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25-year study measures soil carbon accumulation in cropping

Michigan State University research studying the long-term impact of agricultural practices on soil organic matter has reached a major milestone.

Phil Robertson has been collecting data at the Kellogg Biological Station for a quarter century. 

“These sorts of studies are very unusual in the sense that there aren’t many places in the U.S. where soil carbon is steady for this length of time, and there are even fewer places where it’s done in an experimental context.”

He tells Brownfield the research is necessary to give credibility to carbon market programs.

“The models require validation against known rates of carbon accumulation due to a particular cropping practice, and it’s these sorts of 25-year studies that will provide the data,” he explains.

Ten systems are being compared including undisturbed land, perennial crops and four types of rotations of corn, soybeans, and wheat with different tillage and cover crops.

Robertson says he was most surprised by the results from the cover crop system that’s tilled annually to maintain its organic status.

“The cover crop system accumulated carbon at almost twice the rate as the no-till and we think that’s related to additional plant diversity,” he says.

Robertson says all of the systems increased soil carbon levels to some extent but at very different rates.

MSU will continue the project for what Robertson hopes will be long into the future.