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Published 1982 NITROGEN IN AGRICULTURAL SOILS AGRONOMY A Series of Monographs The American Society of Agronomy and Academic Press published the first six books in this series. The General Editor of Monographs I to 6 was A. G. Norman. They are available through Academic Press, Inc., III Fifth Avenue, New York, NY 10003. I. 2. 3. 4. 5. 6. C. EDMUND MARSHALL: The Colloid Chemical of the Silicate Minerals, 1949 BYRON T. SHAW, Editor: Soil Physical Conditions and Plant Growth, 1952 K. D. JACOB: Fertilizer Technology and Resources in the United States, 1953 W. H. PIERRE and A. G. NORMAN, Editors: Soil and Fertilizer Phosphate in Crop Nutrition, 1953 GEORGE F. SPRAGUE, Editor: Corn and Corn Improvement, 1955 J. LEVITT: The Hardiness of Plants, 1956 The Monographs published since 1957 are available from the American Society of Agronomy, 677 S. Segoe Road, Madison, WI 53711. 7. JAMES N. LUTHlN, Editor: Drainage of Agricultural Lands, 1957 General Editor, D. E. Gregg 8. FRANKLIN A. COFFMAN, Editor: Oats and Oat Improvement Managing Editor, H. L. Hamilton 9. C. A. BLACK, Editor-in-Chiej and D. D. EVANS, J. L. WHITE, L. E. ENSMINGER, and F. E. CLARK, Associate Editors: Methods of Soil Analysis, 1965. Part I..LPhysical and Mineralogical Properties, Induding Statistics of Measurement and Sampling A. L. PAGE, Editor: Methods of Soil Analysis, 1982 Part 2-Chemical and Microbiological Properties, Second Edition Managing Editor, R. C. Dinauer 10. W. V. BARTHOLOMEW and F. E. CLARK, Editors: Soil Nitrogen, 1965 (Out of print; replaced by no. 22) Managing Editor, H. L. Hamilton II. R. M. HAGAN, H. R. HAISE, and T. W. EDMINSTER, Editors: Irrigation of Agricultural Lands, 1967 Managing Editor, R. C. Dinauer 12. FRED ADAMS, Editor: Soil Acidity and Liming, Second Edition, 1984 Managing Editor, R. C. Dinauer 13. K. S. QUISENBERRY and L. P. REITZ, Editors: Wheat and Wheat Improvement, 1967 Managing Editor, H. L. Hamilton 14. A. A. HANSON and F. V. JUSKA, Editors: Turfgrass Science, 1969 Managing Editor, H. L. Hamilton 15. CLARENCE H. HANSON, Editor: Alfalfa Science and Technology, 1972 Managing Editor, H. L. Hamilton 16. B. E. Caldwell, Editor: Soybeans: Improvement, Production, and Use, 1973 Managing Editor, H. L. Hamilton 17. JAN VAN SCHILFGAARDE, Editor: Drainage for Agriculture, 1974 Managing Editor, R. C. Dinauer 18. GEORGE F. SPRAGUE, Editor: Corn and Corn Improvement, 1977 Managing Editor, D. A. Fuccillo 19. JACK F. CARTER, Editor: Sunflower Science and Technology, 1978 Managing Editor, D. A. Fuccillo 20. ROBERT C. BUCKNER and L. P. BUSH, Editors: Tall Fescue, 1979 Managing Editor, D. A. Fuccillo 21. M. T. BEATTY, G. W. PETERSEN, and L. D. SWINDALE, Editors: Planning the Uses and Managing Editor, R. C. Dinauer Management of Land, 1979 22. F. J. STEVENSON, Editor: Nitrogen in Agricultural Soils, 1982 Managing Editor, R. C. Dinauer 23. H. E. DREGNE and W. O. WILLIS, Editors: Dryland Agriculture, 1983 Managing Editor, D. A. Fuccillo 24. R. J. KOHEL and C. F. LEWIS, Editors: Cotton, 1984 Managing Editor, D. A. Fuccillo 25. N. L. TAYLOR, Editor: Clover Science and Technology, 1985 Managing Editor, D. A. Fuccillo NITROGEN IN AGRICULTURAL SOILS FRANK J. STEVENSON, editor Editorial Committee F. J. Stevenson J. M. Bremner R. D. Hauck D. R. Keeney Managing Editor: RICHARD C. DINAUER Assistant Editor: KRISTINE E. GATES Editor-in-Chiej ASA Publications: MATTHIAS STELLY Number 22 in the series AGRONOMY American Society of Agronomy, Inc. Crop Science Society of America, Inc. Soil Science Society of America, Inc. Publisher Madison, Wisconsin USA 1982 Copyright © 1982 by the American Society of Agronomy, Inc. Crop Science Society of America, Inc. Soil Science Society of America, Inc. ALL RIGHTS RESERVED UNDER THE U.S. COPYRIGHT LAW OF 1978 (P.L. 94-553) Any and all uses beyond the "fair use" provision of the law require written permission from the publishers and/or author(s); not applicable to contributions prepared by officers or employees of the U.S. Government as part of their official duties. American Society of Agronomy. Inc. Crop Science Society of America. Inc. Soil Science Society of America. Inc. 677 South Segoe Road. Madison. Wisconsin 53711 USA Second Printing 1985 Library of Congress Cataloging in Publication Data Nitrogen in agricultural soils. (Agronomy; no. 22) Includes bibliographies and index. 1. Soils-Nitrogen content. 2. Plants, Effects of nitrogen on. 3. Crops and soils. 4. Nitrogen fertilizers. I. Stevenson, F. 1. II. Series. S592.6.N5N566 631.4'16 82-1704 AACR2 ISBN 0-89\\8-070-2 Printed in the United States of America CONTENTS DEDICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GENERAL FOREWORD AND FOREWORD ................................ PREFACE. .. . . . . . . . . .. . . . .. . . . .. .. .. .. . . . . . . . . . . . . . . . . . .. . . . .. . .. . . . . . .. .. CONTRIBUTORS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONVERSION FACTORS FOR U.S. AND METRIC UNITS. . .. . .. . .. . .. . . . .. Page xv xvi xvii xviii xx 1 Origin and Distribution of Nitrogen in Soil F. J. STEVENSON I. Introduction .............................................. II. The N Cycle. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Geochemistry of N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Evolutionary Aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Mechanisms by Which N is Added to Soil in Nature. . . . . . . . . . . . . A. Nitrogen in Atmospheric Precipitation. . . . . . . . . . . . . . . . . . . . . B. Biological N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Nitrogen Losses from Soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . A. VolatilizationofNH 1 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • B. Bacterial Denitrification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Leaching.............................................. D. Chemical Reactions of NO, - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Factors Affecting the N Content of Soils. . . . . . . . . . . . . . . . . . . . . . . A. Nitrogen Accumulations during Soil Development (the Time Factor) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Effect of Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Vegetation............................................. D. Parent Material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Topography........................................... F. Effect of Cropping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI. Summary................................................. LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 4 6 11 11 12 21 21 22 23 24 24 25 27 30 31 31 32 38 39 2 Inorganic Forms of Nitrogen in Soil J. L. YOUNG AND R. W. ALDAG I. Introduction .............................................. II. Mineral-Fixed NH. +-N . