Science Fair Project Encyclopedia
Sustainable agriculture integrates three main goals: environmental stewardship, farm profitability, and prosperous farming communities. These goals have been defined by a variety of philosophies, policies and practices, from the vision of farmers and consumers.
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 grow. 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, they 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 soil are easily exhausted. Anything that has to be imported, like fertilizer for plants, or petroleum products to run machinery, reduces sustainability because of its reliance on non-renewable resources. The less the farm needs outside inputs to maintain production levels, the greater its level of sustainability.
Suggestions for replenishing the nutrients in soil include recycling crop residues and livestock manure, which usually have nutrients, into the soil. Farm labor, by animals or farmers themselves, is another form of energy recycling if they were fed by the food that they have grown and harvested.
From an environmental perspective, given the finite supply of natural resources, agriculture that is inefficient - low on the sustainability scale - will eventually run out of 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 any by-products of production, such as pollution, financial and production costs. Agriculture that relies mainly on outside inputs 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 then must 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, like 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 participates leads to greater costs and greater reliance on importations of externals to fund the resulting increase in energy consumption. Such as system may be more vulnerable to fluctuation in prices of external material it must import, such as the price of oil.
In a social context, the approaches required for higher sustainability profoundly affect business methods and our way of life. It is believed that current large-scale agricultural practices are not conducive to the goals of sustainable agriculture. Progressing toward sustainability would require significant changes in agriculture practices by such corporations engaged in agribusiness.
From a system's view, the gain and loss factors for sustainability can be listed. The most important factors to an individual site are sun, soil and water as rainfall. These are naturally present in the system as part of the larger planetary processes, thus incur no costs. Of the three, the soil quality and quantity are most amiable to human intervention, through time and labour. (The economic input depends solely on the price of labour, the time on the cost of machinery.)
Natural growth and outputs are also under control of human intervention. What grows, how and where it is grown can be chosen by an individual. Two of the many possible practices of sustainable agriculture are crop rotation and soil amendments, 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 unsustainable because of the required effort from outside resources to maintain annual growth. Outside resources include the use of chemical pesticide, synthesized fertilizers. Moreover, monocultural farming method can deplete the land of other natural resources, and increase the salinity of the soil, rendering the field unfit for further farming.
Pesticides, though beneficial and sometimes necessary in the shorter term, can harm the soil food web, a complex ecology of micro-organisms in soil that help sustain the plant from the roots down. Experiments growing plants in soil compared with growing plants through hydroponics method have shown a 33% higher growth when there are beneficial soil microorganisms available.
Moreover, 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. Growing cacao tree and harvesting cacao beans and growing vanilla are examples of such labor-intensive practices without the benefits 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 crop diseases and crop failure. The Irish potato famine illustrates 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 possible 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 natural environments, resulting in increased resistance to diseases and decrease in effects of erosion and loss of nutrients in soil. Nitrogen fixation from legumes, for example, used in conjunction with other 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 population density to preserve agricultural land point out that urban sprawl is more damaging to the overall environment and unsustainable than living in the cities where cars are generally not needed because food and other necessities are within walking distance. However, other environmentalists have proposed that a sustainable ecocities, a combination of cities and farming side by side, to maintain close proximity between the producers and the consumers may be a better practice.
Ultimately, the use of available city space (e.g., rooftop and community gardens) for cooperative food production may be a way to achieve greater sustainability.
- organic farming
- organic movement
- sustainable development
- The Natural Step
- List of sustainable agriculture topics
- Sustainable Agriculture Research and Education
- National Sustainable Agriculture Information Service
- SANET-MG, a discussion group about sustainable agriculture
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