In the largest field trial of its kind in the United States, researchers have determined that the giant perennial grass Miscanthus x giganteus out performs current biofuels sources – by a lot. Using Miscanthus as a feedstock for ethanol production in the U.S. could significantly reduce the acreage dedicated to biofuels while meeting government biofuels production goals, the researchers report.

The new findings, from researchers at the University of Illinois, appear this month in the journal Global Change Biology.

Using the grass Miscanthus x giganteus as a feedstock for ethanol production would significantly reduce the amount of farmland needed for biofuels, said U of I crop sciences professor Stephen Long.

Using corn or switchgrass to produce enough ethanol to offset 20% of gasoline use – a current White House goal – would take 25% of current U.S. cropland out of food production, the researchers report. Getting the same amount of ethanol from Miscanthus would require only 9.3% of current agricultural acreage.

"What we've found with Miscanthus is that the amount of biomass generated each year would allow us to produce about 2 1/2 times the amount of ethanol we can produce per acre of corn," said crop sciences professor Stephen P. Long, who led the study. Long is the deputy director of the BP-sponsored Energy Biosciences Institute, a multi-year, multi-institutional initiative aimed at finding low-carbon or carbon-neutral alternatives to petroleum-based fuels. Long is an affiliate of the U. of I.'s Institute for Genomic Biology. He also is the editor of Global Change Biology.

In trials across Illinois, switchgrass, a perennial grass which, like Miscanthus, requires fewer chemical and mechanical inputs than corn, produced only about as much ethanol feedstock per acre as corn, Long said.

"It wasn't that we didn't know how to grow switchgrass because the yields we obtained were actually equal to the best yields that had been obtained elsewhere with switchgrass," he said. Corn yields in Illinois are also among the best in the nation.

In field trials in Illinois, researchers grew Miscanthus x giganteus and switchgrass in adjoining plots. Miscanthus proved to be at least twice as productive as switchgrass.

"One reason why Miscanthus yields more biomass than corn is that it produces green leaves about six weeks earlier in the growing season," Long said. Miscanthus also stays green until late October in Illinois, while corn leaves wither at the end of August, he said.

The growing season for switchgrass is comparable to that of Miscanthus, but it is not nearly as efficient at converting sunlight to biomass as Miscanthus, Frank Dohleman, a graduate student and co-author on the study, found.