AgBioResearch Shows Cover Crops, Compost Offset Carbon Loss from Corn Stover Ethanol Production

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Making ethanol from plant waste might quiet the food-versus-fuel debate, but removing organic carbon nutrients from the soil creates new issues. MAES scientists are finding a way around that problem, too.

Corn stover, the leaves and stalks of corn plants left after harvest, is a promising source of cellulosic ethanol. MAES crop and soil scientists Kurt Thelen and Doo-Hong Min and graduate student Bradley Fronning are finding that farming practices such as planting cover crops and adding manure and compost can reduce carbon loss in fields where corn stover is removed.

The team measured soil carbon changes as well as nitrous oxide and methane gas emissions from several test plots. They also assessed the carbon cost of crop inputs, methane emissions from manure sources, greenhouse gases generated during manure storage and application, and fuel use in crop production.

“The results demonstrate that bioenergy cropping systems, particularly those that use livestock manure as part of the management scheme, are a win-win option on both alternative energy and environmental fronts,” Thelen said. “With proper management, livestock manure can replace carbon lost from corn stover removal and actually provide an environmental benefit, both in terms of greenhouse gas mitigation and the improved soil properties associated with increasing soil organic carbon levels, such as increased water retention.”

“It will be important to build on this research by comparing tillage systems—no-till versus conventional tillage—and looking at integrated cropping systems such as corn-alfalfa rotations. In addition to their carbon storage and bioenergy value, these are very important crops as feed sources for the dairy industry,” Min added.

The research is supported by the MAES, the U.S. Department of Agriculture Cooperative State Research, Education and Extension Service, and the Consortium for Agricultural Soils Mitigation of Greenhouse Gases program.

The study, “Use of Manure, Compost and Cover Crops to Supplant Crop Residue Carbon in Corn Stover Removed Cropping Systems,” was published in the November 2008 issue of the Agronomy Journal and is available online.

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