface of clay minerals (Kardos, 1964). The explana­ tion of the "lattice hole" theory, if vermiculite is taken as an example, is as follows. Upon dehydration, a potassium ion, of w h i c h the unhy_ o drated diameter is 2.66 A, just fits in the hexagonal space of the oxygen sheet of the silica tetrahedral layer of the clay (size - 2.8 S in diameter). The perfectness of fit of the potassium ion to the "lattice hole" pulls the adjoining tetrahedral layers so close that no other accessible cations can replace the potassium. Thus fixed potassium is diffi­ cultly rehydrated. Differences in the intensity of negative charge on the clay surface make potassium fixation possible in dif­ ferent ways with respective clays. In illite and vermiculite, more negative charge is derived from the silica tetrahedral layer than the aluminum octahedral layer; in contrast, in montmorillonite more negative charge is derived from the aluminum octahedral layer than the silica tetrahedral layer 24 for a unit surface. The potassium ion is attracted more strongly by the negative charge at the silica tetrahedral layer than the negative charge at the octahedral layer since the distances between the potassium ion, and the charges at the tetrahedral and octahedral negative sites are 2.19 o 4.99 A respectively. Therefore, potassium fixation is o b ­ served in both moist and dry conditions of the soil with illite and vermiculite but only in the dry condition v/ith montmorillonite. The expandability of the clays with p o t a s ­ sium fixed in this way is highest v/ith montmorillonite and lowest v/ith illite in accordance with the charge intencity. These factors also affect the ease of rehydration of p o t a s ­ sium and accessibility of other ions. D. Potassium Availability Measurement Soil potassium is arbitrarily divided into three cate­ gories: difficulty, m o d e rately and easily available. How­ ever, the status of the soil potassium changes b y conditions. Many methods have been devised and used to measure available potassium with greater accuracy. These methods m a y b e cate­ gorized as biological and chemical methods. 1 . Biological Methods Biological methods are: using rye as an indicator plant^ (l) the Neubauer method (2) the Stanford and DeMent method intensifying potassium deficiency in plant seedlings then transferring them onto the soil to be tested^ and (3 ) greenhouse pot and field plot methods. 25 a. Neubauer Method The Neubauer method was devised in Germany in 1 9 2 9 * and became very popular in Europe. In the United States the method was extensively tested and employed b y T h ornton and other investigators to test availability of po t a s s i um as well as other nutrients in the soil (Thornton* McGeorge, b. 1931j 1935j 19*+6#and Pettinge and Thornton* 193*0. Stanford and DeMent Method Stanford and DeMent improved the Neubauer method and devised a more efficient way to test nutrient availability in the soil* first for phosphorus (Stanford and DeMent* and then for potassium (DeMent et a l .* 1959). 19*^7) Since then the method has been employed b y m any investigators. c. Greenhouse and Field Method Field testing began with the establishment of the Rothamsted Experiment Station in 18*13^ and is still a popular orthodox method because plants and nutrients are tested under natural conditions. The greenhouse method using pots with various modifications is extensively employed as w e l l * b e ­ cause plants and nutrients can be tested under conditions similar to the field besides controlling desired factors. Using biological methods* the potassium availability is demonstrated by the difference between yields or p o t a s ­ sium contents of the plants grown with and without potassium. If the difference is small* the potassium availability of 26 the tested soil is said to he high. Biological methods are the most reliable* because the plant itself is the indicator and potassium availability is related to plant production. 2. Chemical Methods a. Extraction of Potassium v/ith Neutral I N Ammonium Acetate Solution Because of simplicity and rapidity* chemical methods employed in the laboratory became more popular in determining available potassium since the biological methods generally require more time and skill than chemical m e t h o d s . The che­ mical methods are considered very useful when correlated v/ith greenhouse and field tests. Although various chemical re­ agents are used to extract available potassium* neutral 1 normal ammonium acetate solution is employed as a standard because exchangeable potassium determined by this method has been successfully correlated to crop yields or potassium uptake (Bray* 1948* Hanway et a l .* 1 9 6 2 ). b. Extraction v/ith Boiling 1 N Nitric Acid Hov/ever* the exchangeable potassium is only a portion of available forms and plants may use some portions of initial nonexchangeable potassium during the growth period. Determi­ nations of both exchangeable and nonexchangeable forms are accomplished by using a boiling 1 N nitric acid extraction (Deturk jat a l . * 1943* Reitemeir at /fl. * 1948* and Schmitz and Pratt* 1953). 27 Other methods in determining nonexchangeable potassium in micaceous soils include the extraction method with sodium tetraphenylborate (NaTFB) solution (Reed and S c o t t , 1961 and 1962, Scott and Welch, 1961, Scott and Reed* 1962a., 1962b., and Schulte and Corey, 19^3 and 1 9 6 5 ). c. Relations of Quantity-Intensity Several methods have been studied from Soil Potassium of potassium availability measurements the activity point of view. The quan- tity-intensity relations of labile soil potassium were studied, and the activity ratio, aK// (aCa + M g ) » in soil solution was proposed as a measure of the intensity factor. The potential Q buffering capacity, -aK / A R e, was proposed as a measure of soil ability to maintain the activity ratio against potassium depletion by the plant (Matthew and Beckett, 1962, Beckett, 1964a, and 1964b). According to Beckett (1967^ P* 32), the labile potassium is defined as: ions present in the soil solution or in exchange­ able form; except for 1 -2^ which is more difficultly exchangeable, equilibrium is very rapidly achieved within the pool of labile potassium, v/ith a halftime measured in minutes or less. In the calculation of potential buffering capacity (PBC ), is the exchangeable potassium supposed to be measured at zero value of chemical activity of potassium in the soil solu­ tion (which is measured in the presence of exchangeable potasslum of the soil proper), and A R e is the activity ratio at an equilibrium where no gain or loss of potassium by soil takes 28 place (aKq=0 ) . Since the values for -aK determine, O 1c and AR_ were difficult to they were obtained from a graph drawn w i t h various activity ratios AR 1c = EL K/s/ a (Ca + Mg) against changes in the exchangeable potassium (&Ke ) b y extrapolating the linear p o r ­ tion of the asymptotic curve to cross the ordinate for -»aK0 value and b y interpolating the curve to cross the ^ K e = 0 line for AR^ value. Calcium and magnesium are used in the activity ratio calculation because they are considered most abundant in the soil; although in some cases other ions such as Al in acid soils and Na in alkali soils must also be inclu­ ded in the calculation. The Beckett method seems to have the advantage of not disturbing the potassium equilibrium in the soil; m a n y i n ­ vestigators have tested the method. {1965) found good correlations Acquaye and MacLean (r =**0 .9 2 ) between p otassium uptake by plants and -aK^ values on Canadian soils as well as between potassium uptake and exchangeable potassium measured v/ith the ammonium acetate method (r - + O . 9 1 ), however, low correlation (r = + O . 5 6 ) between potassium uptake and A R e . Correlation between PBC and nonexchangeable potassium measured v/ith boiling 1 N H N O 3 v/as +O.5 2 . Wild et al. (1 9 6 9 ) found no correlation between p o t a s ­ sium uptake by plants and activity ratio expressed as (K)//(c a-j in sand culture v/hich also contained various amounts of magnesium. 29 Bet t e r correlations were obtained between potassium uptake and potassium potential, calculated b y multiplying -aK° value by FBCk value, than between potassium uptake and exchangeable potassium (Zandstra and MacKenzie, 1 9 6 8 ). When the FBCk is multiplied by -aK° value, the -^K0 value is to be magnified. However, this may benefit the relationship, because exchangeable potassium is slowly supplemented by nonexchangeable potassium during cropping period in potassium fixing soils. CHAPTER II SOIL CROPPING EXPERIMENTS I N THE GREENHOUSE EMPLOYING WHEAT,, SORGHUM AND TOMATO AS THE INDICATOR PLANTS A. Experimental Methods and Materials 1. Soils Pour different soils were used in the experiments: Brookston loam, Genesee loam, Kalamazoo sandy loam, and Landes-Ahscota sandy loam. A soil suspected of having a high capacity for the fixation of potassium was first chosen for the experiment and tentatively named Landes-Abscota b e ­ cause its characteristics were identified between Landes and 1) Abscota series. Genesee loam was similar to the LandesAbscota sandy loam in terms of soil genesis. Kalamazoo sandy loam was adjacent to the Landes-Abscota sandy loam but located on a higher terrace. Similarity was anticipated among the three soils concerning potassium release and fixa­ tion properties. The Brookston loam, whose potassium r e ­ lease and fixation properties were little known, was also chosen to provide a comparison with the other three soils. The characteristics of the four soils are described in Appendix A. ■^Personal communication with Dr. E. P. Whiteside, Crop and Soil Sciences Department, Michigan State University. 30 31 a. Soil Collection Brookston loam was collected on June 13a 1968* from the surface layer (0 - 6.5 Inches) of a field planted to navy beans which had not begun to germinate. located at SW £ of SW £* Sec. The field is 15* Sebewa Township (T5N* R6W)* Ionia County* Michigan. Genesee loam was collected on June 11* 1 9 6 8 * from the plowed layer (0 - 6.5 inches) of the harvested corn field which is located at NE ^ of SW ^ of WW ^-* Sec. 33* Danby Township (T5N* R5W)* I o n i a County* Michigan. Kalamazoo sandy loam was collected on September 18* 1968* from the surface (0 - 6.5 inches) of the plowed h a r ­ vested Sudangrass field. The collection site is about 30 meters east of the barn and 7 meters south of the entrance road in the Sodus Experimental Farm of Michigan State U n i ­ versity located in section 16 of Berrien County* Michigan. Landes-Abscota sandy loam was collected on September 1 8 * 1968* from the surface (0 - 6.5 inches) of a harvested tomato field at 10' E of the tomato plot of the Sodus E x ­ perimental Farm. The collection site was located at a raised part of the flat along the St. Jos e p h River* and about 80 meters east of the river. b. Chemical Analysis Soil samples were submitted to the Soil Test Labora­ tory at the Department of Crop and Soil Sciences* Michigan State University to examine the chemical properties before starting the greenhouse experiment. The result of the 32 chemical analysis is shown in Table 1. 1) Soil Acidity Determination of pH was done with a glass electrode pH meter on 1:1 soil-water suspension. 2) Cation Exchange Capacity Cation exchange capacity was determined b y the author on a 10 gram sample of soil which was saturated with calcium by repeated centrifugings with 1 N CaClg solution. Excess salt was removed with water and then methyl alcohol and the calcium held on the sample was replaced by magnesium by re­ peated centrifugings with 1 N MgCl2 solution. The calcium In the collected supernatant representing cation exchange capacity was determined on a Coleman Flame Photometer model 21. 3) Phosphorus Phosphorus was extracted from a 2.5 gram sample with 20 ml. of Bray P^ solution consisting of 0.3 N NHjjF and 0.25 N HC1. To the extractant 5 drops of ammonium molybdate solution and 5 drops of F-S reducing solution, which con­ sisted of l-amino-2-napthol-4-sulfonic acid (Eastman 36 0 ), sodium sulfite (NaSOlj.) and sodium meta-bi-sulfite (NagSgOpj), were added to develop a blue color the intensity of which was compared on a colorimeter at a wave length of 500 m p with a set of standard phosphorus solutions. 33 Table 1. Soil Chemical analysis of the experimental soil pH CEC. p M e./lOOg--- K Ca Mg Zn Mn Organic Cu matter Ppm. Lb s ./A— a % Brookston loam 6.5 20.7 33 151 6551 723 18 76 10 3.7 Genesee loam 6.3 15.8 14 93 4899 39^ 16 360 8 3.4 Kalamazoo sandy loam 7.3 7.0 321 275 2239 379 13 68 13 1.4 LandesAbscota sandy loam 6.3 13.2 97 75 4658 4o4 13 60 12 2.4 aAll values are averages of 3 determinations on airdried samples except for CECs (cation exchange capacities) which are means of 2 determinations and converted to the oven-dry basis. 34 4) Potassium* Calcium* and Magnesium Potassium* calcium* and magnesium were extracted from the soil with 1.0 N neutral ammonium acetate solution. Po­ tassium in the extract was determined on a Coleman Flame Photometer. Calcium was determined on a Beckman model DU flame emission spectrophotometer with 1*500 ppm. lanthanum in the extract. Magnesium also with lanthanum was determined on a Perkin-Elmer Model 290 Atomic Absorption Spectrophoto­ meter. Each determination was calibrated against a set of standard solutions of the respective elements. 5) Zinc* Manganese* and Copper Zinc and manganese were extracted from a 2.0 gram sample by shaking for 10 minutes with 20 ml. of 0.1 N HC1. Copper was extracted by shaking a 2 gram sample of the soil for 1 hour with 20 ml. of 1.0 N HC1. The three ele­ ments were determined on a Perkin-Elmer Model 290 Atomic Absorption Spectrophotometer. 6) Organic Matter Carbon was analyzed by a Leco carbon analyzer which ignited organic matter with an induction furnace* and the carbon contents were converted to organic matter content (%) by multiplying percentage of carbon by a factor of 1-724. c. Preparation and Treatment The soil was air-dried and mixed thoroughly in order that the soil became homogeneous. The soil was then sieved through a wire screen of quarter inch (6 iron.) openings to 35 remove larger stones and plant roots, and was put into pots (1 gallon cans) lined with plastic bags so that each pot contained 2.7 kg. (6 lbs.) of oven-dry weight. On a sheet of wrapping paper each soil was mixed thoroughly with three nutrient elements: nitrogen as CatNO-^g.^HgO; phosphorus as Ca(H2P0^)2 .4H£0; and potassium as KC1; and returned to the pot. Table 2 shows the amounts of the nutrient elements applied per pot expressed as equi­ valents of pounds per acre of each element converted on the basis of soil weight in the pot. Only nitrogen was applied in solution; element were applied in the solid form. other nutrient Since the phospho­ rus content of the soils varied (Table l), phosphorus rates equivalent to 44 pounds per acre were added to Brookston loam, 66 pounds per acre were applied to Genesee loam, and 22 pounds per acre were applied to both Kalamazoo sandy loam and Landes-Abscota sandy loam to insure this element was not limiting on the basis of recommendation in the Michigan State University Extension Bulletin E -550 (1 9 6 6 ). Potassium was applied as KC1 to the respective soils at five levels equivalent to 0 , 2 0 0 , 400, 80 0 , and 1,600 pounds of K per acre. Each potassium treatment was repli­ cated four times for all crops except for the 6 th crop (tomatoes) which employed two replicates. An additional replicate was prepared for the incubation study which was uncropped during the entire greenhouse experiment. 36 Table 2. Applied rates of nitrogen, phosphorus, potassium and manganese Crop Nutrient element Soil Brookston . Genesee Kalamazoo sandy loam loam loam LandesAbscota sandy loam L b s . element/A 1st crop (Wheat) N 50 50 P 44 66 K 2nd crop (Wheat) 3rd crop (Wheat) 4th crop (Sorghum) 22 (0 , 2 0 0 , 400, 8 0 0 ., and 1,600 to all s o i l s ]) 100 100 100 100 P 88 99 44 44 N 100 100 100 100 P 88 99 44 44 Mn 10 10 10 10 N Mn 6th crop (Tomatoes ) 22 50 (25)a N P 5th crop (Sorghum) 50 (25)a 100 (50)a 100 „ (50) 100 a (50) 100 0 (50) 88 99 44 44 5 5 5 5 100 100 N 100 P (§ r 100 (25)a 99 {W a ( i s )a Mn 5 5 5 5 N 70b 70b 70b 70b P Mn 100 100 100 lOO 20 20 20 20 a Additional nitrogen applied. b Split application; 35 lbs. before planting and the remainder during the growing period. 37 After harvesting each crop, the soils were sieved through a v/ire screen with openings of a quarter of an inch to remove crop roots, and mixed with given amounts of n u ­ trients, excluding potassium. The amounts of nutrients supplied to the soils for the 2nd and succeeding crops are also presented in Table 2. Calcium nitrate and monocalcium phosphate were used as nitrogen and phosphorus sources throughout the experiment. Potassium was applied to the 1st crop only. Manganese was applied in a band as a solution of M n S 0 4 * H 2 0 to the 3rd crop and the succeeding crops, since manganese deficiency was suspected with the 2nd crop at a later stage of growth. The pots were arranged in a randomized complete block design on the benches in the greenhouse. 2. a. Plants Plants Used for the Experiment Three different plants were used in the experiment; wheat (Triticum aestivum v a r . a v o n ) for the 1 st through the 3rd crops; the 4th and sorghum (Sorghum vulgae v a r . pioneer 8 8 5 )for crops; and tomato (Lycopersicon esculentum var. Campbell 1 3 2 7 ) for the 6 th crop. Wheat, sorghum and tomatoes are considered relatively high absorbers of potassium as suggested b y Newton (1 9 2 8 ), Lewis and Eisenmenger (1948) and Drake and Scarseth (1939)* 38 In growing the plants, 25 wheat seeds were planted in each pot and later thinned to 20 plants per pot. Ten s or­ ghum seeds were grown per pot and thinned to 6 plants per pot. Tomato seeds were sown in wooden flats consisting of 2 parts of unfertilized loamy soil, 1 part of sand and 1 part of shredded peat. Fifteen-day old seedlings bearing 2 true leaves were transplanted to each pot, and later thinned to 4 plants. b. Management and Growth of the Plants The 1st crop (wheat) was grown for 71 days, planted on December 5 , 1 9 6 8 , and harvested on February 13.