I 70-20,509 PAILOOR, Govind, 1940- VARIATIONS IN CATION EXCHANGE CAPACITIES OF SOME REPRESENTATIVE MICHIGAN SOILS WITH ANALYTICAL PROCEDURES AND THEIR RELATIONSHIPS TO ACIDITY, CLAY MINERALOGY AND ORGANIC MATTER. Michigan State University, Ph.D., 1970 Agriculture, soil science U n iv e rs ity M icro film s, A XEROX C o m p a n y , A n n A rb o r, M ic h ig a n VARIATIONS IN CATION EXCHANGE CAPACITIES OF SOME REPRESENTATIVE MICHIGAN SOILS WITH ANALYTICAL PROCEDURES AND THEIR RELATIONSHIPS TO ACIDITY, CLAY MINERALOGY AND ORGANIC MATTER By Govind Pailoor 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 1969 ABSTRACT VARIATIONS IN CATION EXCHANGE CAPACITIES OF SOME REPRESENTATIVE MICHIGAN SOILS WITH ANALYTICAL PROCEDURES AND THEIR RELATIONSHIPS TO ACIDITY, CLAY MINERALOGY AND ORGANIC MATTER By Govind Pailoor The CECs were determined by the following common methods on 38 representative acid to near neutral Michigan soil samples from 15 soil types: (1) the CaCl 2 method, (2) the KC1 method, (3) the NH^OAc method, (4) the cation sum­ mation method and (5) the NaOAc method. The results obtained were grouped according to the following kinds of soil horizons and subjected to statisti­ cal analyses: (1) the surface Ap and A^, (2) the illuvial spodic B^, and B^r, (3) the illuvial Bt and Bg, and (4) the A 2 , A '2 and C^ horizons of uncoated materials. The predictive equations for CEC among the five meth­ ods were all highly significant on all but the spodic hori­ zons. In spodic horizons, however, only NH^EC vs NaEC and KEC vs CaEC could be predicted highly significantly for the soils used in this study. The multiple regression analysis showed an 11 to 4 5 meq of charge contribution per 1 0 0 g of clay as would be Govind Pailoor normally expected from soils of dominantly mixed clay minera- logy. The charge contribution from organic matter to NaEC was highest of all horizons and unreasonably high though highly significant in surface horizons. The CaEC and KEC on spodic horizons showed a low charge contribution from organic matter, 14 and 25 meq per 100 g respectively. The organic matter charge contribution was within the normally expected range of 87 to 255 meq per 100 g for all other CEC values on all horizons other than the illuvial B+.t and B_g horizons. The high charge contribution from organic matter found in B. and B horizons for all CEC values indicated t g that a different kind of organic exchange complex is pre­ sent there. The marked increase in both CaEC and KEC values on the same soil samples after 1 N NaOAc treatment were shown as evidence that 1 N NaOAc commonly employed in CEC deter­ mination alters the native soil exchange properties to a significant extent. This is due to one or more of the mechanisms of anion retention, dissolution of amorphous coatings of Fe 20 3 and A ^ O ^ , dissolution of organic Fe and A1 complexes and partial removal of the Al-interlayers when present. Some or all of these characteristics are present in surface horizons of most Michigan soils particularly Spodosols, and the spodic horizons. Due to the reasonable charge contributions from both clay (23 to 45 meq/100 g) and organic matter (156 to 392 Govind Pailoor meq/100 g) contents of soils revealed in NH^EC on all hori­ zons, and the value of NH^EC being intermediate between CaEC and NaEC, it was thought to be the best estimate of the net negative charge of the Michigan soil materials. The soil exchange acidity values were obtained by: (1) BaCl2+TEA method, (2) KC1 method, (3) the NH^OAc method, and (4) the Shoemaker, McLean and Pratt (SMP) buffer method. It was concluded that the EA(BaCl 2 +TEA) and the SMP buffer method could be predicted significantly on all horizon groupings of the acid to near neutral representative Michi­ gan soil materials % Higher values were obtained by the SMP method particularly on spodic horizons. This indicated that the lime requirement recommendations for Spodosols may be overestimated due to the mixing of spodic horizons, norm­ ally occurring at a depth of six to twelve inches, with the surface horizons by plowing. It was concluded therefore that the determination of exchange acidity by BaCl2+TEA or an adjustment of the EA(SMP) values based on its relation­ ship to EA(BaCl 2+TEA) may give a more reliable estimate of the lime requirement of common Michigan soil materials, particularly the Spodosols. TO MY FATHER, MOTHER UNCLE, AUNT SISTERS, BROTHERS SWEET SHARADE PEOPLE AT HOME AND IN MICHIGAN ACKNOWLEDGMENTS The author expresses his solemn gratitude to his major professor. Dr. E. P. Whiteside, for his kind assist­ ance, criticisms and encouragement throughout this study. He sincerely appreciates the guidance of Dr. B. G. Ellis as co-director