Wisconsin revised its composting regulations in the early 2010s; the new rules came into effect on June 1, 2012. The revisions require that composters adhere to the permitting process to ensure the quality of finished compost and minimize potential nuisances from materials mismanagement.
Not all composters are subject to the 2012 rule change, as regulations generally do not apply to home and small-sized (less than 50 cubic yards) composting. The current rules found in Chapter NR 500 – (DNR # WA – 33 – 10) of the Wisconsin Administrative Code provide various composting operations with degrees of licensing exemptions based on the type, capacity, and feedstock of the facility, as summarized below.
According to Jennifer Huffman of Wisconsin’s Department of Natural Resources (DNR), volume thresholds are imposed on composting facilities contingent on the amount of material “believed to be manageable at the time the composting rule was drafted.” In general, operations with higher threshold limits are subject to a higher degree of regulation.
Limited Exemptions
NR 502.12 of the Wisconsin Administrative Code stipulates “limited” exemptions for composting facilities of different sizes handling particular types of organic materials. The Wisconsin DNR refers to these as ‘limited exemptions’ since they are still expected to meet certain criteria, including standards for performance, basic operational and design, location, closure, reporting, and compost application.
The following types of operations have limited exemptions from licensing requirements:
- Facilities for composting yard debris and clean chipped wood processing can’t exceed 20,000 cubic yards or less at one time
- Facilities for composting “source-separated compostable materials” processing does not exceed 5,000 cubic yards or less at one time
The regulations include: general (NR 502.04), which covers general requirements for solid waste collection, storage, transfer, and processing; location (NR 502.12(8)), which determines the distance compost facilities must be from certain features (e.g., 5 ft above groundwater, 250 ft from wells or navigable water); license operation (NR 502.12(10)), which requires approval from DNR; design (NR 502.12(11)), which specifies that construction must maintain integrity, handle traffic, and control runoff; and record keeping (NR 502.12(15)), which mandates annual report submissions to DNR.
On-farm Composting Exemptions
For the most part, farms in Wisconsin are largely exempt from composting licensing regulations, as there is no volume limit for composting farm crop residue and manure generated on-site. On-farm composters need only meet the performance standards in NR 502.04 of the Wisconsin Administrative Code, which require operating in a way that does not cause environmental harm to the farm’s surrounding areas. Additionally, the finished compost must be used for agricultural landspreading, either on the same farm or another farm, unless animal carcasses were used, in which case it can only be used on the farm where it was originally produced.
Farms may accept input materials generated off-site if several additional performance standards in NR 502.04 are met. When including off-site materials, the threshold to remain exempt is 10,000 cubic yards on-site at one time. This calculation is based on the combined volume of collected feedstocks and compost being processed, but excludes finished compost. Food residuals should not exceed 25% of the raw material inputs. Compost mixtures must be blended to achieve an initial carbon-to-nitrogen ratio of at least 20:1.
Feedstocks listed in NR 502.12 require different facilities and regulatory stipulations for facilities over 50 cubic yards. All farm crop residue and manure composted must be generated and processed from agricultural operations on the property of one of these agricultural operations. These operations include: common ownership, common management, or properties located adjacent to each other.
The chart below is modified from Wisconsin’s Department of Natural Resources showing a summary of requirements for composting facilities eligible for exemption:
Non-exempt Facilities
All facilities that do not satisfy the limited or full exemption criteria must obtain a license to compost. Licenses are free.
Non-exempt facilities are subject to more stringent standards, for example:
- Submitting construction documentation before beginning operations
- Designing adequate pad and leachate collection methods (for stormwater management)
- Performing sampling for common characteristics such as carbon to nitrogen ratio, moisture content, oxygen content, pH, etc.
- Potentially providing proof of financial responsibility for closure (for very large sites)
Economic Benefits
The state of Wisconsin recognizes the economic benefits to farmers, businesses, and communities from the sale of finished compost and, accordingly, has written a policy that incentivizes growing markets for compost products. While some states limit the quantity of compost farmers and facilities can sell, Wisconsin allows licensed facilities to sell all of their compost without restriction, provided safety and quality standards are met. If a facility is categorized as exempt, while still strictly regulated by safety requirements, it has no cap on the total volume of finished compost they can sell. This provides additional revenue for both farmers and other composters as compost is a value-added farm product.
The Wisconsin DNR website reports that, as of 2021, approximately 200 licensed composting facilities are operating in the state, collectively processing about 200,000 tons of yard waste each year. In addition, the DNR asserts that “hundreds of thousands more tons of yard materials are managed through home composting and mulching in place.”
More Information
- Wisconsin Administrative Code Chapter NR 502.12 – “Yard, farm, food residuals, and source-separated compostable material composting facilities”
- Wisconsin Dept. of Natural Resources – Composting Facilities Eligible for Exemption
- Wisconsin Dept. of Natural Resources – Composting Rules and Regulations in Wisconsin
- Wisconsin Dept. of Natural Resources – Factsheet: Large-scale Composting of Food Residuals
- Wisconsin Department of Natural Resources – Farms and Composting in Wisconsin
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Original post from July 30, 2012
Updated May 28, 2026