Soil Organic Matter in Sustainable Agriculture

411 Pages·2004·6.11 MB·English

by  Magdoff

SOIL ORGANIC MATTER
IN
SUSTAINAblE AGRICULTURE
Advances in Agroecology
Series Editor: Clive A. Edwards
Agroecosystem Sustainability: Developing Practical Strategies
Stephen R. Gliessman
Agroforestry in Sustainable Agricultural Systems
Louise E. Buck, James P. Lassoie, and Erick C.M. Fernandes
Biodiversity in Agroecosystems
Wanda Williams Collins and Calvin O. Qualset
Interactions Between Agroecosystems and Rural Communities
Cornelia Flora
Landscape Ecology in Agroecosystems Management
Lech Ryszkowski
Multi-Scale Integrated Analysis of Agroecosystems
Mario Giampietro
Soil Ecology in Sustainable Agricultural Systems
Lijbert Brussaard and Ronald Ferrera-Cerrato
Soil Organic Matter in Sustainable Agriculture
Fred Magdoff and Ray R. Weil
Soil Tillage in Agroecosystems
Adel El Titi
Structure and Function in Agroecosystem Design and Management
Masae Shiyomi and Hiroshi Koizumi
Tropical Agroecosystems
John H. Vandermeer
Advisory Board
Editor-in-Chief
Clive A. Edwards
The Ohio State University, Columbus, OH
Editorial Board
Miguel Altieri, University of California, Berkeley, CA
Lijbert Brussaard, Agricultural University, Wageningen, The Netherlands
David Coleman, University of Georgia, Athens, GA
D.A. Crossley, Jr., University of Georgia, Athens, GA
Adel El-Titi, Stuttgart, Germany
Charles A. Francis, University of Nebraska, Lincoln, NE
Stephen R. Gliessman, University of California, Santa Cruz
Thurman Grove, North Carolina State University, Raleigh, NC
Maurizio Paoletti, University of Padova, Padova, Italy
David Pimentel, Cornell University, Ithaca, NY
Masae Shiyomi, Ibaraki University, Mito, Japan
Sir Colin R.W. Spedding, Berkshire, England
Moham K. Wali, The Ohio State University, Columbus, OH
SOIL ORGANIC MATTER
IN
SUSTAINAblE AGRICULTURE
Edited by
Fred Magdoff
Ray R. Weil
CRC PR ESS
Boca Raton London New York Washington, D.C.
1294_C00.fm Page 4 Friday, April 23, 2004 2:14 PM
Library of Congress Cataloging-in-Publication Data
Soil organic matter in sustainable agriculture / edited by Fred Magdoff and
Ray R. Weil.
p. cm. -- (Advances in agroecology)
Includes bibliographical references and index.
ISBN 0-8493-1294-9 (alk. paper)
1. Humus. 2. Soil ecology. 3. Sustainable agriculture. I. Magdoff, Fred, 1942- II. Weil,
Ray R. III. Series
S592.8.S674 2004
631.4′17--dc22 2004043574
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Preface
During the past two centuries, scientists, farmers, and agricultural educators have tended to alternate
their views of soil organic matter (SOM) between the extremes of great appreciation and low
esteem. As an early 20th century bulletin explained, organic matter was “once extolled as the
essential soil ingredient, the bright particular star in the firmament of the plant grower…” before
it “…fell like Lucifer…” as a result of the findings of 19th century agricultural chemists that most
of the plant structure (C, that is) originated in the atmosphere (Hills et al., 1908). In the early 20th
century, soil organic matter was once again viewed as critically important, only to become consid-
ered close to irrelevant to agriculture following the availability of cheap fertilizers, especially N,
following World War II.
