California Code, Public Contract Code - PCC § 12183

(a) All state departments and agencies, including, but not limited to, the Department of Transportation, the Department of Water Resources, the Department of Forestry and Fire Protection, and the Department of Parks and Recreation, shall give purchase preference to compost and cocompost products when they can be substituted for, and cost no more than, the cost of regular fertilizer or soil amendment products, or both, if the cocompost products meet all applicable state standards and regulations, as determined by appropriate testing. The product preference shall include, but not be limited to, the construction of noise attenuation barriers and safety walls, highway planting projects, and recultivation and erosion control programs.