MADISON, WI, MAY 18, 2007 Storing carbon in agricultural soils presents an immediate option to reduce atmospheric carbon dioxide and slow global warming. Farmers who adopt practices that store carbon in soil may be able to "sell" the stored carbon to buyers seeking to offset greenhouse gas emissions. Before farmers can sell carbon credits, however, they need to be able to verify that changing soil management has increased the soil organic carbon (SOC) in their fields.

Researchers at Montana and Colorado State Universities now have evidence that a soil model can be used to accurately estimate carbon levels in soil under certain climate and land conditions. By using this model, farmers and landowners will be able to verify soil carbon change for carbon trading. Scientists report their findings on the reliability of the Century soil model in the May-June 2007 issue of the Soil Science Society of America Journal.

Funding for this research was provided by the Upper Midwest Aerospace Consortium-Public Access Resource Center, the Consortium for Agricultural Soils Mitigation of Greenhouse Gases, and the Montana State University Agricultural Experiment Station.

"The Century model estimates soil organic carbon content and soil organic carbon change using soil texture, weather, and farm management information," said Ross Bricklemyer, lead author of the study.

Working together with farmers from Montana, researchers compared Century model estimates of soil carbon storage to field SOC measurements. Scientists measured carbon storage and soil texture in 10 paired fields under no-till and conventional-till management. They estimated the increase in carbon stored under no-tillage adoption as the difference between carbon levels in no-till and till fields. They then compared the soil carbon values predicted by the Century model to measured SOC and SOC rate of change.

The Century model accurately predicted SOC content and rate
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Contact: Sara Uttech
suttech@soils.org
608-268-4948
American Society of Agronomy
18-May-2007