Carbon cowboys: by storing carbon in the soil, ranch owners can reduce greenhouse gas emissions.
John Wick wasn't always a rancher. In fact, ranching was the farthest thing from the California environmentalist's mind when he and his wife purchased a tract of coastal prairie in 1998. "We thought cows wrecked the land, so we kicked of fall the cattle, tore down all the fences and proceeded to watch the landscape become ruined," says Wick.
As Wick came to realize, cows and other grazing animals are necessary to maintaining a healthy grassland ecosystem. When cows bite a blade of grass, they stimulate the plant's growth. And, as the animals lumber from one patch of pasture to another, cows knead manure and other organic matter into the soil, providing it with essential nutrients that further its growth.
The more plants grow, the more carbon dioxide they pull out of the air, which the roots then bury deep below the dirt for thousands of years. Known as soil carbon sequestration, this natural process already helps curb climate change, and many believe it can be enhanced to provide additional sequestration. According to the Intergovernmental Panel on Climate Change's Third Assessment Report, over the next 50 years approximately 100 billion metric tons of carbon could be sequestered through forest preservation, tree planting and improved agricultural management, offsetting 10% to 20% of the world's projected fossil fuel emissions.
Because of soil's unique ability to sequester carbon, Wick helped found the Marin Carbon Project in 2007 to spread the word about carbon sequestration in rangeland, agricultural and forest soils through participation with ranchers and other landowners. Currently, rangeland ecosystems cover approximately one-third of the land area in the U.S. and an estimated 40% to 70% globally, which means that soil carbon sequestration has a huge potential to trap emissions.
"The number of acres of rangeland on the earth is enough that a very small change in sequestration will do the job," says Wick. "We're looking at this abundance of C[O.sub.2] in the atmosphere as an untapped resource that we want to put to beneficial use in our soil systems."
To establish a baseline for how much carbon soil can sequester without any change in management practices, project researchers surveyed 35 sites in California's Marin and Sonoma counties in 2008. Measuring down to a meter deep, the researchers found a broad range of carbon sequestration levels, from 35 tons to 150 tons of carbon stored per hectare. Once they established the baseline, the researchers began looking into how to enhance that sequestration so that they could then promote those methods to land managers.
They found that by implementing such practices as spreading a thin, half-inch layer of compost on the soil and practicing careful rotational grazing (where cows are frequently rotated to various land plots), landowners can improve their land and sequester more carbon--a win, win situation for ranchers and for the environment.
"When we talk to land managers, our focus isn't carbon sequestration. It's about ecosystem benefits," explains Wick. "The ranchers don't care about carbon; they want to know if it makes more food."
Organizations like the nonprofit Soil Carbon Coalition are working to advance the practice and engage people in the opportunity of turning atmospheric carbon into soil organic matter. Its main project in the works is the Soil Carbon Challenge or World Carbon Cup, a prize competition to see how fast land ranchers can turn atmospheric carbon into soil organic matter. "People hear every day that eating meat is bad for the climate, but cattle raised on grass can have a tremendous positive impact on the carbon cycle," says Peter Donovan, a coalition board member. He believes that local governments should also be interested in promoting better land management practices because they can increase area resistance to flooding and droughts. There is even talk of paying ranchers to sequester carbon through carbon credits, with the caveat that ranchers should only be rewarded for practices that create additional carbon sequestration.
"Farmers are already sequestering carbon and always have as a matter of course, so paying them for maintaining the baseline doesn't help in terms of curbing climate change," says Dork Sahagian, director of the Environmental Initiative at Lehigh University who was also a contributor to three IPCC assessment reports.
He believes that carbon credits for ranchers can work if they are strictly limited to changes in behavior that promote carbon sequestration in the soil. "We're killing two birds with one stone by producing meat and milk from grasslands while also sequestering carbon," he says. "So that should be the baseline and then people get paid for going above that."
CONTACTS: Carbon Sequestration in Agriculture, www.epa.gov/sequestra tion/faq.html; Marin Carbon Project, www.marincarbonproject.org; Soil Carbon Coalition, www.soilcarboncoalition.org.
JESSICA A. KNOBLAUCH is a freelance journalist living in the San Francisco Bay area.
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|Author:||Knoblauch, Jessica A.|
|Date:||May 1, 2010|
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