- Sustainable agriculture
Sustainable agriculture integrates three main goals: environmental
stewardship, farm profitability, and prosperous farmingcommunities. These goals have been defined by a variety of disciplines and may be looked at from the vantage point of the farmeror the consumer.
Sustainable agriculture refers to the ability of a farm to produce food indefinitely, without causing severe or irreversible damage to ecosystem health. Two key issues are biophysical (the long-term effects of various practices on soil properties and processes essential for crop productivity) and socio-economic (the long-term ability of farmers to obtain inputs and manage resources such as labor).
The physical aspects of sustainability are partly understood. [
Altieri, Miguel A.(1995) Agroecology: The science of sustainable agriculture. Westview Press, Boulder, CO.] Practices that can cause long-term damage to soil include excessive tillage (leading to erosion) and irrigation without adequate drainage (leading to accumulation of salt in the soil). Long-term experimentsprovide some of the best data on how various practices affect soil properties essential to sustainability.
airand sunlightare available everywhere on Earth, crops also depend on soil nutrientsand the availability of water. When farmers grow and harvestcrops, they remove some of these nutrients from the soil. Without replenishment, the land would suffer from nutrient depletion and be unusable for further farming. Sustainable agriculture depends on replenishing the soil while minimizing the use of non-renewable resources, such as natural gas (used in converting atmospheric nitrogen into synthetic fertilizer), or mineral ores (e.g., phosphate). Possible sources of nitrogen that would, in principle, be available indefinitely, include:
#recycling crop waste and
livestockor human manure
legumecrops and forages such as, peanuts, or alfalfathat form symbioses with nitrogen-fixing bacteriacalled rhizobia
#industrial production of nitrogen by the
Haber Processuses hydrogen, which is currently derived from natural gas, (but this hydrogen could instead be made by electrolysisof water using electricity (perhaps from solar cells or windmills)) or
#genetically engineering (non-legume) crops to form nitrogen-fixing symbioses or fix nitrogen without microbial symbionts. The last option was proposed in the 1970s, but would be well beyond the capability of early 21st century technology, even if various concerns about biotechnology were addressed. Sustainable options for replacing other nutrient inputs (phosphorus, potassium, etc.) are more limited. This leaves another, often overlooked, option--developing, or returning to,
landraces that are adapted to less than ideal conditions such as drought or lack of nutrients.
In some areas, sufficient rainfall is available for crop growth, but many other areas require
irrigation. For irrigation systems to be sustainable they must be managed properly (to avoid salt accumulation) and not use more water from their source than is naturally replenished, otherwise the water source becomes, in effect, a non-renewable resource. Improvements in water well drilling technology and the development of submersible pumps have made it possible for large crops to be regularly grown where reliance on rainfall alone previously made this level of success unpredictable. However, this progress has come at a price, in that in many areas where this has occurred, such as the Ogallala Aquifer, the water is being used at a greater rate than its rate of recharge.
Socioeconomic aspects of sustainability are also partly understood. Regarding less concentrated farming, the best known analysis is Netting's study on smallholder systems through history. [
Netting, Robert McC.(1993) Smallholders, Householders: Farm Families and the Ecology of Intensive, Sustainable Agriculture. Stanford Univ. Press, Palo Alto.]
Sustainable agriculture was also addressed by the 1990 farm bill [Food, Agriculture, Conservation, and Trade Act of 1990 (FACTA), Public Law 101-624, Title XVI, Subtitle A, Section 1603] .
It was defined as follows:
Stated by:“the term sustainable agriculture means an integrated system of plant and animal production practices having a site-specific application that will, over the long term:
* satisfy human food and fiber needs
* enhance environmental quality and the natural resource base upon which the agricultural economy depends
* make the most efficient use of nonrenewable resources and on-farm resources and integrate, where appropriate, natural biological cycles and controls
* sustain the economic viability of farm operations
* enhance the quality of life for farmers and society as a whole.” [ [http://www.nal.usda.gov/afsic/pubs/agnic/susag.shtml usda.gov] ]
Given the finite supply of
natural resourcesat any specific cost and location, agriculture that is inefficient or damaging to needed resources may eventually exhaust the available resources or the ability to afford and acquire them. It may also generate negative externality, such as pollution as well as financial and production costs.
The way that crops are sold must be accounted for in the sustainability
equation. Foodsold locally requires little additional energy, aside from that necessary for cultivation, harvest, and transportation (including consumers). Food sold at a remote location, whether at a farmers' marketor the supermarket, incurs a different set of energy cost for materials, labour, and transport.
