A CIWMB directive calls for a 50 percent reduction by the year 2020 in the amount of organic materials currently being disposed in California landfills. Meeting that goal will require an additional 15 million tons of organic materials to be recycled annually. New organic diversion facilities will need to be sited, in conjunction with the expansion of existing facilities.
Many of these organic materials ending up in landfills are suitable for composting: food waste, agricultural crop residue, leaves and grass clippings, prunings and trimmings, branches and stumps, chipped wood and manure. In fact, the most recent statewide analysis of solid waste generation, completed in 2004, found that compostable organic materials represent approximately 25 percent, or about 10 million tons, of the solid waste being disposed in California landfills annually.
Food waste is one of the largest categories of compostable materials and represents 15 percent (6 million tons) of the overall total material landfilled. Approximately 10 percent of the landfilled material consists of lumber, most of it suitable for the production of compost or mulch.
CIWMB has several projects under way that support expanded use of compost. This includes: Best Management Practices (BMP) study that is conducting demonstration projects to research the effectiveness of compost for erosion control on fire-damaged land and to gather water quality data related to production and use of compost; Contract to further refine a “compost use index” that specifies particular compost properties that benefit agricultural crops; and Contract for a series of statewide workshops with the California Department of Transportation (Caltrans) on the benefits of using compost for erosion control.
Researchers at the University of California, Riverside have been contracted to study the benefits of compost by analyzing compost-based BMPs in a field demonstration setting. The UC Riverside contract includes two components: Runoff Reduction (see sidebar), and Water Quality and Erosion Control. The effectiveness of compost for erosion control — while maintaining water quality — is being researched at a fire-ravaged site in southern California. The study will attempt to quantify the benefits of compost on fire damaged land by absorbing water, thus reducing surface flow, and by dissipating the energy of the rainfall. The study will also attempt to quantify the ability of compost to promote the growth of micro and mesofauna (microbes, worms, insect larvae), to promote regrowth in the fire damaged soils. Beyond supporting a sustainable environment, this is important in California because thousands of acres are devastated annually by wildfires. The burned out areas are subject to erosion and water quality problems due to flowing sediment from the burned areas.
A search is under way for suitable test sites, and a scope of work is being drafted for each portion of the contract, aided by input from the State Water Resources Control Board and Regional Water Quality Control Board. The contract should be completed by summer 2010, with results and findings posted on the CIWMB website.
COMPOST USE ON CROPS
CIWMB has contracted with UC Riverside for a study on improving and expanding compost use in California agriculture by providing reliable, scientifically sound data on crop-specific compost properties. The contract builds on the Association of Compost Producers’ Use Index, which is updated on an ongoing basis by technical experts affiliated with the UC Cooperative Extension and industry experts working with the compost producers’ group.
Developing crop-specific compost specifications helps farmers avoid using mismatched or poor quality composts, which could result in lower crop yields. The industry experts’ involvement has helped encourage compost producers to develop specialty composts designed to maximize crop yield and minimize negative publicity that could hamper expansion of compost markets into agricultural use.
This contract will focus on three crops: strawberries, lettuce and tomatoes. Information from the study will be added to the Compost Use Index. Past studies sponsored by the CIWMB have focused on compost use with grapes and avocadoes.
After the research phase is complete, the information will be provided to the agricultural community through brochures, informational publications and a series of workshops this year in Fallbrook, Monterey and Yolo County. Details about the workshops will be posted on the events calendar of the CIWMB website.
EROSION CONTROL WORKSHOPS
A series of workshops are planned statewide in 2009 to provide information on using compost to reduce erosion and to promote the start of vegetation growth, including specifications recently developed by Caltrans to achieve these two stated goals. The specifications were developed to help overcome barriers — including cost, availability and quality control — that had limited Caltrans from using large amounts of compost. The CIWMB conducted a similar workshop series in 2006 to 2007, which targeted Caltrans designers and contractors, and also focused on the Caltrans compost specifications.
The current workshops will encourage local governments to adapt the Caltrans specifications for their own use. Speakers will outline ways to draft local ordinances that specify compost use, and measures to ensure compost quality. Two demonstration projects will be conducted concurrently to demonstrate the effectiveness of compost applications for erosion control and for promoting new vegetation growth. These projects will allow case studies to be developed for educational use. University experts will provide updates on the demonstration projects during the workshops. One workshop will be held on April 27 as part of the BioCycle International Conference 2009 in San Diego, California (for more info, go to www.biocycle50.com).
Efforts like these compost studies, as well as ongoing work at CIWMB, will move California closer to the 50 percent organic waste diversion goal for the next decade. The latest news, initiatives and findings are available online at the Waste Board’s Organic Materials Management website (www.ciwmb.ca.gov/Organics).
Gerald Berumen is a Supervising Integrated Waste Management Specialist in the Organic Materials and Green Building Section at CIWMB.