California Department of Resources Recycling and Recovery (CalRecycle) 

Landscape Waste Prevention

Compost Quality Program

Because organic materials, including landscape and tree trimmings, grass clippings, and food scraps, comprise more than 30 percent of California’s waste stream, the CIWMB (now known as the Department of Resources Recycling and Recovery or CalRecycle) designated organic materials management as one of its strategic planning priority areas.

An internal "Greening Team Performance Plan" for this priority material called for focused collaboration with partners in state and local government, the landscape industry, recycling and manufacturing sectors, and other end-use sectors. The plan set a goal of diverting an additional 5 million to 7 million tons of organic materials from landfills by the year 2000. This included diverting an additional 1.5 million  to 2 million tons of landscape and tree trimmings from landfills. Diversion of, and use of compost and mulch made from organic materials reduces environmental impacts at landfills, including reduced green house gas emissions, and yields benefits such as soil revitalization, erosion control, and water conservation.

The plan also called for increasing the number of compost producers registered. CalRecycle actively promoted the voluntary dissemination of verifiable information about compost product characteristics since 1993 and funded initial work to develop a laboratory practices manual and a verification procedures manual.

Based on this work, a registration program was developed focused on ensuring that registered producers comply with applicable CalRecycle regulations, disclose feedstock materials, follow specified quality assurance and quality control protocols, provide samples for independent lab analysis of specified parameters, and disclose results of those lab analyses. This helped ensure that end users could evaluate the physical and chemical characteristics of compost and, as a result, make more informed buying decisions. Physical and chemical properties tested included bulk density, particle size, pH, salinity, and organic matter content. Compost producers who met the disclosure criteria could display the registration seal on their product. With registration, end users, landscapers, horticulturists, nurserymen, groundskeepers, farmers, and others in green industries could  have extra confidence about the characteristics and consistency of the compost products they used.

To further promote markets for compost, in 1999, CalRecycle approved a contract to expand its compost product quality disclosure program. In this contract, CalRecycle worked to build partnerships with compost industry organizations to enhance the existing statewide compost product quality disclosure program. Specifically, the contract called for development, with input from the United States Composting Council, the Organic Materials Review Institute, and other interested parties, new and revised compost product quality disclosure parameters, and revised testing and verification protocols applicable in a California-specific context. Additional disclosure parameters evaluated included caution exchange capacity, humic acid content, organic carbon content, inorganic nitrogen, ammonium nitrate, total nitrogen, salinity, maturity and other factors. The new and revised disclosure parameters, and updated lab practices and inspection verification manuals served as the basis for expanding the registration program.

The contract required promotion of the use and application of these updated parameters to help create new and expanded markets for compost in California. Market outreach and educational efforts targeted both compost producers to increase the number of registered facilities and end-users to increase market demand for compost, including for use in landscaping.

Specific market outreach deliverables under this proposed contract included:

  • Two workshops targeting compost facility inspectors.
  • Four workshops targeting compost end users.
  • New compost product quality brochures.
  • Promoting the compost product quality disclosure program at five or more conferences in California.

An important outcome from this contract was the development of a compost maturity index. This index helps ensure that compost producers are disclosing maturity measurements about their product. This allows customers to better assess the maturity and stability of the compost they purchase. The index also allows end-users to better evaluate the compost product for the end-use they have in mind.

For the second part of the contract, education and outreach materials were developed. These materials were promoted at workshops and conferences to increase both the number of registered facilities and the market demand for compost products. Four end-user workshops were held.

Greening Team Home

Last updated: November 4, 2010
Organic Materials Management http://www.calrecycle.ca.gov/Organics/
Contacts: http://www.calrecycle.ca.gov/Organics/Contacts.htm