The paradigm of industrial agriculture — which developed following World War II and con-
tinues even now to dominate agriculture — views soil and plant constraints that arise while growing
crops as individual problems that are usually considered to be unrelated to one another. The
industrial agriculture mindset believes the best way to deal with these individual problems is to try
to resolve each one separately. The remedies, according to this view, lie in the application of specific
(usually purchased) inputs: fertilizers and lime for soils low in nutrients; pesticides for crops
threatened by diseases, nematodes, insects, and weeds; extra irrigation water for soils with declining
water holding capacity; deep tillage for overly compacted soils, etc. The development, promotion,
and implementation of the industrial agriculture model has been facilitated by the specialized
training that many agricultural scientists and extension specialists receive — causing them to
concentrate efforts in their disciplines (and frequently subdisciplines) with little ongoing active
professional engagement with those in other disciplines.
A renewed appreciation of soil organic matter — in all its astonishing complexity — began
toward the end of the 20th century and continues to this day. Scientists have come to appreciate
SOM’s profound influence on almost all soil properties — such as structure (and hence on water
infiltration and storage, susceptibility to surface runoff and erosion), cation exchange capacity,
nutrient availability, buffering (pH, nutrient availability), color, and plant pest pressure. Additionally,
new tools have become available to help explore SOM’s chemical and physical properties as well
as the diversity of soil life. With its critical role in so many soil properties and processes, organic
matter can provide an integrating concept for understanding and promoting soil health and soil
quality. Viewing healthy (high quality) soils as a major goal fosters a whole-system, preventive
approach to agricultural management. In contrast to the industrial model, this approach aims to
enhance soil properties so as to make the field ecosystem more self regulating, self sufficient,
resistant to degradation, and resilient. Rather than look for post-facto “band-aid” solutions, the
preventive approach emphasizes management to prevent chemical, biological (pest), and physical
problems from developing in the first place.
In addition to an immense volume of scientific journal articles dealing with SOM, a number
of books have been published over the last decade that deal with both scientific and practical aspects
of SOM management. In this book, we have brought together scientific reviews concerning issues
that are key for practical SOM management. We have included evaluations of the various types of
organic constituents in the soil — the living organisms, the relatively fresh residues, and well
decomposed substances (for which we have reserved the use of the term humus). The health (quality)
of a soil is strongly and positively affected by soil organic matter (Weil and Magdoff, Chapter 1)
and the various practices that enhance SOM (Magdoff and Weil, Chapter 2). There are chapters
that focus on the effects of soil and crop management practices on soil organisms (Kennedy et al.,
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Chapter 10) and organic matter gains and losses and the significance of various SOM fractions
(Franzluebbers, Chapter 8; Wander, Chapter 3; Chen et al., Chapter 4). Chapters also discuss the
contributions to soil quality and crop growth by fungi (Nichols and Wright, Chapter 6) and
earthworms (Edwards and Arancon, Chapter 11).
Soil organic matter and its management to promote soil health goes hand-in-hand with the
emergence of an ecologically based approach to soil and crop management that stresses prevention
of imbalances leading to soil and crop problems down the road (Magdoff and Weil, Chapter 2).
This approach is especially apparent with regard to the role of SOM and its management in the
development of soils suppressive to plant diseases (Stone et al., Chapter 5) and the relation of SOM
management to supplying nutrients to crops (Seiter and Horwath, Chapter 9). It also recognizes
the potential effects arising from the interactions between belowground food webs (based on SOM
and its management) and aboveground food webs that influence crop health and productivity
(Phelan, Chapter 7).
We hope this book will provide essential scientific background and pose challenging questions
relevant to both scientists and students as they strive to better understand SOM and develop
improved soil and crop management systems.
Fred Magdoff
Ray R. Weil
REFERENCE
Hills, J.L., C.H. Jones, and C. Cutler. 1908. Soil deterioration and soil humus. Section VIII, in
Vermont Agricultural Experiment Station Bulletin 135, pp. 142–177. College of Agriculture, Bur-
lington, VT.
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Editors
Fred Magdoff, Ph.D., is a Professor of Soil Science in the Department of Plant and Soil Science
at the University of Vermont, Burlington. Dr. Magdoff received his B.A. from Oberlin College and
his M.S. and Ph.D. from Cornell University. He was the Plant and Soil Science Department Chair
for 8 years at the University of Vermont, Burlington. He is a member of the National Small Farm
Commission, and he is the coordinator for the 12-state Northeast region of the U.S. Department
of Agriculture’s Sustainable Agriculture Research and Education Program. He is a Fellow of the
American Society of Agronomy.
