STA’s Response to Persistent Herbicide Challenge

The existence and use of persistent herbicides in horticulture have, for several years, presented a challenge to the composting industry’s reputation.

The USCC is taking many approaches to tackling the persistent herbicide issue: forming a task force, creating information sheets, supporting research into affordable lab test methods, applying for grants to support education/research/policy efforts, soliciting case study information, directly communicating with the EPA, and opposing the EPA’s renewal of specific key problematic persistent herbicides. Additionally, enhancing the USCC’s information disclosure program housed within the USCC’s Seal of Testing Assurance (STA) Certified Compost program is underway as a vital initiative.

STA Certified Compost is a contractually-based information disclosure program (i.e., manufacturers’ accountability). Compost manufacturers in this program must meet the USCC’s definition of compost, test their compost frequently on a program-defined sampling procedure and schedule, and share their feedstocks and results with their customers. They must be permitted (as required) and in compliance with all permit requirements, use only STA-contracted labs that are subject to routine proficiency testing, employ specified lab Test Methods for the Examination of Composting & Compost (TMECC), and meet EPA requirements for product safety (pathogens and trace metals).

STA testing currently includes not only meeting test result requirements for EPA standards for safety (pathogens and trace metals) but also disclosing test results for other parameters such as pH, primary plant nutrients, moisture content, organic matter content, particle size, stability, soluble salts content and maturity.

The STA program provides specifiers and end users with consistent data on a compost product for their own evaluation. As is the case for virtually all composts, there is no warranty on performance or suitability associated with the use of STA Certified Compost. There are many uses for compost, and end users each have different applications and expectations. The STA Certified Compost program requires that test results are disclosed to specifiers, purchasers and/or end users so that they can decide if the unique compost in front of them fits their specific project requirements. Using the STA Certified Compost test data, along with an appropriate specification, has helped compost be utilized properly on numerous projects.

The Compost Consumer Use Program (CCUP) option of the STA Certified Compost Program is meant for supporting specific uses – currently – lawns, flowers, vegetables, trees, and shrubs. The CCUP program has requirements for test results to meet more standards than just for pathogens and metals. The CCUP program requires that STA test results for a specific product stay within defined ranges for stability, maturity, moisture content, organic matter content, particle size, pH, soluble salts, and physical contaminants.

The US Composting Council continually works to improve the STA Certified Compost and Compost Consumer Use (CCUP) programs in order to meet the needs of compost manufacturers and their customers.

The issues related to the use of persistent herbicides and their effects on the composting industry continues. In response, the US Composting Council’s Persistent Herbicide Task Force and the Composting Council Research and Education Foundation’s (CCREF) Standards and Practices Committee (S&P) are collaborating to create, vet, and add an approved Persistent Herbicide General Indicator test method to the STA labs’ manual for the Test Methods for the Examination of Composting & Compost” (TMECC), specifically related to providing information related to the persistent herbicide issue. It is anticipated that a first draft lab procedure will be ready for evaluation in early 2021, with a refined lab protocol to follow as soon as possible.

The STA Advisory Committee is considering how best to use this upcoming Persistent Herbicide General Indicator lab test method in the STA program. That decision will include your participant input on what will reduce the liability exposure to compost manufacturers.

Overall, the STA Certified Compost program exists to support compost manufacturers and end user confidence in the products for those manufacturers who are enrolled and in good standing in the program. The STA program increases communication between compost manufacturers and end users, and identifies professional and accountable manufacturers and products. The USCC strives to continue to improve the STA program’s usefulness in this endeavor and will keep you updated.

If you have any comments or feedback, please contact STA Program Manager Hilary Nichols.