> 19^9* Distilled water was applied as needed. However, the moisture of the soil was brought up to a pot capacity at 7 to 10 day intervals to maintain the proper moisture level. The pot capacity measured with separate pots was the percentage of water retained after the gravitational water had been removed. Since the wheat plants grown in Kalamazoo sandy loam and Landes-Abscota sandy loam showed nitrogen deficiency during the 6th week of growth, additional nitrogen, equiva­ lent to 25 pounds of N per acre, was applied to those soils (Table 2 ). The 2nd crop (wheat) was grown for 72 days from March 26, to June 5 , 1 9 6 9 . The wheat plants showed chlorotic symp­ toms as observed in the 1st crop. as manganese deficiency. T h e symptom was suspected Therefore, manganese was applied 39 to the subsequent crops (Table 2). The growth of the plants is depicted in Appendices B to E. The 3rd crop (wheat) was grown for 47 days from June 7, to July 23* 1 9 6 9 . The daytime temperature in the green­ house sometimes rose to 90°P in July and seemed to have u n ­ favorable effects on the growth of the plants. Therefore, the 3rd crop was harvested with a shorter period of growth than the previous two crops. The 4th crop (sorghum) was grown for 6l days from July 29* to September 2 7 * 1 9 6 9 . Since the sorghum plants showed symptoms of nitrogen starvation* nitrogen* equivalent to 50 pounds per acre* was applied in solution in addition to the basic treatment (Table 2). Daytime greenhouse tem­ peratures sometimes rose above 90°P during the growing period of the 4th crop. This appeared favorable for plant growth* since sorghum prefers rather warm temperatures (Ahlgren* 1956). The plant growth of the sorghum plants is depicted in Appendices B to E. The 5th crop (sorghum) was grown for 72 days from October 11* to December 21* 1 9 6 9 . Prom the 3^d week.* dif­ ferences in plant growth were visibly observable among the potassium treatments. Plants subjected to the K=0 (no K added) and K=200 (200 lbs. K / A . ) treatments showed potassium deficiency symptoms resulting in yellowing of the older leaves* burned edges* and less vigorous growth. The K=800 and K =l*600 treatments resulted in larger* healthier plants. The K=400 treatment produced plants intermediate in growth. 40 Additional nitrogen equivalent to 25 pounds of N per acre was applied during the 5th w e e k before nitrogen deficiency developed. The growth difference of the 5th crop are illus­ trated in Appendices B to E. The 6 th crop (tomatoes) was grown for 42 days; being transplanted on M a r c h 18, and harvested on A p r i l 28, 1970. The tomato plants showed potassium deficiency two weeks after being transplanted in the soils containing 0 pound per acre applied potassium. Prior to harvest, the plants grown on Br o o k s t o n loam showed chlorosis of the older leaves with slight b u r n i n g at the edges on the K=0 treatment. The plants grown on Genesee loam showed po t a s s i u m deficiency following the K=0, K-200, and K=400 treatments. The d e f i ­ ciency was most prominent on the K -0 treatment where ex­ cessive leaf drop of the older leaves occurred and the middle leaves showed chlorosis on the entire leaf w it h m a r ­ ginal leaf burn. Busty b l ack specks irregular in shape 2/5 to 1 mm. in diameter, were observed on and bet w e e n the veins of the older leaves of the potassium deficient plants. This symptom appeared to b e associated with p o t assium defi­ ciency since examination by Mr. Bockstahler, Department of Botany and Plant Pathology, Michigan State University, con­ firmed the absence of fungus causing this symptom. The plants growing on Kalamazoo sandy loam and LandesAbscota sandy loam showed the same tendency for potassium deficiency as described for those growing on Genesee loam. In general, better plant growth was observed on the higher 41 potassium treatments. T h e temperature of the greenhouse was maintained at approximately 7 0 °P. during night but perio d i c ­ ally rose above 80°F in the daytime. The growth of the 6 th crop is illustrated in Appendices B to E. 3. a. Plant Analysis for Potassium, Calcium, and Magnesium Chemical Analysis The harvested plant material was ground in a Willey ^ o mill after having been dried in an oven at 160 F. One gram samples of the ground tissue were placed in 50 ml. beakers and ashed in a muffle furnace at 400°C for 8 hours. sure the ashing 20 ml. To i n ­ of 1 El HNO^ was added to the beakers and evaporated to dryness on a hot plate. T h e residue in the beakers was ashed again at 400°C for 10 minutes. The ashed material was taken up with 0.1 N HC1 in 100 ml. volumetric flasks and the extract used for potassium, calcium, and magnesium determinations. Potassium was determined on a Coleman Flame P h o t o ­ meter Model 21. Calcium and magnesium were determined with a Perkin-Elmer 303 Atomic Absorption Spectrophotometer. T he plant uptake of each element was obtained b y multiplying the concentration (^) of the element by the plant yield (dry matter), and expressed as a m i l l i g r a m of the element per pot. b. Electron Microprobe X - K a y Analysis The electron microprobe X-ray analysis was used for the determination and distribution of potassium, calcium, 42 and magnesium in wheat, stem tissue. Stem segments of* 9-week old wheat plants were obtained 1 -inch above the ground from the 2nd crop grown on Br o o k s t o n loam receiving 400 pounds of potassium per acre and on the 0 potassium treatment of Genesee loam. The stem segments were immediately frozen and s e c ­ tioned after embedding them in Optimum Cutting Temperature compound (Tissue-Tek, -15° "to ~30°C; pany) on the cryostat at -l8°C. Fisher Scientific C o m ­ The thin cross sections (16 pm thick) were mounted on polished carbon discs at room temperature, allowed to air-dry, and then submitted for electron microprobe X - r a y analysis. B. Results and Discussion 1. Plant Yields a. Plant Yields Obtained on Brookston, and Landes-Abscota Soils^ ~ " ” Genesee. Kalamazoo, The plant yields of the 1 st through the 6 th crops are presented in Tables 3 to 6 for Brookston loam, loam, Kalamazoo sandy loam, Genesee and Landes-Abscota sandy loam. The values are averages of 4 replications except for the 6th crop which had only 2 replications. The LSD. (least significant difference) values were calculated only where F test by the analysis of variance showed significant treatment effects at less than 5 percent probability levels as suggested by Steel and Torrie (i9 6 0 ). In addition, regression analyses were carried out to determine the relationships between plant yields and potas­ sium treatments* and are presented in Table 7. The general trends on all soils show that the plants responded favorably to the potassium treatments when potas­ sium became exhausted by continuous cropping. Also shown are the differential responses of the plants to applied potassium. b. Effect, of Potassium Treatment on the Yield of Plants Grown on Brookston Loam In Brookston loam* the initial exchangeable potassium* 151 pounds per acre (Table l)* and nonexchangeable potassium* 2') 31.9 mg. per 100 g.* seemed to be sufficient to supply the 1st and 2nd crops since the two crops did not respond to applied potassium (Tables 3 and 7 * and Figure Al). The 3rd crop responded to potassium application but the 4th and 5th crops did not. This may have been the result of the differ­ ence in the potassium absorbing power of the plants and en­ vironmental effects. Sorghum plants appeared to be higher than wheat in potassium absorbing power as suggested by Drake and Scarseth (1939) in which Sudangrass absorbed more potassium than spring wheat on Crosby silt loam. The green­ house temperature in the daytime rose to more than 9°°F during the growing period of the 3rd crop (June 7 3 to July 23* 1969)3 at which temperature the 3**d crop* wheat* performed poorly but seemed to have received beneficial effect from the applied potassium. " 2 )See Table 21. Plant respiration is generally 44 Table 3. Yields of wheats sorghum, and tomato crops as affected b y potassium treatments on B r o okston loam K treatment 1 Wheat crop 2 3 (Lbs ./A . ) Sorghum crop 4 5 Tomato crop b Total (G m ./p o t ) 9.0 7.1 9*9 11.1 9*5 0 200 400 800 1,600 L.s.d.a . N.s.u :S! 21.0 23.8 22.9 20.4 21.3 6.1 6 .6 7.0 7.4 7*8 23*5 23.5 24.0 23-9 24.6 6.4 7.3 7.4 7.4 7.8 6 .1 6.2 5*9 7-3 8.0 72.8 74.5 77.1 77.5 79-0 N.s. N.s 0.7b 0.73 1.02 1.26 ^ h e least significant difference at 5^> and l^J levels of probability* respectively. b No significant difference in plant yields as detected by F test with analysis of variance. Table 4. Yields of wheat* sorghum* and tomato crops as affected by potassium treatments on Genesee loam K treatment (Lbs./A. 0 200 400 800 1*600 N.s. 1 Wheat crop 2 3 J S orghum crop 4 5 Tomato crop b (G m ./p o t ) 8.1 8.4 8.1 8.1 8.3 15.8 16.1 17.1 17.6 17.3 4.8 5-5 f:? 6.9 20.0 19*5 22.0 22.4 26.6 6.4 6 .6 7.6 9:3 1.7 2.6 3.6 5.4 6.7 1.09 1 .52 0.95 1.57 L. s .d .a i:Si) Total N.s.b N. s . 0.39 0.55 1.94 2.72 ^ h e least significant difference at and 1 % levels of probability* respectively. significant difference in plant yields as detected by F test with analysis of variance. 56.8 58.7 64.3 68.4 75.2 45 Table 5 . K treatment Yields of* wheats sorghum, and tomato crops as affected b y potassium treatments on Kalamazoo sandy loam 1 Wheat crop 2 3 (Lbs./A . ) Sorghum crop 4 5 Tomato crop 6 Total (Gm./potJ H 0O00O OOOO c\j-3-covo a'.l 8.6 8.0 8.1 16.4 16.1 14.8 13.0 13.8 5.1 6.0 6.0 6 .6 6.3 17.6 20.9 22.1 20.8 24.0 2.9 4.3 5.0 6.0 6.8 0.98 1.38 0.58 0.97 56.6 6 3 .O 64.6 62.7 68.9 ! 6.1 7.3 8.1 8.3 9-9 T a L.s.d. !:??! N. s .d 1.33 1.86 0.47 0.66 1.88 2.64 ^ h e least significant difference at 5^ and 1 % levels of probability, respectively. b Ko significant difference in plant yields as detected by F test with analysis of variance. Table 6 . K treatment Yields of wheat, sorghum, and tomato crops as affected by potassium treatments on Landes Abscota sandy loam 1 Wheat crop 2 3 "(Lbs ./A. ) 0 200 400 800 1,600 S orghum crop 4 5 Tomato crop 6 (G m . / p o t ) 9-0 10.4 10.5 10.1 10.8 15.3 15.1 15.4 15.4 16.1 5.4 5-5 6.0 6.6 7.0 20.6 21.8 22.4 22.9 25.8 7.0 7.4 7.9 7.9 8.5 2.9 2.6 4.3 5*5 7.1 0.38 0.53 1.67 2.76 L.s.d.a U i Total 0.42 0 .58 N.s? 0.48 0.68 2.03 2.85 ^ h e least significant difference at 5^ and levels of probability, respectively b No significant difference in plant yields as detected by F test with analysis of variance. 60.2 62.8 6 6 .5 68.4 75-3 46 Table 7- Relationships between plant yields and potassium treatments on Brookston loara, Genesee loam, Kalamazoo sandy loam and Landes-Abscota sandy loam Cro]^- Linear regression equation Simple correlation. coefficient (r) Brookston loam = Wheat (1st crop) 0.62X 4,946 4* 0.52X Wheat (3rd crop) - Tomato (6th crop) ? - 5,067 4- O.47X 0.42 4,358 4* 1.00X 0 .89** H Y X Sorghum (5th crop) 0 .68** 0.24 17,397 4- • - in 0 Sorghum (4th crop) CVJ - • Y - 16,559 0.19 cu 0 1 Wheat (2nd crop) 6,490 4* 0.69X Genesee !loam Wheat (1st crop) ? Wheat (2nd crop) ? VJheat (3rd crop) ? - 6,066 4- 0.01X 12,022 + 0.67X = 0.02 0.48* 3,817 + O.89X 0 .90** Sorghum (4th crop) = 14,971 + 1.34X 0 .6 0 ** Sorghum (5th crop) - 4,849 + 1.42X 0 .86** Tomato (6th crop) - 1,563 + 2.30X 0 .96** 47 Table 7 (cont1d . ) Crop8* Linear regression equation Simple correlation. coefficient (r) Kalamazoo sandy loam Wheat (1st crop) ? = Wheat (2nd crop) 6*291 - 0.21X = 11*760 - 1.33X -0.37 -0 .62** Wheat (3rd crop) ¥ = 4*194 + 0.42X O.56* Sorghum (4th crop) ? = 14*276 + 2.22X 0 .71-** Sorghum (5th crop) ? s 4*946 4 1.54X 0.83** Tomato (6th crop) $ = 2*707 +• I.65X 0 .92** Landes-Abscota sandy loam Wheat (1st crop) = 7*206 4- 0.52X O.58** Wheat (2nd crop) 1? = 11*187 4. 0.43X O.50* Wheat (3rd crop) *? = 4*o46 4. 0.79X 0.86** Sorghum (4th crop) = 15*469 * 2.21X 0.83** Sorghum (5th crop) = 5*347 + 0.62X 0 .82** ? = 2*024 4 2.11X 0.gA** Tomato (6th crop) aEach crop had 4 replicates except for the 6th crop which had only 2. * and ** indicate significance at 5 % and Vfo probability levels respectively. 48 stimulated by higher temperatures and the applied potassium might have affected plant metabolism since plant respiration and potassium consumption are closely related. The 4th crop, sorghum, showed a more favorable growth response under high temperature and high sunlight intensities during the growing period of July 29, to September 27, 1969 than the 5th crop, sorghum, which was grown from October 11, to December 21, 19&9 (Tables 3 and 7; Figures A2 and A3). For the 6th crop, tomatoes, native potassium seemed to be exhausted and available quantities were not sufficient to support the crop without the addition of potassium, even though the tomato plant has a relatively strong absorption power for potassium, as shown by Lewis and Eisenmenger (1948). The differential response between sorghum (the 5th crop) and tomatoes (the 6th crop) may not be explained fully by plant differences but by the depletion of soil p o ­ tassium, since the tomato crop did not show significant yield differences with potassium application when grown on the newly treated (uncropped) soils, as shown in Table 8 and Figure A 5 of Appendix B. c. Effect of Potassium Treatment on the Yield of Plants Grown on Genesee Loam Genesee loam contained only 93 pounds of exchangeable potassium per acre (Table l) which, however, appeared to be sufficient to supply adequate potassium to the 1 st and 2nd crops (Tables 4 and J , and Figure A 6 ). The 3rd and succes­ sive crops responded positively to applied potassium due to 49 the exhaustion of native soil potassium which was c onse­ quently considered to be lower in this soil than in Brookston loam. The good yield of the 4th crop in Genesee loam may be explained in the same manner as the 4th crop grown on Brookston loam. The tomato plants grown on newly treated (uncropped) Genesee loam did not respond to application of potassium as indicated in Table 8 and Figure A 1 0 in contrast with the 6th crop (tomatoes) which showed remarkable benefit from the potassium treatments (Tables 4 and 7, and Figure A9). d. Effect of Potassium Treatment on the Yield of Plants Grown on Kalamazoo Sandy Loam Since the initial exchangeable potassium was as high as 275 pounds per acre (Table l), potassium application seemed to have created detrimental effects on the yields of the 2nd crop on this soil b y supplying the plants with an excess amount of potassium which was apparently not a l l e ­ viated by potassium fixation. The fixation of potassium was very low in this soil in contrast with the other three soils.^ ^ Sunlight stimulates plant metabolism and respiration leading to the activation of root uptake of nutrients. The unfavorable effect of excess potassium v/as not clearly in­ dicated with the 1 st crop because the intensity of sunlight was low during the growing period (December 5* 1988, to February 1 3 , 1 9 6 9 ). On the other hand, during its growing period (March 2 6 , to June 4, 1 9 6 9 ) the 2nd crop received 3)see Table 2 3 . more sunlight causing more plant uptake of potassium and decreasing the yields b y the increased levels of potassium application (Tables 5 and 7). The 3rd and succeeding crops responded positively to applied potassium. T h e discussion of the 4th crop grown on Brookston loam would also be applied to the 4 t h crop of Genesee loam. In contrast with the tomatoes (6th crop) which showed a remarkable yield increase due to the residual potassium, the tomato plants grown on the newly prepared (uncropped) soil did not respond to any of the potassium treatments (Tables 7 and 8, and Figures A l 4 and A15). e. Effect of Potassium Treatment on the Y i e l d of Plants Grown on Landes-Abscota Sandy Loam This soil was initially low (75 lbs./A) in exchange­ able potassium (Table l). It appeared to be partly due to the influence of the previous tomato crop grown at the sample collection site. Tomato plants are generally believed to absorb large quantities of potassium (Fried and Broeshart, 1967)- The application of potassium was effective in i n ­ creasing plant yields of the 1st crop (Table 6). However, the 2nd crop seemed to have absorbed sufficient native p o ­ tassium possibly due to more favorable environmental condi­ tions as previously discussed. W h e n the native potassium became exhausted, the 3rd and successive crops responded to applied potassium (Tables 6 and 7^ and Figures Al6 to A19). The discussion on the general high yield of the 4th crop in Brookston loam may also apply. 51 Table 8 . Yields of* tomato plants on newly treated (uncropped) Brookston, Genesee, Kalamazoo, L andes-Abscota soils K treatment Brookston loam Soil Genesee loam Kalamazoo sandy loam and LandesAbscota sandy loam ( G m ./ p o t ) a (Lb s ./ A . ) 0 11.1 10.3 9*6 10.9 200 10.8 10.4 10.2 12.0 400 10.1 10.8 10.4 12.4 800 10.8 11.2 10.1 11.9 1,600 10.4 10.0 8.6 10.2 N.s.C N.s. N.s. N.s. L.s.d. (.05)b aAll values are averages of 2 replicates. b . The least significant difference at level of probability. cNo significant difference. I 52 The tomato plants grown on the newly prepared (uncropped) soil showed no significant difference in plant yields due to potassium treatments of Appendix D). (Table 8 , and Figure A20 The difference in response to applied p o ­ tassium b etween the 1st wheat crop., which responded to applied potassium, and the tomato plants (also the 1 st crop on the newly prepared soil), which did not respond to a p ­ plied potassium, may be considered as the result of the differential potassium absorbing power between these two plants, i.e., the wheat plants needed applied potassium to meet increasing growth but the tomato plants used sufficient native potassium when potassium application was low. 2. Potassium, Calcium, and Magnesium Concentrations in the Plants a. Potassium, Calcium, and Magnesium Concentrations, Relations among the Concentrations of T h e s e Elements 1) Potassium, Calcium, in the Plants and and Magnesium Concentrations The plant concentrations of potassium, calcium, and magnesium were obtained by plant analysis for each crop, and the results are summarized in Tables 9 "to 12 on the basis of dry weight. The potassium concentration of plants grown on all the soils rose with the increasing level of applied p o ­ tassium, which agreed with the work of DeMent et a l . in 1959* Since it has been reported that antagonistic relationships exist between potassium and calcium or potassium and m a g n e ­ sium, relationships among the three elements were examined (Table 13). 53 2) Relationship between Concentrations of Potassium and Calcium Calcium concentrations seemed to decrease while p o ­ tassium concentrations increased with higher potassium levels although this relationship seemed to be influenced by the initial level of the elements in the soil and also by the plant. Only in Kalamazoo sandy loam did the relationship between potassium and calcium differ from t h e other three soils. 3 ) Relationship between Potassium and Magnesium in the Plants The general relationship between potassium and m a g ­ nesium concentrations was similar to that of potassium and calcium. 4) Relationship between Calcium and Magnesium These two elements seemed to be closely related and to behave similarly when related to potassium. 5) Relationship between Potassium and Calcium plus Magnesium This relationship coincides with that of potassium versus calcium. 