Scientists and lay persons have long recognized that the quality of two great natural resources—air and water—can be degraded by human activity. Unfortunately, few people have considered that the quality of soil can also be affected by differing uses and management practices. Interest in soil quality has heightened during the past three years as a small cadre of soil scientists became more concerned about the role of soils in sustainable production systems and the linkages between soil characteristics and plant-human health.
The concept of soil quality will not be in the mainstream of soil or environmental science programs until there is wide acceptance of the definition for the term and quantitative indicators of soil quality are developed. Air and water quality are well recognized concepts that have standards established by law and regulation. A great deal of study and education will be necessary before soil quality becomes an important national natural resource issue.
A symposium entitled “Defining Soil Quality for a Sustainable Environment” was held at the 1992 annual meeting of the Tri-societies as an initial attempt at dialogue on soil quality within the Soil Science Society of America. This publication contains the papers on soil quality presented at the symposium. Emphasis has been placed on defining soil quality, identifying soil quality indices, and assessing the biological importance of soil quality. The publication represents an excellent first step in educating scientists about the concepts and significance of soil quality.
DARRELL W. NELSON, President
Soil Science Society of America
For humankind, soil is the esence of life and health. As with air and water, human life could not be sustained without the soil because it is the source of most of our food. The economic well-being of the USA and most other nations depends greatly on the soil and how well its productivity is maintained. However, soil does far more for society than just produce food. A healthy or good quality soil acts as an environmental filter for cleansing air and water. It is a major sink for global gases and if managed properly can favorably affect the carbon dioxide balance, which is important for combating global climate change. Soil is the ultimate receptor and incubation chamber for the decomposition and detoxification of organic wastes, and recycling of nutrients from these materials back to plants. If mismanaged, the soil can work against us; it can pollute the air and water and cease producing abundant and nutritious food. Many people believe that, within a community, there is a strong link between the health or quality of the soil, food quantity and quality, and the health, well-being and prosperity of the people who live there.
For many years the USA and other nations have sought policies to protect their agricultural soils against degradation and to improve them to ensure sustainable food production for future generations. Principles of soil conservation have been known for centuries and national conservation programs to safeguard and preserve agricultural lands have been implemented by governments of various countries since the 1930s. Yet recent assessments conducted on regional and global scales indicate that the ravages of human-induced degradation (soil erosion, salinization, organic matter decline, etc.) are causing the loss of millions of hectares of agricultural land every year. Are not the positive interventions by human action having an impact on soil rehabilitation, or are these simply being overwhelmed or masked by the large-scale assessments of degradation processes? In addition to assessments of degradation, a more quantitative assessment is needed of how farming practices are affecting the capacity of the soil to produce food and perform certain environmental functions (i.e., soil quality) and whether the capacity is being degraded, aggraded, or is remaining unchanged. Often the gross benefits to the soil of improved management practices such as increased productivity, water retention, and resistance to erosion occur slowly and are not measurable in the early years of treatment. As a result, soil conservation and soil rehabilitation programs may be abandoned prematurely or lack support, because it is not possible, early on, to determine their potential economic worth in terms of soil improvement. Even where management practices have been imposed over longer periods methodology has not been available to directly quantify the degree of change with respect to certain functions the soil is expected to perform.
Take, for example, the Conservation Reserve Program (CRP) and the Conservation Compliance Provisions of the 1985 Food Security Act. The CRP enables farmers to bid out their highly erodible lands and receive payment from the U.S. government in return for maintaining these lands in grass, tree cover, or both for 10 years. Conservation compliance requires that highly erodible lands must be farmed according to an approved conservation plan for the farmer to be eligible for Government Farm Program benefits. Both programs require a sizeable investment from society, which in turn expects payoff, at least in part, from maintenance and improvement of the soil resource base for future use. But how can changes in the soil condition be evaluated so as to determine whether these policies are achieving an improvement in the soil condition, and if so, by how much and what is the economic worth to society? Through economic analyses like natural resource accounting, these improvements in the soil, if measured, can then be factored in or given proper credits.
There is new emphasis on soil quality as a more sensitive and dynamic way to document the condition of our soils, how they respond to management changes, and their resilience to stresses imposed by natural forces or farming practices. It was toward this goal that the Rodale Institute Research Center took the lead in sponsoring and convening a workshop, “Assessment and Monitoring of Soil Quality,” 11–13 July 1991, in Emmaus, PA. A concensus of the workshop was that soil quality should not be limited to soil productivity, but should encompass environmental quality, human and animal health, and food safety and quality. Possibilities for developing a soil quality index was explored. It was also recognized that past emphasis was given to physical and chemical properties as indicators of soil quality rather than to biological properties, which are more difficult to measure, predict, or quantify. However, biological and ecological-based indicators of soil quality are believed more dynamic than those based on physical and chemical properties, and therefore, have the advantage of serving as early signals of soil degradation, or of aggradation in the case of soil improvement.
