Overview of Organic Agriculture
Organic Farming Management Practices
The USDA organic regulations describe organic agriculture as the application of a set of cultural, biological, and mechanical practices that support the cycling of on-farm resources, promote ecological balance, and conserve biodiversity. These include maintaining or enhancing soil and water quality; conserving wetlands, woodlands, and wildlife; and avoiding use of synthetic fertilizers, sewage sludge, irradiation, and genetic engineering. Organic producers use natural processes and materials when developing farming systems—these contribute to soil, crop nutrition, pest and weed management, attainment of production goals, and conservation of biological diversity. The following list of tools and practices is not intended to be comprehensive, though the primary organic crop production practices are addressed. Note, too, that each farm operation will employ its own combination of tools and practices to build a working organic system. There is no simple cookbook formula for combining them in ideal proportions.
Crop rotation is a system of growing different kinds of crops in recurrent succession on the same land.
Green Manures and Cover Crops
Green manures and cover crops are grown primarily for reasons other than short-term economic gain. In other words, they are not produced for sale, but rather for the benefits they provide to the production of subsequent cash crops. Cover crops are so-called because they protect otherwise bare soil against erosion; green manures improve soil fertility. Because a cover crop is inevitably added to the soil, it becomes a green manure, so the terms are reasonably interchangeable.
Manuring and Composting
Manure and compost not only supply many nutrients for crop production, including micronutrients, but they are also valuable sources of organic matter.
Intercropping and Companion Planting
Intercropping is the growing of two or more crops in close proximity to promote beneficial interactions. Companion planting refers to the establishment of two or more species in close proximity so that some cultural benefit, such as pest control or increased yield, may be achieved between them.
Biological Pest Control
Biological pest control is the use of one or more beneficial orgaismes, usually called natural enemies, to reduce the numbers of another type of organism, the pest.
Sanitation can take on many forms including removal, burning, or deep plowing of crop residues that could carry plant disease or insect pest agents, the destruction of nearby weedy habitats that shelter pests, cleaning accumulated weed seeds from farm equipment before entering a new, and sterilizing pruning tools.
Merely maintaining soil organic matter levels is difficult if soil is intensively tilled (such as with annual use of a moldboard plow.) Reducing tillage means leaving more residue, and tilling less often and less intensively than conventional tillage. No-till is the most extreme version of reduced tillage, but is not desirable on some soils and is not the only way to conserve soil organic matter.
Organic mulches, such as straw or spoiled hay, can reduce the need for cultivation, protect soil from erosion and crusting, and replenish organic matter.
Organic farming management relies on developing biological diversity in the field to disrupt habitat for pest organisms, and the purposeful maintenance and replenishment of soil fertility. Organic farmers are not allowed to use synthetic pesticides or fertilizers.
This term refers to synthetic, organic, or inorganic pesticides that are both low toxicity and exhibit a very low impact on the environment. "Biorationals" also have minimal impact on species for which they are not intended (called non-target species). Biorational pesticides include oils, insecticidal soaps, microbials (such as Bacillus thurengienesis and entomopathogenic nematodes), botanicals (plant-based) and insect growth regulators.
Buffers and Barriers
In the context of organically managed systems, buffer and barriers are required under NOP rules if there is a risk of contamination, via drift or flow, of substances not allowed under organic regulations.
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