Ask a Specialist Answer
Can I use compost from my county’s composting program on my organic farm?
Municipal compost is becoming more common as communities switch to composting yard and kitchen waste instead of sending it to a landfill. The National Organic Standards separates compost in two groups: one that might contain fecal matter from animals or humans, and one that does not. Within each group, the compost must meet specific criteria to qualify for use on organic farms.
Compost that might contain manure must meet the composition, temperature and turning specifications in the National Organic Standards:
(i) Established an initial C:N ratio of between 25:1 and 40:1; and
(ii) Maintained a temperature of between 131 °F and 170 °F for 3 days using an in-vessel or static aerated pile system; or
(iii) Maintained a temperature of between 131 °F and 170 °F for 15 days using a windrow composting system, during which period, the materials must be turned a minimum of 5 times.
The county/city must provide the documentation to show these standards were met before you can use a material as compost. If they cannot prove they have met these standards, it may be possible to still use it, but it will not be considered compost, it will be considered raw manure, and will have different handling requirements:
1) Raw animal manure, which must be composted unless it is:
(i) Applied to land used for a crop not intended for human consumption;
(ii) Incorporated into the soil not less than 120 days prior to the harvest of a product whose edible portion has direct contact with the soil surface or soil particles; or
(iii) Incorporated into the soil not less than 90 days prior to the harvest of a product whose edible portion does not have direct contact with the soil surface or soil particles;
Composted and un-composted plant materials without manure have no application restrictions, but the composting center must verify that the compost contains only 100% plant materials. If there is a possibility that it contains pet waste (animal manure) then it must be handled as raw manure.
Whether or not it contains animal manure, you still must make sure compost contains no prohibited materials:
- Recycled building materials/lumber (due to paints, varnishes and glues)
- Human waste
- Plastics and other un-compostable synthetics
Check with the composting facility to see if they have the necessary documentation. If other organic farmers have been using their product, it is quite likely they have this paperwork on hand. Also check with your certification agency, which can do a product review if it has not already reviewed this compost for other farmers. Ultimately, your certifier makes the final call on whether a product is allowed or not. All new inputs should always be verified and added to your crop input list before use.
Posted: Jul 2017
Answer By: Joe Pedretti