On this page:
- EPA's Wasted Food Scale
- Impacts of Sending Food and Other Organic Materials to Landfills
- Composting Definitions
- Composting Basics and Approaches
- Benefits of Composting
- Benefits of Compost Use
- Composting-Related Policies and Regulations
- Additional Resources
- Sources of Statistics
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.
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.
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.
- Protects the climate by reducing methane emissions from landfills.
- Reduces waste.
- Recycles organic materials into a valuable soil amendment – compost.
- Recovers organic materials and keeps them local.
- Creates green jobs.
- Extends municipal landfill life by diverting organic materials and saving space in landfills.
- Reduces solid waste management costs because food scraps are one of the largest and heaviest portions of the waste stream, making their recovery increasingly cost-effective compared to disposal.
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.
Compost Enriches and Builds Healthy Soil
- Adds organic matter to the soil and increases the nutrient content and biodiversity of microbes in soil.
- Conserves water and reduces water use by helping soils retain moisture.
- Helps prevent soil erosion by reducing soil compaction and runoff.
- Reduces reliance on chemical fertilizers and pesticides.
- Improves plant growth and promotes higher yields of agricultural crops.
- Improves water quality by filtering stormwater and reducing nutrient and sediment runoff.
- Helps regenerate poor soil and remediate (clean up) soils that have been depleted by overuse or contain contaminants.
Compost Aids Climate Adaptation and Resilience
- Improves a community’s ability to adapt to adverse climate impacts by helping soil absorb water and prevent runoff of pollutants during floods. It also helps soil hold more water for longer, mitigating the effects of drought.
- Sequesters carbon in the soil, helping reduce greenhouse gas emissions.
- Strengthens sustainable, local food production by using locally generated food scraps and other organic materials to create a valuable soil amendment that supports plant growth.
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:
- The Environmental Law Institute developed a Toolkit for Incorporating Food Waste in Municipal Climate Action Plans (Environmental Law Institute).
- The Institute for Local Self-Reliance developed a guide for Healthy Soils and Compost Policy (pdf)(1.1 MB) and also maintains a list of different types of compost-related rules by state.
- The National Resources Defense Council and Environmental Law Institute showcase a model policy for compost procurement (pdf)(111KB).
- ReFED offers the U.S. Food Waste Policy Finder, a searchable tool of wasted food and organics recycling policies.
- The Sustainable Economies Law Center, in collaboration with the Institute for Local Self-Reliance, developed a website on compost law and policy. The website focuses on community and small-scale composting.
- The U.S. Composting Council compiles information on state compost regulations, developed a Model Compost Rules Template for States to use in updating their composting permitting regulations, and maintains a map of states’ organics bans.
- The Zero Food Waste Coalition provides a toolkit and template legislation on how to start the process of enacting an organics ban in your community.
Visit the other EPA composting webpages for more information and resources:
Visit the webpages below for more composting information:
- EPA/USDA Composting Fact Sheet (pdf)(620 KB) | Composting Fact Sheet en Español (pdf)(882 KB) | Composting Fact Sheet (horizontal)(jpg)(489 KB)
- EPA Excess Food Opportunities Map
- EPA Managing and Transforming Waste Streams Tool
- EPA Recycling Infrastructure and Market Opportunities Map
- EPA Compost Use Workshop for Specifications
- EPA’s searchable Success Stories table
- EPA Composting Food Scraps in Your Community: A Social Marketing Toolkit.
- BioCycle, an industry resource on composting
- Compost Research and Education Foundation
- Institute for Local Self-Reliance
- Target Organics – A Compost Program Resources Hub
- U.S. Composting Council