The most important factors for an individual site are sun, air, soil and water. Of the four, water and soil quality and quantity are most amenable to human intervention through time and labour.
What grows and how and where it is grown are a matter of choice. Two of the many possible practices of sustainable agriculture are
crop rotationand soil amendment, both designed to ensure that crops being cultivated can obtain the necessary nutrients for healthy growth.
Monoculture, a method of growing only one crop at a time in a given field, is a very widespread practice, but there are questions about its sustainability, especially if the same crop is grown every year. Growing a mixture of crops (polyculture) sometimes reduces disease or pest problems [http://www.nature.com/nature/journal/v406/n6797/abs/406718a0.html Nature 406, 718-722 Genetic diversity and disease control in rice] , Environ. Entomol. 12:625) but polyculture has rarely, if ever, been compared to the more widespread practice of growing different crops in successive years crop rotationwith the same overall crop diversity. For example, how does growing a corn-bean mixture every year compare with growing corn and bean in alternate years? Cropping systems that include a variety of crops (polyculture and/or rotation) may also replenish nitrogen (if legumes are included) and may also use resources such as sunlight, water, or nutrients more efficiently (Field Crops Res. 34:239).
Replacing a natural ecosystem with a few specifically chosen plant varieties as is done in farming results in an artificial ecosystem that lacks the genetic diversity found in wildlife and is thus more susceptible to widespread
disease. The Great Irish Famine (1845-1849) is a well-known example of the dangers of monoculture.
Many scientists, farmers, and businesses have debated how to make agriculture farming sustainable. One of the many practices includes growing a diverse number of perennial crops in a single field, each of which would grow in separate season so as not to compete with each other for natural resources. This system would result in increased resistance to diseases and decreased effects of erosion and loss of nutrients in soil.
Nitrogen fixationfrom legumes, for example, used in conjunction with plants that rely on nitrate from soil for growth, helps to allow the land to be reused annually. Legumes will grow for a season and replenish the soil with ammonium and nitrate, and the next season other plants can be seeded and grown in the field in preparation for harvest.
In practice, there is no single approach to sustainable agriculture, as the precise goals and methods must be adapted to each individual case. There may be some techniques of farming that are inherently in conflict with the concept of sustainability, but there is widespread misunderstanding on impacts of some practices. For example, the
slash-and-burntechniques that are the characteristic feature of shifting cultivators are often cited as inherently destructive, yet slash-and-burncultivation has been practiced in the Amazon for at least 6000 years [Sponsel, Leslie E. (1986) Amazon ecology and adaptation. Annual Review of Anthropology 15: 67-97.] ; serious deforestation did not begin until the 1970s, largely as the result of Brazilian government programs and policies. [Hecht, Susanna and Alexander Cockburn (1989) The Fate of the Forest: developers, destroyers and defenders of the Amazon. New York: Verso.] To note that it may not have been slash-and-burnso much as slash-and-char, which with the addition of organic matter produces terra preta, one of the richest soils on Earth and the only one that regenerates itself
There are also many ways to practice sustainable animal husbandry. Some of the key tools to grazing management include fencing off the grazing area into smaller areas called
paddocks, lowering stock density, and moving the stock between paddocks frequently. [ [http://attra.ncat.org/attra-pub/sustpast.html Pastures: Sustainable Management ] ]
Several attempts have been made to produce an artificial meat, using isolated tissues to produce it
in vitro; Jason Matheny's work on this topic, whichin the New Harvestproject, is one of the most commented. [ [http://www.nytimes.com/2008/04/21/us/21meat.html "PETA’s Latest Tactic: $1 Million for Fake Meat"] , "NYT", April 21, 2008.]
What if a farm is able to "produce perpetually", yet has negative effects on environmental quality elsewhere? Most people concerned with sustainability take a global view, so they try to avoid negative off-farm impacts. For example, over-application of synthetic
fertilizeror animal manures can pollute nearby rivers and coastal waters. On the other hand, if crop yields are too low, because of soil exhaustion of nutrients or reduced ability to retain water, farmers would need to access new lands for agriculture, leading to the decimation of the rainforest, draining wetlands, etc.
We must also consider the impact of sustainability on overall production. If the human population is to continue its growth, it will need food and fiber to do so. The United Nations estimates 9.3 billion people will inhabit the world by 2050, which will necessitate a dramatic increase in production capabilities. The increased production will likely come from one of two different ways. First, you can either break out virgin land to grow crops, though concerns over global warming make this option unsavory. Second, you can increase yields on existing land, which will likely require adopting technologies many sustainable advocates are opposed to, principally
Genetically modified organismcrops.
