Sustainable agriculture
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Sustainable agriculture integrates three main goals: environmental stewardship, farm profitability, and prosperous farming communities. These goals have been defined by a variety of disciplines and may be looked at from the vantage point of the farmer or the consumer.
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Sustainable agriculture described
Sustainable agriculture refers to the ability of a farm to continue producing indefinitely, with a minimum of outside inputs. Crops depend on nutrients from soil, air, water, and sunlight to produce the foodstuff that human beings need to live. When farmers harvest crops, they take what crops have produced from the resources available to them. These resources must be replenished to allow the production cycle to continue. Otherwise, the resources would be exhausted and the land would be unusable for further farming. Although resources like the sun, air, and rain are generally available in most geographic locations, nutrients in the soil are easily exhausted. Adding off-farm inputs, such as fertilizer for plants, or petroleum products to run machinery, reduces sustainability due to a reliance on non-renewable resources. The fewer outside inputs the farm needs to maintain production levels, the greater its sustainability.
Nutrients in the soil may be replenished through recycling of crop residues and livestock manure, with their nutrients, into the soil. Labor, by animals or farmers, is another form of energy recycling, if they are fed with the food grown and harvested from the farm.
From an environmental perspective, given the finite supply of natural resources, agriculture that is inefficient—low on the sustainability scale—will eventually exhaust the available resources, or the ability to afford them, and cease to be viable as a farming method. It will also generate negative externality, an economic term for by-products of production, such as pollution, financial and production costs. Agriculture that relies mainly on inputs that are extracted from the Earth's crust or produced by society (see the natural step), contributes to the depletion and degradation of the environment.
Economics of sustainable agriculture
In an economic context, the farm must generate revenue to acquire things that cannot be produced directly. The way that crops are sold must then be accounted for in the sustainability equation. Fresh food sold from a farm stand requires little additional energy, beyond cultivation and harvest, though the cost of consumers' transport to the site must be included. Food that is packaged and sold at a remote location, such as a farmers' market, incurs a greater energy cost for materials, labour, transport, and so forth. A more complex the economic system in which the farm producer is just the first link in a long chain of processors and handlers leads to greater costs and greater reliance on the use of externals to fund the resulting increase in energy consumption. Such as system is vulnerable to fluctuation in prices of external materials imported, (e.g., oil).
In a social context, the actions required for greater sustainability profoundly affect business methods and lifestyle. Current large-scale agricultural practices are inefficient and not conducive to sustainability. Progressing toward sustainability will require significant changes in agricultural practices by corporations engaged in agribusiness.
From a system's view, the gain and loss factors for sustainability can be listed. The most important factors for an individual site are sun, soil and water as rainfall. These are naturally present in the system as part of the larger planetary processes, and thus incur no costs. Of the three, soil quality and quantity are most amenable to human intervention through time and labour. (The economic input depends solely on the price of labour and cost of machinery used).
Natural growth and outputs are also subject to human intervention. 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 rotation and soil amendment, both designed to ensure that crops being cultivated will obtain all the necessary nutrients for healthy growth.
Methods of sustainable agriculture
Monoculture, a method of growing one crop in a field annually, is generally considered to be unsustainable due to the outside resources required to maintain annual growth. Such resources include the use of chemical pesticides and synthesized fertilizers. Monocultural farming methods can also deplete the land of other natural resources and increase the salinity of the soil, rendering a field unfit for further farming.
Pesticides, though sometimes necessary in the short term, can harm the soil food web, a complex ecology of micro-organisms in soil that helps sustain the plant from the roots down. Experiments comparing plants grown in soil compared to plants grown through hydroponics have shown a thirty-three percent higher growth rate when there are beneficial soil microorganisms available.
Certain pesticides synthesized by chemical companies can impart a sometimes fatal toxicity to humans, livestock and insect pollinators, such as bees and butterflies, which may be necessary for plant success. Without insect pollinators, farm labor must be expended to manually pollinate each plant. Crops such as cacao beans and vanilla are examples of crops requiring highly labor-intensive practices in the absence of natural pollinators.
Throughout history, farmers seeking to grow crops usually confine themselves to growing only the fastest and most productive plants. Such practices can result in growing crops without the genetic diversity found in wildlife. Without such diversity in the genes, crops may become more susceptible to disease and crop failure. The Irish potato famine is a well-known example of the dangers of monocultural and mono-varietal crop cultivation.
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 replicate the biodiversity already found in a natural environment, resulting in increased resistance to diseases and decreased effects of erosion and loss of nutrients in soil. Nitrogen fixation from legumes, for example, used in conjunction with plants that rely on nitrate from soil for growth, will 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. This method is considered to require a minimal amount of outside resources.
In practice, there is no single approach to sustainable agriculture, as the precise goals and methods must be adapted to each individual case.
The city and sustainable agriculture
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 sustainablity in that such communites tend to provide a cooperative environment that supports farming.
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 distance. However, others have theorized that a 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 and community gardens) for cooperative food production is another way to achieve greater sustainability.
See Also
- Agriculture
- Agroecology
- Biodynamic agriculture
- Organic farming
- Organic movement
- Permaculture
- Polyculture
- Reconciliation Ecology
- Sustainable development
- The Natural Step
- List of sustainable agriculture topics
External Links
- Biodynamic Agriculture Australia (http://www.biodynamics.net.au) Promoting the practice and understanding of the Biodynamic system of sustainable agriculture.
- Sustainable Agriculture Research and Education (http://www.sare.org/)
- National Sustainable Agriculture Information Service (http://www.attra.org/)
- SANET-MG (http://lists.sare.org/archives/sanet-mg.html), a discussion group about sustainable agriculturefr:agriculture durable