Sure,  clean-burning bio-fuels sound like the perfect solution to curbing greenhouse gas emissions and decreasing US dependence on foreign oil–it is, after all, “gas you can grow,” and the US has plenty of agricultural land. But is it really energy-efficient to grow bio-fuels crops? A new study from Michigan State University (MSU) Office of Biobased Technology says ‘no.’

Phil Robertson, a University Distinguished Professor of crop and soil sciences, Ilya Gelfand, a postdoctoral researcher, and Sieglinde Snapp, an associate professor of crop and soil sciences, recently published a paper in which they detailed the results of a study analyzing data collected from 1989 to 2007 at the W.K. Kellogg Long-Term Ecological Research site. The scientists compared the energy inputs and outputs of producing corn, soybeans and wheat and energy balances for growing alfalfa (an important forage plant that can be used either for biofuel or for beef cattle feed.) They  found that using non-tilling production to grow grain for food was–surprise, surprise–36% more energy-efficient than growing crops for bio-fuel, as the food crops did not require as much gas for tractors.

image via DOE

The study did, however, come down clearly on the side of using salvaged bio-mass for bio-fuel production. Gelfand said, in a statement. “The ideal is to grow corn for food, then leave half the leftover stalks and leaves on the field for soil conservation and produce cellulosic ethanol with the other half.” Now, will farmers heed the science? That remains to be seen.