Many advocates of sustainable agriculture think that organic agriculture is the only system which can be sustained over the long-term. However, organic production methods, especially in transition, yield less than their conventional counterparts. [ [http://www.organicconsumers.org/organic/041903_organic.cfm organicconsumers.org] ] While there is evidence which gives organic an advantage during periods of drought [ [http://www.newfarm.org/depts/NFfield_trials/1103/droughtresearch.shtml newfarm.org] ] one must be careful not to place too much emphasis on these figures. While drought is a real threat to agriculture production, it is hardly the norm. Even when drought strikes, stockpiles help mitigate food security concerns. Regardless of reduced yields under optimal conditions, it should be noted that during periods of prolonged drought as predicted by global warming scientists, organic production methods should be considered as a way to adapt to a changing climate.
There has been considerable debate about which form of human residential habitat may be a better social form for sustainable agriculture. Generally, it is thought that village communities can improve sustainability in that such communities tend to provide a cooperative environment that supports farmingFact|date=February 2007.
Many environmentalists pushing for increased population density to preserve agricultural land point out that urban sprawl is less sustainable and more damaging to the environment than living in the cities where cars are not needed because food and other necessities are within walking distanceFact|date=February 2007. However, others have theorized that sustainable
ecocities, or ecovillages which combine habitation and farming with close proximity between producers and consumers, may provide greater sustainabilityFact|date=February 2007.
The use of available city space (e.g.,
rooftop gardensand community gardens) for cooperative food production is another way to achieve greater sustainabilityFact|date=February 2007.
One of the latest ideas in achieving sustainable agricultural involves shifting the production of food plants from major factory farming operations to large, urban, technical facilities called vertical farms. The advantages of vertical farming include year-round production, isolation from pests and diseases, controllable resource recycling, and on-site production that eliminates the need for transportation costsFact|date=February 2007. While a vertical farm has yet to become a reality, the idea is gaining momentum among those who believe that current sustainable farming methods will be insufficient to provide for a growing global populationFact|date=February 2007. For vertical farming to become a reality, billions of dollars in tax credits and subsidies will need to be made available to the operation. [http://www.verticalfarm.com/pdf/PopSci-Jul-2007.pdf] It may be difficult to justify spending billions of dollars on a vertical farm that will only feed 50,000 people when agriculture land remains abundant.
Cobb HillFarm-based Cohousing
Land Allocation Decision Support System
List of sustainable agriculture topics
Low carbon diet
Slash-and-burntechnique, a component of Shifting cultivation
Slash-and-char, environmentally responsible alternative to slash-and-burn
Sustainable food system
The Natural Step
* Dore, J. 1997. " [http://www.rirdc.gov.au/pub/shortreps/sr20.html Sustainability Indicators for Agriculture: Introductory Guide to Regional/National and On-farm Indicators] ", [http://www.rirdc.gov.au/home.html Rural Industries Research and Development Corporation] , Australia.
*Gold, Mary. 1999. [http://www.nal.usda.gov/afsic/AFSIC_pubs/srb9902.htm "Sustainable Agriculture: Definitions and Terms"] . Special Reference Briefs Series no. SRB 99-02 Updates SRB 94-05 September 1999. National Agricultural Library, Agricultural Research Service, U.S. Department of Agriculture.
*Hayes, B. 2008. Trial Proposal: Soil Amelioration in the South Australian Riverland.
*Jahn, GC, B. Khiev, C. Pol, N. Chhorn, S. Pheng, and V. Preap. 2001. Developing sustainable pest management for rice in Cambodia. pp. 243-258, In S. Suthipradit, C. Kuntha, S. Lorlowhakarn, and J. Rakngan [eds.] “Sustainable Agriculture: Possibility and Direction” Proceedings of the 2nd Asia-Pacific Conference on Sustainable Agriculture 18-20 October 1999, Phitsanulok, Thailand. Bangkok (Thailand): National Science and Technology Development Agency. 386 p.
Lindsay Falvey(2004) Sustainability - Elusive or Illusion: Wise Environmental Management. Institute for International Development, Adelaide pp259.
* Hecht, Susanna and Alexander Cockburn (1989) The Fate of the Forest: developers, destroyers and defenders of the Amazon. New York: Verso.
