Putting used coffee grounds in your compost can make it burn hotter than if you added manure, researchers and farmers say.

Coffee in the garden

Ah, hot coffee: good for the soul, good for the soil.

Experiments in Lane County suggest that nitrogen-rich coffee grounds could play a role like manure in cooking compost — breaking down organic matter so that it can be used in growing crops.

"Our local restaurants, coffee dealers, home consumption — just think of the amount of coffee grounds," says Cynthia "Sami" Ward of Medford, who started a composting program at the Southern Oregon Research and Extension Center in Central Point last fall.

"It's either going in the garbage disposal or the green curbside cans," she says.

Ward says it's common for people to put coffee grounds in their compost piles, but she also sprinkles the grounds around acid-loving plants such as camelias or azaleas.

"I've even put it around rose bushes," she says, noting that she places the grounds out from the base where the roots are.

"You can just scratch it in two or three inches and the nutrients just flow into the soil. It helps activate microbes and all those good creatures in the soil."

Ward says she plans to do composting experiments at SOREC, and she might try to find some bulk coffee grounds from local retailers or businesses.

Trials by the Oregon State Extension Service in Lane County showed that when 25 percent of compost was coffee grounds, temperatures ran from 135 degree to 155 degrees for at least two weeks, says Cindy Wise, coordinator of the service's compost program.

One organic farmer attests to the grounds' ability to make compost hotter longer.

"I can get the piles hotter than I can with manure," says Jack Hannigan of Pleasant Hill, who has been using grounds for more than a year. He said his coffee-fueled compost can reach 150 degrees.

The service plans more tests on coffee grounds and compost this planting season, ending with trials on bush beans, and it has been working with coffee shops to link grounds and gardeners.

For the past four years, 13 coffee retailers have worked with Extension compost specialists who placed 32-gallon containers at the shops to collect the grounds — collecting almost 200 tons of grounds from shops in five towns for use in gardens, Wise said.

There have been glitches, she said. Some people have tried to reuse the grounds. Some retailers got stuck with heavy loads of grounds that nobody picked up.

Now, Wise said, the Extension Service is surveying coffee shops in Eugene and Springfield to see how many would work with customers who brought their own 5-gallon buckets to be filled at the shops' convenience.

Diverting coffee grounds from the waste stream is good for more than just the health of the soil, said Lane County Waste Management engineer Dan Hurley. Coffee grounds in landfills help to generate the greenhouse gas methane, he said.

On the Net: Lane County compost program:SOREC: OSU Extension, Lane County:

Correction: This article contained an erroneous plant name. This version is corrected.

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