Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (15.52 MB, 301 trang )
J. W. DORAN ET AL.
ated with this scientific paradigm has allowed disciplines within agricultural
research to become intellectually self-contained. As a result, societal concerns
and problems are not always effectively addressed because the “questions and
products” of research are determined and reviewed within disciplinary boundaries (Weinberg, 1967).
It is not appropriate, however, simply to dismiss scientific advances made by
agricultural research following the discipline-oriented paradigm. In fact, information gathered from it is often necessary to solve larger-scale problems. It is
appropriate, however, to challenge the validity of this paradigm for all of agricultural research. Agriculture’s impact on the global ecosphere is well established, and therefore, agricultural research possesses significant social purpose.
It is in this light of social obligation that many agricultural researchers have
recently sought new research strategies to address societal concerns (Bezdicek
and DePhelps, 1994; Gardner, 1990; Hendrix, 1987).
To meet the new expectations of agricultural research, scientists will likely
have to employ alternative research methods such as farmer-participatory research and multidisciplinary cooperation, two research methods generally not
utilized by scientists under the current discipline-oriented paradigm. Leading
proponents for change in agricultural research have stressed the need for more
farmer-participatory research as a means to study innovative management systems, utilize research methods grounded in ecological principles, and increase
farmers’ influence over research priorities (Lockeretz and Anderson, 1993,
Chaps. 8 and 9). Multidisciplinary approaches have been suggested in farmerparticipatory research, especially in studies evaluating the agronomic or economic performance of whole farms (Bezdicek and DePhelps, 1994). This sentiment
has been echoed by farmers critical of the prevalent reductionistic focus in
agricultural research (Kirschenmann, 1991 ; Thornley, 1990; Watkins, 1990).
They believe that farmer-participatory research would force scientists to view
agricultural problems from a farmer’s perspective. Through an appreciation of
the interactions and interdependencies within whole farms, they claim scientists
would develop a better understanding of the values that motivate farmers’ production decisions and conduct research that more appropriately addressed farmers’ concerns.
Should a greater awareness of farmers’ concerns occur in the research community, research questions would likely be directed less toward increasing disciplinary understanding and more toward solving problems. Problem-oriented research, however, would create a dilemma for most agricultural researchers.
Unless agricultural researchers could solve farmers’ problems and increase disciplinary understanding, they would run the risk of not faring well professionally
as long as peer-reviewed publications were upheld as the standard of achievement
(Lockeretz, 1995). In order to survive professionally, problem-oriented researchers would be forced to mold the results of their work to the research
SOIL HEALTH AND SUSTAINABILITY
community, often using the “sterile formalism and jargon of the discipline”
(Lockeretz and Anderson, 1993, p. 156). Doing this, however, would almost
guarantee that their work would be ignored by the people for whom it was
This dilemma that leaves researchers unable to wholly address farmers’ problems represents a fundamental flaw in the current agricultural research paradigm.
The professional reward system in agricultural research is designed primarily to
further discipline understanding, not to solve problems. Tailoring the reward
system to the characteristics of alternative research strategies has been suggested
as one way to circumvent this flaw (MacRae era/., 1989). Lockeretz and Anderson (1993, Chap. 10) have suggested a more aggressive approach. They believe
researchers should think beyond getting the system to accommodate a particular
kind of research, and “challenge the very idea of the dominant system as poorly
suited to the social purposes of agricultural research.” They propose that the
developnient of an appropriate professional reward system would be facilitated
by an institutional realignment that divides agricultural departments into
farming-related and agricultural science-related research areas. Farming-related
research would cover topics closely associated with farms and production systems, while agricultural science-related research would address agriculturally
significant processes and organisms abstracted from the context of production. If
stated similarly, but by the goals of each area, farming-related research would
address farmers’ concerns and agricultural science-related research would answer
disciplinary-related questions. A reorganization of this sort would essentially
erase current problems in the professional reward system because farmingrelated research would have to use entirely different criteria for evaluation of
achievement (Lockeretz, 1995).
At a time when agriculture must address environmental degradation due to
certain yield-promoting practices driven by increasing demands for both greater
and better-distributed food supplies, the concept of soil health can be a useful
communication device in meeting present and future world needs. Stewardship
of the soil resource that enhances soil quality and health while allowing for
acceptable long-term production levels is in everyone’s best interest and satisfies
what has been called the ‘Ecocentric’ notion of the Common Good (Stauber,
1994). Soil management practices must now be evaluated for their impacts across
the temporal scale-short-, middle-, and long-term, as well as across the landscape, to be truly sustainable (Swift et al., 1991).
