Biofuels from corn less beneficial than reported: Study

Biofuels from corn residue may be less beneficial than previously thought as a study has found using corn crop residue to make ethanol and other biofuels reduces soil carbon and can generate more greenhouse gases than gasoline.

Corn stover - the stalks, leaves and cobs in cornfields after harvest - is generally considered a ready resource for cellulosic ethanol production.

The researchers used a supercomputer to estimate the effect of residue removal on 128 million acres across 12 corn belt states in the US.

The team found that removing crop residue from cornfields generates an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced (a joule is a measure of energy and is roughly equivalent to 1 BTU).

They also found the rate of carbon emissions is constant whether a small amount of stover is removed or nearly all of it is stripped.

"If less residue is removed, there is less decrease in soil carbon, but it results in a smaller biofuel energy yield," Adam Liska, an assistant professor at University of Nebraska-Lincoln in US.

To mitigate increased carbon dioxide emissions and reduced soil carbon, the researchers suggested planting cover crops to fix more carbon in the soil.

The study appeared in the journal Nature Climate Change.