6 ) Relationship between Potassium and the Square Root of Calcium plus Magnesium Concentrations Activity ratios such as aVv/a (Ca +■ Mg) soh has been proposed as an availability measure of soil potas­ sium by Beckett (1964a). The relation of potassium concen­ tration and the square root of calcium plus magnesium Table 9 . Potassium* calcium* and magnesium concentrations of plant material as affected by potassium treatments on Brookston loama K b treatment K Lbs./A, Mg Ca K Ca Mg % % 1st crop-wheat 2nd crop-wheat 2.73 O 200 3.88 400 VO 0 Ca K Mg 3rd crop-wheat 2,78 0.62 0.33 1.30 0.74 0.46 0.87 0.34 3.15 0.55 0.29 1.30 0.75 0.45 3.75 0.71 0.27 4.18 O.58 0.25 I.65 0.68 0.43 800 4.65 0.70 0.28 5.43 O.56 0.22 2.60 0.60 0.34 1*600 4.55 0.83 0.31 5.08 0.64 0.20 4.03 0.56 0.21 m 0.39 4th crop-sorghum 5th crop-sorghum 6th crop-tomato 0 0.24 0.68 0.84 O.58 2.22 1.16 1.02 3.42 O.76 200 0.22 0.70 0.87 0.62 2.06 1.17 1.23 2.95 0.70 400 0.18 0.66 0.82 0.54 1.81 1.04 1.33 3.54 0.73 800 0.22 0.62 0.71 0.67 1.75 1.02 1.50 3.19 0.67 1*600 1.46 0.42 0.39 1.27 1.56 0.98 2.09 3.07 0.58 All values are averages of 4 replicates except for the 6th crop which had only 2. ^Potassium was given only to the 1st crop. Table 10. K treatment*3 Potassium,calcium, and magnesium concentrations of plant material as affected by potassium treatments on Genesee loam®' K Lbs./A. Ca Mg K Ca Mg K Ca Mg % % 2nd crop-wheat 1st crop-wheat 3rd crop-wheat 0 l.4o 0.72 0.43 1.10 0.74 0.42 O.85 1.03 0.48 200 2.78 0.51 0.25 2.13 0.71 0.40 1.08 0.99 0.46 400 3*70 0.59 0.23 3.53 0.69 0.34 1.30 0.90 0.43 800 3.88 0.62 0.22 5.28 0.59 0.23 2.28 0.74 0.33 1.600 4.33 0.86 0.25 5.93 0.64 0.20 3.83 0.62 0.19 4th crop-sorghum 5th crop-sorghum 6th crop-tomato 0 0.17 0.88 0.64 0.42 2.70 O.96 O.91 3.90 1.06 200 0.17 0.93 0.71 0.44 2.50 0.94 0.75 4.02 0.90 400 0.12 0.72 O.65 0.48 2.23 0.93 0.82 3.78 0.64 800 0.19 0.65 0.63 O.56 1.94 0.86 O.85 3.07 0.48 1,600 1.05 0.51 0.39 0.83 1.60 0.80 1.59 3.13 0.48 aAll values are averages of 4 replicates except for the 6th crop which had only 2 , ^Potassium was given only to the 1st crop. Table 11. K treatment13 Potassium, calcium, and magnesium concentrations of plant material as affected by potassium treatments on Kalamazoo sandy loama K Lbs./A. Ca Mg K Ca % Mg K Ca % % 2nd crop-wheat 1st crop-wheat Mg 3rd crop-wheat 0 3.20 0.45 0.25 3.50 0.39 0.27 1.38 0.71 0.47 200 3.38 0.44 0.24 4.20 0.39 0.25 2.35 0.48 0.34 400 3*95 0.57 0.29 M 5 0.46 0.24 3.30 0.40 0.26 8oo 3.93 0.61 0.31 6.08 0.79 0.36 3.85 0.40 0.21 1,600 3.88 0.66 0.31 6.43 0.74 0.30 4.33 0.55 0.23 4.th crop-sorghum t5th crop-sorghum 6th crop-tomato 0 0.21 0.65 0.71 0.41 2.23 1.14 0.69 3.01 1.04 200 0.31 0.54 O.69 0,49 1.90 I.09 0.61 3.25 0.90 400 0.44 0.45 0.57 0.59 1.58 1.02 1.07 3.25 0.78 800 1.24 0.45 0.34 O.99 1.32 0.78 1.59 3.13 0.71 1,600 2.13 0.43 0.24 1.60 1.09 0.63 2.85 3.37 0.66 aAll values are averages of 4 replicates except for the 6th crop which had only 2. ^Potassium was given only to the 1st crop. Table 12. K . treatment Potassium* calcium* and magnesium concentrations of plant material as affected by potassium treatments on Landes-Abscota sandy loama K Lbs./A. Ca % Mg K Ca K Ca Mg % % 2nd cron-wheat 3rd crop-wheat . 1st crop-wheat Mg 0 1.35 0,88 0.46 I.65 0.80 0.46 1.10 1.05 0.48 200 2.88 0.62 0.31 2.15 0.70 0.43 1.15 0.90 0.48 400 3.78 0.64 0.24 3.10 0.70 0.38 1.38 O.85 0.47 800 3.98 0.75 0.24 5.28 0.65 0.28 2.43 0.74 0.37 1*600 4.15 0.85 0.25 5-55 0.86 0.26 3.88 O.65 0.22 4th crop-sorghum 5th crop-sorghum 6th crop-tomato 0.87 0.63 0.36 2.36 O.89 0.8l 3.84 0.75 200 0.14 0.74 0.60 O.38 2.49 0.97 0.68 3.45 O.69 400 0.15 0.72 0.64 0.45 2.15 0.90 0.62 3.^3 0.53 800 0.22 0.67 0.61 0.53 I.85 0.78 1.00 3.42 0.49 1*600 m CO O.56 0.43 0.83 1.66 0.68 1.73 3.36 0.43 • 0.20 0 0 aAll values are averages of 4 replicates except for the 6th crop which had only 2. ^Potassium was given only to the 1st crop. 58 Table 13. Relationships among concentrations of potassium, calcium and magnesium in plants grown on Brookston, Genesee, Kalamazoo and Landes-Abscota soils Comparison 1 Crop 3 2 4 5 6 Br o o k s t o n loam K vs. Ca -0.27 0.06 K vs. Mg -0.40 -0.8l** Ca vs. Mg K vs. O.93** 0.26 Ca + M g K vs. -0.87** -0.84** -0.47* -0.37 -0.27 y e a 4- Mg -0.30 -O.98** -0.88** -0.37 0.88** 0.06 O . 93** -0.82** 0.63** 0.51 -0.87** -0.84** -0.47* -0.37 -0.37 -O.95** -0.90** -0.49* -0.50 Genesee loam K vs. Ca K vs. 0.18 Mg -0 .7 6 ** -O.93** -O.69** -0.78**-0.33 -O.87** -O.95** -O.99** -O.89** -0.64**^0.26 Ca vs. Mg 0.25 K vs. 0.18 -0.76** -O.93** -O.69** -0.78**-0.33 -0.25 -0.91** -O.9 7 ** -0.84** -0.80**-0.31 Ca + Mg K vs./ C a + Mg O.85** O.96** O.7 8 ** 0.80** 0.80** Kalamazoo sandy loam K vs. Ca 0.73** 0.88** -O.56* K vs. Mg 0.68** Ca vs. Mg 0.87** O.87** 0.78** K vs. Ca + Mg 0.73** 0.88** -O.57** -0.60** -0.87** 0.02 K vs. / C a + Mg 0.74** O.83** -O.7 6 ** -0.91** -O.93** 0.02 O . 55* -O.95** -0.60** -O.87** 0.02 -O.95** -O.91** 0.62** 0.72** 0.87** 0.01 59 Table 13 (cont'd) Comparison 1 2 Crop 3 ' 4 5 Simple correlation coefficient (r) Landes-Abscota sandy loam K vs. Ca K vs. Mg Ca vs. Mg -0.28 0.13 -0.81** -0 .56** -0.80** -0.48 -O.9 3 ** -o.94**-0.99** -0 .7 8 ** -0.73** - O .58 0.51* K vs. Ca <■ M g -0.28 K vs. / C a + Mg -0.63** 0.05 0.80** O.7 8 ** 0.91** 0.79** 0.13 -0.81** - O . 56** -0.80** -0.48 -0.49* -O.95** -0.71** -0.80** -0.52 6o concentrations in the plants was used to replace the a c t i ­ vity of the elements for the convenience of calculation. The relation was found to be similar to that of potassium and calcium concentrations, and in general indicated that the order of the activity ratios in the soil was comparable to the absorption of these elements by the plants if Beckett's proposal was significantly applicable. b. Electron Microprobe X - r a y analysis of Wheat S tem Tissue for Potassium, Calcium, and Magnesium The electron microprobe X - r a y analyzer was used to determine the relative intensity of potassium, calcium and magnesium, and the distribution of these elements in wheat stems (2nd crop) harvested from Brookston loam and Genesee loam which received 400 and 0 p o u n d per acre p o t assium respectively. employed: T h e following instrumental parameters were 25 kv accelerating voltage, and 0.025 pa sample current. The concentration and distribution of potassium, cal­ cium, and magnesium in the stem tissues are presented b y the X-ray oscillograms (Figures 2 to 4 ’ and 8 to 10) and b y line scans (Figures 5 and 6 ). The cellular detail of 200 pm portions of the stems obtained from Br o o k s t o n and Genesee soils are shown in Figure 1 and 7^ respectively. A contrast is shown in these figures. The potassium concentration of the stem tissue obtained from B r o o k s t o n loam is greater than calcium or magnesium. These results are in 61 good agreement with the following chemical analysis obtained on the plant tissue (2nd crop): 4 . 1 8 $ K, 0 .58$ Ca, and 0.25$ Mg (Table 9 ). On the other hand,, the potassium concentration was considerably lower than calcium and similar to magnesium for the stem tissue obtained from the K=0 treatment on Genesee loam (Figures 7 to 9 ). T h e relative intensity of these elements seems to b e inconsistent with the chemical analysis of the plant material (2nd crop), as shown in Table 10, which indicated 1.10$ K, 0.74$ Ca and 0.42$ Mg. However, because of the potassium stress in the soil, the potassium contained in the stem tissue was rapidly translocated to the leaves. Consequently the concentration of potassium in the stem was lower than that of calcium even though the concentration of potassium in the whole plant was higher than calcium, as shown by the chemical analysis. The traverse profiles of line scan (Figures 5 sricl 6 ) represent the relative intensity of potassium, calcium, and magnesium across the 200 pm portion of the stem tissues from points A to B of Figures 1 and 7 respectively. These data confirm the interrelationships among the three elements c on­ tained in the stem tissue obtained from Br o o k s t o n loam (K = 400 treatment) and Genesee loam (K - 0 treatment). Moreover, as shown b y the line scans, the distribution of potassium, calcium, and m a g nesium in the stem tissue suggests that the three elements are distributed at similar loci in the stem tissue. The three elements are apparently concentrated 62 Figure 1. Cellular detail of* a 200 pm portion of* wheat stem obtained from Brookston loam receiving 400 pounds of potassium per acre (Reverse sample current 3 magnification 42 5x) Figure 2 . Potassium X-ray oscillogram showing the dis­ tribution of potassium in a 200 pm portion of wheat stem obtained from Brookston loam receiving 400 pounds of potassium per acre Figure 3. Calcium X - ray oscillogram showing the d i s ­ tribution of calcium in a 200 pm portion of wheat stem obtained from B rookston loam receiving 400 pounds of potassium per acre Figure 4. Magnesium X-ray oscillogram showing the dis­ tribution of magnesium in a 200 pm portion of wheat stem obtained from Br o o k s t o n loam receiving U 00 pounds of potassium per acre 64 Figure 5 . Relative intensity measurements of potassium, calcium, and magnesium in a 200 jam portion of wheat stem tissue grown on Bro o k s t o n loam receiving 400 pounds of potassium per acre (Points A to B of Figure l) •minTTTTTTPfTT inii-muim**; !.•i-ii-suii;; DISTANCE Figure 6. Relative intensity measurements of potassium, calcium, and magnesium in a 200 (am portion of wheat stem tissue grown on Genesee loam receiving 0 pounds of potassium per acre (Points A to B of Figure 7) Figure 7. Cellular detail of* a 200 p m portion of wheat stem obtained from Genesee loam receiving O pounds of potassium per acre (Reverse sample current* magnification 425x) Figure 8 . Potassium X-ray oscillogram showing the dis­ tribution of potassium in a 200 pm portion of wheat stem obtained from Genesee loam receiving 0 pounds of potassium per acre 66 I J Figure 9 . Calcium X-ray oscillogram showing the dis­ tribution of potassium in a 200 pm portion of wheat stem obtained from Genesee loam receiging 0 pounds of potassium per acre Figure 1 0 . Magnesium X-ray oscillogram showing the dis­ tribution of potassium in a 200 pm portion of wheat stem obtained from Genesee loam re­ ceiving 0 pounds of potassium per acre 67 at xylem, phloem, and their related tissue, through which inorganic ions and metabolic products are translocated res­ pectively as known in plant physiology (Briggle, 1967, and Levitt, 1 9 6 9 ). The high peak, resulting in the line scan for calcium at about 44 pm from point A of Figure 6 is suspected to be due to a contaminant as indicated in Figure 7 . It is believed that nutrient elements are translocated to the upper parts of plants through the ion carrier after entrance to the free space of the root (Fried and Broeshart, 1967). However, it appears necessary to characterize the specificity of the carriers for certain elements at different conditions. The mode of entrance of potassium, calcium, and magnesium to the plant root and translocation to the shoots may be studied in detail by the use of the electron micro­ probe X-ray method as that carried out for aluminium (Rasmussen, 1968; and Rasmussen et al.,1 9 6 8 ) with sufficient knowledge of plant anatomy as well as physiology. c. Relationship between Plant Yields and Concentrations of Potassium, Calcium, and Magnesium In order to examine possible relationships between plant yields and concentrations of potassium, calcium, and magnesium in the plants, simple correlation coefficients were calculated and presented in Table 14. l) Relationship between Plant Yields and Potassium Concentrations The potassium concentrations of the plant were gene­ rally positively related to the plant yields obtained from 68 all the soils except for the earlier crops in Brookston loam and Kalamazoo sandy loam. The relationship between potassium concentration in the plant and the yields generally increased with cropping of the soils due to the depletion of available soil potassium in Kalamazoo and Landes-Abscota sandy loam soils. 2) Relationship between Plant Yields and Calcium Concentrations The calcium concentrations of the plants seemed to be negatively related to the plant yields for all soils gene­ rally, except for the 1st crop grown on Genesee loam, the 6th crop on Kalamazoo sandy loam, and the 2nd crop on Landes-Abscota sandy loam. 3 ) Relationship between Plant Yields and Magnesium Concentrations The relationship between magnesium levels of the plant tissue and yields of the crop was similar to that of calcium. 4) Relationship between Plant Yields and Potassium, Calcium, and Magnesium Concentrations Wo general tendencies in the relationship between the plant yields and the concentrations of potassium, calcium, and magnesium became obvious in all the soils employed. 5) Relationship of Plant Yields and Concentration Ratios of Potassium to Calcium The concentration ratios of potassium to calcium were somewhat positively related to plant yields, especially for Kalamazoo and Landes-Abscota sandy loam soils. 69 Table 14. Relationships between plant yields and potassium, calcium, and magnesium concentrations of the plants grown on Brookston, Genesee, Kalamazoo, and Landes-Abscota soils Relationships of plant yields and 1 cones, of elements Crop 2 3 Wheat 4 5 Sorghum 6 Tomato Simple correlation coefficient (r) O o Brookston loam K -0.25 0 .7 5 ** 0.26 0.20 0 .88** Ca -0 .85** -0.48* •-0.73** -0.45* -0 .70**--0.44 Mg -0.78** -0.16 K f Ca f Mg -0.23 -0.30 0.74** 0.07 -0 .47* •-0 .73** -0.33 -0.18 -0 .79** 0.37 K/Ca O.56* 0.01 0 .75** 0.29 0.38 0 .88** K/Mg 0.4-9* -0.13 0 .69** 0.26 0.19 0 .90** K/Ca + Mg 0 .54* -o.o4 0 .73** 0.27 0.31 0 .88** K//Us. + Mg o'. 36 -o.i4 0.74** 0.27 0.26 0 .89** Genesee loam K 0.02 Ca 0.001 Mg K -0.02 Ca +■ Mg 0.02 0 .60** 0 .87** 0.36 0 .83** 0.57 -0 .51* ■-0 .91** -0.74**'-0.84**--0 .81** -0 .60**.-0 .87** -O.57** -0.71**--0 .92** 0 .60** O.85** -0.33 -0 .71**--0.60 K/Ca -0.0001 0 .60** 0 .86** 0.36 0 .85** 0 .71* K/Mg -0.01 0 .55* 0 .80** 0.36 0 .85** 0 .90** K/Ca t Mg -0.01 0 .58** 0.84** 0.36 O . 85** 0 .76 * 0.01 0 .59** 0 .86** 0.35 0 .85** 0 .68 * K//Ca f Mg 70 Table 14 (cont'd) Relationships of plant yields and cones, of elements Crop R 2 4 r -g o fg h ^ T ? 6 Tomato Simple correlation coefficient (r) Kalamazoo sandy loam K -0.19 -0 .86** Ca -0.21 -0 .87** -0.73**- •0 .7 3 **- 0 .85** 0.14 Mg -0.09 -0 .69** -0.84**-•0 .6 2 **- 0 .78**-.0 .94** K + Ca + Mg -0.20 -0 .88** 0.72** 0 .6 3 ** 0 .84** 0 .87** 0 .6 6 ** 0.53* - 0 .51* 0 .72* K/Ca 0.13 K/Mg -0.13 -0.28 0 .76** 0 .6 3 ** 0 .83** 0 .88** 0.04 0.24 0 .80** 0 .63** 0 .85** 0 .85** -0 .51* 0 .7 8 ** 0 .63** 0 .85** 0 .87** K/Ca 4- Mg K//Ca +• Mg -0.13 0 .54* 0 .8 0 ** 0.64** 0 .85** 0 .83** Landes-Abscota sandy loam K o . 8o** Ca -0.43 Mg -0.79** O .38 0.24 -0.53* 0 .84** 0 .6 8 ** 0 .75 ** 0.84** -0 .86**-■0 .82**-■0 .81**-•0.75* -0 .8 3 **-■0 .6 9 **-.0 .6 9 **-■0 .83** K 4- Ca + Mg 0.77** 0.39 0 .81** 0.07 K/Ca 0 .8l** 0.30 0.84** 0 .7 3 ** 0 .81** 0 .89* K/Mg 0 .7 6 ** 0.45* 0 .77** 0 .6 8 ** 0 .78** 0 .91** K/Ca 4- Mg 0 .81** 0.36 0 .82** 0 .7 0 ** 0 .80** 0 .89** K//Ca ¥ Mg 0 .81** 0.37 0 .83** 0 .7 0 ** 0 .7 8 ** 0 .87** -■0 .66 **--0.24 6 ) Relationship of Plant Yields and Concentration Ratios of Potassium to Magnesium A positive relationship between plant yields and concentration ratios of potassium to magnesium generally existed for all soils. This relationship was best correlated v;ith the yields of the 3 rd (wheat) and 6 th (tomato) crops on all s o i l s . 7) Relationship of Plant Yields and Concentration Ratios of Potassium to Calcium plus Magnesium A similar trend was observed for plant yields as a function of the concentration ratios of potassium to calcium plus magnesium as was cited for the concentration ratios of potassium to calcium. 8 ) Relationship of Plant Yields and Concentration Ratios of Potassium to the Square Root of Calcium plus Magnesium The relationship between plant yields and concentration of potassium divided by the square root of calcium plus magnesium of the plants was positively correlated for the 3rd and 6 th crops grown on Brookston loam. This relation­ ship was generally more meaningful for the other soils. Plants may absorb more nutrients than required for optimum yields when the nutrients are in abundant supply. This phenomenon is called "luxury c o n s u m p t i o n " . Excessive amounts of potassium are commonly absorbed b y plants when present in large supply. The concept of luxury consumption can easily be understood in connection with Marcy's 72 "critical percentage" (Thompson, 1959) • Additions of* a certain nutrient element increase the yields of* a plant with out a great increase in the element to a certain point in the plant tissue. B e y o n d this point the yield increases little, but the concentration of the element in the plant tissue increases greatly, the element. corresponding to the addition of Accordingly, Marcy defined the point at which yields were no longer increased as the "critical percentage'1 which can also be defined as the point above which luxury consumption takes place. The poor correlations between the plant yields and the potassium concentrations of the plants observed with the 1st crop (wheat) grown on Genesee loam and the 1st and 2nd (wheat) crops grown on B r o okston loam and Kalamazoo sandy loam are probably explained b y luxury consumption. 3. Potassium, Calcium, and Magnesium Uptake of the Plants It is important to consider the amount of nutrients taken up by plants, or that removed b y plants from the soil for plant nutrient economy. The uptake of potassium, ca l ­ cium, and magnesium b y the plants are presented in Tables 15 to 1 7 . 73 Table 15. Plant uptake of potassium as affected by potassium treatments on Brookston* Genesee* Kalamazoo* and Landes-Abscota soils Crop K treatment a 1 2 Wheat 3. 6 Tomato 4 5 S orghum Total (Mg.K/pot)u (Lbs./A.) Brookston loam 0 241.5 581.0 89.5 5 6 .O 37.0 61.9 1 *066.9 200 264.0 750.8 86.5 52.1 42.9 76.0 1*272.3 400 369.0 957.5 115.5 43.6 40.1 77.9 1 *603.6 800 520.5 1 ,105.5 191.8 53.7 49.9 109.8 2 *031.2 1,600 431.3 1 ,078.3 312.0 361.8 78.9 167.3 2*429.6 L.s.d.C (0.05) (0 .0 1 ) 160.35 163.68 34.82 6 5 .IO 1 6 .00 38i.23 224.83 229.49 48.82 91.28 2 2 .44 63 .56 Genesee loam 0 114.0 175.3 40.4 33.1 26.9 15.0 404.7 200 232.5 343.5 59.1 32.4 29.5 18.8 715.7 400 300.5 605.3 76.4 24.9 37.1 29.8 1*074.0 800 315.8 929.0 145.1 42.2 47.8 45.3 1 ,525.2 1*600 356.5 O CO H O *Y 263.0 237.2 82.7 105.2 2 *062.6 1 L,s.d.C (0 .0 5 ) 30.08 76.07 13.23 15.83 1 1 .88 34 •55 (0 .01) 42.18 106.65 18.55 22.19 1 6 .65 57 .30 74 Table 15 (cont'd.) Crop K treatment a 2 Wheat 1 4 5 Sorghum 3 Total 6 Tomato _ (Mg.K/pot )u (Lbs./A.) Kalamazoo sandy loam 272.0 282.5 341.8 314.3 313.3 0 200 400 800 1,600 L .s .d • (0 .0 5 ) N.s. 574.5 677.5 727.3 793.3 878.5 d (0 .01) 70.0 141.0 197.6 254.9 270.0 37.5 64.7 96.3 257.1 511.3 25.4 35.3 48.8 82.4 159.0 20.5 25.9 53.5 95.6 193.7 999.9 1,226.9 1 , 465.3 1,797-6 2 ,325.8 50.82 15.25 34.81 2 2 .51 18.99 71.24 21.39 48.81 31. 