OSU Extension-trained composters use coffee grounds

April 4, 2008
Jack Hannigan photo by Linda Renslow

Jack Hannigan, an OSU Extension-trained Compost Specialist, collects coffee grounds to make compost for his farm in Pleasant Hill. Photo by Linda Renslow.

EUGENE, Ore. – Every day thousands of yawning commuters, sleep-deprived college students and caffeine-addicted office workers in Lane County fuel up at coffee shops. But what happens to the dark, steaming, gritty coffee grounds that are left over from each latte, espresso and mocha?

The majority have been trucked to the Short Mountain Landfill, Lane County's only municipal solid waste disposal site. But now some of the county's aromatic grounds are ending up in area gardens, thanks to a composting program launched by the Oregon State University Extension Service in Lane County.

Since 2004, Extension-trained composters have collected almost 200 tons of grounds from 13 coffee shops and kiosks in Eugene, Springfield, Florence, Cottage Grove and Veneta, said Cindy Wise, the coordinator for Extension's Compost Specialist program in Lane County.

That's the equivalent of about 25 large dump trucks, said Dan Hurley, the landfill's waste management engineer.

Last year, the volunteer composters – known as Compost Specialists – collected 53 tons of coffee grounds, Wise said, estimating that coffee shops in Lane County produce a combined 500 tons of grounds each year.

In recognition of their work, Lane County commissioners gave Wise and the Compost Specialist program their Trashbuster Award in 2005.

The coffee ground composting program started when Compost Specialists placed 32-gallon containers at various coffee shops to collect the grounds, which they and other members of the public then used in their gardens.

The system, however, is evolving. In lieu of using 32-gallon containers, Compost Specialists are now hoping to implement a system that uses 5-gallon buckets. They're surveying more than 80 coffee shops in Eugene and Springfield to see which ones would be willing to let the public bring buckets to the shops to retrieve grounds.

"This is something anyone would be able to do at participating coffee shops. Just take a clean five-gallon bucket with a lid, leave it at the shop, and then pick it up at the shop's convenience," Wise said.

Compost Specialists will compile a list of participating shops that will include their addresses and their conditions regarding when and how frequently people must pick up the buckets. Extension in Lane County will publish the list on its Web site and in a brochure, probably in May or June, Wise said. She added that a pilot program is under way at the Starbucks at 801 E. 13th Ave. in Eugene.

Wise said coffee grounds are an excellent addition to compost piles because they add nitrogen, which bacteria need to turn organic matter into compost. She also said earth worms are attracted to the grounds and that the grounds are a safe substitute for nitrogen-rich manure.

"A lot of people don't want to use manure because of concerns about pathogens," she said.

Wise said that informal trials by Compost Specialists in Lane County found that coffee grounds helped sustain high temperatures in compost piles, thus reducing potentially dangerous pathogens as well as seeds from weeds and vegetables that were added to the piles. In the trials, when coffee grounds made up 25 percent of the volume of the compost pile, temperatures were sustained between 135 degrees and 155 degrees for at least two weeks, enough time to have killed a "significant portion" of the pathogens and seeds, she said. In contrast, the manure in the trials didn't sustain the heat as long, she said.

"We were amazed at the results we got with coffee grounds when we did the trial," she said.

Jack Hannigan, a Compost Specialist, is pleased with the results he gets from the coffee grounds he collects from the Fast Lane Coffee Company in Springfield to use on his farm in Pleasant Hill.

"I make hotbeds that run about 150 degrees,” Hannigan said. “It kills the weeds. I can get the piles hotter and break down the compost better with coffee grounds than I can with manure. It works great."

Coffee grounds also can be added directly to soil but the grounds need a few months to break down, Wise said. "We're not certain about how coffee grounds act with the soil, but anecdotally people say they do dig it into the soil," she said.

To gather more data about this, in a couple of weeks Compost Specialists in Lane County will start studying the effect that coffee grounds have on soil at test plots in and near Eugene. In each location, one part of the plot won't have coffee grounds mixed into the soil; another will, and a third will have even more.

"We'll let them sit in the soil and come back in six to eight weeks and take a soil sample and analyze for nitrogen, potassium, phosphorus and how it affects the pH of soil," she said. "We need to find out how long it takes to break down and how it will affect the nutrients in the soil. Then we'll plant bush beans and see how they look."

Extension in Lane County will share the results with the public on its Web site in the fall, Wise said.

Gardening aside, one benefit of diverting coffee grounds from the landfill is that it helps cut greenhouse gas emissions, Hurley said.

"To keep organics out of the landfill is a good thing for reducing greenhouse gas emissions because organics decompose and produce methane. Methane is about 25 times as bad as carbon dioxide, a greenhouse gas," he said.

Sarah Grimm, the waste reduction specialist for Lane County Public Works, said she applauds the program for encouraging interactions between community residents and local businesses. She also likes that the coffee grounds are staying in their communities, meaning that fuel isn't being used to truck them from far-flung areas of the county to the landfill near Eugene.

"It's a wonderful program," she said. "As a waste reduction specialist, I can get behind something like that. Sending it to a compost pile is better than trucking it from there to here."

OSU Extension in Lane County

Compost Specialist Program

Author: Tiffany Woods
Source: Cindy Wise, Peter Thurston