Sustainable agricultural practices are increasingly needed to feed the hungry billions as Earth’s population grows. “Sustainable” refers to a farm’s ability to continue to produce crops without damaging or depleting the ecosystem. Ecosystem damage may occur from erosion, the overuse of synthetic fertilizers and pesticides, groundwater depletion, reduction of soil nutrients and micro-organisms, the loss of pollinating agents (bees and butterflies), lowered resistance to disease through extensive reliance on a single plant (Great Irish Famine 1845-1849), or the accumulation of salt in the soil due to inadequate drainage while using irrigation.

When farmers grow and harvest crops, they remove nutrients from the soil. Without replenishment, their land will suffer from nutrient depletion and be unusable for further farming. Sustainable agriculture thus depends on replenishing the soil while minimizing the loss of non-renewable resources used to create synthetic fertilizers and soil supplements. Recycling crop waste, using livestock or human manure, or growing legume crops and forages such as peanuts or alfalfa that form symbioses with nitrogen-fixing bacteria are possible solutions.

The way that crops are distributed must be factored into the sustainability equation.