56 3 1 .50 Landesi-Abscota sandy loam 0 200 400 800 1,600 122.8 298.3 396.3 402.5 446.5 L. s •d . (0.05) (0 .0 1 ) 253.0 325.0 476.3 809.8 895.3 59.5 63.3 82.5 I6 O .4 271.3 40.8 29.7 33.1 49.7 211.4 24.9 27.8 ?5 *§ 4l. 8 70.4 23.7 17.3 27.5 54.5 121.7 524.7 761.4 1 ,051.6 1,518.7 2 ,016.6 31.29 48.84 17.30 24.24 8.63 8.98 43.89 68.47 24.25 33.98 1 2 .11 14.90 a Potassium was applied to the first crop only All values of uptake are averages of 4 replicates except for the 6th crop which had 2 . cThe least significant difference at 5^ and 1 % levels of probability^ respectively. No significant difference in potassium uptake as detected by F test with analysis of variance. 75 Table 16. Plant uptake of calcium as affected by potassium treatments on Brookston, Genesee., Kalamazoo and Landes-Abscota soils K treatment cL Crop 2 Wheat 3 4 5 Sor g h u m 6 Tom a to Total (Mg.Ca/pot)u (^Lbs./A. ) B r o o k s t o n loam 0 84.3 130.9 49.5 160.3 i4i.o 208.5 774.5 200 56.4 130.8 49.6 1 6 3 .O 148.0 182.6 730.4 4oo 63.7 129.9 47.8 157.0 133.3 207.0 735.7 800 77.3 113.5 44.0 148.3 128.8 232.9 744.8 1,600 78.3 136.1 43.5 102.3 119.3 244.3 723.8 N.s. N.s. L.s.d.c (0 .0 5 ) N.s.d (0 .0 1 ) 16.12! N.s., N.s. 22.59 Genesee loam 0 58.1 116.1 49.1 175.0 171.8 66.3 636.4 200 42.6 115.0 54.3 181.0 I65.8 102.2 660.9 400 47.7 118.3 52.6 158.8 170.8 136.3 684.5 800 50.4 103.1 47.3 144.3 165.0 163.3 673.4 1,600 70.8 110.0 42.4 115.3 149.3 207.9 695.7 L.s.d.c (0 .0 5 ) 1 1 .4g N.s. (0 .0 1 ) 16.11 d 4.32 21.48 6.06 30.11 N.s. 53.81 89.24 Table 16 (cont'd.) Crop K treatment a 1 2 Wheat 4 5 Sorghum 3 6 Tomato Total (Mg.Ca/pot)u (Lbs.k/A. ) Kalamazoo sandy loam 38.4 36.4 49.0 48.7 53.3 0 200 400 800 1,600 L.s.d.c (0.05) (0 .0 1 ) 63.5 62.1 66.9 102.5 101.0 36.5 28.5 24.1 26.5 34.5 11.20 17.34 3*14 15.70 24.32 4.40 115.0 113.0 99.8 92.8 103.0 N.s.d 136.8 138.0 127.8 108.0 107.3 16.57 86.6 137.3 162.1 187.4 228.2 476.8 515.3 529.7 565.9 627.5 83.09 23.24 137.80 Landes-Abscota sandy loam 0 200 400 800 1,600 79.5 64.3 67.2 75.4 91.1 121.9 105.1 106.1 99.3 139.0 L.s.d. c (0.05) 6.80 18.95 (0 .01) 9-53 26.57 56.0 4 9 .1 50.6 49.0 45.3 178.3 159.3 160.8 152.5 144.0 N. s .d N.s. 165.3 183.8 1 6 9 .O 145.3 i 4 o .5 13.30 108.4 113.3 144.5 186.4 169.2 709.4 674.9 698.2 707.9 729.1 N.s. 18.65 Potassium was applied to the first crop only. b All values of uptake are averages of 4 replicates except for the 6th crop which had 2 . cThe lease significant difference at 5^ ar*d 1^ levels of probability, respectively. No significant difference in calcium uptake as detected by F test with analysis of variance. 77 Table 17. Plant uptake of magnesium as affected by potassium treatments on Brookston, Genesee, Kalamaaoo and Landes-Abscota soils K treatment a x Crop 2 Wheat 4 3 _5___ Sorghum 6 Total Tomato (Mg.Mg/pot )u (Lbs. K/A. ) B r o okston loam 0 34.1 68.8 30.6 197.3 74.0 46.4 451.2 200 22.8 67.3 29.6 202.8 84.9 43.4 450.8 400 24.6 56.0 30.1 195.8 77.0 42.7 426.2 800 31.0 45.3 25.3 169.8 74.9 48.5 394.8 1,600 29.4 42.5 16.1 95.5 76.2 46.3 306.0 L. s .d .^ (0.05) N .s.d (0 .0 1 ) 7.08 2.80 19.76 9.92 3-92 27.71 N.s. N. s . Genesee s loam 0 35.0 65.3 22.7 128.0 61.1 17-6 329.7 200 21.0 64.2 2 5 .I 138.0 62.4 22.6 333.3 4oo 18.7 57.4 25.2 143.0 70.8 23.0 338.1 800 17.9 39-6 21.2 i4o.5 72.9 25.3 317.4 1,600 20.2 34.5 13.2 88.7 74.6 31.9 263.1 (0*05) 3.00 7.07 2.45 11.58 10.60 7.90 (0 .0 1 ) 4.21 9.92 3.43 16.24 14.86 13.10 78 Table 17 (cont'd.) Crop K treatment a 1 2 Wheat 6 Tomato 4 5 Sor g h u m 3 Total (M g . M g / p o t )u (Lbs .K/A. ) Kalamazoo sandy loam 0 200 400 800 1,600 L.s.d.c (0 .0 5 ) 21.6 20.3 25.1 24.8 25.4 44.7 39-4 35-1 46.5 41.2 N. S , N.s. (0 .0 1 ) 23.8 20.4 15.4 13.9 14.2 124.3 144.5 125.0 70.0 57-0 69.9 78.8 82.6 64.2 61.5 29.8 38.2 38.8 42.2 44.8 1.32 11.29 11.14 6.73 1.85 15.83 15.62 11.16 314.1 341.6 322.0 261.6 244.1 Landes-Abscota sandy loam 0 200 400 800 1,600 41.3 31.6 24.9 23.8 27.2 L.s.d.c (0.05) (0.0 1 ) a 70.0 64.2 58.4 42.6 41.1 25.9 26.1 27.9 24.4 15.2 1 2 9 .0 130.6 143.0 140.0 110.9 62.5 71.4 71.0 61.2 57.7 21.1 17.7 22.7 26.7 30.3 2.87 4.77 2.48 21.55 4.03 4.02 6.69 3.48 30.22 5.65 12.15 349.9 341.6 347.9 318.7 282.4 6.46 Potassium was applied to the first crop only. All values of uptake are averages of 4 replicates except for the 6 th crop which had 2 . cThe least significant difference at 3 % and 1^ levels of probability, respectively. ^No significant difference in magnesium uptake as detected by P test with analysis of variance. a. Relationships between Potassium Treatment and Plant Uptake of Potassium, Calcium, and Magnesium l) Relationship between Potassium Treatment and Potassium Uptake of the Plants As shown in Table 1 5 5 potassium treatment affected the plant uptake of potassium on all soils. Plant uptake of potassium generally decreased with successive cropping. However^ seasonal and plant differences were found to affect the potassium uptake. The 2nd crop (wheat) absorbed more potassium than the 1st crop (wheat) in all soils since the 2nd crop was grown in the spring season during more favorable conditions than the 1 st crop. Tomatoes (6th crop) absorbed more potassium than sorghum (5"th crop) on all potassium treatments applied to Brookston loam., on K = l 5600 (1*600 lbs. K/A.) treatment in Genesee loam, on K=*K)0* K=800* and K=l*600 treatments in Kalamazoo sandy ]oam, and on K=800 and K=l*600 treatments in Landes-Abscota sandy loam. This may indicate that the tomato plants have a greater capacity for the absorption of potassium than sorghum. Since the soil was the highest in nonexchangeable potassium among the soils* Brookston loam appeared to have met the tom a t o e s 1 high capacity for absorbing potassium by supplying sufficient. Since their non exchangeable potassium was lower, Genesee loam, Kalamazoo sandy loam* and Landes-Abscota sandy loam appeared to have supplied enough potassium only when potassium was applied in larger quantities to meet the t o m a t o e s 1 high capacity for absorbing potassium. 80 2) Relationship "between Potassium Treatment and Plant Uptake of* Calcium It seems to be improper to generalize the influence of potassium treatment to the plant uptake of calcium b e ­ cause the uptake of calcium varied. Calcium absorption de­ creased with the 4th crop grown on Brookston loam and Gene­ see loam, and with the 5th crop grown on Kalamazoo sandy loam and Landes-Abscota sandy loam but tended to increase v/ith the 6 th crop grown on Genesee loam, and with the 1st, 2nd, and 6 th crop grown on Kalamazoo sandy loam while no such trend was shown with the other crops. However, the to ­ tal uptake of calcium b y the 6 succeeding crops tended to increase with high levels of potassium treatment on all the soils except for Brookston loam. This may be an indication of nutrient balance in the plant for a long range: plants absorb more nutrient elements and grow better when soil fer­ tility is high (Cook, 1 9 6 2 ). Further studies seem to be necessary on Brookston loam. 3) Relationship between Potassium Treatment and Plant Uptake of Magnesium The plant uptake of magnesium tended to decrease with increasing levels of potassium treatment in the 2nd, 3rd, and 4th crops grown on Brookston loam; in the 1st,2nd and 3rd crops on Genesee loam; in the 3rd, 4th, and 5th crops on Kalamazoo sandy loam; and in the 2nd crop grov/n on LandesAbscota sandy loam. Magnesium absorption tended to Increase in the 5th, and 6th crops grov/n on Genesee loam; in the 1st and 6th crops on Kalamazoo sandy loam; and in the 6 th crop 81 on Landes-Abscota sandy loam. any such trends. The other crops did not show Consequently it may be irrelevant to gen­ eralize the influence of potassium treatment on the plant uptake of magnesium in this research. A long range of nutrient balance by the 6 succeeding crops as found in the case of calcium uptake was not shown in magnesium uptake. A stronger nutrient balance for a long range may be obtained between potassium and calcium rather than between potassium and magnesium. b. Relationships between Plant Yields and Uptake of Potassium, Calcium, and Magnesium l) Plant Yields and Potassium Uptake In general, the crops which demonstrated favorable effects from the potassium treatment showed correlation b e ­ tween the yields and potassium uptake (Table 18). The negative correlation with the 2nd crop on Kala­ mazoo sandy loam was probably due to excess uptake of potas­ sium by plants. The soil was originally rich in exchangeable potassium containing 275 pounds per acre (Table l) and the 1st crop did not absorb much of the applied potassium b e ­ cause of the low intensity of winter sunlight during the growth period (December 5, 1968 to February 13* 1 9 6 9 )* The 2nd crop absorbed more potassium leading to more than 6$ potassium in the plant tissue at high levels of potassium treatment (Table 11) under Influence of high intensity of sunlight and warm temperatures during the growth period (March 26 to June 5, 1 9 6 9 ). 82 Table 18. Relationship between plant yields and potassium, calcium, and magnesium uptake of the plants Relationship of plant yield and elements Crop 1 2 Wheat 3 4 5 Sorghum 6 Tomato Simple correlation coefficient 0 ) a Brookston loam 0.46** 0 .94** K 0 .81** 0.01 Ca 0.75** 0.05 -0.11 -0.14 0.01 Mg 0 .80** 0.10 -0 .51* -0.10 0 .63** 0.4l K 4- Ca 4* Mg 0 .86** 0.16 0 .80** O.83** 0.35 0.47* 0.73* 0 .80** 0 .94** Genesee loam K 0.21 0 .66** 0 .88** Ca 0.27 0.22 Mg 0.18 -0.39 K + Ca f Mg 0.26 -0.43 O .38 -0.49* -0.08 -0 .60** -0.18 0 .68** O.91** O.91** 0 .86** 0.31 0 .96** 0.87** 0.84** 0 .82** 0 .95** Kalamazoo sandy loam K 0.17 -O.58** 0 .82** Ca 0.05 -0 .7 8 **-0 .4 l Mg 0.28 -0.20 K f Ca f Mg 0.16 -O.6 5 ** 0 .81** 0 .68** O.89** 0 .89** -0.16 - O .38 0 .90** -0 .70** - O .38 -0.10 0 .91** 0 .73** 0 .91** 0 .94** Landes-Abscota sandy loam K 0 .85** 0.45* Ca 0.07 0.48* -0.35 Mg K + Ca + Mg -0.64** O.85** -0.37 0 .4 7 * 0 .86** -O.52* 0 .88** 0.73** 0.83** 0 .92** -O.53* -O.52* 0 .69* -0.23 -0.19 0 .92** O.65** 0.22 0 .92** a* and ** indicate significance at 5^> and 1$> probability levels respectively. 83 2) Relationship between Plant Yields and Calcium Uptake The relationship bet w e e n plant yields and calcium uptake appeared slightly negative except Tor the 6 th crop, tomatoes, in which yields showed as good correlation with calcium uptake as w i t h potassium uptake (Table 18). 3) Relationship between Plant Yields and Magnesium Uptake The relationship between plant yields and magnesium uptake appeared slightly negative except for the 6 th crops, tomatoes, as between plant yields and calcium uptake 18). (Table The plant yields of the tomato crop correlated with magnesium uptake except on B r o o k s t o n loam. 4) Relationship between Plant Yields and the Total Uptake of Potassium, Calcium, and Magnesium In general, the relationship between plant yields and the uptake of potassium plus calcium and magnesium was simi­ lar to that obtained for potassium uptake and the yield of the various p l a n t s . c. Relationships among the Plant Uptake of P o t a s s i u m , Calcium, and Magnesium l) Relationship between Plant Uptake of Potassium and Calcium In general the simple correlation coefficients for potassium versus calcium uptake were negative except for the 1st and 6th crops grown on all the soils and for the 2nd crop on Kalamazoo sandy loam and Landes-Abscota sandy loam (Table 19). An antagonistic relationship bet w e e n the 2 elements was further demonstrated b y Burkhart and Collins (1941)^ and Oya (1 9 6 5 ). The factors which induced the p o s i ­ tive correlation between potassium and calcium for the 1 st crop on all the soils, and the 2nd crop on Kalamazoo sandy loam and Landes-Abscota sandy loam must be studied in the future with more refined methods. The relationship between potassium and calcium uptake was positive for the 6th crop on all the soils. The reason seemed to be that the soils had b e e n depleted of potassium by the time of the 6th crop; consequently increased levels of potassium application remarkably affected plant growth (Table 7) which led to more absorption of calcium coupled with the high requirement of the tomato plant for calcium. 2) Relationship between Plant Uptake of Potassium and Magnesium The relationship between the plant uptake of p o t a s ­ sium and magnesium was generally negative (Table 19)3 which may indicate the apparent antagonistic relationships between the 2 elements in the plant absorption. However, the p o s i ­ tive relationship between the potassium and mag n e s i um u p ­ take for the 1st crop grown on Brooks ton loam, for the S'th crop on Genesee loam, for the 1st crop on Kalamazoo sandy loam, and for the 2nd crop on Landes-Abscota sandy loam must be studied further. The positive relationship between potas slum and magnesium uptake of the 6 th crop on all the soils demonstrates similar reasons to the relationship between potassium and calcium uptake in the same crop. 3) Relationship between Plant Uptake of Calcium and Magnesium The relationship between the plant uptake of calcium and magnesium was positive for all the crops without any exception (Table 1 9 ). Calcium and magnesium m a y b e c o n s i ­ dered to be absorbed in somewhat similar order b y the plants. 4) Relationship between Plant Uptake of Potassium and Calcium plus Magnesium The relationship between the plant uptake of p o t a s ­ sium and calcium plus magnesium appeared to be similar to that of the plant uptake of potassium and calcium on Brookston loam and Kalamazoo sandy loam, or of potassium and magnesium on Genesee loan and Landes-Abscota sandy loam (Table 19). 5) Relationship between Plant Uptake of Potassium and the Square Root of Calcium and Magnesium The relationship between the plant uptake of p o t a s ­ sium and the square root of calcium plus magnesium was almost the same as that of the plant uptake of potassium versus calcium plus magnesium. 4. a. Quantity of Potassium Released from Nonexchangeable Forms Potassium Released from Nonexchangeable Forms In order to find the amounts of potassium released to the plants from the original nonexchangeable forms in the 86 Table 1 9 . Relationship between the potassium, calcium, and magnesium uptake of* the plants Crop Comparison 1 2 3 4 5 6 Simple correlation coefficient (r ) B r o okston loam K vs. K vs. Ca vs. K vs. K vs. Ca Mg Mg Ca 4-M g >/Ca4. M g 0.45* 0 .4 7 * O . 95** 0.46* 0.49* -0.07 -0.52* -0.80**-0.91** 0.28 0.71** -0.48* -0.80** -0.48* -0.8l** -0.8 5 * * ~ 0 .33 -0 .86**-0.34 O.93** 0.49* -0.87**-0.07 -0.87**-0.07 O.69* 0.23 0.50 0.67* 0.66* Genesee loam K vs. Ca K vs. Mg Ca vs. Mg K vs. Ca 4- M g K vs. v/Ca 4- M g 0.24 -0.35 -0.71** -0 .80** -0.90**-0.89** 0.28 0.64** 0 .88** -0.17 -0.7 5 * * - 0 .82** -0.16 - 0 .7 5 * * - 0 .83** -0.77**-0.27 -0 .91** 0 .7 2 ** O.6 5 ** 0.24 -O.92** 0.05 -O.92** 0.06 0.84** 0 .91 ** 0.91** 0.86** O. 83** Kalamazoo sandy loam K vs. Ca K vs. Mg Ca vs. Mg K vs. Ca 4. M g K vs. \/Ca 4 Mg - 0.73** 0.70**-0.30 0.69** -0.07 -0.94** 0.84** O . 55* 0.51* 0.74** 0.58* -0.67** 0.73** O . 57* -O.6 5 ** -0.28 -0.58** O . 83** -0.89**-0.44 0.76** 0.48* 0.62** O. 97** -0.8l**-0.<58** 0.83** -0.82**-0.58** 0.8l** Landes-Abscota sandy loam K vs. Ca K vs. Mg Ca vs. Mg K vs. Ca + Mg K vs. v/Ca + Mg 0.17 - 0 .8 7 ** 0.15 -0.30 -0.30 0.07 -O.52* -0.44 - 0 .6 8 ** 0.56 o.88**-0.87** -0.60**-0.43 0 .85** 0.0001 0 .56** O.56* 0.80** O .63 0.09 -0.78** -0.59**-0.64** 0.62 0.10 -0.79** -0.58**-0.65** 0.6l 8-7 soils, the amount of potassium ( m g . ) taken up from K =0 treatment by the respective crops per pot were converted to pounds of plant potassium per acre from which the exchange­ able soil potassium, analyzed before the start of the ex ­ periment, was subtracted (Table 20). The weights of soil per pot were 2.70 kg., 2,65 hg., 2.60 kg., 2.55 kg., 2.50 kg., and 2.45 kg. for the 1 st, 2nd, 3 rd, 4th, crops respectively. 5"^, 6 th The negative values for the "release from nonexchangeable K" in Table 20 show that the potassium uptake of that crop was less than the potassium originally in exchangeable form. The potassium release from the n o n ­ exchangeable forms in the experimental soils were in the order of Brookston loam > Kalamazoo sandy loam > LandesAbscota sandy loam > Genesee loam for the sequence of 6 croppings. The original exchangeable potassium, 151* 9 3 > and 275 pounds per acre for Brookston loam, Genesee loam, and Kalamazoo sandy loam respectively, appeared to be a sufficient source of potassium for the 1 st crop grown on these three soils since the crop did not show any response to applied potassium under the conditions of the experiment. In general, nonexchangeable potassium was released only in small quantities after the 3rd crop in all soils (Table 20, and Figures 11 to 14). b. Potassium Release as Affected b y Potassium Treatment The amounts of potassium taken up b y the plants from the nonexchangeable forms were calculated at the respective 88 Table 20. Potassium released to the plants from nonexchangeable forms In Brookston, Genesee, Kalamazoo, and Landes-Abscota soils K in plant and from nonex­ changeable formsa Crop 1 2 3 4 K uptake 5 6 Total Plant K 241.5 581.0 Plant K K from non­ exchangea­ ble forms 178.9 438.4 Brookston loam (Mg./pot) 89.5 56.0 37.0 (Lb s ./ A .) 68.8 43.9 29.6 27.9 438.4 68.8 29.6 50.5 659.1 114.0 175-3 15.0 4o4.6 84.4 132.3 Genesee loam (Mg./pot) 40.4 33.1 26.9 (Lbs./A.) 31.1 26.0 21.5 12.2 307.5 -8.6 123.7 31.1 755.3 Plant K 1 ,066.9 50.5 810.1 C\1 • OJ H Plant K K from nonexchangea­ ble forms 43.9 61.9 214.5 Plant K 272.0 574.5 999-9 Plant K K from nonexchangea­ ble forms 201.5 433.6 Kalamazoo sandy loam (Mg./pot) 70.0 37.5 25.4 20.5 (Lbs./A.) 53.8 29.4 20.3 16.7 -73.5 360.1 53.8 16.7 480.3 122.8 524.7 91.0 Landes-Abscota sandy loam (Mg./pot) 253.0 59-5 40.8 24.9 23.7 (Lbs./A.) 19.3 190.9 45.8 32.0 19.9 16.0 190.9 Plant K Plant K K from nonexchangea­ ble forms 45.8 26.0 29.4 32.0 21.5 20.3 19.9 19.3 398.9 323.9 a K release from nonexchangeable forms = (plant uptake of K from K=0 plots) - (exchangeable K before cropping)° ^Exchangeable K before cropping was 151* 93 j 2 7 5 s and 75 lbs./A. for Brookston loam, Genesee loam, Kalamazoo sandy loam, and Landes-Abscota sandy loam, respectively (Table 1 ). 