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . A. General Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Origin.............................. ... . . . . . . . . . . . . . . . . . C. Methods of Estimation .................................. D. Amounts of Distribution in Soil Profiles. . . . . . . . . . . . . . . . . . . . E. Effect on C/N Ratios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. Stability, Transformation, Fluctuation, and Movement. . . . . . . III. Exchangeab!e and Water-soluble Forms. . . . . . . . . . . . .. . . . . . . .. . A. Methods of Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Amounts and Distribution ............................... IV. Soil Nitrogen Gases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Methods of Determination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Amounts and Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v 43 44 44 44 46 48 54 55 56 57 58 60 61 61 62 vi CONTENTS 3 Organic Forms of Soil Nitrogen F. 1. STEVENSON I. Introduction .............................................. II. Fractionation of Soil N...................................... A. Distribution of Organic Forms of N in Mineral Soils. . . . . . . . . . B. Distribution of the Forms of N in Histosols and Aquatic Sediments ....................... . . . . . . . . . . . . . . . . . . . . . . C. Humic and Fulvic Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Distribution and Stabilization of Newly Immobilized N. . . . . . . E. Natural Variations in N Isotope Abundance. . . . . . . . . . . . . . . . III. Amino Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Extraction and Quantitative Determination. . . . . . . . . . . . . . . . . B. Identification of Amino Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Distribution Patterns in Soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Factors Affecting the Distribution of Amino Acids. . . . . . . . . . . E. Amino Acids in Humic and Fulvic Acids ................... F. Stereochemistry of Amino Acids. .. . . . . . . .. .. . . . .. . . . . .. . . G. Free Amino Acids....................................... H. State of Amino Acids in Soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Amino Sugars. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . A. Extraction and Quantitative Determination. . . . . . . . . . . . . . . . . B. Isolation of Amino Sugars ............................... V. Other N Compounds.. . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . A. Nucleic Acids and Derivatives ............................ B. Chlorophyll and Chlorophyll Degradation Products ......... C. Phospholipids.......................................... D. Amines, Vitamins, and Other Compounds. ................. E. Pesticide and Pesticide Degradation Products. . . . . . . . . . . . . . . VI. Stability of Soil Organic N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII. Summary ............................ '.' . . . . . . . . . . . . . . . . . . . LITERATURE CITED.......................................... 67 67 70 77 79 83 87 88 89 90 91 94 96 97 97 99 101 102 103 105 105 107 109 109 III 112 114 114 4 Retention and Fixation of Ammonium and Ammonia in Soils HANS NOMMIK AND KAAREL VAHTRAS I. Introduction.............................................. II. Exchangeable Binding of NH. + in Soils and Clay Minerals. . . . . . . . A. Cation Adsorption and Exchange. . . . . . . . . . . . . . . . . . . . . . . . . B. Cation Exchange Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Nonexchangeable Binding (Fixation) of NH. + in Soils and Clay Minerals ............................................. A. Mechanism of NH. + Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Methods Used for Studying NH. + Fixation. . . . . . . . . . . . . . . . . . C. Factors Affecting Rate and Magnitude of NH. + Fixation. . . . . . D. Release of Fixed NH. + from Soils and Minerals by Different Extraction and Distillation Procedures. . . . . . . . . . . . . . . . . . . . . E. Availability of Fixed NH: to Soil Microorganisms. . . . . . . . . . . F . Availability of Fixed NH. + to Higher Plants. . . . . . . . . . . . . . . . . IV. Retention of NH, and Fixation of NH, in Soil Organic Matter .... A. General Remarks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Physical Sorption of NH, .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Chemisorption ofNH,................................... D. Fixation ofNH, in Soil Organic Matter. . . . . . . . . . . . . . . .. . . . . LITERATURE CITED.......................................... 123 123 124 126 127 127 130 132 139 143 148 152 152 154 156 156 166 CONTENTS vii 5 Biochemistry of Ammonification J. N. LADD AND R. B. JACKSON I. Introduction .............................................. II. Proteins, Peptides, Amides, Amidines, and Amino Acids ........ A. Proteinases and Peptidases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Proteinases and Peptidases in Soil. . . . . . . . . . . . . . . . . . . . . . . . . C. Amidohydrolases and Amidinohydrolases . . . . . . . . . . . . . . . . . . D. Amino Acid Dehydrogenases and Oxidases . . . . . . . . . . . . . . . . . III. Aminopolysaccharides and Amino Sugars. . . . . . . . . . . . . . . . . . . . . A. Origin and Hydrolysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Stability of Aminopolysaccharides in Soil. . . . . . . . . . . . . . . . . . . C. Hydrolysis of Aminopolysaccharides in Soil. . . . . . . . . . . . . . . . . D. Ammonia Production From Amino Sugars................. IV. Nucleic Acids, Nucleotides, Nucleosides, Purines, and Pyrimidines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Nucleic Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Nucleotides and Nucleosides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Nucleases, Nucleotidases, and Nucleosidases in Soil. . . . . . . . . . D. Deamination of Nucleotides and Nucleosides ............... E. Catabolism of Purines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. Degradation of Pyrimidines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. Degradation of Purines and Pyrimidines in Soil. . . . . . . . . . . . . . V. Urea..................................................... A. Ureases................................................ B. SoiIUreases........ ... ............ ..................... VI. Other Compounds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 174 175 178 186 187 189 190 191 192 193 194 195 197 198 198 199 204 207 208 209 210 221 222 6 Mineralization and Immobilization of Soil Nitrogen S. L. JANSSON AND J. PERSSON I. Background............................................... A. The Processes of Mineralization and Immobilization. . . . . . . . . B. Relations to the Universal N Cycle. . . . . . . . . . . . . . . . . . . . . . . . . C. Partition of the Universal N Cycle Into Three Subcycles. . . . . . . D. Competition Among the N Subcycles . . . . . . . . . . . . . . . . . . . . . . E. Mineralization-Immobilization Turnover (MIT) . . . . . . . . . . . . . II. Features and Functions of MIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Inadequacies of Net Effect Determinations . . . . . . . . . . . . . . . . . B. Possibilities of Measuring Gross Effects: Usefulness of Tracer Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Confusion Caused by MIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Priming Effect and Related Phenomena. . . . . . . . . . . . . . . . . . . . E. Fertilizer N and MIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. Evaluation of N Fertilizers ............................... G. MIT and Nitrification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. Consequences of N, Fixation and Denitrification on MIT . . . . . I. MIT Interactions with Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Effects of Physical and Chemical Soil Factors . . . . . . . . . . . . . . . K. Energy-Nutrient Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . L. The C/N Ratio: C and N Interdependence. . . . . . . . . . . . . . . . . . M. The Phase Concept of Soil Organic Matter. . . . . . . . . . . . . . . . . . N. Humus Formation and Decay: A Dynamic Phenomenon..... 229 229 230 231 232 233 233 233 233 234 235 236 238 239 239 240 240 240 241 242 242 viii CONTENTS O. Use of Equilibrium Concepts in Phase Determinations. . . . . . . . P. "A" and Related Values................................. Q. Attempts at Extended Phase Separations. . . . . . . . . . . . . . . . . . . III. Problems and Prospects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. A New Line in Soil Organic Matter Research. . . . . . . . . . . . . . . . B. Inorganic Phase Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Simulation Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Future Role of Tracer Techniques. . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED........ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 243 244 244 245 245 247 247 248 248 Nitrification in Soil EDWIN L. SCHMIDT I. Introduction.............................................. II. The Process of Nitrification in Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . A. Factors Regulating Nitrification in Soils. . . . . . . . . . . . . . . . . . . . B. Substrates and Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Interactions with Other N Cycle Events. . . . . . . . . . . . . . . . . . . . . D. Approaches to Soil Nitrification .......................... III. Microbiological Basis of Nitrification . . . . . . . . . . . . . . . . . . . . . . . . . A. Nitrification by Heterotrophs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Methane Oxidizing Bacteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Autotrophic Nitrifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Ammonium Oxidizing Bacteria in Soil. . . . . . . . . . . . . . . . . . . . . . . . . A. Biochemistry of NH: Oxidation . . . . . . . . . . . . . . . . . . . . . . . . . . B. Carbon Metabolism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Soil Genera. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Nitrite Oxidizing Bacteria of Soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Biochemistry of NO,- Oxidation .......................... B. Carbon Metabolism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI. Study of Nitrifying Populations of Soils. . . . . . . . . . . . . . . . . . . . . . . A. Isolation............................................... B. Most Probable Number (MPN) Enumeration. . . . . . . . . . . . . . . C. Fluorescent Antibody (FA) Techniques. . . . . . . . . . . . . . . . . . . . . D. Short Term Nitrification Activity. . . . . . . . . . . . . . . . . . . . . . . . . . VII. Regulation of Nitrifying Populations in Soils. . . . . . . . . . . . . . . . . . . A. Naturally Occurring Inhibitors. . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Inhibition by Pesticides Added to Soil. . . . . . . . . . . . . . . . . . . . . . C. Specific Inhibitors of Nitrification. . . . . . . . . . . . . . . . . . . . . . . . . VIII. Growth of Nitrifying Bacteria in Soil. . . . . . . . . . . . . . . . . . . . . . . . . . A. Growth Rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. yields................................................. C. Activity............................................... IX. Concluding Comments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ACKNOWLEDGMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 254 254 257 258 259 260 260 262 263 264 264 267 268 269 269 269 270 271 271 272 272 273 274 275 276 278 278 280 281 282 283 283 8 Biological Denitrification M. K. FIRESTONE I. Introduction .............................................. II. Biochemical and Microbiological Basis. . . . . . . . . . . . . . . . . . . . . . . . A. Definition and Pathway. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289 290 290 CONTENTS ix B. Organisms Involved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Cellular Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Characteristics of Specific Reductases. . . . . . . . . . . . . . . . . . . . . . E. Energy Conservation During Denitrification. . . . . . . . . . . . . . . . III. Denitrification in Soil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Carbon Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Oxygen Control ........................................ C. Nitrate Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Effect of Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Effect of pH ........................................... IV. Concluding Comments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED.......................................... 292 294 299 305 306 306 3 IO 314 315 316 318 318 9 Gaseous Losses of Nitrogen Other Than Through Denitrification DARRELL W. NELSON I. Introduction .............................................. II. Ammonia Loss From Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Ammonia Volatilization Following Ammonium Fertilization of Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Ammonia Losses from Soils Following Anhydrous Ammonia Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Gaseous Nitrogen Loss From Soils Through Nitrite Reactions. . . . . A. Nitrite-Nitrous Acid Equilibria in Soils. . . . . . . . . . . . . . . . . . . . . B. Factors Affecting Nitrite Instability in Soils. . . . . . . . . . . . . . . . . C. Gaseous Products of Nitrite Reactions in Soils. . . . . . . . . . . . . . . D. Mechanisms for Gaseous Loss of Nitrite N from Soils. . . . . . . . E. Importance of Nitrite Reactions in Nitrogen Losses from Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Gaseous Nitrogen Loss from Soils Through Reactions of Nitrate and Hydroxylamine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Management Techniques to Minimize Gaseous Nitrogen Losses. . . LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 327 328 339 341 343 343 344 346 354 356 357 358 10 Biological Nitrogen Fixation U. D. HAVELKA, M. G. BOYLE, AND R. W. F. HARDY I. General Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Extent of N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Nitrogenase Enzyme .................................... C. Nitrogenase Reaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Nitrogenase Regulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . II. Microbiology of N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Introduction........................................... B. Free-Living Diazotrophs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Symbiotic N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Physiology and Agronomy of N, Fixation-Legume/Rhizobium Symbiosis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Introduction........................................... B. Nodulation Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Energy Relationships in N, Fixation ....................... D. Methodology ofN, Fixation Measurement.................. E. Rhizobium ClassIfication .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365 366 366 366 367 367 367 370 375 383 383 384 387 398 406 x CONTENTS F. Legume/Rhizobium Interactions.. . . . . . . .. .. . .. . . . . .. . . . . . G. Seed Inoculant Technology.. . . .. .. . . .. . . . .. . . . .. . . . . . . . . . H. Inoculant Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Future Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED.......................................... 11 408 409 411 413 413 Nitrogen Transport Processes in Soil D. R. NIELSEN, J. W. BIGGAR, AND P. J. WIERENGA I. Introduction .............................................. II. Deterministic Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Soil Water Movement. '" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Soil Solute Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Stochastic Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423 424 425 426 433 445 12 Nitrogen Transformations in Submerged Soils W. H. PATRICK, JR. I. Introduction .............................................. II. Properties of Submerged Soils that Affect Nitrogen Behavior. . . . . III. Nitrogen Transformations in Submerged Soils. . . . . . . . . . . . . . . . . . A. Mineralization and Immobilization. . . . . . . . . . . . . . . . . . . . . . . . B. Nitrification-Denitrification.............................. C. Nitrogen Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Ammonium Volatilization ............................... IV. Management of Submerged Soil to Minimize Nitrogen Loss...... LITERATURE CITED.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449 449 452 452 454 457 460 461 462 13 Advances in Methodology for Research on Nitrogen Transformations in Soils J. M. BREMNER AND R. D. HAUCK I. Introduction .............................................. II. Determination of Different Forms of Nitrogen ................. A. Total Nitrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Inorganic Forms of Nitrogen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Organic Forms of Nitrogen. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . D .. Gaseous Forms of Nitrogen .............................. III. Tracer Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Stable N Techniques .................................... B. Nitrogen-13 Techniques.................................. C. Use of Variations in Natural Nitrogen-15 Abundance. . . . . . . . . IV. Methods for Assay of the Activity of Enzymes Causing Nitrogen Transformations in Soils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Nitrogenase Activity .................................... B. Urease Activity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Other Enzymes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Methods for Research on Biological Nitrogen Fixation. . . . . . . . . . . VI. Methods for Research on Denitrification. . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467 468 468 471 473 474 479 479 483 484 486 487 487 488 488 491 493 xi CONTENTS 14 Soil Nitrogen Budgets J. O. LEGG AND J. J. MEISINGER I. Introduction .............................................. II. The N Cycle in Relation to N Budgets. . . . . . . . . . . . . . . . . . . . . . . . . A. Nitrogen Cycle Diagrams ................................ B. Soil N Equilibrium Concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Nitrogen Sources in Soil-Plant Systems. . . . . . . . . . . . . . . . . . . . . . . . A. Indigenous Soil Organic N ............................... B. Additions Through Crop and Animal Wastes. . . . . . . . . . . . . . . C. Additions by Precipitation and Irrigation Water. . . . . . . . . . . . . D. Adsorption of Atmospheric Gases. . . . . . . . . . . . . . . . . . . . . . . . . E. Biological N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F. Commercial Fertilizers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. Miscellaneous Items. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Nitrogen Losses from Soil-Plant Systems. . . . . . . . . . . . . . . . . . . . . . A. Removal by Crops and Livestock. . . . . . . . . . . . . . . . . . . . . . . . . . B. Erosion and Runoff. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Leaching Losses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Denitrification and Other Gaseous Losses. . . . . . . . . . . . . . . . . . E. Ammonium Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Recent Studies of N Budgets in Soil-Plant Systems. . . . . . . . . . . . . . A. Use of Labeled N in N Budgets. . . . . . . . . . . . . . . . . . . . . . . . . . . . B. N Balance Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Problems in N Balance Studies. . . . . . . . . . . . . . . . . . . . . . . . . . . . D. N Balance Studies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Summary.............................................. VI. Applications ofN Balances to Soil and Crop Problems........... A. General Aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Nitrogen Budgets Applied to Environmental Problems .. . . . . . C. Summary.............................................. VII. Summary and Conclusions .................................. LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 503 505 505 505 507 507 507 508 509 510 512 512 512 513 513 516 518 520 521 521 522 523 525 546 547 547 547 555 555 557 Crop Nitrogen Requirements, Utilization, and Fertilization R. A. OLSON AND L. T. KURTZ I. Introduction .............................................. II. Plant Use of N. