Sonoma Compost: Celebrating 25 Years


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Sonoma Compost: Celebrating 25 Years
by Patricia Dines
Sonoma-Marin Farm News, Feb. 2010
(c) Patricia Dines, 2010. All rights reserved.
Overlooking the expansive dairylands of Petaluma, Will Bakx, co-owner of Sonoma Compost Company (SCC), ponders the long rows of steaming compost and says, "They're alive, beautiful, inspiring -- at least in my eyes."
For 25 years, SCC's soil amendments, created from local yard trimmings and agricultural discards, have been nourishing local crops, landscaping, school and home gardens, public lands, and more. Bakx explains that most soils are poor in organic matter, so adding compost can increase soil productivity by improving its structure, providing nutrients, conserving water, reducing erosion, and increasing microbial activity.
Even more exciting, SCC's operations divert more waste from the landfill each year than any other Sonoma County recycling service. Since 1993, the company has made use of over 1.2 million tons of discarded material, vitally contributing to the County's diversion mandates and helping reduce the financial and ecological impacts of hauling our garbage out of county.
A Seed Is Planted
The idea for SCC was sparked when co-owners Bakx and Alan Siegle met at Sonoma State University, where Bakx was managing the student farm and Siegle taught the Ecological Food Production class.
Siegle also co-owned Bennett Valley Farm, which since 1977 had been selling organic vegetables and flowers through Bay Area farmers' markets and stores, plus upscale catalogs.
When Siegle had difficulty finding organic compost, he and Bakx talked about creating a company to fill this need. Thus, in 1985, Santa Rosa's Bennett Valley Farm Compost was born, turning unwanted local horse and turkey manure into a resource that fed local soils naturally.
Moving to the Landfill
In 1989, a new opportunity emerged for the company when California passed AB 939 (The Integrated Waste Management Act). This law sought to address the state's increasing waste and decreasing landfill space by mandating specific targets for diverting usable materials from our garbage.
The first reduction target was organic (e.g., carbon-based) materials, and Empire Waste Management soon invited SCC to partner in creating a yard debris composting program.
Bakx was delighted to help, long frustrated by the "terrible waste" of organic matter going into landfills. And so, in 1993, SCC's current program was launched at Sonoma County's Central Disposal Site.
Daily Operations
Standing on SCC's 29 acres, Bakx describes to me how their 20 employees process over 93,000 tons a year of yard trimmings, agricultural discards, wood debris, and vegetative food scraps.
The materials arrive here via curbside green cans, individual drop-offs, and local farms, wineries, and food processors. The company starts by removing contaminants (such as plastic and glass) and recovering reusable wood items (such as pallets, lumber, and firewood, which it sells at discounted prices).
SCC then grinds what's left into composts and mulches that are placed in 42 windrows (long piles) stretching 7 feet tall, 18 feet wide, and from 180 to 650 feet long. These windrows are turned, monitored, and irrigated as needed during their 70- to 100-day processing periods.
The company's harvest for its efforts is 84,000 cubic yards annually of quality soil amendments, including two mulches plus its Sonoma Compost, Organic Hi-Test Compost (with chicken feathers for higher nitrogen), Mallard Plus Compost (with rice hulls for lightness), Feather-Lite Amended Soil (with sandy loam added to the Mallard), and lime and other custom blends.
All SCC products except its Path Mulch are OMRI-listed and allowed on organic farms, helping local farmers serve the growing organic market while reducing synthetic pesticide and fertilizer use.
The Next Frontier
In 2007, a Sonoma County Waste Management Agency study gave SCC good news: yard waste in our local garbage had been cut 73% from 1990 to 2007 (from 86,000 to 23,000 tons annually), and now was just 6% of total waste. SCC was delighted, says Siegle, "that we were doing a great job of getting the yard waste out of the landfill."
The report also highlighted the next area that SCC seeks to address: the 80,000 tons of food waste currently in our trash, which is 21% of total waste.
By finding ways to divert and make use of this material, Bakx and Siegle hope that they'll get closer to their ultimate goal: recovering all compostable materials from our waste stream.
And that's an objective that benefits us all.
Patricia Dines has been a freelance writer and sustainability consultant for 26 years. For more about her work, see For more about Sonoma Compost, see or call (707) 578-5459.


"Dear Patricia -- Thanks for the story on Sonoma Compost. It's a great read that our readers will find both interesting and educational. We are happy to have the work of a pro and welcome further stories by you on topics related to the agricultural industry in Sonoma and Marin Counties."
Tim Tesconi, Editor Sonoma-Marin Farm News, Previously Ag Staff Writer for the Press Democrat (33 years)


"Patricia -- This article so wonderful. I shared it with all my co-workers and will with others too as the opportunity arises. Thanks again."
Karina Chilcott, Waste Management Specialist, Sonoma County Waste Management Agency

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