San Francisco-based Recology says composting food scraps through that city’s green bin program has helped turn regional vineyards and orchards “into carbon sinks—farms that store carbon deep in the soil.”
Applying compost to farmland increases stable carbon in the soil, which helps plants grow robust root structures. As well, says Recology, healthy plants pull carbon from the atmosphere and push carbon into their roots, which in turn exude carbon into the soil.
“The roots are what really provide the most effective forms of carbon, and the location of their carbon deposition makes them the big, quiet story in cover cropping. It’s all about the roots,” says agronomist Bob Shaffer, who advises farms in California, Australia and Guatemala on using compost to improve soil health.
Many vineyards and orchards in California plant cover crops, such as mustard, between row crops including wine and table grapes, almonds, cherries and olives, according to Recology. Farm crews then apply a half-inch of compost over the surface of the topsoil.
Farmers say the carbon and nitrogen in compost can cover crop roots and become dynamic food sources for the microorganisms that give life to soil, adds the waste and recycling firm.
Boosted by the availability of increased carbon, the microbial colonies in topsoil thrive and multiply. The microorganisms then break nutrients in the soil into smaller and smaller pieces making them available to primary crops. This form of climate-smart farming also helps protect topsoil from erosion.
And, importantly, compost is a natural sponge that attracts and retains water so applying it helps farms survive droughts.
“More than 150 cities across the country have followed San Francisco’s lead and implemented curbside food scrap collection programs for composting,” states Recology. Now in compliance with California SB 1383, a new state law requiring cities to reduce landfilling of compostable materials by 75 percent, municipalities throughout California are among those following San Francisco’s lead.
“Curbside composting saves landfill space, reduces methane emissions, and helps farms grow healthy food and save water, and when we compost at the curb, we help turn local farms into carbon sinks,” says Greg Pryor, who helped launch San Francisco’s composting program and heads Recology’s composting operations on the West Coast.
Curbside collection programs for composting allow residents and businesses to place food scraps in kitchen pails and other receptacles designated for compostable materials. They then can empty the contents of the pails into curbside composting collection bins, along with any sticks and leaves from gardening activities.
Recology describes itself as a 100 percent employee-owned integrated resource recovery company providing collection, recycling, composting and outreach and education services to communities in California, Oregon and Washington. It has more than 3,800 employees serving nearly 150 communities.