89 levels of the potassium treatment in the same way for Table 20 and presented in Figures 11 to 14. In B r o okston loam, the amounts of nonexchangeable soil potassium released to the plants were 659* 6l4, 664, 588, and 106 pounds per acre from K = 0 , K=200, K=400, K =800, and K=l,600 treatments respectively (Figure 11). From Figure 11, it will be understood that nonexchangeable soil potassium was utilized intensively b y earlier crops grown on plots with low potassium applications. The release of nonexchangeable soil potassium gradually decreased when the cropping advanced. During the period of 6 croppings, the release of nonexchangeable soil potassium from K=0, K=200, K=400, and K=800 treatments reached similar amounts. The lower release from the K=l,600 treatment than from other treatment m a y mean that the initial large application of potassium reduced the necessity of plant absorption of n o n ­ exchangeable soil potassium or caused potassium fixation which induced difficulty in the release of nonexchangeable soil potassium. From the release pattern in Figure 1 1 , it may be expected that nonexchangeable soil potassium will be released from the K=l,600 treatment for further cropping, if the cropping continues, to attain n e a r l y the same amounts released from the lower potassium treatment-plots at a slow rate. In Genesee loam, more nonexchangeable soil potassium was released to the plants in K=200, K=*400, and K=800 treatments than in the K=0 treatment (Figure 12). The clay 1*800 Cumulative 1*600 1*400 1*200 1*000 Fertilizer K Crop release of nonexchangeable (Lbs./A) Nonexchangeable K 800 6 oo 4oo 200 Exchan g e able K 0 1 200 I 400 L 1*600 K treatments Figure 11. i i. (Lbs. K/A) Release of nonexchangeable potassium to the plants at various levels of potassium treatment for Brookston loama ^ h e broken line indicates the original level of exchangeable K. The dotted line indicates exchangeable K plus fertilizer K. 91 Cumulative release of nonexchangeable (Lbs./A) 1 ,800 1,600 Nonexchangeable K 1,200 1,000 800 o Fertilizer K 600 400 200 Exchangeable K __ 0 200400 ----- 8 0 S ---- ------------- K treatments Figure 1 2 . (Lbs.K/A) Release of nonexchangeable potassium to the plants at various levels of potassium treatment for Genesee loama ^ h e broken line indicates the original level of exchangeable K. The dotted line indicates exchangeable K plus fertilizer K. 92 2,000 Nonexchangeable K Cumulative release of nonexchangeable (Lbs./A} 1,800 1,400 1,200 1,000 800 Fertilizer K “O o 600 4oo Exchangeable K 200 0 200400 Boo K treatments Figure 13. 17600 (Lbs. K/A) Release of* nonexchangeable potas­ sium to the plants at various levels of potassium treatment for Kalamazoo sandy loama ^ h e broken line indicates the original level of exchangeable K. The dotted line indicates exchangeable K plus fertilizer K. 93 Cumulative release of nonexchangeable (Lbs./A) 1,800 i,6oo Nonexchangeable K 1,400 1,200 1,000 800 o 6oo Fertilizer K 200 Exchangeable K 0 200 400 800 K treatments Figure 14. eteo (Lbs. K/A) Release of nonexchangeable p o t a s ­ sium to the plants at various levels of potassium treatment for Landes-Abscota sandy loam ^ h e broken line indicates the original level of exchangeable K. The dotted line indicates exchangeable K plus fertilizer K. 94 minerals such as vermiculite-chlorlte-montmorillonite interstratified minerals and mica (or illite) present in 4) Genesee loam seemed to promote the release of nonexchange­ able soil potassium by stimulated root growth* which may have intensified plant weathering of the mica or illite (Mortland* ej; al_. * 19 5 6 * and Conyers and McLean* the application of potassium. 1 9 6 8 )* by Genesee loam containing 10^ vermiculite and 18^ mica in its clay fraction-^ also appeared to fix the applied potassium at the It=l*600 treat­ ment where the original amount of nonexchangeable soil p o ­ tassium was not released at all during 6 croppings (Figure 12). The release of nonexchangeable soil potassium from Kalamazoo sandy loam was much lower in K=800 and K=l*600 treatments than in K®0* K=200* and K=400 treatments (Figure 13) which released from 437 to 480 pounds of nonexchangeable potassium per acre. The plants on this soil seemed to be sufficiently furnished with the fertilizer and original exchangeable soil potassium without absorbing too much non­ exchangeable soil potassium at K=800 and K=l*600 treatments. The exchangeable soil potassium was initially as high as 275 pounds per acre and potassium fixing clay was low (1 .7^) in the clay fraction (1 3 .5^)* ^ S e e Table 3 1 . ^ S e e Table 3 1 . 6 ^See Table 29 and 3 1 . 6) 95 In Landes-Abscota sandy loam, as shown in Figure 14, nearly the same amounts of nonexchangeable soil potassium were released from the K=0 to K=800 treatments where the potassium release ranged from 319 pounds to 275 pounds per acre. At the K=l,600 treatment, no release was indicated from the nonexchangeable soil potassium. The initial appli­ cation of such a large quantity of potassium seemed to have caused potassium fixation, since the soil clay was predomi7) nated by vermiculite-chlorite interstratified minerals Fixed potassium by vermiculite is released at a slower rate than native potassium in biotite (Ellis and Mortland, 1959)* The potassium release from Landes-Abscota sandy loam seemed to be slower than from Brookston loam. Sufficient potassium must be supplied to plants grown on a soil to fix potassium and release it very slowly. Miller (1970), who investigated response of tomatoes to p o ­ tassium on a Sodus Experimental Farm soil classified as Genesee sandy clay loam (18.6$ vermiculite) suggested that 1,126 and 150 pounds of potassium per acre be applied b r oad­ cast and sidedressed respectively to obtain 4 4,000 pound per acre fresh market yield for transplanted C1327 tomatoes. 7 ^See Table 31. CHAPTER III CHEMICAL PROPERTIES OP T H E SOILS A. 1. Methods and Materials Exchangeable and Nonexchangeable Potassium Exchangeable and nonexchangeable p o t assium was deter­ mined on the original soil samples, the samples collected after the 5th crop, and the incubated samples. All the samples were air-dried, thoroughly m ixed and passed through a sieve with 2 mm. openings. Soil incubation vras carried out in one gallon containers for a p e r iod of 5 croppings (13 months) with fertilizer treatment administered as for growing plants in the greenhouse. Water was added to maintain the soil at field capacity. Exchangeable potassium was extracted b y shaking a 2.5 gram sample of the soil with 20 ml. of neutral I N NH^OAc solution for 1 minute and by centrifuging the suspension to collect the clear supernatant. times with NH^OAc solution. The soil was washed 3 more The coiJected supernatant was determined for potassium on a Coleman Model 21 Flame Photometer. Nonexchangeable p o t a s s i u m was obtained by subtracting the e x c h a n g e a b l e p o t a s s i u m v a l u e f r o m t h e v a l u e 96 of t o t a l 97 • p o t a s s i u m e x t r a c t e d w i t h "boiling 1 N H N O ^ A 2.5 g r a m s a m p l e o f t h e s o i l w a s in a 1 0 0 ml. b e a k e r and Morse, 1954). on t h e h o t p l a t e The v;ith 0.1 W H N O 3 . The soil was solution. boiled with 1 N HNO^ for 25 minutes (Pratt then filtered and washed combined leachate a n d v/ashing w a s de­ termined f o r p o t a s s i u m . 2. Potassium Release and Fixation b y Wetting and Drying Treatments P o t a s s i u m r e lease and were f i x a t i o n of t h e o r i g i n a l soils studied b y alte r n a t e w e t t i n g and d r y i n g periods. method e m p l o y e d was essentially the s a m e as t h a t The of V o l k (193*0 . A 2.5 g r a m s a m p l e o f t h e soil was p l a c e d Erlenmyer f l a s k t o w h i c h 2.5 ml. added. The m i x t u r e was allowed in a 1 2 5 ml. of 0 . 1 W K C 1 s o l u t i o n w a s to stand for 1 hour to obtain a t h o r o u gh w e t t i n g of t h e s o i l a n d t h e n it was p l a c e d o n a hot p l a t e at 7 0 ° C sample, 2.5 ml. the second one. to attain dryness. of w a t e r w a s added for To the dried soil each experiment Such wetting and drying procedures peated 10 times. neutral 1 N N H ^ O A c The after were re­ s o i l was t h e n s h a k e n f o r 1 m i n u t e w i t h solution and transferred to a centrifuge tube for c e n t r i f u g a l s e p a r a t i o n of t h e c l e a r supernatant. The soil was w a s h e d 4 m o r e t i m e s w i t h N H ^ O A c solution. changeable p o t a s s i u m w a s flame p h o t o m e t r i c a l l y . determined on the collected Released the w e t t i n g a n d d r y i n g t e c h n i q u e , or f i x e d p o t a s s i u m , was calculated by ing the r e c o v e r e d p o t a s s i u m a f t e r t h e t r e a t m e n t Ex­ solution using subtract­ from the 98 originally exchangeable potassium plus the added potassium in 2.5 ml. of 0.1 N KC1 solution. The control was kept moist with 2.5 ml. of 0.1 N KC1 solution added for two days during the period of the wetting-drying treatment. 3. Potassium Release and Fixation by Freezing and Thawing Treatment Potassium release or fixation by freezing-thawing treatments were studied on the original soils with the similar method to Fine et a l . , (1940). A 2-g gram sample of the soil was placed in a centri­ fuge tube to which distilled water was added to attain near saturation. The amount of water was twice the moisture con­ tent held by the soil when kept at 1/3 atmospheric pressure 2 (4.9 lbs./in. ) for 24 hours. The moisture contents of the experimental soils at 1/3 atmospheric pressure were 2 0 .5$ for Brookston loam, 17-0$ for Genesee loam, 12.6$ for K a l a ­ mazoo sandy loam and 14.2$ for Landes-Abscota sandy loam. The centrifuge tube containing the soil was placed in a deep freezer for 30 minutes to become frozen. The t e m p e r a ­ ture of the freezer was kept at -23°C The soil (-9.4°F). was then thawed at room temperature of 25-6°C (78°F) for 1 hour. Subsequent to IO freezing-thawing treatments, the soil was washed 5 times with neutral 1 _N NH^AOc solution by shaking with a mini-shaker and b y centrifuging the suspen­ sion. The supernatant collected from each washing v/as brought up to 100 ml. with distilled water and exchangeable potassium determined v/ith a flame photometer. The control was kept 99 at saturation for 3 days* the same period required Tor the freezing-thawing treatment. 4. Studies of Potassium Potential and Quantity-intensity Relationships of Potassium in the Original, Cropped and Xncuhated Soils The quantity-intensity relationships of soil potassium were determined on the experimental soils before cropping and following the 2nd and 5th crops. T h e method employed was essentially the same as that of Mat t h e w and Beckett (1 9 6 2 ). Five gram samples of the soil were placed into five 125 ml. Erlenmeyer flasks and shaken for 1 hour with 0.002 M. CaClg solution in various concentrations of K C 1 : 0, 0.25^ O.50, 1.0 and 2.0 mM. The suspensions were filtered after a shaking (1 hr.) and equilibrating (1 hr.) period at a constant temperature of 25°C. Potassium, nesium were determined in the filtrate. calcium and m a g ­ T h e activity of each element was calculated from the concentration of p o t a s ­ sium, calcium and magnesium in the filtrate according to the formula A = rCM where: A is the activity of a given ion, r is the activity coefficient, and Cm is the molar concentration of the given ion. For c a l c u l a t i o n of t h e a c t i v i t y c o e f f i c i e n t Deby-Huckel e q u a t i o n w a s employed, -log r = (AZ^Z_\/ p)/(l + Bai v/p) (r), the f o l l o w i n g 100 where: A is a constant for a given solvent water, O . 508O at 25°C* Z + is the charge of positive ion* Z_ is the charge of negativeRion* B is a constant* O .3281 x 10° at 25 C, ai is a constant which varies for different ions* 3 x 10 "° for K * * 6 x lO-o for 8 x 10"° for Mg++* and 3 * 10-° for Cl" (Klotz* 1958)* and p is ionic strength. The ionic strength was calculated by the formula* H “ ^ s c mzm2 v/here: CM is the concentration of ion M* and Zj^ is valance of ion M. Further* activity ratio (AR1^) such as aK/v/d'(Ca -t* Mg) v/as calculated after the equilibration. The gain or loss of potassium by the soil was also calculated by subtracting the potassium concentration of the equilibrated solution from the initial potassium concentration* defined as A Ke. relationship between the AR ■tr cally in Figures A21 to A24. The and A K e are presented graphiThe AR values are on the abscissa a n d A K e values on the ordinate. The activity ratio of the equilibrating solution at A K e = 0 , which is the point where the soil shov/s no gains or losses of potassium* was obtained by interpolating the curve to cross theAKe = 0 K K line and was defined as A R e . The A R e value is regarded as an intensity measurement for labile soil potassium. A quantity of easily exchangeable soil potassium was obtained by extrapolating the linear portion of the 101 asymptotic c u r v e of* t h e AR^ a K s -AR 0 l i n e and was d e f i n e d as r e l a t i o n s h i p to cross t h e -a K^. The potential buffering capacity (FBC ) for soil potassium was calculated by dividing the -aK° value by the ARe value as a measure of the capacity of the soil to m a i n ­ tain the potassium availability (Beckett 196^ a ) . The potassium potential as proposed by Zandstra and Mackenzie (1 9 6 8 ) was obtained by multiplying the -aK° value by the FBCK value. B. 1. Results and Discussion Exchangeable and Nonexchangeable Potassium a. Exchangeable and Nonexchangeable Potassium in the Soils as Affected by Cropping As shorn in Table 21, the exchangeable potassium de­ creased by cropping except for Landes-Abscota sandy loam of K=i,600 treatment. The magnitude of the decrease was greater in the soils with lower potassium treatments. The soils with higher potassium treatments retained exchangeable potassium near the levels in the original soils. This seems to indicate that the exchangeable potassium was hardly d e ­ pleted from these soils with higher potassium treatments by cropping because of the equilibrium movement from nonexchange­ able forms which were enriched b y the potassium applications. With Landes-Abscota sandy loam the enrichment of nonexchange­ able potassium by the applied potassium seemed to be great enough to release it when the plants had absorbed all p r e ­ viously exchangeable potassium. 102 Application of more than 200 pounds of potassium per acre on all soils increased nonexchangeable potassium over the respective original soils except for Kalamazoo sandy loam where only the K=l,600 treatment resulted in an in­ crease of nonexchangeable potassium. The nonexchangeable potassium of Kalamazoo sandy loam seems to be very easily released in nature being different from other three soils. The rate of decrease at K-0 treatment from the level of the original Kalamazoo sandy loam v/as the greatest among the soils. b. Exchangeable and Nonexchangeatale Potassium in the Soils as Affected by Incubation By soil incubation both exchangeable and nonexchange­ able potassium increased v/ith the potassium additions ex­ cept for Kalamazoo sandy loam where nonexchangeable potas­ sium decreased v/ith K=80O and K=l,600 treatments (Table 21). Nonexchangeable potassium in the incubated soil at K=1,600 treatment for Brookston, Genesee and Landes-Abscota soils, and K-200 treatment for Kalamazoo soil v/ere 156 184 186 ^ and 101 % respectively, when compared v/ith that of K=0 treatment in each soil. The rate of the increase in nonexchangeable potassium seemed to be related to the ori­ ginal potassium level, clay content, and clay mineralogy of the soils. Brookston loam contained 1 8 .5^ clay v/hich v/as higher than Genesee loam and Landes-Abscota sandy loam, and 8 .3^ 103 Table 21. Exchangeable and nonexchangeable pot a s s ium in original, cropped and, incubated soils3- K treatment Exchange­ able K Nonexchange­ able K Exchange­ able K Non exchange­ able K B r o o k s t o n loam Original sample 10.6 31.9 A f t e r incubation A f t e r 5 crops 0 7-1 31.7 10.4 34.0 200 7.4 31.9 12.6 37.1 400 7.1 35*0 14.6 40.7 800 7.9 35.0 21.7 45.6 1,600 8.8 36.1 33-6 53.1 Genesee loam Original sample 5*7 24.3 After incubation A f t e r 5 crops 0 4.6 23.7 5.4 27.0 200 4.6 23.7 7.2 30.2 400 4.4 25.4 8.6 32.3 800 4.7 27.6 11.9 39-6 1,600 5.4 33-0 25.2 49.6 104 Table 21(cont'd.) K treatment Exchange able K N onexchange­ able K Exchange­ able K Nonexchange­ able K IMg./lOO g* ) (Lbs./A.; Kalamazoo s.andy loam Original sample 15.0 26.7 Aft e r 5 crops A f t e r incubation 0 3-3 17.4 14.5 27.9 200 3-3 17*5 21.6 28.1 400 4.0 18.7 29.5 26.0 800 5.0 22.8 46.5 25.2 1,600 11.5 28.0 83.3 19.7 Landes-Abscota sandy loam Original sample 4.4 20.8 After 5 crops A f ter incubation 0 3.6 18.6 4.1 22.6 200 3.7 20.5 5-3 27.8 400 3.6 21.2 6.5 30.4 800 4.3 21.0 9.3 34.1 1,600 5-2 25.7 20.6 42.0 £L All values are averages of 2 d e t e r m i n a t i o n s . 105 vermiculite in the clay fraction®). Its original n o n e x ­ changeable potassium was 31-9 mg* per 100 g. soil (Table 20). The clay contents of Genesee loam and Landes-Abscota sandy loam were 11.59& and 14.8$ respectively, and the v e r ­ miculite contents of the clay fraction were 1 0 .0 ^ and 8 .9^ respectively. H o w e v e r * the original nonexchangeable p o t a s ­ sium of the two soils was much lower than Br o o k s t o n loam. The rate of nonexchangeable potassium increase b y higher levels of potassium application v/as, therefore, greater v/ith Genesee loam and Landes-Abscota sandy loam than v/ith Brookston loam. In Kalamazoo sandy loam, the soil incubation v/ith more than K-200 treatment resulted in a decrease of n o n e x ­ changeable potassium. The reason is not clear and should be studied in the future. Potassium which v/as non extract able with 1 N H N O 3 before the incubation became extractable and significant as nonexchangeable potassium during the incubation period since nonexchangeable potassium at K»0 treatment v/ith incubation treatment v/as higher than the original soil in all cases. Nitric acid nonextractable potassium m a y Include more tightly fixed and mineral constituent potassium. c. Ratio of Exchangeable Potassium to Nonexchangeable Potassium The percentage ratios of exchangeable potassium to nonexchangeable potassium were calculated from Table 21 8) See Tables 29 and 31. 106 and presented in Table 22. The percentage ratio obtained for the soils receiving no potassium ranges from 19 to 22. The ratio appears constant in all the soils which were d e ­ pleted of potassium b y the plants as shown at K=0 t r e a t ­ ments of the cropped soils independent of the soil's clay content and mineralogy. Therefore, it might b e possible to predict that only the soils with a percentage ratio of ex ­ changeable potassium to nonexchangeable potassium the same or lower than this range respond to potassium application in plant production if the analyzed sample is not collected immediately after cropping. this matter. Further study is necessary on In fact, the 1st crop responded little to the applied potassium in all the soils (Table 3 to 6) where the percentage ratio was higher than 23 except for Landes-Abscota sandy loam where the percentage ratio was 21. The tomato plants grown on the newly treated soils did not respond to the applied potassium (Table 8) indicating stronger power to utilize nonexchangeable potassium than wheat. Some potassium treated soils show a lower percentage ratio than at K=0 treatment in Brookston loam, Genesee loam, and Landes-Abscota sandy loam. However, the percentage ratios at higher potassium treatments are expected to i n ­ crease, for it takes a certain period of time to attain the equilibrium between exchangeable and nonexchangeable p o t a s ­ sium. This increase will be expected from the phenomenon shown in the percentage ratio with the incubated soils. 