Producers around the globe receive advice, whether provided gratis by govern-
J. W. DORAN ET AL.
ment agencies or solicited for a fee from consultants, on recommended production practices. Unfortunately, much of this advice is often aimed at relatively
short-term ( 1 or 2 years) economic gains to their operation, rather than on longterm resource conservation (Stauber, 1994). Additionally, advice may be valueladen, or linked to agribusiness sales, such as soil tests performed by private
companies which may indicate need for chemical fertilizers and pesticides in
excess of what is needed for good crop production (Cramer, 1986; Soule and
Piper, 1992). Management recommendations are often developed for regions
which may encompass a wide variation in soil type, topography, and resource
availability. In such cases, practices which are appropriate for experimental
conditions may be inappropriate on a large portion of the individual farms to
which they are recommended. To begin the move toward site-specific best management practices, tests for soil quality indicators should be developed as meters
for gauging both the short- and long-term effects of various production practices
on soil health. Soil quality tests that yield results uncoupled from value judgments will allow both land stewards and researchers to evaluate production
practices objectively under a wide range of conditions, to identify those that are
truly improving soil health. Clearly, there will likely always be value judgment
necessary to reconcile the need for food production with the need to maintain soil
in a near-natural state, such as the decision as to whether increasing herbicide use
may be an acceptable tradeoff for reducing tillage. Nevertheless, tests which
accurately measure the soil quality impacts of various options will help make the
consequences of the different options more apparent. If tests are made to be used
by producers and other land stewards, production practices will not only be
efficiently tailored for individual situations, but researchers will have a manyfold increase in the information available to better understand soil processes.
The concept of soil health can be a key tool for educating farmers about some
of the less obvious potentials for soil degradation due to poor management.
There is some evidence that a concern for soil health may lead land stewards to
production practices that indeed improve some soil characteristics. Van Kooten et
al. (1990) found in southwestern Saskatchewan that farmer concern for soil
quality was in fact correlated to production practices which improved soil physical parameters. The authors found, however, that farmers were less likely to be
seriously concerned with soil quality in areas with deep topsoil, which pinpoints
the need to emphasize the long-term vision of soil health.
Producers and land managers need practical tools which they can use to
determine the effectiveness of their management practices on soil health and
sustainable production. Traditional research has identified management practices
SOIL HEALTH AND SUSTAINABILITY
that conserve the soil resource, protect air and water quality, or maximize crop
yields. However, development of sustainable management strategies that maintain soil quality and health and balance production needs with environmental
concerns require new research approaches and on-site evaluation to confirm the
specific applications of general strategies across the range of climatic, soil,
economic, and social conditions experienced by agriculture. Facilitating producer participation in the research process is essential to development of practical
production systems and assessment approaches which address the needs of both
producers and society in general. Indicators of soil health and practical assessment tools are essential to forming this necessary partnership between producers
and the technical community. National standards of soil quality and health will
likely be established within the next decade to provide policy makers and action
agencies with a means of monitoring the state of our soil resources. It is imperative that the indicators be useful to producers in some form especially if incentives or regulations based on soil quality or health are enacted.
To include producers as active participants in on-site assessment of soil quality/health, tools and methodologies used by researchers must be adapted to be
easily accessible to the producers themselves (Sarrantonio et al., 1996). Tests
should be simple to perform, require little in the way of expensive equipment,
and give rapid results. Additionally, tests should be able to measure soil characteristics that are meaningful to the producers’ understanding of soil and soil
processes, and give results that are reliable, accurate within an acceptable range,
and interpretable with a minimum amount of training. A soil quality test kit is
currently being developed by USDA-ARS to help producers, researchers, conservationists, environmentalists, and consultants assess the health and quality of soil
and facilitate technology transfer (Crarner, 1994). The test kit provides on-site
capability for assessment of many of the indicators for screening soil quality and
health (see Table I ) such as soil pH, electrical conductivity, soil and water nitrate
levels, soil density, water infiltration, water-holding capacity, soil water content,
water-filled pore space, soil temperature, and soil respiration. The kit provides
producers and agricultural specialists with the tools necessary for a cursory
assessment of the complex suite of physical, chemical, and biological factors
which comprise soil quality/health and facilitates on-site identification of the soil
resource condition and its degree of degradation. Currently the cost of the test kit
is under $250, yet results obtained with this kit compare well with standard
laboratory procedures that are more time consuming and costly (Liebig ct al.,
1994). The utility of this test kit is currently being evaluated by conservationists
(USDA-NRCS), researchers, extension educators, environmental monitors
(EPA-EMAP), and producers at locations in the United States, Australia, Canada, Cuba, Honduras, India, Poland, and Ru
. Preliminary results suggest the
kit is useful to specialists in fostering appreciation for the complexity of soil, in
bridging disciplinary boundaries, and in facilitating assessment of soil quality
J. W. DORAN E T AL.
and health. However, the overall procedure for on-site assessment of soil quality
and health was found to be too complicated and time consuming for practical use
by farmers. One extension educator in Illinois suggested that the “test” kit might
best be used by farmers as a ‘tool’ kit from which specific tests can be used as
needed to assess soil quality and health.
