Wisconsin composting overview

Compost is an environmentally friendly way to create healthy soil for Wisconsin's landscape, benefiting agriculture and horticulture industries and improving soil for home gardens and landscaping. Compost produced from yard materials and other organics, such as food scraps, can replenish vital soil organic matter, microorganisms and nutrients. Compost production also diverts yard materials from Wisconsin's landfills into productive use.

Overview

Wisconsin law banned the disposal of yard materials starting in 1993. Today, more than 200 state-licensed composting sites manage some 200,000 tons of yard materials each year, and many additional hundreds of thousands of tons of yard materials are managed through home composting and mulching in place. Yard materials (or "yard waste" as defined in Wisconsin law) include leaves, grass clippings, brush and woody material under 6 inches in diameter.

Wisconsin generates an additional 500,000 tons of materials annually – including food scraps – that could be composted and made into useful products. DNR staff are working with nonprofits, local governments and businesses to facilitate the growth and expansion of composting operations in Wisconsin.

What is compost?

Compost is a soil-like material rich in stabilized carbon produced from the breakdown of organic materials. It is considered a soil amendment, rather than a fertilizer, because it usually contains only small amounts of nutrients such as nitrogen, phosphorus and potassium. Lawn fertilizer contains significant amounts of all three.

Benefits of applying compost include:

  • restoring or enhancing the ability of sandy soil to hold moisture and clay soils to drain;
  • repairing or preventing damage caused by erosion; and
  • aiding plant growth – e.g. in residential gardens, public landscapes or after construction and mining projects are completed.

Composting at home

Composting at home

Home composting yard materials and certain food scraps can provide valuable material for gardens and landscaping while reducing costs for off-site composting or disposal.

Home composting bin
Home composting bin
Photo: Milwaukee Dept. of Public Works

Wisconsin law bans the landfilling of yard materials such as leaves, grass clippings and branches less than 6" in diameter. Composting is a preferred alternative to burning such materials, which is banned in many communities. Through home composting, residents can enjoy the benefits of compost spread on their vegetable and flower gardens or in landscape projects.

Home composting can be done in bins or in a heap; however, bins are a better way to manage the materials. There are a number of home composting containers available commercially, and it is also fairly simple to create your own. Your community may also offer composting bins at special sales. For more information on different types of home composting equipment, see the DNR brochure Home Composting: The Complete Composter [PDF]. If you do not include food scraps in your compost, you may not need a specialized container.

DNR does not regulate small-scale, home composting operations of less than 50 cubic yards. All composting should be done in a nuisance-free and environmentally sound manner, however. This includes minimizing odors, not attracting excessive numbers of rodents and other pests, and not siting compost piles in wetlands or other sensitive areas.

Certain food scraps can also be easily composted with yard materials at home. Be sure to follow recommendations on what types of food scraps can be composted in order to prevent odors and avoid attracting animals and other pests.

Examples of materials for composting.
What to compost What not to compost
  • Yard materials
  • Vegetable and fruit scraps
  • Coffee grounds and filters
  • Tea bags
  • Nut shells
  • Eggshells
  • Clean, unwaxed paper, such as newspaper and cardboard
  • Animal manure (not pet waste)
  • Meat or fish scraps, bones and packaging
  • Dairy products (milk, cheese, egg yolks, etc.)
  • Fats and oils or foods containing fats and oils
  • Pet waste
  • Diseased or insect-ridden plants
  • Highly invasive plants like garlic mustard, unless completely dry and without flowers or seeds

Large-scale composting

Compost rule updates

Finished compost
Finished compost.

Changes to Wisconsin's compost rule, s. NR 502.12, Wis. Adm. Code [exit DNR], took effect June 1, 2012. DNR staff have developed guidance documents to help compost facility owners understand how the changes will affect them. See the resources tab for links to these documents, or visit the compost rules and regulations page for more details.

Large-scale composting

Large-scale compost production includes municipal and commercial facilities composting high volumes of yard materials and/or food scraps, and farm composting of these materials with animal manure.

The most common type of large-scale composting involves placing the compostable materials directly on the ground in orderly rows or piles, called windrows. The material is turned periodically to mix and aerate it. Aeration helps the microorganisms digest the materials and eventually produce finished compost. For more about compost quality, see the Compost Quality and Marketing page.

Other types of large-scale composting include:

  • static windrows that are aerated using perforated tubes or blowers instead of turning;
  • "in-vessel" composting that uses a continuously turning vessel and blower to provide aeration in a building or other facility, a method used to compost sludge or mixed solid waste in addition to yard waste; and
  • vermiculture, which is composting using worms. This can be done either on a small (home) or large scale.

How much land?

Typical windrow compost system
Typical windrow composting system.

Seven acres is the smallest possible area required for a 20,000-cubic-yard windrow composting facility. There are additional regulations for facilities larger than this. This estimate assumes the finished compost is produced in one year or less and rapidly moved off site. A much larger area would be needed if the materials were turned only infrequently, or if portions of the property were unsuitable for the composting operation. It is important to follow state regulations on the siting of large-scale composting facilities [exit DNR] to protect surface and groundwater from contamination and avoid other potential hazards and nuisances.

Factors to consider

Important factors in large-scale composting include:

  • temperature;
  • the ratio of carbon to nitrogen in compostable materials;
  • the pH of compostable materials;
  • moisture content; and
  • oxygen content or concentration.

More information

Resources

DNR publications

Large-scale composting
Home composting

DNR forms

Other publications and resources

Last revised: Monday July 07 2014