107 Table 22. Ratio of exchangeable to nonexchangeable p otassium in original., cropped and incubated soils K Ratio of exchangeable to nonexchangeable K____ treatment Original After 5 After ______ _______________sample_____________ crops_____________ incub at ip] (Lbs ./A. ) ('$) Br o o k s t o n loam 33 0 200 22 23 20 23 24 boo 800 1.600 31 34 36 48 63 Genesee loam 23 19 19 17 17 16 0 200 400 800 1.600 20 24 27 30 51 Kalamazoo sandy loam 56 0 200 400 800 1,600 19 19 21 22 41 52 77 113 185 423 Landes-Abscota sandy loam 0 200 4oo 800 1,600 21 19 18 17 20 20 18 19 21 27 49 108 Wonexchangeable potassium is present about 5 times much as exchangeable potassium in the potassium depleted soils. The percentage ratio of exchangeable potassium to non exchangeable potassium in the incubated soils increased with the increase in nonexchangeable potassium except for Kalamazoo sandy loam. This tendency demonstrates that the soil released more potassium when its capacity to hold n on­ exchangeable potassium approached the limit or that more external potassium was required to satisfy the nonexchange­ able potassium holding capacity of the soils approaching the limit. 2. Potassium Release and Fixation by Wetting and Drying Treatments The effects of the wetting-drying treatment on potas­ sium release and fixation of the soils are presented in Table 23. A comparison of the control samples indicates that all the soil except Kalamazoo sandy loam fixed potas­ sium when kept moist as control with 0.1 N KC1 solution. The potassium fixation was in the order of Landes-Abscota >Genesee loam > Brookston loam. The reversed order of percentage of potassium saturation for the cation exchange capacity of the respective soils could be expected (Table 24). The release of potassium was observed only with Kala­ mazoo sandy loam. The percentage of potassium saturation for this soil was exceptionally higher than for the other soils. The results obtained appear to be a good indication 109 of potassium equilibration in the soil; that is, equilibra­ tion moved toward fixing of potassium when a quantity of potassium in the solution was added to the already equili­ brated state at comparatively low levels of exchangeable and nonexchangeable potassium for the soil's capacity as observed with Brookston loam, Genesee loam, and LandesAbscota loam. In Kalamazoo sandy loam the equilibrium moved toward releasing potassium from the equilibrated state at a comparatively high level of exchangeable and n on­ exchangeable potassium for the soil's capacity even when potassium was given to the solution equivalent to 10 me. of K per 100 g. soil higher than the 0.39 me- exchangeable potassium of the soil (Table 24). Potassium fixation was observed with all four soils when undergoing wetting-drying treatments, indicating some effects of clay content, clay mineralogy and degree of potassium saturation. Brookston loam, with the highest clay content (montmorillonite and vermiculite predominated) among the soils,9) fixed the highest amount of potassium. Landes-Abscota sandy loam with vermiculite-chlorite inter­ stratified minerals and mica (or illite) as dominant clay minerals, and Genesee loam with kaolinite and vermiculitechlorite-montmorillonite interstratified minerals also fixed large amounts of potassium. The mechanisms of potas­ sium fixation have already been discussed in the section, 9) See Tables 29 and 31. 110 Table 23. Potassium release and fixation of the soils as affected by wetting and drying Treatment (3,900 ppm. K added) Soil Release (-) or fixation (t) of K Change (Mg./lOO g.)a Control (kept moist) Brookston loam 21.3 (+■) 5-3 34.3 (+) 8.7 2.2 (-) o .6 41.8 (+) 10.6 B r o okston loam 127.9 (+) 31.9 Genesee loam 100.4 (+) 25.4 33.5 (*) 8.3 112.5 (-) 28.8 Genesee loain Kalamazoo sandy loam Landes-Abscota sandy loam 10 wetting and drying cycles w * Kalamazoo sandy loam Landes-Abscota sandy loam £L All values are averages of 2 determinations. ^Percentage of change = (released or fixed K / original K + added K) x 100. "Mechanisms of Potassium Release and Fixation in Soils'1. Kalamazoo sandy loam also fixed potassium but only in small amounts. The minera l o g y of the soil is m a i n l y vermi- culite-chlorite interstratified minerals and kaolinite. Potassium fixing sites of vermiculite-chlorite interstratified Ill Table 24. Percentage of potassium saturation for the soils' cation exchange capacity CEC.a Soil Exchange­ able Kh K saturation Me./lOO a. Brookston loam 2 0 .r 0.27 1.3 Genesee loam 15.8 0.14 0.9 7.0 0.39 5.6 13.2 0.11 0.8 Kalamazoo sandy loam Landes-Abscota sandy loam ^ h e cation exchange capacity of the soils was taken from Table 1 . ^The exchangeable K(mg./100 g . ) was taken from Table 24 and converted to me./lOO g. basis. minerals were already highly saturated (5 .€%) in Kalamazoo sandy loam before the treatment since the soil was originally high in exchangeable potassium unlike Landes-Abscota sandy loam. 3- Potassium Release and Fixation b y Freezing and Thawing Treatments All four soils, Brookston loam, Genesee loam, K a l a ­ mazoo sandy loam, and Landes-Abscota sandy loam, tended to release potassium when kept moist as the control (Table 25). Since potassium was not added to the solution, the increase in exchangeable potassium resulted from a release of potassium from non exchangeable forms. Freezing and thawing treatments had only a slight effect on the soils to fix or release potassium. ite rich soil, Brookston loam, Montmorillon- and kaolinite and vermi- culite-chlorite-montmorillonite interstratified mineralrich soil, Genesee loam tended to fix potassium. sandy loam, rich in exchangeable potassium, Abscota sandy loam, stratified minerals, Kalamazoo and Landes- rich in vermiculite-chlorite i n ter­ still tended to release potassium. The release of potassium from Kalamazoo and Landes-Abscota soil, however, was to a lesser degree with the freezing and thawing treatment than with the control. Therefore, it may be presumed that the freezing and thawing treatment of the tested soils without addition of potassium effected the release or the lessening of fixation of potassium. 4, Quantity-intensity Relationships of Soil Potassium in Original, Cropped, and Incubated Soils The quantity-intensity relationship of soil potassium was plotted with the determined activity ratio (AR ) on the abscissa and the changes of potassium concentration 10) (A Ke ) in the equilibrating solution on the ordinate. The linear portion of the asymptotic curve was extrapolated to cross the points of A R k =0 a n d A K e=0. of the curve and AR^=0, The cross points and the curve and A K e =0 were deter­ mined as -a K° and ARg respectively. The represents the changes of potassium concentration in the equilibrating ^ ^ S e e Figures A21 to A24. 113 Table 25- Treatment Potassium release and fixation of the soils as affected by freezing and thawing Soil Exchangeable K R elease ^ Bef o r e After (-) or Change treatment?" treatment fixation (4-) (Mg. K/100 g.)--------- Control (kept moist) Brookston loam 10.61 10.71 5.66 5.86 Kalamazoo sandy loam 14.95 16.56 LandesA bscota sandy loam 4.44 4.85 o.4i <-) 9.2 10.61 IO.51 0.10 (t ) 0.9 5.66 5.46 0.20 (t) 3.5 Kalamazoo sandy loam 14.95 16.36 i.4l (“ ) 9.4 LandesAbscota sandy loam 4.44 4.55 0.11 2.5 Genesee loam 10 freezing and thawing cycles (fo) Brookston loam Genesee loam 0.10 0.9 0.20 (~ ) 3.5 1.61 (“ ) 10.8 Exchangeable k before treatment was determined on air-dry samples. ^Percentage of change = (released or fixed K/origi nally exchangeable K) x 100. Q All values are averages of 2 determinations. 114 solution when the activity ratio, A R k »aK / 1 .00** 1 . 1 .00** 1 .00** -0.86 - O .87 O.99** 0 .99** O .83 0.80 -0.75 0.85 0.70 0.67 -0.65 0.74 O.96** O.96** -O.93** 0.94* 0 .97** 0 .97** O.97** O.96** -0 .90* -0 .89* O.96** O.96* O .83 0.70 0 .91* 0 .88* 0.97* O.98** O.99** 0.84 1 .00** 1 .00** 1 ,00** 0.79 Landes-Abscota sandy loam O.97** 0.99*': 1 .00*^ O.89* 0.82 -0.08 O.95* O.97** 0.96** -0.43 O.92* O.93* O.98** -0.68 0.79 1 .00** 0.97*^ 0.99** 0.99*^ -0.52 -0.45 O.89* 0.94* 0.94* 0.95* -0.69 0 .90* O.92* O.96** -0.77 O .87 0.80 0.83 -0.68 0.74 0 .95* O. 89* 0.97** 0 .92* - O .65 -0.75 0 .91* 0.83 O.89* 0 .99** 0 .94* O.96** 0 .98*- 0 .8 l 0.84 O.91* O.95* 0 .91* 0.93* O.97** O.98** 0 .92*0 .95* a* and ** indicate significance at 5^ and 1^ probability levels respectively. 123 that of Bro o k s t o n loam., as the po t a s s i u m depletion advanced. The nonexchangeable potassium correlated poorly v/ith the plant uptake of po t a s s i u m on B r o okston loam. The total soil potassium measured after the 5th crop correlated v/ith plant uptake of potassium similar to that of exchangeable potassium on Genesee loam, and to a similar extent to that for nonexchangeable potassium on Kalamazoo and Landes-Abscota sandy loam soils. The total soil p o tas­ sium of Br o o k s t o n loam v/as not as v/ell correlated as the exchangeable pot a s s i u m v/ith plant uptake of po t a s s i um but better correlated than the nonexchangeable potassium. CHAPTER XV PHYSICAL AND MINERALOGICAL PROPERTIES OF T H E SOILS A. Methods and Materials 1. Mechanical Analysis In order to examine the physical properties of the soils used for the experiment,, a mechanical analysis was carried out with the hydrometer method as described b y Day (1965). A 40 g. sample of the soil was placed in a dispersing cup, to which 1 0 0 ml. of dispersing reagent ( Calgon solu­ tion) and 400 ml. of distilled water were added. sample v/as soaked, After the it v/as mixed for 5 minutes v/ith a motor mixer and transferred to a sedimentation cylinder. The suspension v/as brought to 1,000 ml. v/ith distilled water and allowed to stand in a constant temperature room, and t h o r ­ oughly mixed when the temperature of the suspension became constant (20.5°C). Hydrometer measurements were performed at predetermined time i n t e r v a l s . The summation percentage was calculated after c or­ rections for the Calgon concentration and temperature were made. The particle sizes were calculated v/ith sedimentation 124 125 time and sedimentation parameters suggested by D a y (1 9 6 5 ). The percentages of the separates were interpolated from a curve that was obtained b y plotting the summation percentage against the particle size on the log scale of semilogarithmic paper. The sand fraction was obtained by subtracting the percentage of silt and clay from 1 0 0 . 2. X - r a y Diffraction Studies From each soil, ^ different samples were used for the X-ray diffraction studies. T h e y included the original soils, samples collected after the 5th crop on the K -0 treatment and K=l,600 treatment, and samples collected from the K=l,600 treatment after incubating the soils for 13 months without cropping. The soils were screened through a sieve with 2 mm. openings and pretreated to remove organic matter, carbonates, soluble salts and free iron oxides by the methods described by Kunze (1 9 6 5 ). Clay films for the X-ray diffraction studies were prepared according to the method designed b y Mortland (1 9 6 9 ). a. Dissolution of Carbonate and Soluble Salts A given amount of soil, 30 g. for Br o o k s t o n loam, and g. for Genesee loam, Kalamazoo sandy loam, and Landes- Abscota sandy loam, was placed in a 400 ml. beaker to which 75 ml. of buffer solution (1 _N sodium acetate solution ad­ justed to pH 5 v/ith acetic acid) v/as added, and the soil v/as suspended b y stirring. The soil suspension was digested on a hot plate at low temperature (about 7 0 °C) for 30 126 minutes with intermittent stirring. The suspension was then centrifuged and the supernatant discarded. b. Removal of Organic Matter The soil in the centrifuge tubes was wetted with sodium acetate buffer solution and transferred to a 400 ml. beaker v/ith a small increment of water. To the beaker 5 ml. of 30^ H 2 O2 v/as added and the mixture v/as carefully stirred. A second 5 ml. increment of Hg02 v/as added to the beaker containing the soil after the reaction had subsided and the mixture was digested on a hot plate. In order to insure completion of the reaction* 2 more 10 ml. Increments of H2O2 were added after the reaction subsided and the sus­ pension v/as digested for 4 hours. The suspension* as it manifested the loss of dark color due to organic matter* was evaporated to a thin paste* v/hich v/as stirred well with a solution of sodium acetate and centrifuged. T h e recovered mineral matter v/as v/ashed once with distilled v/ater. c. Removal of Free Iron Oxides To the soil in the centrifuge tube* were added 40 ml. of 0.3 M. sodium acetate solution to chelate ferrous and ferric forms of iron and 5 ml. to buffer the solution. of 1 M. sodium bicarbonate The suspension v/as v/armed on the hot plate for a total of 15 minutes with occasional stirring. A 10 ml. solution of saturated sodium chloride v/as added to promote flocculation* centrifuged. and the suspension v/as 127 d. Collection of the Clay Fraction The clay fraction was collected b y repeated siphoning of the dispersed soil. The soil in the centrifuge tube-, treated for the removal of free iron oxides 3 was transferred to a sedimentation cylinder (1^000 ml.)., which was filled with distilled water and kept in the constant temperature room. The suspension was stirred vigorously v/ith a plunger after it had attained a constant temperature (21°C)., and stood for 23 hours to allow the coarser fractions (> 2 p) to settle below 30 cm. from the surface of the suspension^ according to Stokes law. Then the suspension was siphoned from the depth of 30 cm. The volume of the siphoned sus­ pension v/hich contained only the clay fraction was reduced by centrifuging v/ith addition of a saturated sodium chloride solution. The clay v/as v/ashed several times v/ith distilled v/ater to remove excess salt and transferred to appropriate jar for storage. e. Preparation of the Clay Film About 10 ml. of the clay suspension kept in the storage jar v/as placed in a test tube and allowed to stand overnight after the addition of several drops of glycerol. Onto a porous ceramic plate in the plate holder on a vacuum flask., 5 to 10 drops of the glycerol-solvated clay suspension v/ere added with distilled water and vacuum v/as applied. 128 The clay film deposited on the porous ceramic plate was leached with three increments of 1 N magnesium chloride solution containing 10$ glycerol to saturate the clay with magnesium. The clay film was then washed with 5 increments of water containing 10$ glycerol to remove excess magnesium chloride and air-dried in a desiccator over calcium chloride. f. X-ray Diffraction Patterns The clay film prepared was used for the first X-raying as a magnesium-saturated, glycerol-solvated* oriented aggre­ gate. A Phillips-Norelco X-ray unit v/as used v/ith a copper source and nickel filter for X-ray diffraction patterns. After the first X-raying* the clay film was leached v/ith 1 N potassium chloride solution to saturate the clay with potassium* and v/ashed v/ith v/ater to remove excess salt. The potassium saturated clay film was air-dried and used for the 2nd X-raying* then heated at 300°C* cooled and X-rayed for the 3rd time. The clay film v/as heated at 550°C* cooled and X-rayed for the 4th time. Heating lasted for 2 hours each time. 3. Cation Exchange Capacities and Total Potassium of the Clay Fraction The cation exchange capacity and total potassium of the clay fractions v/ere determined according to the method designed by Mortland (1 9 6 9 ). 129 The clay fraction ( < 2 p) which had been stored after the pretreatment for the X-ray diffraction studies were used for both the determinations of cation exchange capacity and total potassium. First the cation exchange capacity (Ca/Mg) v/as determined by saturating the clay v/ith calcium ion and then replacing it with the magnesium ion. Secondly, the cation exchange capacity (K/NH^) v/as determined by saturating the clay v/ith potassium ion and then replacing it with the ammonium ion. The difference in the cation exchange capa­ city (me./lOO g.), determined b y the tv/o methods was used for the calculation of vermiculite content in the clay fraction employing the following equation; percentage of vermiculite =((CEC. by Ca/Mg - C E C . by K/NH^) / 153*9) x 100. For the determination of total potassium, the clay v/as digested v/ith hydroflorlc acid in a platinum crucible and taken up with 0.1 N hydrochloric acid, then the solu­ tion v/as used for the determination of potassium. The total potassium v/as employed to estimate mica content in the clay fraction by multiplying the percentage of total potassium by a factor of 1 2 . B. 1. Results and Discussion Textural Designation of the Soils The results of the mechanical analysis are shown in Table 2 9 . Also listed in the table are the textural desig­ nations for each soil after referring to the textural triangle (Soil Survey Manual, 1953)* 130 Table 2 9 . Mechanical analysis of the soils and their textural designation Soil Brookston Genesee Kalamazoo Landes— Abscota Size Separate $ of separate Mm. Sand 2.0 Silt - 0.05 32.0 51.0 60.2 63.5 0.05 - 0.002 49-5 37.5 26.3 21.7 Coarse silt 0.05 - 0.02 15.0 15.2 7.8 4.2 Fine silt 0.02 - 0.002 3^.5 22.3 18.5 17.5 18.5 11.5 13.5 14.8 Loam Loam Sandy loam Sandy loam Clay < 0.002 Textural designation All values are averages of 2 determinations. 2. Active Fractions of the Soils The clay fraction is the most active portion of the mineral fraction of the soil. The clay content of the various soils (Table 2 9 ) is shown in the following order: Brookston loam > Landes-Abscota sandy loam > Kalamazoo sandy loam > Genesee loam. However, the order in cation exchange capacity (Ca/Mg) of the whole soil (Table l) is: Brookston loam > Genesee loam > Landes-Abscota sandy loam > Kalamazoo sandy loam. The fact that the clay content of the soils and their cation exchange capacities are not *53^* 131 directly related suggests that the clay content is. not the only factor involved in the activity of the soil in the economy of the plant nutrients, but the kinds of clay as well as the organic matter content must be considered; the coarser fractions such as silt may also be involved. If the CEC. (cation exchange capacity) is taken as a measure of physical and chemical activity of the soil, the contribution of the silt fraction to the CEC. of the soils is shown in Table 30The CEC. of the organic matter and clay fractions was obtained by multiplying the percentage of organic matter of the soils (Table l) by 200, and b y multiplying the percentage of clay (Table 29) B y the CEC. (Ca/Mg) of the clay fraction (Table 31) respectively. The C E C . derived from the silt fraction was obtained by subtracting the C E C . of the organic matter plus that of the clay fraction from the CEC. of the whole soil. A large portion of the CEC. of Brookston loam is derived from the organic matter and silt fractions as well as from the clay fraction. Brookston loam had the highest clay content and consequently the highest CEC. among the experimental soils. Genesee loam on the other hand contained the least clay, and among the soils it had the highest con­ tribution to the CEC. and silt fractions. (nearly 70^) from the organic matter Table 30. Cation exchange capacity of the organic matter, clay, and silt fractions of Brookston, Genesee, Kalamazoo, and Landes-Abscota soils Whole soil Soil Organic matter CEC. Brookston loam Clay Silt (Me ./100 g.) 2°.7 a (100.0) 7.2 (34.8) 8.4 (40.6) (2^6) Genesee loam 15.8, (100.0) 6.6 (41.8) 5.0 (3 1 .6 ) 4.2 (2 6 .6 ) Kalamazoo sandy loam 7.0 (100.0) 2.7, (3 8 .6 ) 3.8 (54.3) 0.5 ( 7 .1 ) 13.2 (1 0 0 .0 ) 4.6 (34.8) 6.3 (47.7) 2.3 (17.4) Landes-Abscota sandy loam aThe values in the parentheses show the percentages of CEC. derived f rom 1he respective fractions. Kalamazoo sandy loam and Landes-Abscota sandy loam received the major portion of the CEC. organic matter. from the clay and The silt fraction contributed less CEC. to these two soils than to the Bro o k s t o n and Genesee soils. 