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What is STA Certified and OMRI Listed Compost?

STA Certified Compost Logo

Available from

St. Louis Composting:

Black Gold Compost

Field & Turf Enhancer

STA Certified

Quality is in the eye of the consumer:  Compost use and selection decisions consider many factors, and therefore are not one-size-fits-all.  The Seal of Testing Assurance (STA) Program helps you make the best decision for your application by providing the 3 C’s:

STA Certified


Similar to a nutrition label, the STA Program’s Compost Technical Data Sheet (CTDS) includes test results, a list of ingredients, and recommended directions for use.


The STA Program provides checks and balances within the STA Lab and Participant network to ensure proficiency and consistency with testing procedures and compliance, providing apples to apples comparisons of compost properties.


Similar to trusting a vehicle history report when purchasing a vehicle, the STA’s CTDS report provides consumers with confidence and knowledge of what is in the compost and how it was produced.

STA stands for the U.S. Composting Council's Seal of Testing Assurance. It is designed to let the consumer know that the compost they are buying is tested at regular intervals by a permitted facility and tested for EPA 503 pathogen reduction and metal limits.

In the early days of composting, everyone had their way of producing this wonderful soil amendment. Some used organic food scraps or landscaping waste, while others might add manure. Whatever the method, in the year 2000, it was decided that a standard should be adopted so homeowners and landscapers could rely on safe compost, with testing results available to the consumer.

While the industry helped design a testing program that included physical, chemical and biological tests, it was decided that outside independent labs would provide analysis. This way, users of compost could be assured that the compost they were buying would be scientifically analyzed, free of outside bias, so when it was STA Certified they knew it was tested by a reputable, independent lab (CAP proficiency tested labs with TMECC).

In addition, the program testing frequency was designed to correlate with the raw tonnage of compost produced by a manufacturer. At St. Louis Composting, as one of the Midwest's largest compost producers, we test monthly, the highest level of frequency the program requires.

So what does the laboratory test for you ask? In addition to rules which require us to be fully compliant with all Federal and State mandates to assure public health/safety and environmental protection, our compost is evaluated on the following properties:

  • pH

  • soluble salts

  • nutrient content (total N, P2O5, K2O, Ca, Mg)

  • moisture content

  • organic matter content

  • bioassay (maturity)

  • stability (respirometry)

  • particle size (report only)

  • pathogen (Fecal Coliform or Salmonella)

  • trace metals

What does STA Certified mean to you? All of our compost is tested at regular monthly intervals to make sure we satisfy our benchmark for consistent results and safety. If you see an STA logo on your compost, you can be confident you're buying a product that will deliver the wonderful benefits of compost in your yard or garden, manufactured and tested regularly to company and government standards by a properly permitted facility (required for STA certification).


In addition, as part of the program, all STA Certified manufacturers are required to provide a Compost Technical Data Sheet (CTDS) on request, ensuring transparency and accountability to the markets they serve.

It should be noted that participation in this program is voluntary and is not required by law. We participate in U.S. Composting Council's STA Certification to demonstrate commitment to our customers that we strive to operate in a manner consistent with the requirements defined by the program's guidelines and industry standards.

OMRI Listed Logo

Available from

St. Louis Composting:

Premium Gold Compost

Premium Field & Turf Enhancer

OMRI Listed

OMRI refers to the Organic Materials Review Institute. OMRI is a non-profit organization that provides an independent review of a variety of products, from fertilizers to health care products, looking to certify those products that are to be utilized for organic production and processing, like our compost.

OMRI reviews products against a set of organic standards and once the product satisfies their criteria, the product is listed on their website under their Organic Products List.

OMRI's Mission (taken from their website):

OMRI's mission is to support the growth and trust of the global organic community through expert, independent and transparent verification of input materials, and through education and technical assistance.


OMRI Certified


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