Composting is nature’s way of recycling and is one of the most powerful actions we can take to reduce trash in landfills, address climate change, and build healthy soil. Composting is in the fourth tier of EPA's Wasted Food Scale.
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In 2019, 66.2 million tons of wasted food were generated in the food retail, food service and residential sectors in the United States. Only 5% of that wasted food was composted. 1
In the U.S., food is the single most common material sent to landfills, comprising 24.1 percent of municipal solid waste. When yard trimmings, wood and paper/paperboard are added to food, these organic materials comprise 51.4 percent of municipal solid waste in landfills. 2
When food and other organic materials decompose in a landfill where anaerobic (without oxygen) conditions are present, bacteria break down the materials and generate methane, a powerful greenhouse gas. Municipal solid waste landfills are the third largest source of human-related methane emissions in the U.S, accounting for approximately 14% of methane emissions in 2021. 3 Wasted food is responsible for 58% of landfill methane emissions. 4
When we send food and other organic materials to landfills or combustion facilities, we throw away the valuable nutrients and carbon contained in those materials. By composting our food scraps and yard trimmings instead and using the compost produced, we can return those nutrients and carbon to the soil to improve soil quality, support plant growth and build resilience in our local ecosystems and communities.
Composting is a fundamentally local process. Organic materials are typically collected and processed into compost near where they are generated, often in the same county, city or even neighborhood. In this way, composting also supports local jobs and economies.
Learn more about the connection between food waste and methane in this fact sheet from USDA and EPA (pdf)(2.1 MB).
Composting is the controlled, aerobic (oxygen-required) biological decomposition of organic materials by microorganisms. Organic (carbon-based) materials include grass clippings, leaves, yard and tree trimmings, food scraps, crop residues, animal manure and biosolids.
Compost is a dark, crumbly, earthy-smelling, biologically-stable soil amendment produced by the aerobic decomposition of organic materials.
Regardless of size or scale, the basic principles of composting are generally the same. The composting process requires a proper ratio of carbon-rich materials (such as dry leaves or wood chips) to nitrogen-rich materials (such as food scraps or grass clippings). Maintaining adequate moisture level, oxygen flow, particle size, and temperature ensures microorganisms effectively break down organic materials into quality compost.
The method of composting used, as well as the equipment, is often determined by the scale or size of the site and the volume and type of materials, or feedstocks, being composted. The feedstocks accepted vary by composting facility and should always be free of contaminants such as herbicides, non-compostable packaging, and produce stickers.
Composting can take place at many scales/sizes – backyard, community, on-farm, municipal and regional – and at a range of locations in urban to rural areas. A small-scale system can be as simple as a backyard compost pile or vermicomposting (worm composting) bin, whereas a large-scale system may be a centralized, commercial composting facility processing organic materials from around the region.
Check out these EPA fact sheets on stormwater and erosion control with compost:
In the United States, our soils suffer from topsoil loss and erosion, which can lead to water quality issues and reduce the productivity of agricultural land. Compost adds much-needed organic matter to soil to enhance soil health. Compost has other uses as well in green infrastructure and stormwater management. Additionally, the use of compost sustains green jobs throughout the organics recovery cycle.
Markets and applications for compost include agricultural and horticultural, landscape and nursery, vegetable and flower gardens, sod production and roadside projects, wetlands creation, green infrastructure, soil remediation and land reclamation, sports fields and golf courses, sediment and erosion control, and stormwater management.
Composting policies and regulations are set at the state and local government level.
Some states ban or restrict landfill disposal of organic materials such as yard and tree trimmings and wasted food. Some bans only affect large generators of organic materials, whereas others affect all generators of wasted food, down to the household level.
Below are some composting and compost use policy resources:
Visit the other EPA composting webpages for more information and resources:
Mention of or referral to commercial products or services or links to non-EPA sites does not imply official EPA endorsement of or responsibility for the opinions, ideas, data, or products presented at those locations or guarantee the validity of the information provided. Mention of commercial products/services on non-EPA websites is provided solely as a pointer to information on topics related to environmental protection that may be useful to EPA staff and the public.
Visit the webpages below for more composting information:
