Compost and Mulch

Composting is the process of the controlled aerobic decomposition of organic material such as leaves, twigs, grass clippings, and food scraps. Aerobic means with oxygen.

Compost is the finished product that results from aerobic composting. It is a soil amendment containing a wide variety of nutrients, micro-nutrients, and organic matter, all of which benefits the soil. Whether it’s done on site, at the point of waste generation or in a large-scale, centralized facility, composting helps to keep the high volume of organic material out of landfills and turns it into a product that is useful for soil restoration.

Small-scale on-site composting reduces the cost of hauling materials to the landfill and is generally exempted from solid waste regulations. Consult current composting regulations and contact your Local Enforcement Agency for guidance on any local permit requirements prior to beginning a compost project.

Large-scale compost facilities handle more material and typically produce a more consistent compost product, and they are required to comply with regulatory and permitting standards.

Mulch ground organic material that has not gone through the decomposition process.  It is not a soil amendment, like compost.  It may be used as a protective layer over the soil to control weeds, retain moisture, prevent erosion and buffer temperature extremes. Mulch-like material that has been through the composting process and screened out, frequently called overs, provide some of the benefits of compost, all of the benefits of mulch, and pose lower risk of spreading pests or disease.

Composting Environmental Issues

Compost Demonstration Projects

For more information contact: Organic Materials, organics@calrecycle.ca.gov