Practical tools for soil quality and health assessment by producers must aid
their comprehension of the concept of soil health and be useful to them within the
context of their normal work routines (after Nowak in Leopold Letter, 1995).
Knowledge of soil for most producers is largely limited to that which they gain
through their sensory experiences in working the soil with agricultural implements and watching plant growing conditions during the growing season.
Knowledge derived from studying soil test results (mainly organic matter), conservation plans, and information from farm supply dealers are of less importance
to farmers in understanding soil. Information from soil conservation offices
(USDA-NRCS), taking soil samples, and experience of others are the least relied
upon sources of knowledge about soils. Clues farmers most often use to differentiate soils include soil color (largely organic matter), the workability of soil
(structure and compaction), wetness or dryness of soil (drainage, storage, and
infiltration capacity), and topsoil texture and depth (indicators of soil erosion and
production potential). Crop yield and input costs are indicators which producers
most often rely upon to assess the short-term sustainability of their management
practices. Inclusion of other tools for rapid assessment of efficiency of resource
use such as quick tests for soil and water nitrate levels, adequacy of plant growth
and N content, and synchronization of soil nitrogen supplies with crop plant
needs will facilitate development of reduced input management systems and
management strategies for long-term sustainability (see Table 111).
VIII. SUMMARY AND CONCLUSIONS
Soil is a finite and dynamic living resource that acts as an interface between
agriculture and the environment and is vital to global function. Soil health can be
defined as the continued capacity of soil to function as a vital living system,
within ecosystem and land-use boundaries, to sustain biological productivity,
maintain the quality of air and water environments, and promote plant, animal,
and human health. Advantages to giving value to soil health and its assessment
include: (i) importance as a resource for evaluation of land-use policy, (ii) use in
identification of critical landscapes or management systems, (iii) use in evaluation of practices that degrade or improve the soil resource, and (iv) utility in
identifying gaps in our knowledge base and understanding of sustainable management.
SOIL HEALTH AND SUSTAINABILITY
To assure the sustainability of agricultural management systems, producers
and land managers must be included as active participants in the quantitative and
qualitative assessment of soil health. Present research and education needs critical to assessment and enhancement of soil quality/ health include:
I . Coordinated development of standards for soil quality/health by national
and local agencies and farming interest groups to assess sustainability changes
with time. This requires establishment of reference guidelines and thresholds for
indicators of soil qualitylhealth that enable identification of relationships between soil measures and soil function which permit valid comparisons across
variations in climate, soils, land use, topography, and management systems. This
will also require identification of appropriate scales of time and space for assessment of soil quality/health and development of standardized protocols for sampling, processing, and analysis.
2. Development of practical approaches and tools for on-site assessment of
soil quality/health by farmers, researchers, extension, conservationists, and environmental monitors that can also be used by resource managers and policy
makers to determine the sustainability of land management practices.
We are beginning to realize that soil health, by its broadest definition, is
inseparable from issues of sustainability. The challenge before us is to develop
holistic approaches for assessing soil health that are useful to producers, specialists, and policy makers in identifying agricultural management systems that are
profitable and environmentally benign, and which will sustain our soil resources
for future generations.
Acton, D. F. 1993. “A Program To Assess and Monitor Soil Quality in Canada: Soil Quality
Evaluation Program Summary (Interim).” Centre for Land and Biological Resources Res. Contr.
No. 93-49, Research Branch, Agriculture Canada, Ottawa.
Acton, D. F., and Gregorich. L. I. 1995. “The Health of Our Soils: Toward Sustainable Agriculture
in Canada.” Agric. Agri-food Can.. CDR Unit, Ottawa, Canada.
Acton, D. F., and Padbury, G . A . 1993. A conceptual framework for soil quality assessment
and monitoring. In “A Program To Assess and Monitor Soil Quality in Canada: Soil Quality
Evaluation Program Summary (Interim)” (D. F. Acton, Ed.), pp. 2-1-2-7. Centre for Land
and Biological Resources Res. Contr. No. 93-49, Research Branch, Agriculture Canada,
Ahrens. E., Elsaidy, S., Samaras, I., Saniaras, F., and Wistinghausen, E. 1983. Significance of
fertilization for the post-harvest condition of vegetables, especially spinach. I n
“Environmentally Sound Agriculture’’ (W. Lockeretz, Ed.), pp. 339-346. Praeger. New York.
