Compost use, quality and marketing

Compost use

Using compost

You do not need DNR approval to landspread yard material, 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. However, 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 the 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 scraps 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 the 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 at 100 feet, water supply wells at 200 feet and nearby residences at 500 feet.

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

Product quality

Compost 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.

The DNR published new compost rules (effective June 1, 2012) that establish a category of high-quality compost called Class A compost, made from source-separated organic materials. Meeting the requirements in the new compost rules should ensure a compost facility's ability to publicly distribute its compost. For more information on Class A compost, see Requirements for Marketing Class A Compost (WA-1589) [PDF].

The U.S. Composting Council (USCC) 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 the sale and distribution of fertilizers and soil conditioners. More information about DATCP regulation is provided under compost as fertilizer.

Class A compost

Class A compost

The DNR provides the ability for a compost facility to produce compost that can be labeled as "Class A compost." Providing this category of compost allows those willing to spend the time and resources to develop a superior product to distribute it to consumers who may desire the knowledge that the material has undergone specific tests and meets specific standards.

For compost to be designated and distributed as Class A compost, it must meet several requirements:

• include source-separated compostable material only;
• use a process that reduces pathogens with temperatures recorded each day until the time and temperature criteria are met;
• test the compost using specified methods and provide results upon request; and
• document compost test results do not exceed specified limits.

More details about these requirements are available in Requirements for Marketing Class A Compost (WA-1589) [PDF].

Compost as fertilizer

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. 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. Visit DATCP’s Pesticides and Fertilizers: Certification and Licensing webpage and contact their office for more information.

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.