Standards for Compost
What are OMRI review standards for compost products?
Applications for compost products must include lab results for pathogens and heavy metals. Composts which have levels above the pathogen threshold will be listed as Allowed with Restrictions in the Category: Manure-raw. Composts which do not meet the heavy metal requirements may receive a caution statement, or may not be eligible for OMRI Listing. For information about maximum allowable levels of pathogens or heavy metals see the Review Standards for Lab Analyses information sheet in your Application Kit (you need to be logged in to the OMRI website to follow the link provided). Depending on the compost type, additional requirements may apply. See compost requirements by category on pages 80-81 of the OMRI Generic Materials section of the OMRI Policy and Standards Manual and in the table below.
If you have ordered an Application Kit, then you can login to the website and access advanced application support materials such as a completed Sample Compost Application. The Sample Compost Application is an excellent reference for applicants applying for a product review of a compost product.
| Table of Compost Categories for Comparison | |||||
| OMRI Listed Category | OMRI Listed Status | Feedstocks | Time at Temperature 131-170°F | Turning Frequency | C:N Ratio of initial uncomposted feedstocks
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| Compost – in-vessel or static aerated pile (plant and animal materials)
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Allowed | Plant and/or animal materials | 3 days | n/a | Between 25:1-40:1 |
| Compost – windrow | Allowed | Plant and/or animal materials | 15 days | 5 times in 15 days | Between 25:1-40:1 |
| Compost – plant materials | Allowed | Plant materials only | 3 days | Periodic | n/a |
| Compost – other | Allowed | Plant and/or animal materials | 3 days | Periodic | n/a |