Netting, Robert McC.(1993) Smallholders, Householders: Farm Families and the Ecology of Intensive, Sustainable Agriculture. Stanford Univ. Press, Palo Alto.
* [http://publishing.royalsociety.org/sustainable-agriculture Dedicated double issue of "Philosophical Transactions B" on Sustainable Agriculture. Some articles are freely available.]
Central Carolina Community College, Pittsboro, North Carolina
Clemson University, Clemson, South Carolina
The Evergreen State College, Olympia, Washington
Imperial College London, UK
Iowa State University, Ames, Iowa
Makerere University, Kampala, Uganda
* "Educational and Training Opportunities in Sustainable Agriculture". 17th ed. 2006. World-wide directory of academic and organizational programs. Alternative Farming Systems Information Center,
National Agricultural Library. http://www.nal.usda.gov/afsic/pubs/edtr/EDTR2006.shtml
North Carolina State University, Raleigh, North Carolina
Penn State University, University Park, Pennsylvania
Purdue University, West Lafayette, Indiana
Santa Rosa Junior College, Santa Rosa, California
Sterling College (Vermont), Craftsbury, Vermont
Universidad Bolivariana de Venezuela, Caracas- Ciudad Bolivar- Coro- Maracaibo, Venezuela
University of Alaska, Fairbanks, Alaska
University of British Columbia
University of California, Davis, California
University of Florida, Gainesville, Florida
University of Hawaii, Honolulu, Hawaii
* University of Illinois, Urbana-
University of Kassel/Faculty of Organic Agricultural Sciences, Witzenhausen, Germany
University of Kentucky, Lexington, Kentucky
University of Maine, Orono, Maine
University of Massachusetts, Amherst, Massachusetts
University of Missouri, Columbia, Missouri
University of Vermont, Burlington, Vermont
Wageningen University, Netherlands
Washington State University, Pullman, Washington
West Virginia University, Morgantown, West Virginia
Yale Sustainable Food Project, Yale University, New Haven, Connecticut
* [http://www.ifpri.org/pubs/books/oc53.asp Strategies for Sustainable Land Management in the East African Highlands] by John Pender, Frank Place, and Simeon Ehui (2006)
* [http://www.michaelpollan.com/omnivore.php The Omnivore's Dilemma: A Natural History of Four Meals] by Michael Pollan (2007)
*"The No-Nonsense Guide to World Food" by Wayne Roberts (2008)
* [https://enduser.elsevier.com/farmmanagement A special issue of the "Journal of Environmental Management"] focuses on farm management and sustainable agriculture.
* [http://www.cefs.ncsu.edu/ Center for Environmental Farming Systems]
* [http://csanr.wsu.edu/ Center for Sustaining Agriculture & Natural Resources] (
* [http://www.biodynamics.net.au Biodynamic Agriculture Australia] Promoting the practice and understanding of the Biodynamic system of sustainable agriculture.
* [http://www.sare.org/ Sustainable Agriculture Research and Education (SARE) ]
* [http://www.attra.org/ National Sustainable Agriculture Information Service]
* [http://www.sustainableagriculture.net/ National Campaign for Sustainable Agriculture]
* http://www.saiplatform.org/ is an industry-based initiative promoting sustainable agriculture for the production of mainstream agricultural materials.
* [http://www.rainforest-alliance.org/programs/agriculture/ Rainforest Alliance's Sustainable Agriculture program]
* [http://www.verticalfarm.com The Vertical Farm Project] Envisioning the future of human food production as a mechanism for environmental restoration, protection from infectious disease, and a source of sustainable energy
* [http://www.oired.vt.edu/sanremcrsp/ SANREM CRSP] Sustainable Agriculture and Natural Resource Management Collaborative Research Support Program at Virginia Tech
* [http://www.landinstitute.org/ The Land Institute] Research on sustainable perennial crop systems
* [http://www.shdi.org Self Help Development International] SHDI is an Irish agency engaged in promoting long term sustainable development projects in Africa.
* [http://www.newwest.net/index.php/topic/main/C520/L40 Spade & Spoon: Localizing the Way Westerners Eat]
* [http://www.safecrop.org/ SAFECROP Centre for research and development of crop protection with low environment and consumer health impact]
* [http://www.iied.org/NR/agbioliv/index.html] Sustainable Agriculture, Biodiversity and Livelihoods Programme, part of the Natural Resources Group, International Institute for Environment and Development (IIED)
* [http://www.odi.org.uk/agriculture Research on Agriculture] and its' role in international development from the
Overseas Development Institute
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