Albrecht, W. A. 1975. “The Albrecht Papers‘’ (C. Walters. Ed.). Acres U.S.A., Raytown. MO.
Aicxandcr, M . 1971. Agricultures responsibility in establishing soil quality criteria. I n “Environmental Improvement-Agricultures Challenge in the Seventies,” pp. 66-7 I . National Academy of
Sciences, Washington, DC.
J. W. DORAN ET AL.
Allaway, W. H. 1975. “The Effect of Soils and Fertilizers on Human and Animal Health.” Agriculture Information Bull. No. 378. USDA, Washington, DC.
Anderson, J. M. 1988. The role of soil fauna in agricultural systems. In “Advances in Nitrogen
Cycling in Agricultural Ecosystems” (R. Wilson, Ed.), pp. 59-1 12. CAB Inter., Wallingford,
Angers, D. A., and Mehuys, G. R. 1988. Effects of cropping on macroaggregation of a marine clay
soil. Can. J. Soil Sci. 68, 723-732.
Angers, D. A., Sampson, N., and Legere, A. 1992. Early changes in water-stable aggregation
induced by rotation and tillage in a soil under barley production. Can. J. Soil Sci. 73, 51-59.
Arshad, M. A., and Coen, G. M. 1992. Characterization of soil quality: Physical and chemical
criteria. Am. J. AIrernative Agric. I, 12-16.
Avery, D. T. 1995. “Saving the Planet with Pesticides and Plastic: The Environmental Triumph of
High-Yielding Farming.” Hudson Institute, Indianapolis, IN.
Balfour, E. B. 1948. “The Living Soil: Evidence of the Importance to Human Health of Soil Vitality,
with Special Reference to National Planning.” Devin-Adair, New York.
Barnes, B. T., and Ellis, F. B. 1979. Effects of different methods of cultivation, direct drilling, and
dispersal of straw residues on populations of earthworms. J. Soil Sci. 30, 669-679.
Bauer, A., and Black, A. L. 1994. Quantification of the effect of soil organic matter on soil
productivity. Soil Sci. Sue. Am. J . 58, 185-193.
Berry, E. C. 1994. Earthworms and other fauna in soil. In “Advances in Soil Science; Soil Biology:
Effects on Soil Quality” (J. L. Hatfield and B. A. Stewart, Eds.), pp. 61-90, Boca Raton, FL.
Bezdicek, D. F., and DePhelps, C. 1994. Innovative approaches for integrated research and educational programs. Am. J. Alternative Agric. 9, 3-8.
Bhagdt, S . P. 1990. “Creation in Crisis.’’ Brethren Press, Elgin, IL.
Blum, W. E. H., and Santelises, A. A. 1994. A concept of sustainability and resilience based on soil
functions. In “Soil Resilience and Sustainable Land Use” (D.J. Greenland and I. Szabolcs,
Eds.), pp. 535-542. CAB Inter., Wallingford, Oxon, UK.
Bohlen, P. J., and Edwards, C. A. 1994. The response of nematode trophic groups to organic and
inorganic nutrient inputs in agroecosystems. In “Defining Soil Quality for a Sustainable Environment” (J. W. Doran, D. C. Coleman, D. F. Bezdicek, and B. A. Stewart, Eds.), pp. 235244. Soil Sci. SOC.Am. Spec. Publ. No. 35, Madison, WI.
Bongers, T. 1990. The maturity index: An ecological measure of environmental disturbance based on
nematode species composition. Oecologia 83, 14- 19.
Bouma, J. 1989. Using soil survey data for quantitative land evaluation. Adv. Soil Sci. 9, 177-213.
Brown, L. R., Kane, H., and Roodman, D. M. 1994. “Vital Signs 1994: The Trends that Are
Shaping Our Future,” p. 27. Worldwatch Institue, W. W. Norton & Co., New York.
Campbell, C. A,, Lafond, G . P., Zentner, R . P., and Jame, Y. W. 1994. Nitrate leaching in a Udic
Haploboroll as influenced by fertilization and legumes. J. Environ. Qual. 23, 195-201.
Campbell, C. A., Paul, E. A., and McGill, W. B. 1976. Effect of cultivation and cropping on the
amounts and forms of soil N. In Proceedings, Western Canada Nitrogen Symposium (W. A.
Rice, Ed.), pp. 9-101. Alberta Agriculture, Edmonton, Alberta, Canada.
CAST. 1992a. “Preparing U.S. Agriculture for Global Climate Change. Task Force Report No. 119.”
Council for Agricultural Science and Technology, Ames, IA.
