BioCycle February 2005, Vol. 46, No. 2, p. 33
Compost made from yard trimmings and commercial and residential source separated organics is applied on 30 California vineyards in Napa, Sonoma, Mendocino and El Dorado counties.
Molly Farrell

FORGET about the Grapes of Wrath. There’s a new story in California: the Grapes of Food Scraps. Vineyards in four northern California counties are using compost made from commercial and residential food residuals to grow healthier vines and grapes. The food scraps are collected, composted and sold by subsidiaries of Norcal Waste Systems, Inc., a solid waste company headquartered in San Francisco.
Norcal’s haulers collect about 300 tons of food residuals each day from San Francisco households and 2,330 food-related businesses in San Francisco and Oakland including restaurants, delis, markets, coffee shops, hotels and bakeries. The materials are then brought to Norcal’s Jepson Prairie Organics facility for composting. The Jepson Prairie facility has been making compost from food scraps since 1998, but Norcal began target marketing its Four Course compost to vineyards in 2002. Since then, more than 30 vineyards in northern California have applied Four Course Compost, and the results are in.
Remi Cohen, winegrower at the 100-acre Bouchaine Vineyards in Napa, had been applying compost for years when a colleague at a vineyard management company told her about the Four Course program. “I switched to their compost three years ago, and it has helped improve water retention and permeability into the soil by building and improving soil structure,” says Cohen. “We also have healthier, more uniform vineyard blocks and less nutrient deficiencies.”
Terry Wilson, owner and manager of Rancho Chimiles vineyard in Napa, tried Four Course in the fall of 2003. He had been purchasing composted yard trimmings from refuse companies, but was looking for an alternative. “I was less than ecstatic about the yard trimmings compost because sometimes it wasn’t fully composted and had weed seeds,” he notes. “The Four Course compost was the best looking stuff I’ve found. It also was price-competitive and was a richer blend with more nutrients because it contains food scraps. It didn’t have any weed seeds, probably because the food scraps make the compost cook better.”
Kathleen Inman, owner and winemaker at Inman Family Vineyards in Sonoma County, tried out the Four Course compost in 2003 and used it extensively in 2004. “I noticed the Jepson Prairie Organics stand at the Sonoma County Winegrowers trade show,” she remembers. “I was attracted to the fact that it was made of kitchen scraps, rather than solely suburban yard waste, which often has more residual herbicides and nonorganic fertilizers.”
THE SAN FRANCISCO FOOD SCRAP PROGRAM
Norcal’s hauler subsidiaries, Golden Gate Disposal & Recycling Company and Sunset Scavenger Company, collect the food scraps from businesses and homes in San Francisco. The commercial food scrap program began as a pilot project in San Francisco in 1996 and was expanded citywide in 1998. The city’s goal is to divert 75 percent of all waste generated annually in San Francisco by 2010. Food scraps account for about 19 percent of the city’s solid waste.
Although the Four Course compost is also made of yard trimmings, food-soiled paper, waxed cardboard and wood crates, the primary ingredient is food scraps. Most are restaurant food scraps, from fast food to fancy. “One of the primary reasons growers love our compost is because of our extremely diverse feedstock,” notes Robert Reed, Norcal’s director of corporate communications. “It includes melon skins, steak bones, red bell pepper, broccoli, pasta from North Beach restaurants, and fish heads and fish bones from Fisherman’s Wharf.”
Restaurants and food-related businesses participating in the Four Course program receive a discount for separating out the food scraps. “San Francisco has a ‘pay as you throw’ policy for refuse disposal rates,” explains Reed. “The more garbage you generate and the more service you require, the more you pay. Black carts are designated for nonrecyclable trash, blue carts for bottles, cans and paper, and green carts for food scraps. At the city’s direction, we provide a 25 percent discount on green cart service for commercial addresses.”
Restaurants are given 23-gallon containers to collect kitchen trimmings in food prep areas and plate scrapings at dishwashing stations. Restaurant workers then transfer the food scraps into the larger 64-gallon wheeled green carts, which are collected up to three times a week.
San Francisco’s residential program diverts food scraps and soiled paper from homes and apartments as part of its “Fantastic Three” 3-stream sort program. Residents receive blue, green and black containers for recyclables, organics and trash, respectively, and place the containers at the curb for weekly collection. The voluntary program started as a pilot in 1997. Today, approximately 150,000 single-family households in San Francisco receive the collection service.
Materials are compacted in the bodies of the collection trucks and delivered to San Francisco’s transfer station, which is operated by Norcal’s San Francisco Recycling & Disposal, Inc. There the materials are further compacted by being run over with a loader and then top-loaded with yard trimmings into transfer trucks. Most of the trucks are 18-wheel possum belly trailers that run on liquefied natural gas; some are walking floor trailers. (Reed notes that Norcal built the Bay Area’s first liquefied natural gas (LNG) fueling station, which is located just outside the transfer station.) The compacted food residuals are hauled from the transfer station 79 miles north to Norcal’s Jepson Prairie Organics Compost Facility in rural Solano County, near Dixon, California.
The materials are ground using a Peterson Pacific 5400 and composted for two months in aerated Ag-Bags, each measuring 180 to 200 feet in length. Next, the bags are unloaded and material is formed into windrows, turned every three days and cured for a month or more, and then screened to quarter-inch size.
