Sustainable agriculture: Difference between revisions

Sustainable agriculture is the practice of farming using principles of ecology^W, the study of relationships between organisms and their environment. It has been defined as "an integrated system of plant and animal production practices having a site-specific application that will last over the long term:

• Satisfy human food and fiber needs
• Make the most efficient use of non-renewable resources^W 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.”^[1]

Sustainable Agriculture in the United States was addressed by the 1990 farm bill.^[2] More recently, as consumer and retail demand for sustainable products has risen, organizations such as Food Alliance and Protected Harvest^W have started to provide measurement standards and certification programs for what constitutes a sustainably grown crop.^[3]

Farming and Natural Resources

The physical aspects of sustainability are partly understood.^[4] Practices that can cause long-term damage to soil include excessive tillage^W (leading to erosion) and irrigation without adequate drainage (leading to salinization^W). Long-term experiments^W have provided some of the best data on how various practices affect soil properties essential to sustainability. There is a federal agency, USDA-Natural Resources Conservation Service that specializes in providing technical and financial assistance for those interested in pursuing natural resource conservation and production agriculture as compatible goals.

The most important factors for an individual site are sun, air, soil and water. Of the four, water and soil quality^W and quantity are most amenable to human intervention through time and labour.

Although air^W and sunlight^W are available everywhere on Earth^W, crops also depend on soil nutrients and the availability of water^W. When farmers grow and harvest^W crops, they remove some of these nutrients from the soil. Without replenishment, land suffers from nutrient depletion and becomes either unusable or suffers from reduced yields^W. 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:

1. recycling crop waste and livestock or treated human manure^W
2. growing legume^W crops and forages such as peanuts^W or alfalfa^W that form symbioses with nitrogen-fixing^W bacteria^W called rhizobia^W
3. industrial production of nitrogen by the Haber Process^W uses hydrogen, which is currently derived from natural gas, (but this hydrogen could instead be made by electrolysis^W of water using electricity (perhaps from solar cells or windmills)) or
4. 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 is only recently becoming feasible.^[5][6] Sustainable options for replacing other nutrient inputs (phosphorus, potassium, etc.) are more limited.

More realistic, and often overlooked, options include long-term crop rotations^W, returning to natural cycles that annually flood cultivated lands (returning lost nutrients indefinitely) such as the Flooding of the Nile^W, the long-term use of biochar, and use of crop and livestock landraces^W that are adapted to less than ideal conditions such as pests, drought, or lack of nutrients.

Crops that require high levels of soil nutrients can be cultivated in a more sustainable manner if certain fertilizer management practices are adhered to.

Water

In some areas, sufficient rainfall is available for crop growth, but many other areas require irrigation. For irrigation systems to be sustainable they require proper management (to avoid salinization) and must 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 submersible pumps^W combined with the development of drip irrigation and low pressure pivots have made it possible to regularly achieve high crop yields 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^W, the water is being used at a greater rate than its rate of recharge.

Several steps should be taken to develop drought-resistant farming systems even in "normal" years, including both policy and management actions: 1) improving water conservation and storage measures, 2) providing incentives for selection of drought-tolerant crop species, 3) using reduced-volume irrigation systems, 4) managing crops to reduce water loss, or 5) not planting at all.^[7]

Indicators for sustainable water resource development are: ¤ Internal renewable water resources. This is the average annual flow of rivers and groundwater generated from endogenous precipitation, after ensuring that there is no double counting. It represents the maximum amount of water resource produced within the boundaries of a country. This value, which is expressed as an average on a yearly basis, is invariant in time (except in the case of proved climate change). The indicator can be expressed in three different units: in absolute terms (km3/yr), in mm/yr (it is a measure of the humidity of the country), and as a function of population (m3/person per yr).

¤ Global renewable water resources. This is the sum of internal renewable water resources and incoming flow originating outside the country. Unlike internal resources, this value can vary with time if upstream development reduces water availability at the border. Treaties ensuring a specific flow to be reserved from upstream to downstream countries may be taken into account in the computation of global water resources in both countries.

¤ Dependency ratio. This is the proportion of the global renewable water resources originating outside the country, expressed in percentage. It is an expression of the level to which the water resources of a country depend on neighbouring countries.