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Functions of N in Plant Growth. . . . . . . . . . . . . . . . . . . . . . . . . . . B. Uptake, Translocation, and Storage of N. . . . . . . . . . . . . . . . . . . C. Biochemical Pathways of N in the Plant. . . . . . . . . . . . . . . . . . . . D. Genetic Effects on Biochemical Pathways. . . . . . . . . . . . . . . . . . III. Nitrogen in Crop Production ................................ A. Nitrogen Levels in Crops Associated with Deficiency, Sufficiency, and Excess. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Amounts of N in Crops and Distribution within the Crop. . . . . C. Influence of Fertilizer N on Crop Quality. . . . . . . . . . . . . . . . . . . D. Impact of Applied Fertilizer N on Crop Utilization of Other Nutrients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Efficient Use of N Fertilizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Influence of Climate and Cropping Systems on N Use. . . . . . . . . . . . A. Climate and N Fertilization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Nitrogen Carriers and Cropping Systems . . . . . . . . . . . . . . . . . . . 567 568 568 570 575 578 579 579 581 585 590 592 596 596 598 xii CONTENTS V. Nitrogen Fertilization in the Future. . . . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 598 599 Nitrogen Management for Maximum Efficiency and Minimum Pollution DENNIS R. KEENEY I. Introduction .............................................. II. N Requirements for Food and Fiber. . . . . . . . . . . . . . . . . . . . . . . . . . . III. Adverse Health and Environmental Impacts of N ...... . . . . . . . . . A. Nitrogen and Human Health ............................. B. Animal Health ......................................... C. Environmental Impacts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Perspectives............................................ IV. Trends in Anthropogenic N Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . A. Worldwide............................................. B. United States. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Sources of N Pollution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Point Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Nonpoint Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI. Some Examples of Agricultural N Pollution. . . . . . . . . . . . . . . . . . . . A. U.S. Corn Belt......................................... B. Irrigated Agriculture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Livestock Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Grasslands .............................. , . . . . . . . . . . . . . . E. Tropical Agriculture .................................... VII. Factors Affecting Crop Yields and Use of N . . . . . . . . . . . . . . . . . . . . VIII. Control of N Pollution From Croplands. . . . . . . . . . . . . . . . . . . . . . . A. Agricultural Best Management Practices.. . . . . . . . . . . . . . . . . . . B. Improved Management of Nutrient Systems................ C. Limitations on Rates of Fertilizer Applications. . . . . . . . . . . . . . D. Fundamental Changes in Agriculture. . . . . . . . . . . . . . . . . . . . . . IX. Summary................................................. LITERATURE CITED.......................................... 605 605 606 606 608 608 610 611 611 612 613 614 614 615 615 617 621 623 624 626 627 628 631 638 638 641 641 17 Assessment of Soil Nitrogen Availability GEORGE STANFORD I. Introduction .............................................. II. Estimating Residual Mineral Nitrogen in Soils. . . . . . . . . . . . . . . . . . III. Incubation Methods for Measuring Mineralization of Soil Organic Nitrogen ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Short-term Incubation Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . B. Potentially Mineralizable Soil Nitrogen .................... IV. Chemical Indexes of Soil Organic Nitrogen Availability. . . . . . . . . . A. Intensive Extraction Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Extraction Methods of Intermediate Intensity. . . . . . . . . . . . . . . C. Relatively Mild Extraction Methods ....................... V. Interpreting Chemical and Biological Assays of Soil Nitrogen Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Under Controlled Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Under Field Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERA TURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651 653 658 659 662 664 665 666 669 673 675 676 683 CONTENTS xiii 18 The Effects of Pesticides on Nitrogen Transformations in Soils C. A. I. GORING AND D. A. LASKOWSKI Introduction .............................................. Soil Variability ... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Behavior of Pesticides ...................................... Effects of Pesticides on N Transformations. . . . . . . . . . . . . . . . . . . . A. Mineralization/Immobilization........................... B. Nitrification ........................................... C. Denitrification ......................................... D. Symbiotic N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Nonsymbiotic N, Fixation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Agronomic Implications .................................... VI. Environmental and Regulatory Implications. . . . . . . . . . . . . . . . . . . . LITERATURE CITED.......................................... I. II. III. IV. 689 689 691 692 693 693 694 694 695 695 713 714 19 Modeling of the Soil Nitrogen Cycle KENNETH K. TANJI I. Introduction .............................................. II. Computers and Simulation MOdels. . . . . . . . . . . . . . . . . . . . . . . . . . . A. Computers and Programming ............................ B. Development and Application of Systems Simulation Models. . III. Representative Nitrogen Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Survey of Dynamic N Simulation Models. . . . . . . . . . . . . . . . . . . B. Evaluation of Selected Simulation Models. . . . . . . . . . . . . . . . . . IV. Technical and Philosophical Critique. . . . . . . . . . . . . . . . . . . . . . . . . . A. General Critique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Specific Critique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERA TURE CITED... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 721 721 722 724 725 726 731 767 767 768 770 Economic Implications of Controls on Nitrogen Fertilizer Use EARL R. SWANSON Introduction .............................................. Alternative Methods of Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Economic Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Per-Hectare Restrictions on N Fertilizer Use. . . . . . . . . . . . . . . . . . . . A. National Analyses ...................................... B. Regional Analyses ...................................... C. State Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Restrictions on NO J - -N Concentration in Leachate or Effluent. . . . VI. Treatment of Water to Reduce NO J - -N Content ................ VII. Restrictions on the N Balance at the Farm Level. . . . . . . . . . . . . . . . . VIII. An Excise Tax on N Fertilizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IX. An Effluent Charge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X. A Market for Rights to Use N Fertilizer. . . . . . . . . . . . . . . . . . . . . . . . XI. Information Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XII. Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ACKNOWLEDGMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LITERA TURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. II. III. IV. 773 774 775 778 778 779 780 780 781 781 782 783 784 786 787 788 788 xiv CONTENTS 21 Recycling of Nitrogen Through Land Application of Agricultural, Food Processing, and Municipal Wastes J. H. SMITH AND J. R. PETERSON I. Introduction.............................................. II. Agricultural Wastes ................................... " . .. A. Crop Residues ...................... '" . .. . .. .. .. .. .. .. . B. Animal Manures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III. Food Processing Wastes .................................... A. The Nature and Composition of Food Processing Wastes. . . . . B. Irrigating Agricultural Land. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C. Nitrogen Loading and Utilization on Land. . . . . . . . . . . . . . . . . . D. Nitrification and Denitrification. . . . . . . . . . . . . . . . . . . . . . . . . . E. Pollution Potential. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Municipal Wastes. .. . . . .. .. .. .. . . . . .. .. .. .. .. . .. .. .. .. .. . .. A. Sewage Effluent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Sewage Sludge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Summary................................................. LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791 791 791 797 806 806 811 812 814 814 815 815 818 825 826 22 Energetics of Nitrogen Transformations R. F. HARRIS I. Introduction .............................................. II. Bioenergetic Principles of Environmental Nitrogen Transformations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Nonequilibrium Thermodynamics and Reaction Kinetics. . . . . . B. Ecological Considerations. . . . . . . . . . • . .. . . . . . . . . . . . . . . . . . . III. Calculations and Interpretation of Group Transfer Energetics. . . . . A. General Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Energetics of Proton Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Pathway Energetics of Nitrogen Transformations. . . . . • . . . . . . . . . A. Assimilatory Pathways .................................. B. Dissimilatory Pathways ...................... " . . . . . . . . .. C. Hydrogen Cyanide Metabolism. . . . . . . . . . . . . . . . . . . . . . . . . . . V. Efficiency of Reductive Dinitrogen Fixation ... _. . . . . . . . . . . . . . . . VI. Appendix................................................. A. Selected Values of Thermodynamic Properties for Nitrogen. . . LITERATURE CITED.. . . . . .. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. 833 835 835 842 845 845 847 869 869 871 875 875 879 879 888 23 Nitrogen Transfers and Mass Balances R. D. HAUCK AND K. K. TANJI I. Introduction.............................................. II. N Transformations and Transfers ............................ A. General Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. N Income, Outgo, and Transfer. . . . . . . . . . . . . . . . . . . . . . . . . . . III. N Mass Balances and Models ................................ A. N Mass Balance Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B. Small-Scale Models and N Balances. . .. .. .. .. .. .. .. . . . .. .. . C. Regional Models and N Balances. . . . . . . . . . . . . . . . . . . . . . . . . . D. Global Models and N Balances. . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Perspective................................................ LITERATURE CITED.. .. .. .. .. . .. . . .. .. . . .. .. .. .. .. .. .. .. .. .. . 915 920 922 SUBJECT INDEX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 926 891 892 892 893 902 902 903 908 DEDICATION It is highly appropriate that Nitrogen in Agricultural Soils is dedicated to the memory of Dr. George Stanford, whose research career over the past 4 decades centered chiefly on elucidating nitrogen behavior and transformations in soils as a basis for achieving more effective use of nitrogen fertilizers. Born 7 March 1916 near Pierre, South Dakota, he received his B.S. degree from South Dakota University in 1938. His research career and studies for advanced degrees began in 1939 at Iowa State University. The M.S. degree was received in 1941 and the Ph.D. in 1947. This period included military service as an infantry officer in World War II. His professional career was spent at Cornell University (1948-50); Iowa State GEORGE STANFORD University (1950-55); TVA (1955-60); 1916-1981 Hawaiian Sugar Planters Association and Hawaii Agricultural Experiment Station (1960-65); and USDA, Beltsville, Maryland (1965-80). He retired as a research soil scientist from USDA due to ill health that culminated in his death on 28 January 1981. Dr. Stanford's research accomplishments were numerous and had considerable influence on soil fertility practices at a time when major expansion in fertilizer use was just beginning. His major research accomplishments dealt with ammonium fixation in soils; a rapid greenhouse-laboratory method for evaluating the relative effectiveness of diverse nitrogen, phosphorus, and