CAST. 1992b. “Water Quality: Agriculture’s Role. Task Force Report No. 120.’’ Council for Agricultural Science and Technology, Ames, IA.
Clancy, K. L. 1986. The role of sustainable agriculture in improving the safety and quality of the
food supply. Am. J. Alternative Agric. 1, 11-18.
Cline, R. G., and Ruark, G. A. 1995. Management of forest soils. In “Advances in Soil Science; Soil
Management and Greenhouse Effect“ (R. Lal, J. Kimhle, E. Levine, and B. A. Stewart, Eds.),
pp. 365-371. Lewis, Boca Raton, FL.
SOIL HEhLTH AND SUSTAINABILITY
Costanza. R . . Norton, B. G., and Haskell, B. D. 1992. “Ecosystem Health: New Goals for Environmental Management.” Island Press, Washington, DC.
Cramer, C. 1986. “The Farmer’s Fertilizer Handbook.” Regenerative Agri. Assoc., Emmaus, PA.
Cramer. C . 1994. Test your soils health: A three part series. New Farm ;Magazine qf’Regenerarive
Agric. Jan., 17-21; Feb., 40-45; May/June, 46-51.
Crosson, P. R. 1982. Future economic and environmental costs of agricultural land. I n “The
Cropland Criais” (P. R . Crosson, Ed.), p. 165-191. Johns Hopkins Univ. Press, Baltimore,
Cserni I., and Prohaska, K . 1987. The effect of N supply on the nitrate, sugar and carotene content of
carrots. Acra Horric~ulrurae220, 303-307.
Culliney, T. W., Pimentel, D., and Pimentel, M. H. 1992. Pesticides and natural toxicants in foods.
Agric-. Ecosystems Environ. 41, 297-320.
DeEII, J. R . , and Prange, R. K. 1992. Postharvest quality and sensory attributes of organically and
conventionally grown apples. Hortscience 27, 1096- 1099.
Domanico, J. L., Madden. P., and Partenheimer, E. J. 1986. Income effects of limiting soil erosion
under organic, conventional, and no-till systems in eastern Pennsylvania. Am. J . Abrrnurive
Agric. 1, 75-82.
Doran, J. W. 1995. Building Quality Soil. I n “Proceedings of the 1995 Alberta Conservation Tillage
Workshop on ‘Opportunities and Challenges in Sustainable Agriculture.”’ February 23-25,
1995, Red Deer, Alberta, Canada.
Doran, J. W.. and Linn. D. M. 1994. Microbial ecology of conservation management systems.
I n “Advances in Soil Science : Soil Biology; Effects on Soil Quality” ( J . L. Hatfield and B. A .
Stewart, Eds.), pp. 1-27. Lewis, Boca Raton. FL.
Doran, J. W.. and Parkin, T. B. 1994. Defining and assessing soil quality. I n “Defining Soil Quality
for a Sustainable Environment” (J. W. Doran, D. C. Coleman, D. F. Bezdicek, and B. A.
Stewart. Eds.), pp. 3-21. Soil Sci. Soc. Am. Spec. Publ. No. 35, Madison, WI.
Doran, J. W., and Smith, M. S . 1991. Overview: Role of cover crops in nitrogen cycling. /pi “Cover
Crops for Clean Water‘’ (W. L. Hargrove, Ed.), pp. 85-90. Soil Conser. Soc. Amer., Ankeny,
Doran, J. W.. and Werner M. R . 1990. Management and soil biology. I n “Sustainable Agriculture in
Temperate Zones” (C. A. Francis, C. B. Flora, and L. D. King, Eds.), pp. 205-230. Wiley,
Doran, J. W., Varvel, G. E.. and Culley. J . B. L. 1994a. Tillage and residue management effects on
soil quality and sustainable land management. I n “Proc. Inter. Workshop on Sustainable Land
Management” (R. C. Wood and 1. Dumanski, Eds.), V01.2, pp. 59-74. Agric. Inst. of Canada,
Doran, J. W.. Sarrantonio, M . , and Janke, R. 1994b. Strategies to promote soil quality and soil
health. I n “Proc. OECD Intern. Workshop on Management of the Soil Biota in Sustainable
Farming Systems” (C. E. Pankhurst, B. M. Doube. V.V.S.R. Gupta, and P. R . Grace, Eds.),
pp. 230-237. CSIRO. Melbourne, Victoria, Australia.
Dorniaar, J. F., Lindwall. C. W., and Kozub. G . C. 1988. Effectiveness of manure and commercial
fertilizer in restoring productivity of an artificially eroded dark brown chernozemic soil under
dryland conditions. Can. J . Soil Sci. 68. 669-679.
