Chapter 10

Compost Management on Organic Farms

National Organic Program Standards

The National Organic Program (NOP) final rule (United States Department of Agriculture [USDA], 2000) states that any plant and animal material can be composted for organic production, provided that it does not contain any synthetic substances prohibited by the National List or any incidental residues that would lead to contamination. However, recognizing that background levels of pesticides are present in the environment (referred to as unavoidable residual environmental contamination—UREC—in the regulations) and may be present in organic production systems, NOP regulation does not mandate zero tolerance for synthetic pesticide residues in inputs, such as compost. Such materials may be used for organic production provided any residual pesticides do not contribute to contamination of crops, soil, or water. Of course, it is the responsibility of the organic producer—assisted by the certifying organization—to make sure that any amendment added to the soil has been approved for organic production. All manure and compost sources and management techniques must be clearly documented as part of the certification process.

NOP Standards on Compost Used for Crop Production

Composted plant and animal manures (§ 205.203(c)(2)) are those that are produced by a process that: (i) established an initial carbon-to-nitrogen (C:N) ratio of between 25:1 and 40:1; and (ii) maintained a temperature of 131 to 170 degrees F (50 to 77°C) for 3 days using an in-vessel or static aerated pile system; or (iii) a temperature of between 131 and 170 degrees F for 15 days using a windrow composting system, during which period, the materials must be turned a minimum of five times. Records documenting compost production methods must be maintained for on-farm produced compost as well as for compost obtained from an outside source. Growers should verify that the compost supplier is following all of the current NOP regulations, and that the accredited certifying agency will approve that compost for organic production.

Vermicompost

Vermicomposting is a process that relies on earthworms and microorganisms to help stabilize active organic materials and convert them to a valuable soil amendment and source of plant nutrients. Vermicompost can be used without restriction for organic production of crops not intended for human consumption provided the feedstocks meet the requirements listed above.

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