Sustainable agriculture refers to how well a farm indefinitely produces food. Also taken into account is the amount of severe or irreversible damage the farm inflicts on the ecosystem. There are two important issues involved in sustainable agriculture:
• Biophysical- The long term effects of the various techniques and practices used on the soils in the process of creating essential crop productivity.
• Socio-Economic- The long-term ability of farmers to obtain inputs as well as to manage other farming resources such as labor.
These physical aspects of sustainable agriculture are only partially understood. Negative practices are those that cause long-term damage to the soil which include erosion causing tillage, and poorly drained irrigation which can lead to excessive salt buildup in the soil.
Sustainable agriculture crops rely on more than just air and sunlight but also on soil nutrients and readily available water. During the harvesting of crops, farmers remove some of the nutrients from the soil. Later on it is necessary for the soil to be replenished. Without replenishment, the land suffers from nutrient depletion and becomes either completely unusable or suffers from reduced yields. Sustainable agriculture is dependent upon replenishing the soil while it minimizes the use of non-renewable resources like natural gas or mineral ores.
Nitrogen is a key nutrient in soils and needs replenishing. There are many ways to assist in the process. The following ideas have become very popular:
1. Recycling crop waste as well as livestock and human manure.
2. Growing legume crops and forages such as peanuts form a mutually beneficial relationship with nitrogen-fixing bacteria called rhizobia.
3. Nitrogen can be produced industrially using a technique called the Haber process.
4. Genetically engineer non-legume crops to form nitrogen-fixing bacteria or to fix nitrogen without microbial action at all.
Water is another nutrient that obviously needs replenishing. In some areas sufficient rainfall is available for crop re-growth but many others require irrigation. It is necessary that proper drainage is developed to avoid salination. The systems must also use water from a source that is naturally replenished otherwise the water sources becomes a non-renewable source.
Finally, sustainable agriculture integrates three main goals: environmental stewardship, farm profitability, and prosperous farming communities.
1. Environmental stewardship is an ethic that plans and manages environmental resources. This is to prevent the loss of habitat and facilitate its recovery in the interest of long-term sustainability. According to the EPA, environmental stewardship is the responsibility for environmental quality shared by all those whose actions affect the environment.
2. Farm profitability is the way that crops are sold must be accounted for in the sustainability equation. Food sold 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’ market or the supermarket, incurs a different set of energy cost for materials, labor, and transport.
3. Prosperous farming communities refer to locations with the large amounts of farming land, where the farmers work in unison to benefit the environment.