Dr. Magdoff’s area of specialty is soil fertility and management. He has worked on problems
of sodic and saline soils, acid soils, use of manures and sewage sludges, phosphorus soil tests, and
nutrient cycling. He developed the first reliable soil test for nitrogen availability to corn for the
humid regions of the U.S. This test, called the presidedress nitrate test (PSNT) and the spring or
late spring nitrate test, is now used throughout much of the Northeast, Mid-Atlantic, and Midwestern
states, as well as eastern Canada. It has also been adopted for use with a number of vegetable crops.
Dr. Magdoff has oriented his outreach activities to explaining how to apply ecological principles
to agricultural production. His book Building Soils for Better Crops (2000; co-authored with Harold
van Es) describes an ecologically based approach that explains how to work with and enhance the
inherent built-in strengths of plant-soil systems. He is also interested in political and economic
issues surrounding agriculture. He is the senior editor of Hungry for Profit: The Agribusiness Threat
to Farmers, Food, and the Environment (2000).
Ray R. Weil, Ph.D., is a Professor of Soil Science in the Department of Natural Resource Sciences
and Landscape Architecture at the University of Maryland, College Park. He earned his B.S. at
Michigan State University, his M.S. at Purdue University, and his Ph.D. at Virginia Tech University.
Dr. Weil began his career in the early 1970s as a farm manager for a 200-hectare organic farming
training center. He has become a leader in researching and promoting sustainable agricultural
systems in both industrial and developing countries. His research focuses on organic matter man-
agement for enhanced soil quality and nutrient cycling for water quality and sustainability. During
the past decade much of his research has benefited from collaboration with dozens of local
innovative farmers.
Dr. Weil also has an active university teaching program that includes five undergraduate and
graduate courses. He is co-author of the widely used textbook The Nature and Properties of Soils.
Dr. Weil is a Fellow of both the Soil Science Society of America and the American Society of
Agronomy. He has twice been awarded a Fulbright Fellowship to support his work in developing
countries.
Dr. Weil lives with his wife, Trish, in Hyattsville, Maryland, where he enjoys gardening, helping
the town protect its urban forest, and commuting by bicycle to the University of Maryland in nearby
College Park.
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Contributors
Norman Q. Arancon Ann C. Kennedy
Soil Ecology Laboratory USDA-Agricultural Research Service
The Ohio State University Washington State University
Columbus, Ohio Pullman, Washington
Tsila Aviad Fred Magdoff
Department of Soil and Water Sciences Department of Plant and Soil Science
Faculty of Agricultural, Food and University of Vermont
Environmental Quality Services Burlington, Vermont
Hebrew University of Jerusalem
Rehovot, Israel Kristine A. Nichols
USDA-Agricultural Research Service
Yona Chen North Great Plains Research Laboratory
Department of Soil and Water Sciences Mandan, North Dakota
Faculty of Agricultural, Food and
Environmental Quality Services P. Larry Phelan
Hebrew University of Jerusalem Department of Entomology
Rehovot, Israel The Ohio State University
Wooster, Ohio
Heather M. Darby
Department of Plant and Soil Science Steven J. Scheuerell
University of Vermont Department of Botany and Plant Pathology
Burlington, Vermont Oregon State University
Corvallis, Oregon
Maria De Nobili
Universita Degli Studi de Udine William F. Schillinger
Departimento Di Produzione Vegetale, Department of Crop and Soil Sciences
E. Techonologie Agrarie Washington State University
Udine, Italy Lind, Washington
Clive A. Edwards Stefan Seiter
Soil Ecology Laboratory Department of Agricultural Sciences
The Ohio State University Linn-Benton Community College
Columbus, Ohio Albany, Oregon
Alan J. Franzluebbers Alexandra G. Stone
USDA-Agricultural Research Service Department of Horticulture
Watkinsville, Georgia Oregon State University
Corvallis, Oregon
William R. Horwath
Department of Land, Air and Water Research
University of California, Davis
Davis, California