Drinkwater, L. E., Letourneau. D. K . . Workneh, F., van Bruggen. A. H. C . , and Shennan. C. 1995.
Fundamental differences between conventional and organic tomato agroecosystenis in California. Ecol. Appl. 5 , 1098-1 112.
Duda, A. M. 1985. Environmental and economic damage caused by sediment from agricultural
nonpoint sources. Wuter Res. Bull. 21, 225-234.
Edwards, E. 0..and Bell, P. W. 1961. “The Theory and Measurement of Business Income.” Univ. of
California Press, Berkeley.
J. W. DORAN ET AL.
Eppendorfer, W. H. 1978. Effects of N-fertilization on amino acid composition and nutritive value of
spinach, kale, cauliflower and potatoes. J. Sci. Food Agric. 29, 305-3 I I .
Faeth, P. 1993. Evaluating agricultural policy and the sustainability of production systems: An
economic framework. 1. Soil Water Conserv. 48, 94-99.
Faeth, P., Repetto, R., Kroll, K., Dai, Q.,and Helmers, G . 1991. “Paying the Farm Bill: U.S.
Agricultural Policy and the Transition to Sustainable Agriculture.” World Res. Inst., Washington, DC.
Friedman, D. B. 1993. Carbon, nitrogen, and aggregation dynamics in low-input and reduced tillage
cropping systems. M. S. Thesis, Cornell University.
Gardner, J . C. 1990. Responding to farmers’ needs: An evolving land grant perspective. Am. J.
Alternative Agric. 5 , 170- 173.
Gardner, J. C., Jamtgaard, K., and Kirschenmann, F. 1995. What is sustainable agriculture? In
“Planting the Future: Developing an Agriculture that Sustains the Land and Community” (A. R.
Bird, G. L. Bultena, and I. C. Gardner, Eds.), pp. 45-65. Iowa State Univ. Press, Ames, I A .
Garlynd, M. J., Romig, D. E., Hams, R. F., and Kurakow, A. V. 1994. Descriptive and analytical
characterization of soil quality/health. In “Defining Soil Quality for a Sustainable Environment”
(J. W. Doran, D. C. Coleman, D. F. Bezdicek, and B. A. Stewart, Eds.), pp. 159-168. Soil
Sci. Soc. Am. Spec. Publ. 35, Madison, WI.
Glanz, J. T. 1995. “Saving Our Soil: Solutions for Sustaining Earth’s Vital Resource.” Johnson
Books, Boulder, CO.
Gliessman, S. R. 1984. An agroecological approach to sustainable agriculture. In “Meeting the
Expectations of the Land’ (W. Jackson, W. Berry, and B. Colman, Eds.), pp. 160-171. North
Point Press, San Francisco, CA.
Gore, A. 1993. “Earth in the Balance : Ecology and the Human Spirit.” Houghton Mifflin, New
Granatstein, D., and Bezdicek, D. F. 1992. The need for a soil quality index : Local and regional
perspectives. Am. J. Alternative Agric. 7 , 12-16.
Haberern, J. 1992. Viewpoint: A soil health index. J. Soil Water Conserv. 47, 6.
Hallberg, G . R. 1987. Agricultural chemicals in ground water: Extent and implications. Am. J.
Alternative Agric. 11, 3- 15.
Hamblin, A. 1991, “Environmental Indicators for Sustainable Agriculture,” Report of a National
Workshop. Publ. LWRRDC and GRDC.
Hansen, H. 1981. Coniparison of chemical composition and taste of biodynamically and conventionally grown vegetables. Qual. Plant Plant Foods Hum. Nutr. 30, 203-21 I .
Hanson, J. C., Johnson, D. M.,Peters, S. E. ,and Janke, R. R. 1990. The profitability of sustainable
agriculture on a representative grain farm in the Mid-Atlantic Region. 1981- 1989. Norrheastern
J . Agric. Resource Econ. 19, 90-98.
Hams, G . H., Hesterman, 0. B., Paul, E. A., Peters, S. E., and Janke, R. R. 1994. Fate and
behavior of legume and fertilizer IsN in a long-term cropping systems experiment. Agron. J . 86,
9 10-9 15.
Harris. R . F., and Bezdicek, D. F. 1994. Descriptive aspects of soil quality/health. In “Defining Soil
Quality for a Sustainable Environment” ( J . W. Doran, D. C. Coleman, D. F. Bezdicek, and
B. A. Stewart, Eds.). pp. 23-35. Soil Sci. SOC.Am. Spec. Publ. 35, Madison, W1.
Harrison, F. 1913. “Roman Farm Management: The Treatises of Cato and Varro.” Macmillin, New
Harwood, R. R. 1990. A history of sustainable agriculture. I n “Sustainable Agricultural Systems’’
(C. A. Edwards, R. Lal, P. Madden, R. H. Miller, and G. House, Eds.), pp. 3- 19. Soil Water
Conserv. SOC.Amer., Ankeny, IA.
