The 4 Classes of Compost Quality
Not all compost products are created equal, and it is silly to buy them as if they are. For a long time, there were no clear criteria set for determining unique specifications and soil amendments in compost. This made it challenging for landscape architects and other bulk compost purchasers to effectively communicate what they needed to suppliers, and even more challenging for suppliers to provide them with the right products.
A1 Organics recognized the need for creating a classification system to set the criteria for types and quality of compost. This system would innovate the landscaping industry by providing a standard needed for landscapers and suppliers to collaborate effectively. Landscape architects would be able to identify the best class of compost for their project and ask for it directly. In turn, the compost producer would be held accountable to a certain standard of quality and be able to provide exactly what the landscaper asked for.
We worked with landscapers, contractors, sustainability experts, and composting professionals to develop the following classification system:
Class IV: Non-composted feedstock product
What is it?
This product is made from raw, unstable feedstock material (such as manure) that has undergone primary and secondary nutrient testing but has not earned a U.S. Composting Council Seal of Testing Assurance (STA) or undergone the Test Method for the Examination of Composting and Compost (TMECC).
Applications
Its only application is agriculture.
Incorporation information
This product cannot be used as a high percentage of the soil profile. Incorporation in the top 10 inches or more is recommended.
Class III: Semi-composted dehydrated product
What is it?
This is partially composted or dehydrated product. It may be “shredded” or screened, but it is unstable to moderately unstable and has not matured. Unlike Class IV product, Class III is tested according to the U.S. Composting Council’s STA and TMECC testing standards.
Applications
This product can be applied to crop production, certain turf and topsoil blends, backfill, erosion control, and mulch.
Incorporation information
This product cannot be used as more than 15 percent of the soil profile. Incorporation in the top eight inches or more is recommended. If possible, incorporate at least 90 days before planting. Deep incorporation and thorough mixing is very important.
Class II: Fully composted, stable, mature product
What is it?
This is a fully stable product generally made from manure-based feedstocks. It normally has increased levels of nutrients and can be used to supplement fertilizers. Quantity control and careful incorporation are required for ideal plant germination and sustainability. Class II product is tested according to the U.S. Composting Council’s STA and TMECC testing standards.
Applications
This product is ideal for use in turf, sod, seed bed preparation, raised gardens, vegetable gardens, topsoil blends, backfill, and erosion control.
Incorporation information
This product should not be used as more than 30 percent of the soil profile. Incorporation in the top six inches or more is recommended. If possible, incorporate at least 60 days before planting and make sure to water thoroughly before and after planting.
Class I: Fully composted, very stable, mature product
What is it?
This is a fully stable, top-tier product generally made from non-manure-based feedstocks. This product is “goof-proof” — it will germinate and sustain plants without much risk of over-application or poor incorporation. Watering to leach excess salts is not required. Class I compost is tested according to the U.S. Composting Council’s STA and TMECC testing standards.
Applications
This product is extremely versatile and has a number of ideal applications, including horticulture, nursery, container mixes, turf, sod, seed bed preparation, raised garden, vegetable garden, topsoil blends, backfill, and erosion control.
Incorporation information
This product can be used as a high percentage of the soil profile. Shallow incorporation in the top four inches is recommended, and it can be applied generously without risk of over-application.
Learn More At A1 Organics
If you want to learn more about this compost classification system, please reach out to the A1 Organics team today. We work closely with landscapers and local organizations including Denver Water, Denver Parks and Recreation, and the Colorado Department of Transportation to provide high-quality organic soil, multi-purpose compost, and premium mulch for a variety of landscaping needs. We are passionate about consistently providing the right landscape materials for the project, and we strive to educate the public about the benefits of composting and organic recycling.
Whether you know what you’re looking for and would like to place a bulk order for topsoil delivery right now, or you want to chat with us first to find out what class of compost you need, our team is here to help. Contact us today to get started!