potassium sources; optimal use of nitrogen fertilizer on sugarcane; development of a nitrogen availability index (extractable ammonia) for rapidly estimating the nitrogen-supplying capacities of soils; denitrification and nitrogen losses from soils; and long-term field experiments using stable nitrogen isotopes. Throughout his career, Dr. Stanford's fine qualities as a researcher and team leader were often demonstrated. His careful planning, attention to detail, and good judgment contributed greatly to the success of experiments. He directly involved himself in all phases of the work. His ability to assimilate research data and to reduce it to its most significant terms was a trait admired by all who knew him. Dr. Stanford's research greatly expanded our knowledge of nitrogen in agronomic systems and has resulted in more than 75 publications. He devoted a large share of his life to nitrogen research, and his findings will continue to influence the trends in research on this important element for years to come. His frank and forthright manner left no doubt as to where he stood on critical or controversial issues. His approach to research was realistic and involved a critical examination of the problems, alternate procedures, possibilities for success, and what contribution the research results made to scientific knowledge and to practical solutions. All those who conduct research in the future may do well to follow his example. xv GENERAL FOREWORD Nitrogen in Agricultural Soils is an update of the 1965 edition of Soil Nitrogen, ASA Monograph 10, and replaces the depleted supply of Soil Nitrogen. The new book incorporates the significant advances made in this field during the past 17 years and is the 22nd monograph in the series Agronomy that was started in 1949. The first six volumes were published by Academic Press, Inc., New York. In 1957, the American Society of Agronomy took over publication of the monographs and continued to be the sole publisher through the 18th monograph published in 1977. The Crop Science Society of America and the Soil Science Society of America were invited to participate in the series and have been copublishers since 1977. The monographs represent an important and continuing effort of the associated societies, their officers, and the 11,700 members located in 100 countries to provide mankind worldwide with the most recent information available. On behalf of the members of the associated societies and myself, I sincerely thank the Editorial Committee members chaired by Dr. F. 1. Stevenson for their diligent work, the many authors for their writings, Managing Editor Richard C. Dinauer for his inexhaustible patience in the compilation of the contents of this book, and all others who have contributed directly or indirectly to the accomplishment of this worthy project. December 1981 MATTHIAS STELLY Executive Vice President, ASA-CSSA-SSSA and Editor-in-Chief, ASA Publications FOREWORD The nitrogen reactions in soils and the nitrogen nutrition of crops are insufficiently understood. Soil nitrogen derived from organic matter is essential for plant growth and the formation of proteins required by living matter. The principal source of protein for a major portion of the human population is cereal grain. Humans depend on foraging animals to capture plant proteins and provide meat and milk. These basic characteristics of soil nitrogen challenge our interest in the mechanisms and processes by which people obtain food and fiber products. An increase in the protein content of cereal grains would enhance the nutritional status of the human population. In many soils and for many crops, farmers increase the nutrient supply of nitrogen by the addition of various forms of nitrogen to the soil or by biological dinitrogen fixation with legumes. Plants consume only about 50"70 of the added nitrogen forms, and there is a strong need to increase this utilization level. The nitrogen cycle in soils follows a complex series of reactions that require continuing study to utilize this nutrient more effectively and to assure an adequate supply for plants. In the overall process of removing barriers to crop productivity, nitrogen supply to plants plays a major role. We express appreciation and gratitude to Dr. F. 1. Stevenson, editor, and his editorial committee, Drs. 1. M. Bremner, R. D. Hauck, and D. R. Keeney for their important functions leading to this publication. We acknowledge and thank the xvi PREFACE xvii authors for their cooperation and efforts and the help of society members who reviewed manuscripts. We are grateful to the Headquarters staff for editorial and production efforts, which makes it possible to place this fine volume in your hands. November 1981 STERLING R. OLSEN president ASA KENNETH J. FREY president CSSA BOBBY A. STEWART president SSSA PREFACE Nitrogen in Agricultural Soils provides an authoritative review of the principles governing the behavior of nitrogen in the soil-plant system. The volume supersedes ASA Monograph 10 Soil Nitrogen, published in 1965. Significant advances on all aspects of the subject have been made since that time, and the need had arisen for a compilation and critical analysis of current knowledge. Material contained in the 1965 monograph has been extensively revised and updated, and new chapters have been introduced in response to increasirlg concern about energy conservation and preservation of the environment. Authors were allowed considerable latitude in developing their topics, with the result that both panoramic and specific views have been presented for each major component of the soil nitrogen cycle. The volume covers many facets of soil nitrogen, including forms and distribution, biological and nonbiological transformations, gains, losses, and recycling, plant availability and uptake, modeling and transport, pesticide interactions, experimental approaches, and economic implications of restrictions on fertilizer nitrogen use. The field of study is broad and has involved researchers working in many specialized areas. Because of the voluminous literature that has accumulated over the past two decades, an exhaustive coverage of the literature was not always possible, and selection of references has often been rather arbitrary. The editors and authors apologize for omission of important work. The editorial committee expresses appreciation to the authors and the organizations they represent for cooperation and support. Acknowledgment is given to Richard C. Dinauer, Matthias Stelly, and other members of the Headquarters staff for advice and assistance in editing and preparing the manuscripts for