FUNDAMENTALS OF SOIL SCIENCE FUNDAMENTALS OF SOIL SCIENCE EIGHTH EDITION HENRY D. FOTH Michigan State University JOHN WILEY SONS New York • Chichester • Brisbane • Toronto • Singapore Cover Photo Soil profile developed from glacio-fluvial sand in a balsam fir-black spruce forest in the Laurentian Highlands of Quebec, Canada. The soil is classified as a Spodosol (Orthod) in the United States and as a Humo-Ferric Podzol in Canada. Copyright © 1943, 1951 by Charles Ernest Millar and Lloyd M. Turk Copyright © 1958, 1965, 1972, 1978, 1984, 1990, by John Wiley & Sons, Inc. All rights reserved. Published simultaneously in Canada. Reproduction or translation of any part of this work beyond that permitted by Sections 107 and 108 of the 1976 United States Copyright Act without the permission of the copyright owner is unlawful. Requests for permission or further information should be addressed to the Permissions Department, John Wiley & Sons. Library of Congress Cataloging In Publication Data: Foth, H. D. Fundamentals of soil science / Henry D. Foth.-8th ed. p. cm. Includes bibliographical references. ISBN 0-471-52279-1 1. Soil science. I. Title. S591.F68 1990 631.4-dc20 90-33890 CIP Printed in the United States of America 1098765432 Printed and bound by the Arcata Graphics Company PREFACE The eighth edition is a major revision in which and water flow is discussed as a function of the there has been careful revision of the topics hydraulic gradient and conductivity. Darcy's Law covered as well as changes in the depth of cover- is used in Chapter 6, "Soil Water Management," age. Many new figures and tables are included. in regard to water movement in infiltration, drain- Summary statements are given at the ends of the age, and irrigation. Chapter 6 also covers dis- more difficult sections within chapters, and a posal of sewage effluent in soils and prescription summary appears at the end of each chapter. athletic turf (PAT) as an example of precision Many nonagricultural examples are included to control of the water, air, and salt relationships in emphasize the importance of soil properties when soils used for plant growth. "Soil Erosion," Chap- soils are used in engineering and urban settings. ter 7, has been slightly reorganized with greater The topics relating to environmental quality are emphasis on water and wind erosion processes. found throughout the book to add interest to many Chapters 8 and 9, "Soil Ecology" and "Soil Or- chapters. Several examples of computer applica- ganic Matter," are complimentary chapters relat- tion are included. ing to the biological aspects of soils. The kinds The original Chapter 1, "Concepts of Soil," was and nature of soil organisms and nutrient cycling split into two chapters. Each chapter emphasizes remain as the central themes of Chapter 8. An an important concept of soil-soil as a medium expanded section on the rhizosphere has been for plant growth and soil as a natural body. Topics included. The distinctions between labile and sta- covered in Chapter 1 include the factors affecting ble organic matter and the interaction of organic plant growth, root growth and distribution, nutri- matter with the minerals (especially clays) are ent availability (including the roles of root inter- central themes of Chapter 9. Also, the concept of ception, mass flow and diffusion), and soil fertil- cation exchange capacity is minimally developed ity and productivity. The importance of soils as a in the coverage of the nature of soil organic matter source of nutrients and water is stressed in Chap- in Chapter 9. ter 1 and elsewhere throughout the book. Chapter Chapter 10, "Soil Mineralogy," and Chapter 11, 2 covers the basic soil formation processes of "Soil Chemistry", are complimentary chapters re- humification of organic matter, mineral weather- lating to the mineralogical and chemical proper- ing, leaching, and translocation of colloids. The ties of soils. The evolution theme included in important theme is soil as a three-dimensional Chapter 2 is used to develop the concept of body that is dynamic and ever-changing. The con- changing mineralogical and chemical properties cepts developed in the first two chapters are used with time. Soils are characterized as being mini- repeatedly throughout the book. mally, moderately, and intensively weathered, The next five chapters relate to soil physical and these distinctions are used in discussions of properties and water. The material on tillage and soil pH, liming, soil fertility and fertilizer use, soil traffic was expanded to reflect the increasing ef- genesis, and land use. fect of tillage and traffic on soils and plant growth Chapters 12 through 15 are concerned with the and is considered in Chapter 4. The nature of soil general area of soil fertility