of this thesis. He has a high esteem for the other members of his guidance committee. Drs. R. L. Cook, M. M. Mortland, A. E. Erickson and H. Eick for their co­ operation in this study. The author thanks in earnest Dr. G. L. Johnson for the concepts in Agricultural Economics developed through his association. He is mindful of the pleasant atmosphere of reassurance amongst his colleagues and members of the Department. The author admires the title of an Yearbook of Agri­ culture, Soils and Men. He is grateful to his Alma Mater, Michigan State University, for giving him an opportunity to peep into the nature of both these. TABLE OF CONTENTS Page ACKNOWLEDGMENTS ........................................... iii LIST OF TABLES ............................................. V LIST OF FIGURES ............................................ vii INTRODUCTION ................................................ 1 LITERATURE REVIEW ........................................ 3 Early History of Cation Exchange Capacity .... 3 Cation Exchange Theories ............................. 4 Sources of Cation Exchange in Soils .............. 11 Exchangeable Aluminum and Soil Acidity as Factors Influencing Cation Exchange ............ 18 Methods of Cation Exchange Capacity Determination ...................................... 22 MATERIALS AND M E T H O D S .......................................25 Soils Used in the S t u d y ............................... 25 Methods Used in this Study ............................. 35 C aC l 2 method for CEC determination ............... 36 KC1 method for CEC determination ................. 37 NH 4OAC method for determination of CEC and exchangeable bases ............................ 37 NaOAc method for CEC determination ............... 39 Barium chloride plus triethanolamine method for the determination of exchange acidity . 40 KC1 extraction and fluoride titration pro­ cedure for determination of extractable acidity and exchangeable a l u minum ............ 41 RESULTS AND DISCUSSION .................................... 4 3 SUMMARY AND CONCLUSIONS ................................. 82 NEED FOR FURTHER RESEARCH .................................. 87 LITERATURE CITED ........................................... 88 APPENDIX 99 LIST OF TABLES Table Page 1. Soil type names and legal descriptions of loca­ tions of the profiles studied ..................26 2. Information on soils studied ....................... 30 3. Effect of washing procedures in CaCl~ method of CEC determination ................................45 4. Relationship between effective replacement of K+ by NH^+ with increasing number of washings . 48 5. Cation exchange capacity values for 15 soil samples determined by the NaOAc method at pHs 7.0 and 8 . 2 . ................................49 6 . The mean CEC values determined by five methods grouped according to the kinds of soil hori­ zons ..................................................53 7. Regression equations and correlation coefficients among CEC values determined by five methods grouped according to the kinds of soil h o r i z o n s ......................................... 56 8 . Relationships between CEC values and clay and carbon contents, their partial and multiple correlation coefficients and levels of signifi­ cance, on soils grouped according to horizons . 57 9. Relative charge contributions from clay to CEC values grouped according to the kinds of soil horizons .................................... 58 10. Relative charge contributions from organic matter to CEC values grouped according to the kinds of soil horizons .................... 60 11. The effect of IN NaOAc on CEC of soil materials . 70 12. The mean values of acidity components grouped according to the kinds of soil horizons .... 74 v LIST OF TABLES - Continued. Table Page 13. Relationships between soil acidity measurements and clay and organic carbon contents grouped according to the kinds of soil horizons . 76 14. Relative acidity contributions from clay to excahnge acidities grouped according to the kinds of soil horizons ........................ 77 15. Relative acidity contributions from organic matter to exchange acidities grouped accord­ ing to the kinds of soil horizons ............ 78 16. Data on chemical analyses of soils studied . 100 17. Estimation of clay minerals in the clay frac­ tion of the horizons of similar soil types as used in this study ........................ 10 2 LIST OF FIGURES Figure Page 1. The charges on the edges of clay particles under acid and alkaline conditions as affected by mineralogical composition ....................... 13 2. Map of Michigan showing location of representa­ tive soils used in this s t u d y ...................... 27 3. Depth