Compost Use, Quality and Marketing

Marketing compost and achieving the compost quality needed for specific uses are important considerations for a composting facility owner. It's important to identify the target market, ensure an appropriate compost quality and develop a suitable marketing strategy. Otherwise, it may be difficult to market the compost.

Compost Use

You do not need DNR approval to landspread yard material (raw), composted yard material, or composted vegetable food waste and other similar composted vegetable matter (this exemption is found in s. NR 518.04, Wis. Adm. Code). The following recommendations and requirements apply to all landspreading of these materials:

• The material must be applied as a soil conditioner or fertilizer in accordance with accepted agricultural practices, and in a safe, nuisance-free manner.
• Do not spread materials while the ground is frozen or excessively wet.
• Consider the soil type and nutrient needs at the location where materials will be applied. Soil tests can be used to help determine appropriate application rates. If the material is high in nutrients, be sure to limit application to what plants need, so that excess nutrients do not run off into surface or groundwater. Material containing lots of grass clippings or food discards will contain more nutrients than leaves or brush.
• Make sure there are no contaminants, such as plastic bags, in materials to be composted or spread.

For landspreading bulk quantities of material, such as on farm fields, the following requirements also apply:

• Immediately incorporate the materials into the soil. The landspreading exemption does not cover storage of materials at landspreading locations, so deliver only the amount of material that can be spread and incorporated right away (within one to three days). Excess materials must be maintained at a storage or composting facility, which requires a license from DNR if more than 50 cubic yards of material will be on-site at any one time.
• Maintain setbacks from floodplains (100 feet), water supply wells (200 feet) and nearby residences (500 feet).

Small farms also do not need an approval to landspread agricultural crop residue, manure or composted animal carcasses (this exemption is found in s. NR 518.04, Wis. Adm. Code). All of the recommendations and requirements described above apply. Management of agricultural wastes from larger farms and confined animal feeding operations (CAFOs) is regulated by a wastewater discharge permit.

For more information, see Composting and Landspreading Source Separated Solid Waste Rule Summary, PUB-WA 1057 2006 [PDF 94KB].

Compost Product Quality

The DNR regulates compost product quality only to the extent necessary to protect public health and the environment, not as a consumer protection service or to legitimize marketing claims.

Because yard materials and food scraps generally pose little risk of causing environmental contamination, the DNR does not regulate the quality of compost produced from these materials.

The DNR must review the use of compost made from other types of solid wastes. If the composted materials are acceptable for the use identified by the facility owner, DNR staff will issue an exemption to allow that use. Based on the quality of the compost product, a facility owner may propose a limited or controlled compost use, or may seek to distribute the compost under a broad exemption, such as through retail outlets.

While the DNR does not have rules that specify a required compost quality, we have developed the following publications that describe test parameters and concentrations likely to ensure a compost facility's ability to publicly distribute its compost:

Overview and Composting Product Approval Guidance, PUB-WA 613 2005 [PDF 98KB]

Beneficial Use Under the Low Hazard Waste Exemption, PUB-WA 1022 2004 [PDF 58KB]

The U.S. Composting Council (USCC) [exit DNR] is a private organization that, among other things, has helped to establish industry accepted standards for laboratory testing of compost products, the Seal of Testing Assurance (STA) Program. The STA program is a set of standards for the proper testing of compost (laboratory methods, sampling frequency, etc.) but does not contain standards for compost quality.

The Department of Agriculture, Trade & Consumer Protection (DATCP) regulates sale and distribution of fertilizers and soil conditioners. More information about DATCP regulation is provided below.

Compost as Fertilizer or Other Products Regulated by DATCP

DATCP regulates products that are marketed with performance claims for nutrient content or ability to enhance plant growth or crop yield. Although DATCP generally does not regulate materials that are land applied in a controlled manner under DNR rules, composting facility owners may wish to obtain a DATCP review and permit so that the compost marketing information may include beneficial performance claims and to help promote the product. Rules that may apply and product types regulated include chs. ATCP 29, 35, 40 and 41, Wis. Adm. Code. [exit DNR]

Product types regulated by DATCP include:

• fertilizers;
• soil or plant additives (includes acidifiers);
• liming materials (products that contain calcium or magnesium, and are labeled to increase soil pH); and
• pesticides.

Products may not contain substances that are toxic or harmful to plants, animals or humans when handled or applied under reasonably foreseeable use conditions, unless the hazards are disclosed on the label with proper instructions to avoid injury.

More specifically, fertilizer used in accordance with its guaranteed nutrient content must not be harmful to humans or the environment, and DATCP also regulates metals that do not serve as nutrients and other contaminants in fertilizers. Soil or plant additive non-nutritive metals limits are based on application rates in s. ATCP 40 , Appendix C, Wis. Adm. Code [PDF 6KB, exit DNR].

For more information, contact DATCP or visit DATCP's farming and agriculture Web page [exit DNR] and look under the "Fertilizer" heading.