Hendrix, P. F. 1987. Strategies for research and management in reduced-input agroecosystems. Am.
J. Alternative Agric. 2, 166-172.
SOIL HEALTH AND SUSTAINABILITY
Hillel, D. J. 1991. “Out of the Earth: Soil and the Sustainability of Civilization.” The Free Press,
Hodges. R . D.. and Scofield, A. M. 1983. Effect of agricultural practices on the health of plants and
animals produced: A review. I n “Environmentally Sound Agriculture” (W. Lockeretz, Ed.),
pp. 3-33. Praeger, New York.
Hornick, S. B. 1992. Factors affecting the nutritional quality of crops. Am. J. Alternative A@. 7 ,
Houghton, R. A., Hobbie. J. E., Melillo, J. M..Moore. B., Peterson, B. J.. Shaver, G . R., and
Woodwell, G . M. 1983. Changes in the carbon content of terrestrial biota and soils between
1860 and 1980: A net release of CO, to the atmosphere. Ecol. Monogr. 53. 235-262.
Howard. Sir A. 1943. “An Agricultural Testament.” Oxford tiniv. Press, New York.
Howard, Sir A. 1947. “The Soil and Health: A Study of Organic Agriculture.” Devin-Adair, New
Jackson, W. 1980. “New roots for agriculture.” North Point Press, Berkeley, CA.
Jackson, W.. and Piper, J. 1989. The necessary marriage between ecology and agriculture. Ecology
Janzen, H. H.. Larney. F. J., and Olson, B. M. 1992. Soil quality factors of problem soils in Alberta.
f‘roc. Alberta Soil Sci. Workshop. Lethbridge. Alberta. Canada.
Jenny, H. 1984. The making and unmaking of fertile soil. In “Meeting the Expectations of the Land”
(W. Jackson. W. Berry, and B. Colmun, Eds.), pp. 44-52. North Point Press, San Francisco,
Jenny, H. 1980. The soil resource: origin and behavior. Ecological studies 37. Springer-Verlag, New
Kader, A. A. 1987. Influence of preharvest and postharvest environment on nutritional composition
of fruits and vegetables. I n “Horticulture and Human Health: Contribution of Fruits and Vegetables” (B. Quebedeaux and F. A. Bliss, Eds.), pp. 18-32. Prentice-Hall, EnglewoodCliffs, NJ.
and Am. Soc. Horticultural Sci.. Alexandria, VA.
Karlen, D. L., Berti, W. R., Hunt, P. G.. and Matheny, T. A. 1989. Soil-test values after eight years
of tillage research on a Norfolk loamy soil. Comm. Soil Sci. Plant Anal. 20, 1413-1426.
Karlen, D. L. and Stott, D. E. 1994. A framework for evaluating physical and chemical indicators of
soil quality. In “Defining Soil Quality for a Sustainable Environment” ( J . W. Doran, D. C.
Coleman. D. F. Bezdicek, and B. A. Stewart. Eds.), pp. 53-72. Soil Sci. Soc. Am. Spec. Publ.
35. Madison. WI.
Karlen, D. L.. Wollenhaupt, N . C . , Erbach.D. C . , Berry, E. C . , Swan, J. B., Eash, N. S., and
Jordahl, J. L. 1994. Crop residue effects on soil quality following 10-years of no-till corn. Soil
Tillage Rcs. 31, 149-167.
Kay. B. D., Angers, D. A.. Groenvelt, P. H., and Baldock. J. A. 1988. Quantifying the influence of
cropping history on soil structure. Can. J. Soil Sci. 68, 359-368.
Kellogg, R. L.. TeSelle, G. W., and Goebel, J. J. 1994. Highlights from the 1992 national resources
inventory. J. Soil Water Conserv. 49, 521-527.
Kennedy, A. C., and Papendick, R. I. 1995. Microbial characteristics of soil quality. J. Soil Water
Conserv. 50, 243-248.
Killham, K. 1994. “Soil Ecology.” Cambridge Univ. Press, Cambridge, UK.
Kirschenmann, F. 199 I . Fundamental fallacies of building agricultural sustainability. J . Soil Water
Conserr,. 46, 165-168.
Knorr, D., and Vogtman, H. 1983. Quality and quantity determination of ecologically grown foods.
In “Sustainable Food Systems” (D. Knorr. Ed.), pp, 352-381. AVI, Westport, CT.
