Since 1996, San Francisco has saved more than 900,000 tons of food scraps and yard trimmings from ending up in the landfill through its composting program, according to new data from Recology, the city’s garbage and recycling collection company. The San Francisco-based company produces about 95,000 cubic yards of rich soil amendment from these discards and sells the organic product to farms and vineyards in Northern California.
“Compost returns nutrients to the soil, saves space in the landfill and provides farmers with an alternative to chemical fertilizers. It also helps farmland retain water, so farmers don’t have to irrigate as much,” said Robert Reed, Recology’s public relations manager.
Now, scientists have discovered another reason to compost: It can slash carbon emissions. Many farmers add Recology’s compost to their soil to grow cover crops – crops that help manage soil quality or pests. These crops draw in carbon from the air, and their roots deposit the carbon deep in the soil, essentially creating a sink for carbon, a gas that contributes to climate change. Reed said applying compost to one acre of land can sequester 12,000 pounds of carbon in one year.
Using this data, San Francisco’s composting program actually offsets the city’s carbon emissions by 354,000 metric tons – the equivalent of offsetting emissions from all the vehicles traveling across the city’s Bay Bridge for just over two years.
Started as a pilot program in 1996, the city’s composting program originally collected food scraps from the city’s distribution center for wholesale produce and soon expanded to serve large hotels and restaurants. By 2003, the composting program was available to all residents and businesses. The city mandated composting for all properties in 2009.
“Prior to the ordinance, we collected 400 tons of food scraps and plants a day,” Reed said. “Today, we’re collecting 540 tons a day. That’s a 25 percent increase in less than two years.”
Also subject to the mandatory composting ordinance are apartment buildings, often a difficult place to collect recyclables due to tenant turnover and space limitations. But San Francisco’s apartment composting program is flourishing, Reed said 80 percent of the city’s apartment buildings – 6,000 apartment buildings – participate in the composting program, a true testament to how far the program has come.
“We’ve crested a great hill. Six years ago, people had the ‘ick’ phobia – a fear that composting was going to smell. But actually it was the same garbage [people had produced before], just sorted differently,” Reed said. “Between our efforts and the city’s ordinances, we have great momentum. We’ll continue to get each property participating in the program and help the city reach its zero waste goal, set by the San Francisco Board of Supervisors.”