¤ Water withdrawal. In view of the limitations described above, only gross water withdrawal can be computed systematically on a country basis as a measure of water use. Absolute or per-person value of yearly water withdrawal gives a measure of the importance of water in the country's economy. When expressed in percentage of water resources, it shows the degree of pressure on water resources. A rough estimate shows that if water withdrawal exceeds a quarter of global renewable water resources of a country, water can be considered a limiting factor to development and, reciprocally, the pressure on water resources can have a direct impact on all sectors, from agriculture to environment and fisheries.^[8]

Soil

Soil erosion is fast becoming one of the worlds greatest problems. It is estimated that "more than a thousand million tonnes of southern Africa's soil are eroded every year. Experts predict that crop yields will be halved within thirty to fifty years if erosion continues at present rates."^[9] Soil erosion is not unique to Africa but is occurring worldwide. The phenomenon is being called Peak Soil as present large scale factory farming techniques are jeopardizing humanity's ability to grow food in the present and in the future.^[10] Without efforts to improve soil management practices, the availability of arable soil^W will become increasingly problematic.^[11]

Some Soil Management techniques

1. No-till farming
2. Keyline design^W
3. Growing wind breaks^W to hold the soil
4. Incorporating organic matter back into fields
5. Stop using chemical fertilizers^W (which contain salt)
6. Protecting soil from water runoff

Economics

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.^[12] The Oxford Sustainable Group^W defines sustainability in this context in a much broader form, considering effect on all stakeholders in a 360 degree approach

Given the finite supply of natural resources^W at 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^W, such as pollution as well as financial and production costs.

The way that crops are sold^W must be accounted for in the sustainability equation^W. Food sold locally does not require additional energy for transportation (including consumers). Food sold at a remote location, whether at a farmers' market or the supermarket^W, incurs a different set of energy cost for materials, labour^W, and transport.

Methods

What grows where and how it is grown are a matter of choice. Two of the many possible practices of sustainable agriculture are crop rotation^W and soil amendment^W, both designed to ensure that crops being cultivated can obtain the necessary nutrients^W for healthy growth. Soil amendments would include using locally available compost from community recycling centers. These community recycling centers help produce the compost needed by the local organic farms.

Many scientists, farmers, and businesses have debated how to make agriculture sustainable. Using community recycling from yard and kitchen waste utilizes a local area's commonly available resources. These resources in the past were thrown away into large waste disposal sites, are now used to produce low cost organic compost for organic farming. Other 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.^[13] This system would result in increased resistance to diseases and decreased effects of erosion and loss of nutrients in soil. Nitrogen fixation^W from 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.

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. Today it is realized to get around this problem local cities and farms can work together to produce the needed compost for the farmers around them. This combined with growing a mixture of crops (polyculture) sometimes reduces disease or pest problems ^[14] but polyculture has rarely, if ever, been compared to the more widespread practice of growing different crops in successive years (crop rotation^W) with the same overall crop diversity^W. 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 reduces the genetic diversity found in wildlife and makes the organisms susceptible to widespread disease. The Great Irish Famine (1845–1849) is a well-known example of the dangers of monoculture. 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. Today the growth of local farmers' markets offer small farms the ability to sell the products that they have grown back to the cities that they got the recycled compost from. By using local recycling this will help move people away from the slash-and-burn^W techniques that are the characteristic feature of shifting cultivators^W are often cited as inherently destructive, yet slash-and-burn cultivation has been practiced in the Amazon for at least 6000 years;^[15] serious deforestation did not begin until the 1970s, largely as the result of Brazilian government programs and policies.^[16] To note that it may not have been slash-and-burn so much as slash-and-char^W, which with the addition of organic matter produces terra preta^W, 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^W, lowering stock density, and moving the stock between paddocks frequently.^[17]

Several attempts have been made to produce an artificial meat, using isolated tissues to produce it in vitro^W; Jason Matheny^W's work on this topic, which in the New Harvest^W project, is one of the most commented.^[18]

Soil treatment

Soil steaming^W can be used as an ecological alternative to chemicals for soil sterilization. Different methods are available to induce steam into the soil in order to kill pests and increase soil health. Community and farm composting of kitchen, yard, and farm organic waste can provide most if not all the required needs of local farms. This composting could potentially be a reliable source of energy.

Off-farm impacts

A farm that is able to "produce perpetually", yet has negative effects on environmental quality elsewhere is not sustainable agriculture. An example of a case in which a global view may be warranted is over-application of synthetic fertilizer or animal manures^W, which can improve productivity of a farm but can pollute nearby rivers and coastal waters (eutrophication). The other extreme can also be undesirable, as the problem of low crop yields due to exhaustion of nutrients in the soil has been related to rainforest^W destruction, as in the case of slash and burn^W farming for livestock feed.

Sustainability affects overall production, which must increase to meet the increasing food and fiber requirements as the world's human population expands to a projected 9.3 billion people by 2050^W. Increased production may come from creating new farmland, which may ameliorate carbon dioxide emissions if done through reclamation of desert as in Palestine^W, or may worsen emissions if done through slash and burn^W farming, as in Brazil^W. Additionally, Genetically modified organism^W crops show promise for radically increasing crop yields, although many people and governments are apprehensive of this new farming method.