Jepson Prairie (formerly B&J Composting Facility) was permitted to compost yard trimmings in 1995, and expanded its permit to food residuals in 1996. By 1998, it was processing the food residuals of almost 180 San Francisco businesses including supermarkets, restaurants, and wholesale produce suppliers. It is currently processing food scraps from about 2,200 restaurants and food-related businesses in San Francisco and another 130 in Oakland. Food scraps make up about 50 percent of the compost.
Four Course is sold for $8 a cubic yard to vineyards, as well as farms, golf courses and wholesalers who bag and sell it to the public. In the Bay Area, bagged compost blends are sold as Golden State Premium Garden Humus in Ace Hardware stores. In addition to Four Course Compost, Norcal makes several blends to specification for landscape supply yards. “Wine Country Soils coordinates sales between Jepson Prairie and landscape supply yards, which often request that we blend in other materials such as gypsum, lime, rice hulls and redwood sawdust,” notes Reed.
THE VINEYARDS
Four Course compost has been applied in 30 vineyards in Napa, Sonoma, Mendocino and El Dorado counties. Some vineyards have reported needing less fertilizer after using the compost. “We by far prefer compost because it is not toxic to the soil,” says Remi Cohen. “Fertilizer often contains inorganic salts, which can create toxicity in the soil and sometimes renders plant nutrients unavailable. Nutrient deficiencies can often be corrected in the short term by fertilizer applications, but compost, which adds organic matter and nutrients to the soil, can create sustained nutrient availability.”
At Bouchaine Vineyards, Cohen incorporates ten or more tons/acre of compost into the soil when planting new vines, and applies 3- to 5-tons/acre in existing vineyards every few years in the fall. Lime also is added to preplant compost applications. In recent under-the-vine applications, she has added potash for potassium. “Compost builds the microbial communities in the soil which help cycle nutrients and render them available for plant uptake,” she says. “This sustained nutrient availability helps create healthy, balanced grapevines.”
The eight-acre Inman vineyard has 13,000 vines, including 100 Pinot Gris and 12,000 Pinot Noir vines. The property was planted in 2000. Inman says she uses Four Course compost as a topdressing to maintain moisture and as a soil conditioner. Compost was applied as a mulch – a 12-inch wide, 3-inch deep layer directly below the vines. Inman says this had three benefits. “First, it worked as a weed deterrent. I only hand weed and do not use herbicides. Second, the compost helped retain moisture in the soil and helped conserve water when I did utilize irrigation. Third, when irrigated in the summer – about six times in total -the water percolated though the compost to gently feed the plants. It is now being worked into the soil by the rains and will be improving the texture of the soil and feeding the vines.”
Inman had been making her own compost prior to buying Four Course. “It was a relatively small amount, limited to what I could produce on the property from leaves, grass cuttings, vine prunings and table scraps,” she says. She combined her homemade compost with worm castings from Jack Chamber’s Sonoma Valley Worm Farm and a blend of blood, fish and bone meals and chicken manure. Inman is still using the worm castings with the Four Course compost. “I believe the castings have special microbial benefits that are unique,” she explains. In addition, Inman applies Ceres and Liquicomp, organically certified microbial teas, that she says help the vines take up nutrients in the soil more efficiently.
The biggest challenge, says Inman, is the cost of getting more than 500 yards of the compost hauled from Dixon to her vineyard outside of Santa Rosa. “The cost of shipping is more than the cost of the actual compost,” she notes.
ANALYSIS
Four Course compost was approved for use on organic soils by the Organic Material Review Institute (OMRI) in June 2001. OMRI provides certifiers, growers, manufacturers and suppliers an independent review of products intended for use in certified organic production, handling, and processing.
Norcal has hired different laboratories to test the finished compost and provide independent analysis, including Woods End Research Laboratory in Mount Vernon, Maine. “Woods End is conducting research and testing trials to determine the specific benefits of this compost,” says Will Brinton, president of Woods End. He notes that in testing, “Four Course has consistently scored high in Nutrient-Grade Compost. This is an unusual category reserved for composts that have sufficient combined nutrients of nitrogen, phosphorus, potassium, calcium and magnesium.”
The fact that Jepson Prairie’s compost is “higher in nutrients than almost all other green-waste composts results partly from the process,” he adds, noting that a form of lactobacillus composting is taking place inside the Ag-Bags that Norcal uses. “This causes slower carbon loss and greater nutrient retention,” he says.
Brinton has visited several California vineyards to get grower feedback on Four Course: “The success margins of these growers are so low that no one can afford to use compost that does not have specific identifiable benefits.”
The word about food scrap composting has spread to other cities. Los Angeles officials flew to San Francisco in 2002 to check out Norcal’s commercial food scrap program, and in May 2004, the City of Los Angeles hired Norcal to initiate a three-year pilot program in areas of Los Angeles with high concentrations of restaurants. “City officials are very pleased with the progress to date,” says Reed. “We currently have more than 40 restaurants in Los Angeles participating.” The pilot Norcal provides there calls for increasing the number of Los Angeles restaurants to 150 by May 2005. “Los Angeles is estimated to have more than 10,000 restaurants so we envision significant expansion of the program in the years ahead.”