Kretzchmar. A. 1982. Description des galaries des Vers de terre et variation saisonniere des reseaux.
Rev. EcoI. B i d . Sol 19, 579-591.
Krohn, W.. and Schifer, W. 1983. Agricultural chemistry. The origin and structure of a tinalized
J. W. DORAN ET AL.
science. Irr “Finalization in Science: The Social Orientation of Scientific Progress” (W. Schafer,
Ed.), pp. 15-52. D. Reidel, Dordrecht.
Lairon, D., Spitz, N., Termine, E., Ribaud, P., Lafont, H. and Hauton, I. 1984. Effect of organic
and mineral nitrogen fertilization on yield and nutritive value of butterhead lettuce. Qua/. Planr
Plant Foods Hum. Nuir. 34, 97-108.
Lal, R. 1994. Sustainable land use systems and soil resilience. I n “Soil Resilience and Sustainable
Land Use” (D.J. Greenland and 1. Szabolcs, Eds.), pp. 41-67. CAB Inter., Wallingford, Oxon,
Lal, R., and Pierce, F. J. 1991. The vanishing resource. In “Soil Management for Sustaindbihty”
(R. La1 and F. I. Pierce, Eds.), pp. 1-5. Soil and Water Conservation Society, Ankeny, IA.
Lantz, E. M., Gough, H. W., and Campbell, A. M. 1958. Nutrients in beans, effects of variety,
location and years on the protein and amino acid content of dried beans. J. Agric. Food Chem. 6,
Larson, W. E., and Pierce, F. J. 1994. The dynamics of soil quality as a measure of sustainable
management. I n “Defining Soil Quality for a Sustainable Environment” ( J . W. Doran, D. C.
Coleman, D. F. Bezdicek, and B. A. Stewart, Eds.), pp. 37-5 I . Soil Sci. Soc. Am. Spec. Publ.
35, Madison, WI.
Ldrson, W. E., and Pierce, F. J. 1991 Conservation and enhancement of soil quality. In “Evaluation
for Sustainable Land Management in the Developing World,” Vol. 2, “Technical Papers.”
Bangkok, Thailand: International Board for Soil Research and Management. IBSRAM Proc.
No. 12 (2).
Leclerc, J., Miller, M. L., Joliet, E., and Rocquelin, G. 1991. Vitamin and mineral contents of carrot
and celeriac under mineral or organic fertilization. Biol. Agric. Hort. 7 , 349-361.
Lee, K. E. 1985. “EdrthWormS: Their Ecology and Relationship with Soils and Land Use.” Academic Press, New York.
Lehninger, A. L. 1973. “Bioenergetics: The Molecukdr Basis of Biological Energy Transformations,”
second ed. W. A. Benjamin, Menlo Park, CA.
Leopold, A. 1949. “A Sand County Almanac and Sketches Here and There.” Oxford University
Press, New York.
Leopold Letter. 1995. Perspectives on soil health: A discussion among scientists and farmers (March
issue). Leopold Center for Sustainable Agriculture, Ames, 1A.
Lewis, C. D. 1940. “The Georgics of Virgil.” Alden Press, Oxford.
Liebig, J. 1862. “Chemistry in Its Application to Agriculture and Physiology,” 7th ed. Vieweg,
Liebig, M. A . , Doran, J. W., and Gardner, J. 1994. Field and laboratory evaluations of management
induced changes in soil quality. Agronomy Absr. p. 295.
Linden, D. R., Hendrix, P. F., Coleman. D. C., and van Vliet, P. C. J. 1994. Faunal indicators of
soil quality. In “Defining Soil Quality for a Sustainable Environment” ( J . W. Doran, D. C.
Coleman, D. F. Bezdicek, and B. A. Stewart, Eds.), pp. 91-106. Soil Sci. Soc. Am. Spec.
Publ. 35, Madison, WI.
Linder, M. C. 1985. Food quality and its determinants from field to table: Growing food, its storage,
and preparation. In “Nutritional Biochemistry and Metabolism” (M. Linder, Ed.), pp. 239-254.
Elsevier, New York.
Lockeretz, W. 1995. Removing applied agricultural research from the academy. Am. J. Altern. Agric.
Lockeretz, W., and Anderson, M. D. 1993. “Agricultural Research Alternatives.” Univ. of Nebraska
Press, Lincoln, NE.
Lovelock. J. E. 1991. “Gaia: A New Look at Life on Earth.’’ Oxford Univ. Press, Oxford.
Mackay, A. D., and Kladivko, E. J. 1985. Earthworms and rate of breakdown of corn and soybean
residues in soil. Soil Biol. Biorhern. 17, 851-857.