Some advocates favour sustainable agriculture as the only system which can be sustained over the long-term. However, organic production methods, especially in transition, yield less than their conventional counterparts and raise the same problems of sustaining populations globally.

Urban planning

There has been considerable debate about which form of human residential habitat may be a better social form for sustainable agriculture.

Many environmentalists advocate urban developments with high population density as a way of preserving agricultural land and maximizing energy efficiency. However, others have theorized that sustainable ecocities, or ecovillages which combine habitation and farming with close proximity between producers and consumers, may provide greater sustainability.

The use of available city space (e.g., rooftop gardens^W, community gardens, garden sharing^W, and other forms of urban agriculture for cooperative food production is another way to achieve greater sustainability.

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 reduces transportation costs. 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 population.^[19]

See also

• Agroforestry
• Aquaponics
• Biomass
• Composting
• Ecological sanitation

• Forest gardening
• How to practice sustainable agriculture
• List of sustainable agriculture topics
• Organic farming

• Organic food
• Permaculture
• Sustainable development
• Urban agriculture

References

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Sources

• Dore, J. 1997. Sustainability Indicators for Agriculture: Introductory Guide to Regional/National and On-farm Indicators, Rural Industries Research and Development Corporation, Australia.
• Gold, Mary. 1999. Sustainable Agriculture: Definitions and Terms. Special Reference Briefs Series no. SRB 99-02 Updates SRB 94-5 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.
• Dedicated double issue of Philosophical Transactions B on Sustainable Agriculture. Some articles are freely available.

Further reading

• Laki, G. (2002): Added value as the basis of sustainable agriculture’s subsidy system. In: (Eds. Trebicky, V. - Novak, J.) "Rio+10 Transition from Centrally Planned Economy to Sustainable Society? (Visegrad Agenda 21)", Institute for Environmental Policy, Prague, 2002, 49. p.
• Laki, G., Szakál, F. (2002): Added Value as a key indicator for sustainable agriculture. In: A mezőgazdasági termelés és erőforrás-hasznosítás ökonómiája - VIII. Nemzetközi Agrárökonómiai Tudományos Napok, SZIE Gazdálkodási és Mezőgazdasági Főiskolai Kar, Gyöngyös, 6 p.
• Madden, Patrick (March/April 1986). "Debt-Free Farming is Possible". Farm Economics (Pennsylvania: Cooperative Extension Service, U.S. Dept. of Agriculture [and] The Pennsylvania State University). ISSN 0555-9456
• Pender J., Place F., Ehui S. (2006) Strategies for Sustainable Land Management in the East African Highlands
• Pollan M. (2007) The Omnivore's Dilemma: A Natural History of Four Meals by
• Roberts W. (2008) The No-Nonsense Guide to World Food by Roberts W. (2008)

External links

• Africa Project 2020 An Effort to Eradicate Hunger in Africa by empowering Farmers through Sustainable Agriculture.
• Agricultural Sustainability Institute at UC Davis
• Biodynamic Agriculture Australia Promoting the practice and understanding of the Biodynamic system of sustainable agriculture.
• Center for Environmental Farming Systems
• WSU Center for Sustaining Agriculture & Natural Resources
• Food Alliance The most credible and comprehensive certification for sustainable agriculture and food handling in North America.
• A special issue of the Journal of Environmental Management focuses on farm management and sustainable agriculture.
• Greenpeace Sustainable Agriculture campaign
• The Land Institute Research on sustainable perennial crop systems
• National Sustainable Agriculture Information Service
• National Campaign for Sustainable Agriculture
• What is Sustainable Agriculture? (from SAREP: University of California Sustainable Agriculture Research and Education Program)
• Sustainable Agriculture Research and Education (SARE)
• SAREP: University of California Sustainable Agriculture Research and Education Program
• Sustainable Commodity Initiative
• Industry-based initiative promoting sustainable agriculture for the production of mainstream agricultural materials
• Rainforest Alliance's Sustainable Agriculture program
• 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
• SANREM CRSP Sustainable Agriculture and Natural Resource Management Collaborative Research Support Program at Virginia Tech
• Self Help Development International SHDI is an Irish agency engaged in promoting long term sustainable development projects in Africa.
• Spade & Spoon: Localizing the Way Westerners Eat
• SAFECROP Centre for research and development of crop protection with low environment and consumer health impact
• Sustainable Agriculture, Biodiversity and Livelihoods Programme, part of the Natural Resources Group, International Institute for Environment and Development (IIED)
• Research on Agriculture and its role in international development from the Overseas Development Institute
• A Natural Step Case Study: Planning for the future harvest: Sustainability in the food industry - The Organically Grown Company
• Sustainable Agriculture Portal on WiserEarth
• List of Sustainable Agriculture Organizations on WiserEarth
• Center for Sustainable Energy Farming

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