3. The Cation Exchange Capacities, and Kinds and Relative Amounts of Minerals Present in the Clay Fractions of the Original Soils The cation exchange capacity values (CECs.) deter­ mined by Ca/Mg and K/NH^ methods, the percentage of vermiculite, the total amount of potassium and the percentage of mica in the clay fractions of the original soils are 133 summarized in Table 31. The kinds and relative amounts of minerals found in the clay fractions are also indicated in Table 31. The more important X-ray diffraction patterns, which were used as a basis for identifying the clay minerals present in the soils, are presented in Figures A 2 5 to A 4 6 . It was found when the CECs. are higher, the amount of montmorillonite and vermiculite were higher. The re­ ported CEC. values are: 80 - 100 for montmorillonite, 100 - 150 for vermiculite, 10 - 40 for Illite, 3 - 15 for kaolinite, and 10 - 40 for chlorite when expressed as me. per 100 g. of the respective clays (Grim, 1953)* Since the clay fraction of B r o okston loam contained a large quantity of montmorillonite plus vermiculite, it shows a higher CEC, (Ca/Mg) than that of other three soils. In Genesee loam, the randomly interstratified minerals of vermiculite-chlorite-montmorillonite seemed to b e quite active resulting in a high CEC (Ca/Mg). T h e clay fraction of Kalamazoo sandy loam showed lower activity in the CEC, (Ca/Mg) and in the fixation of potassium, which was indicated by the difference between the CECs. b y Ca/Mg and b y K/NH^, when compared with the other soils. Vermiculite-chlorite interstratified minerals were dominant in the clay fraction of both Kalamazoo sandy loam and Landes-Abscota sandy loam. However, the CEC. and potassium fixation were higher for the clay fraction of Landes-Abscota sandy loam than for Kalamazoo sandy loam. The difference of the clay fraction of the two Table 31. Mineralogical properties of the clay fractions of the original, cropped, and incubated Brookston, Genesee, Kalamazoo, and Landes-Abscota soils K treatment and cropping CEC k/NH4 Ca/Mg Vermiculite Total K Mica Me./lOO g. % $ % i£indsa and relative amounts’ 3 of minerals present in clay fraction Brookston loam + 444 44 44 4+ +4 + 5 crops with 0 lbs.K/A. 5 crops with 1,600 lbs.K/A. 45.1 32.4 8.3 2.3 27.6 Mo>V>Mi> Q>Ka>Ch ■t/ET Original soil 4.4.4+ +4 ++ 4+ 4+ + 48.1 33.3 9.6 43.2 31.2 7.8 Incubated with 1,600 lbs.K/A. 41.5 32.6 1.9 22.8 1.9 22.8 Mo>?>Mi>Ka>Q>Ch 44 + 4 44 4+ 4 4 +4 4 Md>V>Mi> Q?Ka>Ch 1-444 44 4+ 44 44 4 5.9 2.3 27.6 Mo>V>Mi>Q>Ka> Ch Genesee loam Original soil 43.1 27.7 10.0 1.5 18.0 5 crops with 0 lbs.K/A. 5 crops with 1,600 lbs.K/A. 44.5 28.6 10.3 1.5 18.0 45.3 32.8 8.2 1.7 20.4 Incubated with 1,600 lbs.K/A. 43.2 444 +44 4 4 Ka>V-ch-mo >Mi > Q 44+ 444 4 4 Ka > V-ch-mo > Mi > Q 444 +44 +4 4 Ka > V-ch-mo > Mi > Q 444 33.1 6.6 1.7 20.4 44+ 44 Ka> V-ch-mo> Mi 4 Table 31■(cont1d.) K treatment and cropping CEC. Ca/Mg K/NH^ Vermiculite Me../loo g. Original soil 5 crops with 0 lbs.K/A 5 crops with 1,600 lbs.K/A. Kinds3- and relative amounts13 of minerals Mica present in clay fraction % 18.0 25.2 22.4 1.8 1.4 16.8 26.0 23.9 1.4 1.5 18.0 +4+ 4"++ + 4 4 + V-ch>Ka>Q>Mi >Ch 44+ H 4 4+ + 4 V-ch >Ka > Q > Mi > Ch 444 44 4+ 4 4 V-ch> Ka > Q >Mi> Ch 27,3 1.8 1.5 18.0 +44+ 44 +4 4 4 V-ch >Ka> Q> Mi> Ch 42.7 Landes-Abscota sandy loam 29.0 2.4 5.9 46.6 27.9 12.2 2.0 41.7 28.5 8.6 2.4 Incubated with 1,600 lbs.K/A. 37.6 28.5 5*9 2.7 44+ 44 +4 4 28.8 V-ch> Mi >Ka > Q 44+ 44 44 +4 4 24.0 V> Mi> Ka >V-ch-mo>Q +4+ + 4 + 4 4 4 28.8 V> Mi >Ka >Mo-ch> Q 32.4 444 44 4+ 4 4 Mi > V-ch > Ka > Mo4'ch>Q aCh= chlorite; Ka- kaolinite; Mi- Mica (or illite); Mo= montmorillonite; Mo-ch= montmorillonite-chlorite interstratified minerals; Q= quartz; V* vermiculite; V-ch= vermiculite-chlorite interstratified minerals; and V-ch-mo- vermiculitechlorite-montmorillonite interstfatified minerals, b Number of + indicates relative quantity of the minerals; 4*+++= very high, +++= high, +■+= medium and 4-- low. 135 28.2 Kalamazoo sandy loam 25.5 1.7 1.5 Incubated with 1,600 lbs.K/A. 30.0 Original soil 5 crops with 0 lbs. K/A. 5 crops with 1,600 lbs.K/A. % Total K 136 soils in the CEC. and potassium fixation, although it must be studied in the f u t u r e , was probably that: (l) the m i nor minerals in Kalamazoo sandy loam were kaolinite, quartz, mica (or illite), and chlorite in decreasing order, whereas mica (or illite), kaolinite, sandy loam, and quartz in Landes-Abscota (2 ) gibbsite-like layers m a y have been formed in vermiculite-chlorite interstratified minerals of K a l a m a ­ zoo sandy loam but brucite-like layers in that of LandesAbscota sandy loam, and (3) the vermiculite-chlorite inter­ stratified minerals of Kalamazoo sandy loam may have been larger in size and higher in crystallinity than those of Landes-Abscota sandy loam. 4. Effects of Potassium Exhaustion and Incubation on Clay Mi n e r a l o g y of the Soils Changes in clay mineralogy which were caused by cropping and Incubation were presented in Table 31assumptions are that: The (1 ) the potassium fixation (the difference between the cation exchange capacity b y Ca/Mg and K/NH^) was caused only b y vermiculite; total potassium was derived only from mica. and (2 ) the The parts of the X-ray diffraction patterns used for identifying the kinds and relative amounts of clay minerals are presented in Appendices G to J. In Brookston loam the percentage of vermiculite increased slightly and the percentage of m i c a decreased when soil potassium was exhausted b y 5 croppings without the addition of potassium. If the assumptions were appropriate, 137 the results would "be an indication of the change of mica, after releasing its potassium, to vermiculite. When the soil was cropped 5 times with enough potassium applied (K=l,600), the percentage of vermiculite did not increase but stayed near the level of the original soil. The de ­ crease of mica in this case may be an indication of plant weathering of mica (Mortland et a l ., 1956* and Conyers and McLean, 1 9 6 8 ), by which mica released its potassium directly to the plant roots and may have changed to montmorillonite through vermiculite. This process would take place more: intensively in Brookston loam than in the other three soils because the plant growth was most vigorous in Brookston 12) loam. The percentage of vermiculite markedly decreased v;hen the soil was incubated for 13 months with K = l ,600 treat­ ment. An increase in the percentage of mica was not indi­ cated by potassium analysis when compared with the original soil, but a slight increase in 10 R peak was recognised in the X-ray diffraction pattern (Figure A27) indicating the change of vermiculite to mica (or illite). The alteration of clay minerals appears more sensitively reflected in the X-ray diffraction pattern than in the potassium content of the clay minerals (Mortland et a l ., 1 9 5 6 ). Mineralogical changes occurring in Genesee loam were not detected from potassium exhaustion by cropping. This is likely to mean that the soil potassium had already been depleted before the experiment was initiated. ■^^See Tables 3 and 6. The decrease in the percentage 138 of vermiculite and the increase in the percentage of mica (or illite) took place when the soil was cropped with enough potassium (K=lj600) and also when incubated with this rate of potassium., indicating the changes of vermiculite to mica (or illite) after fixing applied potassium as observed by Rich and Lutz (1 9 6 5 ). Only minor changes in the clay mineralogy upon the cropping of Kalamazoo sandy loam were evidenced with and without the addition of potassium. The vermiculite-chlorite interstratified minerals increased when incubated with K=l,600 treatment as identified from the X-ray diffraction patterns. The percentage of vermiculite in Landes-Abscota sandy loam increased markedly due to potassium exhaustion by 5 croppings without the addition of potassium. The decrease in the percentage of mica suggests the change of mica to vermiculite. The X-ray diffraction patterns show that discrete vermiculite was formed from vermiculite-chlorite interstratified minerals upon the depletion of potassium. Also identified was the formation of vermiculite-chloritemontmorillonite interstratified minerals. The decrease of vermiculite and increase of mica in the soils with applied potassium indicated the change of vermiculite to mica by fixing potassium. The results obtained may imply some important rela­ tionships between clay mineralogy of the soils and fertili­ zation practices. If soils such as Brookston loam, Genesee 139 loam, and Landes-Abscota sandy loam were cropped with only 4 small applications of potassium, the soils would eventually become potassium depleted and become rich in vermiculite* resulting in the fixation of applied potassium and the de ­ crease of its availability for immediate use to plants. If a large amount of potassium were applied to these soils* it would be bound in clay minerals such as mica and illite* and released later to meet the plant requirements. In con­ trast* applied potassium would be exposed to the hazard of leaching in Kalamazoo sandy loam which has a clay mineralogy capable of fixing little potassium. The bound potassium by fixation in Brookston* Genesee* and Landes-Abscota soils may 13} be released at different rates. 1 If the rate of release is too slow* it may become a barrier for potassium supply of the soils to p l a n t s ^ ^ a s suggested by Mortland (1958)- See Figures 11* 12* and 14. See Figures 12 and 14. SUMMARY The objectives of this thesis were to study and com­ pare the ability of Brookston loam* Genesee loam, Kalamazoo sandy loam, and Landes-Abscota sandy loam to release and/or fix soil potassium under different cropping programs, and to relate these phenomena to their physical, chemical, and mineralogical properties. Five levels of potassium, 0, 200, 400, 800, and 1,600 pounds per acre were applied initially to all soils and the soils were planted to 6 crops in the following se­ quence: 3 crops of wheat, 2 crops of sorghum, and 1 crop of tomatoes. Plant response to the applied potassium, the interrelationships among potassium, calcium, and magnesium uptake of the plants were investigated and the potassium supplying powers of the soils were evaluated. The 3rd crop (wheat) and the 6th crop (tomatoes) grown on Brookston loam were the only crops to show a yield response to the potassium treatments. In the case of Genesee loam the 3rd crop (wheat) and the succeeding crops, 2 crops of sorghum and 1 crop of tomatoes, potassium treatments. responded to the The plant response obtained from 140 lA l applied potassium on Kalamazoo sandy loam was the same as that obtained for Genesee loam, but the yields of* the 2nd crop (wheat) was negatively affected by the potassium treat­ ments. All crops except the 2nd (wheat) grown on Landes- Abscota sandy loam responded to applied potassium. Potassium concentration of the plants rose with in­ creasing levels of applied potassium while the concentrations of plant calcium and magnesium generally decreased. Potassium concentration in the plants declined as the cropping advanced whereas that of calcium and magnesium in ­ creased . Potassium uptake of the plants grown on all the soils was significantly affected by potassium treatments. However, plant uptake of calcium and magnesium varied with the crop and soils. Plant yields were generally positively correlated with potassium uptake and with the uptake of potassium plus cal­ cium and magnesium, but negatively correlated with uptake of calcium and magnesium except for the 6th crop (tomatoes) in which the yields were positively correlated with all uptake measurements. The overall potassium supplying power, as measured by potassium uptake of the plants at K=0 treatment, was in the following order: Brookston loam > Kalamazoo sandy loam > Landes-Abscota sandy loam > Genesee loam. 142 The stem tissue of wheat (2nd crop) was analyzed by the electron microprobe X-ray technique. A higher concen­ tration of potassium but a lower concentration of calcium and magnesium was obtained for the sample from the K=400 treatment on Brookston loam; on the other hand, a lower concentration of potassium but a higher concentration of calcium and magnesium was obtained from the K=0 treatment on Genesee loam. Chemical properties of the soils were studied in relation to potassium availability by determining exchange­ able and nonexchangeable forms of potassium, the release and fixation of potassium upon wetting-drying, and freezing thawing treatments, and quantity-intensity relationships of soil potassium. After 5 croppings the levels of exchangeable soil potassium for all soils were found to be considerably less than that of the original soil levels. Nonexchangeable potassium was retained at levels higher than the original levels, even after 5 croppings, v/hen potassium was initially applied to the rate of 400 or more pounds of K per acre on Brookston loam, Genesee loam, and Landes-Abscota sandy loam, and at the rate of 1,600 pounds of K per acre on Kalamazoo sandy loam. The applied potassium seems to have been converted to nonexchangeable forms and then released gradually upon the depletion of exchangeable potassium b y the plants. 14-3 The rate of potassium release was considered to be more rapid for Kalamazoo sandy l oam3 which had the lowest potas­ sium fixing and cation exchange capacities among the soils. When the soil was incubated for 13 months with the various levels of applied potassium both the exchangeable and nonexchangeable potassium increased except in the case of Kalamazoo sandy loam in which the nonexchangeable potas­ sium decreased with levels of applied potassium exceeding 400 pounds per acre. The degree of increase in exchangeable and nonexchange­ able potassium appeared greater when the initial levels of potassium in the 2 forms were lower and the contents of potassium fixing clay were higher in the soils. The alternate wetting and drying treatments resulted in the fixation of potassium by all soils. Potassium fixa­ tion was in the following order: Brookston loam > LandesAbscota sandy loam > Genesee loam > Kalamazoo sandy loam. Only small quantities of potassium were released by Kalamazoo sandy loam and Landes-Abscota sandy loam* and conversely small amounts of potassium were fixed by Brookston loam and Genesee loam when the soils were alternately frozen and thawed. Soil potassium as defined in terms of *^K O k and A R D decreased by cropping but increased with the levels of applied potassium in both cropped and incubated soils. FBC decreased with the levels of applied potassium in the cropped soil but showed various tendencies by different 144 soils when incubated. Effects of cropping on the PBC^ were varied among the soils. multiplying The K potential obtained by by P B C k values tended to increase with the levels of applied potassium in b o t h cropped and incubated soils but decreased by cropping. When -^K°, ARgj nonexchangeable, FBCk , K potential, and exchangeable, and total potassium (the sum of exchange­ able and nonexchangeable potassium) were correlated with the o k plant uptake of potassium, -a K , A R e and exchangeable p o tas­ sium offered better measurements to evaluate availability of soil potassium for B r o okston loam; AR]| and exchangeable, nonexchangeable, and total potassium for Genesee loam; n o n ­ exchangeable and total potassium for Kalamazoo sandy loam; 1r and -^K , AR„ and exchangeable, nonexchangeable, and total potassium for Landes-Abscota sandy loam. Physical properties of the soils were evaluated by mechanical analysis; and the mineralogical properties by cation exchange capacity determination, total potassium contents of the clay fractions, and X - r a y diffraction patterns. The clay contents of the soils were: 1 8 .5^, 11.5$* and 14.8$ for Brookston loam, Genesee loam, K a l a m a ­ zoo sandy loam, and Landes-Abscota sandy loam respectively. The cation exchange capacities of the soils w e r e : 20.7 , 1 5 .8 , 7 .0 , and 13*2 mill!equivalents per 100 grams for Brookston loam, Genesee loam, Kalamazoo sandy loam, and JL*-.*"1'- 1^5 Landes-Abscota sandy loam respectively. The organic matter, silt, and clay fractions contributed to the cation exchange capacity values of Brookston and Genesee loam soils. The silt fraction, however, was of minor significance in the cation exchange capacity values obtained for Kalamazoo and Landes-Abscota sandy loam soils. The percentage of vermiculite in the clay fractions of the original soils was determined as 8 .3 , 1 0 .0 , 1 .7 , and 8.9 for Brookston loam, Genesee loam, Kalamazoo sandy loam, and Landes-Abscota sandy loam respectively. The percentage of mica in the clay fractions of the original soils was; 27.6, 18.0, 18.0, and 28.8 for Brookston loam, Genesee loam, Kalamazoo sandy loam, and Landes-Abscota sandy loam soils respectively. Montmorillonite was the predominant clay mineral in Brookston loam; kaolinite and vermiculite-chlorite-montmorillonite interstratified minerals predominated in Genesee loam; vermiculite-chlorite interstratified minerals and kaolinite were dominant in Kalamazoo sandy loam; and ver­ miculite-chlorite interstratified minerals were predomi­ nant in Landes-Abscota sandy loam. The cation exchange capacities of the clay fractions tended to increase when the soil potassium was depleted by cropping, the only exception was Kalamazoo sandy loam. When Brookston loam and Landes-Abscota sandy loam were incubated with 1,600 pounds of potassium per acre, their cation exchange capacities tended to decrease. The vermiculite contents of the clay fractions tended to increase as soil potassium was depleted by the cropping, most remarkably in Landes-Abscota sandy loam. 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Soil Sci. Soc. Amer.* Proc. 2 9 : 7 6 -7 8 . 