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Michigan State Researchers Uncover Carbon Debt in Conversion of CRP Land to Bioenergy Production

September 29, 2011 |

As fossil fuel supplies deplete and prices rise, demand for biofuel substitutes has increased. This growing demand for the development of renewable energy has even caused some to propose converting Conservation Reserve Program (CRP) grasslands to agricultural production to boost availability of such crops as corn and soybean for use as feedstock.

However, a recent study conducted by Michigan State University researchers found that converting these CRP lands to bioenergy production would negatively impact the environment as a result of the increased levels of C02 and greenhouse gas emissions that would be generated.

As background, the Conservation Reserve Program (CRP) provides farmers with annual rental payments and cost-share assistance in exchange for removing from row crop production farmland that is highly susceptible to topsoil erosion. The funds provided to the landowner are in turn used to establish conservation practices such as planting vegetative cover to prevent soil runoff and protect streams, rivers, and other bodies of water as well as the creation of habitats for area wildlife. Currently, more than 30 million acres of land have been classified as CRP land in the United States.

The Michigan State University study, which was published in July by the Proceedings of the National Academy of Sciences (PDF), examined and compared the carbon deficits that resulted from utilizing such practices as traditional farming, no-till (or not plowing the soil) farming, or planting perennial grasses when converting CRP lands for use in bioenergy production.

After a year of monitoring activity in a no-till crop production area that had previously been CRP land for 22 years, the researchers found that even when added caution is taken to protect soil from carbon loss, a carbon debt resulted. That is, the overall loss of carbon and greenhouse gases to the atmosphere from the conversion of the CRP land to corn and soybean-based biofuel production exceeded the potential of the biofuel product to offset the loss of carbon to the atmosphere. Researchers noted that the negative impact to the environment and atmosphere resulting from this carbon debt was equivalent to that which results from burning fossil fuels.

“No-till practices [planting without plowing] reduced by two-thirds the amount of debt created by the conversion, but still it would take 29 to 40 years for it to be repaid by growing corn and soybean for biofuel,” said Michigan State University postdoctoral researcher Ilya Gelfand. “Alternatively, growing CRP grasses harvested for cellulosic ethanol would create no debt and provide immediate energy and climate mitigation benefits.”

These grasses could have an even greater impact if the fields were fertilized or co-planted with legumes to increase productivity, the study states.

According to a press release from Michigan State University’s AgBioResearch, the study’s research indicates that conversion of CRP lands to corn and soybean production has a larger climate consequence than was previously estimated because much of the debt comes from the loss of soil carbon that would have been stored in CRP land in the future had it not been converted.

The study implores these farmers and others in the agricultural industry to consider these losses before deciding to convert CRP land to agricultural production.

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