and fertilizer use. water is presented as a continuum of soil water Chapters 12 and 13 cover the macronutrients and potentials in Chapter 5. Darcy's law is developed micronutrients plus toxic elements, respectively. V vi PREFACE Chapters 14 and 15 cover the nature of fertilizers taxonomy is covered in Chapter 17. This allows a and the evaluation of soil fertility and the use of consideration of soil classification after soil fertilizers, respectively. Greater stress has been properties have been covered. This arrangement placed on mass flow and diffusion in regard to also makes the book more desirable for use in nutrient uptake. The interaction of water and soil two-year agricultural technology programs and fertility is developed, and there is expanded cov- overseas, in countries where Soil Taxonomy is not erage of soil fertility evaluation and the methods used. used to formulate fertilizer recommendations. The final chapter, "Land and the World Food Recognition is made of the increasing frequency Supply," includes a section on the world grain of high soil test results and the implications for trade and examines the importance of nonagro- fertilizer use and environmental quality. Greater nomic factors in the food-population problem. coverage is given to animal manure as both a Both English and metric units are used in the source of nutrients and a source of energy. Infor- measurement of crop yields, and for some other mation on land application of sewage sludge and parameters. Using both kinds of units should sat- on sustainable agriculture has been added. isfy both United States and foreign readers. Throughout these four chapters there is a greater Special thanks to Mary Foth for the artwork and emphasis on the importance of soil fertility and to my late son-in-law, Nate Rufe, for photographic fertilizers and on the environmental aspects of contributions. Over the years, many colleagues growing crops. have responded to my queries to expand my The next four chapters (Chapters 16, 17, 18, and knowledge and understanding. Others have pro- 19) relate to the areas of soil genesis, soil taxon- vided photographs. The reviewers also have pro- omy, soil geography and land use, and soil survey vided an invaluable service. To these persons, I and land use interpretations. In this edition, the am grateful. subjects of soil taxonomy (classification) and of Finally, this book is a STORY about soil. The soil survey and land use interpretations have re- story reflects my love of the soil and my devotion ceived increased coverage in two small chapters. to promoting the learning and understanding of The emphasis in the soil geography and land use soils for more than 40 years. I hope that all who chapter is at the suborder level. References to read this book will find it interesting as well as lower categories are few. Color photographs of informative. soil profiles are shown in Color Plates 5 and 6. No Henry D. Foth reference to Soil Taxonomy (USDA) is made until East Lansing, Michigan BRIEF CONTENTS VII DETAILED CONTENTS CHAPTER 1 CHAPTER 3 SOIL AS A MEDIUM FOR SOIL PHYSICAL PROPERTIES 22 PLANT GROWTH 1 SOIL TEXTURE 22 FACTORS OF PLANT GROWTH 1 The Soil Separates 22 Particle Size Analysis 24 Support for Plants 1 Soil Textural Classes 25 Essential Nutrient Elements 2 Determining Texture by the Field Method 25 Water Requirement of Plants 3 Influence of Coarse Fregments on Oxygen Requirement of Plants 4 Class Names 26 Freedom from Inhibitory Factors 5 Texture and the Use of Soils 26 PLANT ROOTS AND SOIL RELATIONS 5 SOIL STRUCTURE 27 Development of Roots in Soils 5 I mportance of Structure 28 Extensiveness of Roots in Soils 7 Genesis and Types of Structure 28 Extent of Root and Soil Contact 8 Grade and Class 29 Roles of Root Interception, Mass Flow, and Diffusion 8 Managing Soil Structure 29 SOIL FERTILITY AND SOIL PRODUCTIVITY 9 SOIL CONSISTENCE 31 Soil Consistence Terms 31 DENSITY AND WEIGHT RELATIONSHIPS 32 Particle Density and Bulk Density 32 Weight of a Furrow-Slice of Soil 33 Soil Weight on a Hectare Basis 34 CHAPTER 2 SOIL PORE SPACE AND POROSITY 34 SOIL AS A NATURAL BODY 11 Determination of Porosity 34 Effects of Texture and Structure on Porosity 35 THE PARENT MATERIAL OF SOIL 12 Porosity and Soil Aeration 35 Bedrock Weathering and Formation of Parent Material 12 SOIL COLOR 36 Sediment Parent Materials 13 Determination of Soil Color 37 Factors Affecting Soil Color 37 SOIL FORMATION 13 Significance of Soil Color 37 Soil-Forming Processes 14 Formation of A and C Hori zons 14 SOIL TEMPERATURE 38 Formation of B Horizons 14 Heat Balance of Soils 38 The Bt Horizon 15 Location and Temperature 39 The Bhs Horizon 17 Control of Soil Temperature 39 Permafrost 40 Formation of E Horizons 17 Formation of 0 Horizons 18 CHAPTER 4 SOILS