NRCS Compost Test Suite

NRCS Certified Compost Test

Definition of Compost

Knowing what compost is (and what it’s not) is an important first step in ensuring that you use compost in the best way possible. Below is the official definition for what can be considered compost.

Compost - is the product manufactured through the controlled aerobic, biological decomposition of biodegradable materials. The product has undergone mesophilic and thermophilic temperatures, which significantly reduces the viability of pathogens and weed seeds (in accordance with EPA 40 CFR 503 standards) and stabilizes the carbon such that it is beneficial to plant growth. Compost is typically used as a soil amendment, but may also contribute plant nutrients. (AAPFCO definition, official 2018) Finished compost is typically screened to reduce its particle size, to improve soil incorporation.

Related and Allowable Products

1. Vermicompost/Worm castings for which all feedstocks have been composted prior to it utilized as worm bedding or feed, and the final product meets EPA 40 CFR 503 standards;
2. Digested solids (materials anaerobically digested) that have been composted after removal from the digester and which the final product meets EPA 40 CFR 503 standards; or
3. Any other substance that undergoes composting and is similar to Compost Product(s) in appearance, application and performance may apply to be considered by the STA Advisory Committee on a case by case basis.
   

1. Composted Mulch – Compost of a coarser particle size, containing a larger percentage of composted wood particles, and that meets the STA Program rules. The product is commonly used on the surface of the soil.
2. Erosion Control Compost – Compost of a coarser particle size, containing a larger percentage of composted wood particles, and that meets the STA Program rules, and meets user defined specifications related to particle size distribution. The product is commonly used as an erosion control blanket, berm, or sock media.
3. Soil Remediation / Storm water Management Compost – Compost of a coarser particle size, containing a larger percentage of composted wood particles, and that meets the STA Program rules, and meets user defined specifications related to particle size distribution. The product is commonly used in soil incorporation in soil remediation and storm water management applications.

Frequent Testing

Testing compost often is key to staying on top of understanding a product that is constantly evolving.
Manufacturers who produce:

Over 17,501 wet tons / year must test monthly
17,500 to 6,201 wet tons / year must test every two months
Under 6,200 wet tons / year must test every three months

Turnaround Time is 10 Business Days