Since the workshop in Emmaus, many new projects on soil quality have been initiated, and some on-going projects have begun to coordinate efforts among scientists, both nationally and internationally. It will require the concerted efforts of scientists from many disciplines, working with farmers, to achieve our goal of developing a realistic, useful, soil quality index.
This publication is comprised of papers from a symposium on soil quality held at the 1992 American Society of Agronomy annual meeting in Minneapolis, MN. The objectives were to identify the major components of soil that define soil quality and to quantify soil-derived indicators of soil quality with major emphasis on soil biology. Themes addressed by the authors include approaches to defining and assessing soil quality relationships between various soil properties and soil quality and land-use sustainability, models for characterizing soil quality, and defining biological criteria for evaluating the effects of management practices on soil quality. Several papers relate to measurement of specific soil quality components.
The papers in these proceedings contribute new perspectives on the definition of soil quality and how it may be measured and quantified. It is hoped that the knowledge presented here will help lead toward national and global soil quality monitoring and assessment programs as a strategy to help preserve and enhance the long-term use of the valuable soil resource base for food and environmental needs. Reliable indicators will make it possible to evaluate the long-term impact of land use and management on soil and environmental quality. only then will farmers, scientists, extension specialists, policy-makers, and the public have the necessary fore hand knowledge to understand measures to protect and preserve the health of our soil resource base for sustainable land-use.
RHONDA R. JANKE
Rodale Institute Research Center
ROBERT I. PAPENDICK
USDA-ARS, Washington State University
Meaningful change occurs slowly. The first step and lengthiest ordeal usually involves convincing responsible people that change is necessary, desirable, and possible. In social causes, this is known as raising awareness. Since its inception, first as the Soil and Health Foundation in 1947 and now in its present form, the Rodale Institute has worked toward raising awareness among agricultural researchers, policy makers, and farmers regarding the importance of soil quality and its relationship to human health issues. We are pleased by the increasing convergence of thought and attention on the important role of soil in the natural environment.
The 18 manuscripts and extended papers published here by some of today's finest soil and agricultural researchers is evidence that meaningful positive change is occurring, that soil quality issues have been recognized—outside of the Rodale circle—as bearing equal environmental impact to water and air quality concerns in the USA and abroad. The first step is safely on its way. Now we must consider how to apply what we have learned so far, and what we will do with each newly discovered truth, because knowledge without application is frequently a futile exercise.
It is my fervent hope that these thoughtful papers will help propel those of us grappling with soil quality issues toward the next step, the creation of an international soil quality index. We need to know the state of the world's soils and then to document changes in that status on a regular basis if we are to protect the soil we all depend on for life. I believe that when this is accomplished we will be able to achieve, through public awareness, an appreciation of soil quality and its contribution to human health and well-being.
JOHN HABERERN, president
D. F. Bezdicek, Director, Center for Sustaining Agriculture and Natural Resources, Washington State University, Pullman, WA 99164-6240
Robert L. Blevins, Professor, Department of Agronomy, University of Kentucky, Lexington, KY 40546-0091
Patrick J. Bohlen, Doctoral Candidate, Department of Entomology, Ohio State University, Columbus, OH 43210
Scott D. Bridgham, Research Associate, Natural Resources Research Institute, University of Minnesota, Duluth, MN 55811
Ingrid C. Burke, Assistant Professor, Department of Forest Sciences, Colorado State University, Fort Collins, CO 80523
R. Chaussod, Research Scientist, Laboratoire des Sols, Institut National de la Recherche Agronomique (INRA), 21034 Dijon, France
H. H. Cheng, Professor, Department of Soil Science, University of Minnesota, St. Paul, MN 55108
C. Vernon Cole, Soil Scientist, USDA-ARS, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523
David C. Coleman, Professor of Ecology, Ecology/Biosciences, Institute of Ecology, University of Georgia, Athens, GA 30602-2602
Harold P. Collins, Research Associate, Kellogg Biological Station, Michigan State University, Hickory Corners, MI 49060-9516
Richard P. Dick, Associate Professor of Soil Science, Department of Soil Science, Oregon State University, Corvallis, OR 97331
John W. Doran, Soil Scientist, USDA-ARS, University of Nebraska, Lincoln, NE 68583
John M. Duxbury, Professor of Soil Science, Cornell University, Ithaca, NY 14853
Neal S. Eash, Research Associate, Iowa State University, Ames, IA 50011