publication. We pay special tribute to George Stanford, author of Chapter 17, whose untimely death occurred while the monograph was in progress. The assistance of J. J. Meisinger in proofreading and indexing Dr. Stanford's chapter is gratefully acknowledged. August 1981 The Editorial Committee F. J. STEVENSON, editor, University of Illinois, Urbana, Illinois J. M. BREMNER, Iowa State University, Ames, Iowa R. D. HAUCK, Tennessee Valley Authority, Muscle Shoals, Alabama D. R. KEENEY, University of Wisconsin, Madison, Wisconsin CONTRIBUTORS Rudolf W. Aldag Dr. sc. agr., Dr. habil., Institut fur Bodenkunde, Universitat Gottingen, Gottingen, West Germany James W. Biggar Professor of Water Science, Department of Land, Air, and Water Resources, University of California, Davis, California John M. Bremner Professor, Department of Agronomy, Iowa State University, Ames,lowa Mark G. Boyle Agronomist, Central Research and Development Department, E.1. DuPont DeNemours Company, Wilmington, Delaware Mary K. Firestone Assistant Professor of Soil Microbiology, Department of Plant and Soil Biology, University of California, Berkeley, California Cleve A. I. Goring Technical Director, Agricultural Products Department, The Dow Chemical Company, Midland, Michigan Ralph W. F. Hardy Director, Life Sciences, Central Research and Development Department, E.1. DuPont DeNemours Company, Wilmington, Delaware Robin F. Harris Professor of Soil Microbiology, Department of Soil Science and Bacteriology, University of Wisconsin, Madison, Wisconsin Roland D. Hauck ~esearch Soil Scientist, National Fertilizer Development Center, Tennessee Valley Authority, Muscle Shoals, Alabama U. D. Havelka Research Staff, Central Research and Development Department, E.1. DuPont DeNemours Company, Wilmington, Delaware Ron B. Jackson Experimental Officer, Division of Soils, CSIRO, Glen Osmond, South Australia, Australia Sven L. Jansson Professor, Department of Soil Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden Dennis R. Keeney Professor and Chairman, Department of Soil Science, University of Wisconsin, Madison, Wisconsin Lester T. Kurtz Professor of Soil Fertility, Department of Agronomy, University of Illinois, Urbana, Illinois Jeffrey N. Ladd Senior Principal Research Scientist, Division of Soils, CSIRO, Glen Osmond, South Australia, Australia Dennis A. Laskowski Research Leader, Environmental Chemistry, Agricultural Products Department, The Dow Chemical Company, Midland, Michigan Soil Scientist (retired), Soil Nitrogen and Environmental Chemistry Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland. Currently Adjunct Professor, Agronomy Department, University of Arkansas, Fayetteville, Arkansas xviii CONTRIBUTORS xix J. J. Meisinger Soil Scientist, Soil Nitrogen and Environmental Chemistry Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland Donald R. Nielsen Professor of Soil and Water Science, Department of Land, Air, and Water Resources, University of California, Davis, California Darrell W. Nelson Professor of Agronomy, Department of Agronomy, Purdue University, West Lafayette, Indiana Hans Nommik Professor of Soil Chemistry, Department of Forest Soils, Swedish University of Agricultural Sciences, Uppsala, Sweden Robert A. Olson Professor of Agronomy, Department of Agronomy, University of Nebraska, Lincoln, Nebraska J. Persson Department of Soil Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden William H. Patrick. Jr. Boyd Professor, Laboratory for Wetland Soils and Sediments, Louisiana State University, Baton Rouge, Louisiana James R. Peterson Soil Scientist Ill, Research and Development Department, The Metropolitan Sanitary District of Greater Chicago, Cicero, Illinois Edwin L. Schmidt Professor, Department of Soil Science, University of Minnesota, SI. Paul, Minnesota Jay H. Smith Soil Scientist, Snake River Conservation Research Center, Agricultural Research Service, U.S. Department of Agriculture, Kimberly, Idaho George Stanford Research Soil Scientist, Soil Nitrogen and Environmental Chemistry Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland. Deceased 28 January 1981 Frank J. Stevenson Professor of Soil Chemistry, Department of Agronomy, University of Illinois, Urbana, Illinois Earl R. Swanson Professor of Agricultural Economics, Department of Agricultural Economics, University of Illinois, Urbana, Illinois Kenneth K. Tanji Professor of Water Science, Department of Land, Air, and Water Resources, University of California, Davis, California Kaarel Vahtras Agronomie Licentiat, Department of Soil Sciences, Swedish University of Agricultural Sciences, U ppsala, Sweden Peter J. Wierenga Professor of Soil Science, Department of Agronomy, New Mexico State University, Las Cruces, New Mexico J. L. Young Research Chemist and Professor of Soil Science, Agricultural Research Service, U.S. Department of Agriculture, and Soil Science Department, Oregon State University, Corvallis, Oregon CONVERSION FACTORS FOR U. S. AND METRIC UNITS To convert column I into column Z, multiply by Column Column 2 1 To convert column Z into column 1, multiply by Length 0.621 1.094 0.394 kilometer, km meter, m centimeter, cm 0.386 247.1 2.471 kilometer, km2 kilometer2 , km2 hectare, ha 0.00973 3.532 2.838 0.0284 1.057 meter", m 3 hectoliter, hI hectoliter, hI liter liter 1.102 2.205 ton (metric) quintal, q 2.205 0.035 kilogram, kg gram, g 14.50 0.9869 0.9678 14.22 14.70 bar bar kg(weight)/cm 2 kg(weight) /cm 2 atmosphere, atm 0.446 0.892 0.892 Yield or Rate ton (metric)/hectare ton (U.S.)/acre kg/ha Ib/acre quintal/hectare hundredweight/ acre mile, mi yard, yd inch, in 1.609 0.914 2.54 mile 2 , mj2 acre, acre acre, acre 2.590 0.00405 0.405 acre-inch cubic foot, ft3 bushel, bu bushel, bu quart (liquid), qt 102.8 0.2832 0.352 35.24 0.946 ton (U.S.) hundredweight, cwt (short) pound,lb ounce (avdp), oz 0.9072 0.454 Ib/inch 2 , psi atmosphere, atm atmosphere, atm Ib/inch 2 , psi Ib/inch 2 , psi 0.06895 1.013 1.033 0.07031 0.06805 Area Volume Mass 0.454 28.35 Pressure ( ~ OC) + Celsius 32 -17.8C Temperature Fahrenheit OF OC 32F 212F 100C 8.108 97.29 0.08108 0.973 0.00973 0.981 440.3 0.00981 4.403 2.24 1.12 1.12 Water Measurement hectare-meters, ha-m acre-feet hectare-meters, ha-m acre-inches hectare-centimeters, ha-cm acre-feet hectare-centimeters, ha-cm acre-inches meters 3 , m 3 acre-inches hectare-centimeters/hour, ha-cm/hour feet"/sec hectare-centimeters/hour, ha-cm/hour U.S. gallons/min meters"/hour, m"/hour fect"/sec U.S. gallons/min meters"/hour, m" /hour Plant Nutrition Conversion-P and K P (phosphorus) X 2.29 = P20S K (potassium) X 1.20 = K 2 0 xx 0.1233 0.01028 12.33 1.028 102.8 1.0194 0.00227 101.94 0.227