On April 30, 2019, the USDA Agricultural Marketing Service published an amendment to the National List of Allowed and Prohibited Substances (National List). This updated rule added elemental sulfur to the National List for use in organic livestock production and reclassifies potassium acid tartrate from a non-agricultural substance to an agricultural substance, which requires the use of the organic form when the ingredient isnu2019t commercially available. The rule is effective May 30, 2019. Operations with potassium acid tartrate on their material list will be notified separately.