153 Pratt, P. F . , and Morse, H. H. 1954. Potassium release from exchangeable and nonexchangeable forms in Ohio soils. Ohio Agr. Exp. Sta. Res. Bui. 7^7Raman, K. V. , and Jackson, M. L. 1 9 6 5 . M i c a surface morphology changes during weathering. Soil Sci. Soc, Amer,, Proc. 2 9 : 29-32. Rasmussen, H. P. I 9 6 8 . Entry and distribution of aluminum in Zea m a y s . The mode of entry and distribu-tfon of aluminum in Zea m a y s : Electron microprobe X-ray analysis. Planta ol: 28-37. Rasmussen, H. P . , Shull, V. E . , and Dryer, H. T. 1968. Determination of element localization in plant tissue with the microprobe. Developments in Applied Spectroscopy 6 : 29-42. Reed, M. G . , and Scott, A. D. 1 9 6 1 . Flame photometric methods of determining the potassium in potassium tetr a p h e n y l b o r a t e . Anal. Chem. 3 3 • 773-775. Reed, M. G . , and Scott, A. D. 1 9 6 2 . Kinetics of potassium release from biotite and muscovite in sodium tetraphenylboron solution. Soil Sci. Soc. Amer., Proc. 2 6 : 437-440. Reitemeir, R. F . , Holmes, R. S., Brown, X. C., Klipp, L. W . , and Parks, R. Q. 1948. Release of n onexchange­ able potassium b y greenhouse, Neubauer, and labo­ ratory methods. Soil Sci. Soc. Amer., Proc. 12: 1 5 8-1 6 2 . Rich, C. I., and Lutz, J. A., Jr. 1 9 6 5 . Mineralogical changes associated with ammonium and potassium fixation in soil clays. Soil Sci. Soc. Amer., Proc. 2 9 : 167-170. Richards, G. E . , and McLean, E. 0. 1 9 6 1 . Release of fixed potassium from soils b y plant uptake and chemical extraction techniques. Soil Sci. Soc. Amer., Proc. 2 5 : 9 8 -IOI. Schmitz, G. W. , and Pratt, P. F. 1953Exchangeable and nonexchangeable potassium as indexes to yield increases and potassium absorption by corn in the greenhouse. Soil Sci. 7 6 : 345-353. Schneider, -1 . F. , Whiteside, E. P., and Johnson, R. W. I9 6 7 . Classification of Michigan Soils. In mimeograph. 154 Schulte, E. E., and Corey, R. B. 1 9 6 5 * Extraction o f 1 potassium from soils with sodium tetraphenylboron. Soil Sci. Soc. Amer., Proc. 2 9 : 33-35* Scott, A. D . , and Reed, M. G. 1 962a. Chemical extraction of potassium from soils and micaceous minerals with solutions containing sodium tetraphenylboron: II. Biotite. Soil Sci. Soc. Amer., Proc. 26: 41-45* Scott, A. D.j and Reed, M. G. 1962b. Chemical extraction of potassium from soils and micaceous minerals with solutions containing sodium tetraphenylboron: III. Illite. Soil Sci. Soc. Amer., Proc. 2 6 : 45-48. Scott, A. D . , and Welch, L. F. 1 9 6 1 . Release of n o n ­ exchangeable soil potassium during short periods of cropping and sodium tetraphenylboron extraction. Soil Sci. Soc. Amer., Proc. 25: 128-132. Soil Survey Staff. 1951* Soil Survey Manual* Agr. Handbook Wo. 18. p. 2 0 9 . U.S. Dept. Stanford, G. 1947* Fixation of potassium in soils under moist conditions and on drying in relation to type of clay mineral. Soil Sci. Soc. Amer., Proc. 12: 167 -170 . Stanford, F. , and DeMent, J. D. 1957* A method of measuring short-term nutrient absorption b y plants: I. Phosphorus. Soil Sci. Soc. Amer., Proc. 21: 612-617. Steel, R. G. D . , and Torrle, J. H. i9 6 0 . Principles and Procedures of Statistics. McGraw-Hill B o o k Company, Inc., New York. pp. 106-107* Thompson, L. M. 1959. Soils and Soil Fertility. McGrawHill B o o k Company, Inc., New York. pp. 353-357* Thornton, S. F. 1 9 3 1 . Experiences w i t h the Neubauer method for determining mineral deficiencies in soils J. Amer. Soc. Agron, 23: 193-208. Thorton, S. F. 1935. Soil and fertilizer studied b y means of the Neubauer method. Purdue Univ. Agr. Exp. Sta. Bui. 3 9 9 . Tisdale, S. L . , and Nelson, W. L. 1966. Soil Fertility and Fertilizers. 2d ed. The Macmillan Company, New York. p. 267. 155 Vlamis, J., and Davis, A. R. 1944. Effect of Oxygen tension on certain physiological responses of rice, barley, and tomato. Plant Physiol. 1 9 ' 33-51* Volk, N. J. 1934. The fixation of potash in difficulty available form in soils. Soil Sci. 3 7 * 2 6 7 -2 8 7 . Weber, J. B., and Caldwell, A. C. 1964. Soil and plant potassium as affected b y soil temperature under controlled environment. Soil Sci. Soc. Amer., Proc. 2 8 : 6 6 1 -6 6 7 . Welch, L. F . , and Scott, A. D. 1 9 6 1 . A v a i l a b i l i t y of nonexchangeable soil potassium to plants as affected by added potassium and ammonium. Soil Sci. Soc. Amer., Proc. 2 5 : 102-104. Whiteside, E. P., Schneider, I. F . , a n d Cook, R. L. 1963Soils of Michigan. Michigan State Univer s i t y Agr. Exp. Sta. Spec. Bui. 402. Wiklander, L. 1964. Cation and anion exchange phenomena. In F. E. B e a r (ed.) Chemistry of the Soil. 2d ed. Reinhold Publishing Corporation, New York, pp. 163-2 0 5 . Wild, A., Rowell, D. L. , and Ogunfowora, M. A. 19^9* The activity ratio, as a measure of the intensity factor in potassium supply to plants. Soil Sci. 10b: 432-439 Worley, R. E. , Blaser, R. E . , and Thomas, G. W. 1963Temperature effect on potassium uptake and respi­ ration by warm and cool season grasses and legumes. Crop Sci. 3 : 13-16. Zandstra, H. G. , and Mackenzie, A. F. 1 9 6 8 . Potassium exchange equilibria and yield responses of oats, barley and corn on selected Quebec soils. Soil Sci. Soc. Amer., Proc. 32: 76-79- APPENDICES APP E N D I X A DESCRIPTIONS OP T H E SOILS 1. B r o okston Loam The p o o r l y drained Bro o k s t o n series developed from loam or silt loam parent materials (Whiteside et a l . , 1 9 6 3 ). The soil profile description of B r o o k s t o n loam at the collection site follows: Horizons Ap Depth 0 - 9n 9 - 2 1 11 Cg Description Loam; very dark grayish brown (10YR 3/ 2 ); weak* coarse, granular structure; friable; p H 7-0; abrupt smooth boundary. Clay loam; gray (5Y 5/1 )> moderate; medium, subangular blocky structure; firm; p H 7*5; clear smooth boundary. 21 - 34" Silt loam; yellowish b r o w n (10YR 5/6) to b r o w n (7 .5Y R 5/ 3 ) w i t h dark brown (7.5YR 3/2) mottles; weak, coarse, subangular blocky structure; friable; p H 7*8; abrupt w a v y boundary. 34" -t- Silt; mottles of dark grayish brown (10YR 4/2) and strong b r o w n (7.5^R 5/6 ); weak, thin, p l a t y structure; friable; calcareous. 156 157 2. Genesee Loam The well-drained Genesee series developed from loam to silt stratified alluvial material (Schneider et a l . , 1967). These soils occur on level flood plains along creeks and rivers. The soil profile description of Genesee loam at the collection site follows: Horizons Depth Description 8" Loam;dark "brown (7 .5YR 3 / 2 ) ; weak, fine to medium granular structure; friable; pH 6.3$ irregular clear boundary. Ap 0- B2 8 26" Loam; dark reddish brown (5Y R 3/4); moderate, medium subangular blocky structure; friable; p H 7-0$ abrupt wavy boundary. XIC^ 26 - 45" Sandy loam; yellowish brown (10YR 5/ 6 ); weak, medium subangular blocky structure; friable; pH 7*5$ clear' wavy boundary. IIIC2 45" + Gravelly sand; yellowish brown (10YR 5/ 6 ); single grained; loose; calcareous. 158 3. K a l amazoo Sandy Loam The well-drained Kalamazoo series developed on level to strongly sloping areas on valley trains, outwash plains, moraines, kames, and eskers (Kerr et a l ., 1927)* The soil profile description of Kalamazoo sandy loam at the coll e c ­ tion site follows: Descriptions Horizons Depth Ap 0 - 8" B 21t 8 - 15 " Clay loam; dark reddish b r o w n (5YR 3/4 ) ; weak, fine* subangular blocky structure; friable; pH 6.75 g r a ­ dual wavy boundary. B 22t 15 - 20u Gravelly loam and clay loam; dark reddish brown (5YR 3/4); weak, fine subangular blocky structure; friable; pH 5 .5 ; clear irregular boundary. B 23 20 - 25 " Loamy sand; dark brown (7.5YH 4/4); weak, fine, subangular bloc k y structure; very friable; pH 5*4; clear wavy boundary. IIC S a ndy loam; dark reddish brown (5YR 3/2); vieakj fine granular structure; very friable; pH 7-1; abrupt smooth boundary. 25 - 5 0 M Loamy sand to sand; dark brown (7-57R 4/4); single grain structure; loose, pH 5 .8 ; gradual w a v y boundary. 50" * Sand; very pale brown (10YR 7/3); single grain structure; loose; calcareous. 159 4. Landes-Abscota Sandy Loam The well-drained soil collected from the Sodus Experimental Farm, B e r r i e n County had characteristics of both the Landes and Abs c o t a series. These series developed on flood plains along creeks and rivers. The parent materials of the Landes soils are stratified loamy fine sand to fine sandy loams while the Abs c o t a soils are strati­ fied sand to loamy sand (Kerr e_t a l . , 1 9 2 7 3 and Schneider et al., 1 9 6 7 ). T h e soil profile description at the collec­ tion site follows: Description Horizons Depth Ap 0 - 8" A12 8 - 12 " S a ndy loam; very dark gray b r own to very dark brown (10YR 3/2 - 10YR 2/2 ;; weak, fine granular structure; very friable; p H 7*5; clear wavy boundary. A: 12 - 14" Loamy sand; dark reddish brown (5YR 3/ 3 ); weak, fine granular structure; very friable; p H 7.8; clear wavy boundary . B 21 14 - 2 0 " Loamy sand; dark reddish brown (5^R 3/4); weak, very fine subangular b l o c k y structure; very friable; pH 8 .0 ; clear wavy boundary. b 22 20 Sand; strong brown (7.5YR 5/6); single grain structure; loose; pH 8.0; abrupt wavy structure. XIC 32 - 42" - 32" Sandy loam; very dark gray brown (10YR 3/2); weak,, fine granular structure; very friable; pH 7.0; abrupt smooth boundary. Fine sand and silt; light brownish gray (10YR 6/2); stratified; friable; calcareous; abrupt wavy boundary. l6 o Horizons IIIC Depth 42" + Description Sand and gravel; splotches of strong brown (7-5YR 5/8) in light gray (10YR 7/ 2 ) ; single grain structure ; l o os e; calcareous. l6l APPENDIX B PHOTOGRAPHS OF THE GROWTH RESPONSE OF WHEAT,, SORGHUM, AND TOMATOES TO POTASSIUM ON BROOKSTON LOAM Figure Al. The 2nd crop (wheat) at 40 days of growth on Brookston loam. Potassium treatments had no effect on plant yields (Tables 3 and 7). i Figure A 2 . The 4th crop (sorghum) at 48 days of growth on Brookston loam. Potassium treatments had no effect on plant yields (Tables 3 and 7). 162 Figure A 3 . The 5"th crop (sorghum) at 70 days of growth on Bro o k s t o n loam. Potassium treatments had no effect on plant yields (Tables 3 and 7). jBBOQKSTOH Lj Figure A4. T h e 6th crop (tomato) at 40 days of growth on Br o o k s t o n loam. Potassium treatments significantly affected plant yields (Tables 3 and 7). 163 ( BBflOKSTDM t t Figure A 5 . Tomato plants at 40 days of growth on the uncropped soil of Bro o k s t o n loam. Plant yields were not affected b y potassium treatments (Table 8). 164 APPENDIX C PHOTOGRAPHS OF THE GROWTH RESPONSE OF WHEAT, SORGHUM, AND TOMATOES TO POTASSIUM ON GENESEE LOAM BEKE5EE K-4QO K-80o'1k^ Figure A6. The 2nd crop (wheat) at 40 days of growth on Genesee loam. Potassium treatments had no effect on plant yields (Tables 4 and 7)* Figure A7. The 4th crop (sorghum) at 48 days of growth on Genesee loam. Potassium treatments significantly affected plant yields (Tables 4 and 7). 165 Figure A8. The 5th crop (sorghum) at 70 days of growth on Genesee loam. Potassium treatments significantly affected plant yields (Tables 4 and 7)* in-rrvr&pr, ,»■r -y ; CEHEStE Figure A9. t The 6th crop (tomato) at 40 days of growth on Genesee loam. Potassium treatments significantly affected plant yields (Tables 4 and 7). 166 GmsEf i Figure A10. Tomato plants at 40 days of growth on the uncropped soil of Genesee loam. Potassium treatments had no effect on plant yields (Tahle 8 ). 167 APPENDIX D PHOTOGRAPHS OF THE GROWTH RESPONSE OF WHEAT* SORGHUM* AND TOMATOES TO POTASSIUM ON KALAMAZOO SANDY LOAM Figure All. The 2nd crop (wheat) at 40 days of growth on Kalamazoo sandy loam. The plants were unfavorably affected b y the potassium treatments because soil potassium was originally high (Tables 1* 5* and 7). Figure A 1 2 . The 4th crop (sorghum) at 48 days of growth on Kalamazoo sandy loam. Potas­ sium treatments significantly affected plant yields (Tables 5 and 7). 168 F i g u r e A13. T h e 5t h c r o p ( s o r g h u m ) at T O d a y s o f g r o w t h on K a l a m a z o o s a n d y loam. Po­ tassium treatments significantly a f f e c t e d p l a n t y i e l d s ( T a b l e s 5 a n d 7)* Figure Al4. T h e 6 t h c r o p ( t o m a t o ) at 4 0 d a y s of g r o w t h on K a l a m a z o o s a n d y loam. Po­ tassium treatments significantly a f f e c t e d p l a n t y i e l d s ( T a b l e s 5 a n d 7)- 169 [_KAj.AHAZOO F i g u r e A15. St j T o m a t o p l a n t s at 4 0 days of* g r o w t h o n t h e u n c r o p p e d soil of K a l a m a z o o s a n d y loam. Potassium treatments h a d n o ef f e c t on p l a n t y i e l d s (Table 8). 170 APPENDIX E PHOTOGRAPHS OF T H E GROWTH RESPONSE OF WHEAT, SORGHUM, AND TOMATOES TO POTASSIUM O N LANDES-ABSCOTA SANDY LOAM Figure A l 6 . The 2nd crop (wheat) at 40 days of growth on Landes-Abscota sandy loam. Potassium treatments had no effect on plant yields (Tables 6 and 7)- Figure A 1 7 . The 4th crop (sorghum) at 48 days of growth on Landes-Abscota sandy loam. Potassium treatments significantly affected plant yields (Tables 6 and 7)- 171 'E£ J & R - l A H O E S - A B SCOTA S I .Jh L H ] K-0 K-2 0 0 1K*400 |K-800 (K-1600 F i g u r e Al8. T h e 5th crop (sorghum) at 70 days of g r o w t h on L a n d e s - A h s c o t a s a n d y loam. Potassium treatments significantly a f f e c t e d p l a n t y i e l d s (Tables 6 and 7)• lABPfS-ABSCflTA Stj Fi g u r e A19, T h e 6 t h crop (tomato) at ^ 0 days of g r o w t h on L a n d e s - A b s c o t a s a n d y loam. Potassium treatments significantly a f f e c t e d p l a n t y i e l d s (Tables 6 and 7)- 172 EAlfOES ABSCOEA SE K-400lK-800BKM^nn Figure A20. T o m a t o p l a n t s at 4 0 d a y s of g r o w t h on the u n c r o p p e d soil of LandesA b s c o t a s a n d y loam. Potassium t r e a t m e n t s h a d n o e f f e c t on p l a n t y i e l d s ( T a b l e 8). 173 APPENDIX F RELATIONSHIPS OF POTASSIUM ACTIVITY RATIO (AR ) TO POTASSIUM ADSORPTION OR RELEASE ^ K „ ) O N T H E UNCROPPED SOILS 174 1.0 0.8 AKe (me./100g) 0.6 0.4 0.2 0.0 -0.2,/ 0.010---1 A R K ( M . / i .) Figure A 2 1 . 2 Relationship; of potassium activity ratio (ARk ) to potassium adsorption or release (a K g ) on Brookston loam 175 1*0 (Me./100g) 0.8 0.4 AKe 0.2 0.0 - 0.2 0 0.005 0.010 ark Figure A 2 2 . 0.015 0.020 (m :/i .)^ Relationship of potassium activity ratio (ARk ) to potassium adsorption or release (AKe) on Genesee loam \ 0.4 0.2 (Me./lOO 0.0 ^Ke tsD 0.2 -0.4 0 0.005 0.010 0.015 ark Figure A23. 0.020 0.025 0.030 (Myi.)* Relationship of potassium activity ratio {AR ) to potassium adsorption or release (AKe) on Kalamazoo sandy loam 177 1.0 AKe (Me./lOOg) 0.6 0.4 0.2 0.0 - 0.2 Figure A24. Relationship of potassium activity ratio (AR1^) to potassium adsorption or release (AKe) on Landes-Abscota loam 178 APPENDIX G X-RAY DIFFRACTION PATTERNS OF THE CLAY FRACTION OF BROOKSTON LOAM Legend: A: Mg saturated, glycerol-solvated, air-dried sample. B: K saturated^ air dried sample. C: K saturated, heated (300° C.) sample. D: K saturated, heated (55°° c *) sample. 179 d space (&) 7.1 10 14 18 A B C D 12 Figure A 25. 10 Degrees 20 X-ray diffraction pattern of the clay fraction of Brookston loam before cropping 180 d space («) 10 7,1 12 14 18 10 Degrees 20 Figure A26. X-ray diffraction pattern of the clay fraction of Brookston loam after the crop on the 0 potassium treatment l8l d space (2) ] 12 Degrees 28 Figure A27. X - r a y diffraction pattern of the clay fraction of B r o okston loam after the 5th crop on the 1^600 pound per acre potassium treatment 182 d space ($) 7-1 1° B A C D lU Figure A28. 12 10 Degrees 29 X-ray diffraction pattern of the clay fraction of Brookston loam after a 13-month incubation period with 1*600 pounds of potassium per acre 183 APPENDIX H X-RAY DIFFRACTION PATTERNS OF THE CLAY FRACTION OF GENESEE LOAM Legend: A: Mg saturated, glycerol-solvated, air-dried sample. B: K saturated, air-dried sample. C: K saturated, heated (300° C.) sample. . o . K saturated, heated (550 C . ) sample. D: 184 d space (i?) 7.1 10 14 18 A B 14 12 10 8 6 4 Degress 29 Figure A29- X-ray diffraction pattern of the clay fraction of Genesee loam before cropping 185 d space (*) 7 |.i 8 r c D 12 j . 10 Degrees 20 Figure A29 {cont'd.) ■d- t 186 d space («) 8 7-1 X? A B X 14 12 Figure A 3 0 . 10 8 Degrees 20 X - r a y diffraction pattern of the clay fraction of Genesee loam after the on the 0 potassium treatment crop 187 d space (S) ^ G D 12 Degrees 29 Figure A 30 (cont’d , ) ^ 188 d space (£) 7-1 14 \0 1 A B 14 12 10 ^ t if Degrees 20 Figure A 3 1 . X-ray diffraction pattern of the clay fraction of Genesee loam after the 5th crop on the 1,600 pound per acre potassium treatment 14 12 10 Degrees 20 Figure A31 (cont’d . ) 8 6 4 190 I__________________i_______________________ I_____________________ I____________________ I___________________I___ 14 12 Figure A32. 10 Degrees 2© 8 6 4 X - r a y diffraction pattern of the clay fraction of Genesee loam after a 13-month incubation period with 1 3600 pounds of potassium per acre 191 d space (2) 14 10 7.1 I I c D TT 12 J. 10 Degrees 20 Figure A32 (cont'd.) 8 18 192 APPENDIX I X-RAY DIFFRA C T I O N PATTERNS OF CLAY FRACTION OF KALAMAZOO SANDY LOAM Legend: A: Mg saturated, B: K saturated, C: K saturated, heated (300° C.) sample. / 0 V K saturated* heated (550 C . ) sample. D: glycerol-solvated, air-dried sample. air-dried sample, 193 d space (X) 7.1 10 I 1 8 1 A B C D 12 Figure A33. 10 Degrees 29 X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam before cropping 194 d space (A) 7.1 r ■? f A B C D 14 12 10 8 6 Degrees 20 Figure A34. X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam after the 5th crop on the O potassium treatment 195 d space (S) 7.1 10 1*1- 18 A B C D 14 12 Figure A35- 10 Degrees 20 8 6 4 X-ray diffraction pattern of the clay fraction of Kalamazoo sandy loam after the 5"kh crop on the 1^600 pound per acre potassium treatment 196 d space <*) 7.-1 10 8 I A B G D 12 Figure A 36. 10 8 Degrees 20 6 X - r a y diffraction pattern of the clay fraction of Kalamazoo sandy loam after a 1 3 -month incubation period with 1*600 pounds of potassium per acre 197 APPENDIX J X-RAY D I F F R A C T I O N PATTERNS OF T H E CLAY F R ACTION OF LANDES-ABSCOTA SANDY L OAM Legend: A: Mg saturated, glycerol-solvated, air-dried sample. B: K saturated, air-dried sample. C: K saturated, heated (300° C.) D: K saturated, heated (550° C.) sample. sample. 198 d space (£) 14 7.1 12 Figure A 3 7 . 10 14 18 10 Degrees 20 X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam before cropping 199 d space (A) 7*1 10 1^ 18 A B _____________________I____________________ I____________________ I____________________ 1____________________ L 14 12 Figure A 3 8 . 10 Degrees 20 8 6 X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam after the 5th crop on the 0 potassium treatment 4 200 d space (S) 10 7*1 i i G D 1 1 12 10 Degrees 2© Figure A 38 (cont’d , ) 14 18 I 201 d space (i?) 7*1 1° 18 A B C D 14 12 Figure A39* 10 Degrees 20 X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam after the 5th crop on the 1 3600 pound per acre potassium treatment 202 d space (*> 7,1 r i° i8 A B JL 14 12 Figure A40, 10 8 Degrees 20 6 4 X-ray diffraction pattern of the clay fraction of Landes-Abscota sandy loam after a 13-month incubation period with lj600 pounds of potassium per acre 203 d space (fi) 14 10 I C D X 14 10 12 Degrees 26 Figure A40 (cont'd.) 8 xf