This advanced notice of proposed rulemaking (ANPR) requests comments on options for updating the USDA organic regulations for compost used in organic agriculture. Compost is a soil amendment made from the microbial breakdown of plant and animal feedstock materials. Current USDA organic regulations prohibit compost that contains intentionally added synthetic substances that are not allowed on the National List of Allowed and Prohibited Substances (National List).

In 2023, AMS received a petition for rulemaking to allow synthetic compostable plastics as compost feedstocks and allow de minimis traces of contamination in compost. AMS has also received multiple recommendations from the National Organic Standards Board (Board) between 2024 and 2026 on the topic of compost and the issues raised by the petition. The Board has also provided recommendations between 2025 and 2026 on related issues of residue testing and unintended contamination.

The ANPR would outline the potential rulemaking options based on the petition, the Board’s recommendations, and AMS’s analysis of the petition and recommendations. Three options that would be presented are: 1) implementing the petition for rulemaking, 2) implementing the Board’s recommendations, and 3) adjusting the regulations to distinguish between unintentional and intentional additions of synthetic substances in compost. The third option would explicitly allow de minimis traces of unintentional contaminants in organic compost (and fertilizers), while continuing to require that each intentionally added, synthetic compost feedstock be listed as allowed on the National List. In addition to requesting comments on the three options, the ANPR would request information on the organic compost market that would inform potential rulemaking.