Clive A. Edwards, Professor of Environmental Science, Department of Entomology, Ohio State University, Columbus, OH 43210
Edward T. Elliott, Senior Research Scientist and Associate Director, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523
Mary F. Fauci, Research Assistant, Oregon State University. Currently Research Associate, Department of Crop and Soil Science, Washington State University, Pullman, WA 99164-6420
Serita D. Frey, Research Associate, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523
Wilbur W. Frye, Professor of Agronomy and Director of Regulatory Services, University of Kentucky, Lexington, KY 40546-0275
Fernando 0. Garcia, Research Scientist, Institut Nacional de Technologia Agropecuaria, Estacion Experimental Agropecuaria, C.C. 276-7620 Balcarce, Argentina
M. J. Garlynd, Research Assistant, Department of Soil Science, University of Wisconsin, Madison, WI 53706-1299
Peter R. Grace, Research Fellow, CRC for Soil and Land Management, Glen Osmond, South Australia 5064
V. V. S. R. Gupta, Research Scientist, Division of Plant Industry, CSIRO, Canberra, ACT 2601, Australia. Currently Research Fellow, CRC for Soil and Land Management, Glen Osmond, South Australia 5064
Ardell D. Halvorson, Soil Scientist-Research Leader, USDA-ARS, Central Great Plains Research Station, Akron, CO 80720
Jonathan J. Halvorson, Research Associate/Ecologist, USDA-ARS/NORCUS, Washington State University, Pullman, WA 99164
R. F. Harris, Professor, Department of Soil Science, University of Wisconsin, Madison, WI 53706-1299
Paul F. Hendrix, Soil Ecologist, Institute of Ecology and Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602
Michael V. Hickman, Research Agronomist, USDA-ARS, Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-1155
Sabine Houot, Research Scientist, Laboratoire des Sols, Institut National de la Recherche Agronomique (INRA), 7885 Thiverval-Grignon, France
David R. Huggins, Assistant Professor of Soil Science, Southwest Experiment Station, University of Minnesota, Lamberton, MN 56152
M. D. Jawson, Chief, Subsurface Processes Branch, USEPA, Robert S. Kerr Environmental Laboratory, Ada, OK 74820
Carol A. Johnston, Senior Research Associate, Natural Resources Research Institute, University of Minnesota, Duluth, MN 55811
Douglas L. Karlen, Research Soil Scientist, USDA-ARS, National Soil Tilth Laboratory, Ames, IA 50011
A. C. Kennedy, Research Scientist, USDA-ARS-LMWC, Washington State University, Pullman, WA 99164-6421
A. V. Kurakov, Professor, Department of Soil Science, Moscow State University, Moscow, Russia
W. E. Larson, Professor Emeritus, Soil Science Department, University of Minnesota, St. Paul, MN 55108
Dennis R. Linden, Soil Scientist, USDA-ARS, Soil Science Department, University of Minnesota, St. Paul, MN 55108
Drew J. Lyon, Assistant Professor of Agronomy, Panhandle Research and Extension Center, University of Nebraska, Scotts Bluff, NE 69361-4939
J. A. E. Molina, Professor, Department of Soil Science, University of Minnesota, St. Paul, MN 55108
Christopher A. Monz, Research Associate, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523. Currently Research Manager, National Outdoor Leadership School, Lander, WY 82520-3128
B. Nicolardot, Research Scientist, Laboratoire des Sols, Institut National de la Recherche Agronomique (INRA), 21034 Dijon, France
Sipho V. Nkambule, Graduate Research Assistant, Cornell University. Currently Lecturer, Crop Production Department, University of Swaziland, P.O. Luyengo, Swaziland
Robert I. Papendick, SOil Scientist, USDA-ARS, Washington State University, Pullman, WA 99164-6421
Timothy B. Parkin, Research Microbiologist, USDA-ARS, National Soil Tilth Laboratory, Ames, IA 50011
John Pastor, Senior Research Associate, Natural Resources Research Institute, University of Minnesota, Duluth, MN 55811
Eldor A. Paul, Chair and Professor, Department of Crop and Soil Science, Michigan State University, East Lansing, MI 48824
Keith H. Paustian, Assistant Professor (Research), Kellogg Biological Station, Michigan State University, Hickory Corners, MI 49060-9516. Currently Research Scientist, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523
F. J. Pierce, Associate Professor, Crop and Soil Sciences Department, Michigan State University, East Lansing, MI 48824
Charles W. Rice, Associate Professor, Department of Agronomy, Kansas State University, Manhattan, KS 66506-5501
D. E. Romig, Research Assistant, Department of Soil Science, University of Wisconsin, Madison, WI 53706-1299
M. M. Roper, Senior Research Scientist, CSIRO, Laboratory for Rural Research, Wembley, Western Australia 6014
Jeffrey L. Smith, Soil Biochemist, USDA-ARS, Washington State University, Pullman, WA 99164-6421
Diane E. Stott, Soil Microbiologist, USDA-ARS, National Soil Erosion Research Laboratory, Purdue University, West Lafayette, IN 47907
Ronald F. Turco, Associate Professor, Department of Agronomy, Laboratory for Soil Microbiology, Purdue University, West Lafayette, IN 47907
Karen Updegraff, Assistant Scientist, Natural Resources Research Institute, University of Minnesota, Duluth, MN 55811
Petra C. J. van Vliet, Soil Ecologist, Institute of Ecology, University of Georgia, Athens, GA 30602