Can I use compost?

Yes! The use of compost is encouraged. The Organic Materials Review Institute (OMRI) and the Washington State Department of Agriculture (WSDA) both maintain lists of approved compost suppliers. You can also use MyCCOF: Materials Search to find and add materials approved for use in organic production or to request the review of a material you would like to use.

Manure-based composts must be produced according to NOP regulations in order to be considered compost. Composts composed entirely of plant-based materials are considered mulch and are generally not subject to restrictions on their use or production.

The NOP requires that compost containing manure be produced following one of these methods:

  • Compost must maintain a temperature of between 131° F and 170° F for three days using an in-vessel or static pile system.

     OR,

  • Maintain a temperature of between 131° F and 170° F for 15 days using a windrow composting system, during which time the materials must be turned a minimum of five times.

If the compost does not meet these requirements, it is considered “raw manure.” Raw manure must be incorporated into the soil no less than 120 days prior to the harvest of a product whose edible portion touches the soil (such as lettuce) or incorporated into the soil no less than 90 days prior to the harvest of a product whose edible portion does not touch the soil (such as corn). Application timing and compost production methods will be verified to these restrictions during annual inspections.