The University of Illinois (www.illinois.edu) Energy Farm project has devoted 320 acres to create the largest biofuels research farm in the United States, growing crops that could be used to produce renewable energy. Last year the farm planted miscanthus, switchgrass, corn, and restored prairie as bioenergy crops, and researchers say miscanthus has produced more than double the biomass per acre as corn.

Early research results show that miscanthus may also be a good fit for bioenergy because it produces without the need for any nitrogen fertilizer, very few other inputs and it adds significant amounts of organic matter to the soil.

On the negative side, reasearchers say miscanthus is labor-intensive to plant, because it is a sterile crop and doesn”t produce a seed. So while it isn”t a threat to become invasive, it is difficult to reproduce at an agronomic scale.

Researchers are working to develop machinery that can efficiently plant and harvest it, rather than digging it up with a shovel or by hand.

On the other hand, restored prairie grass as an energy crop is a relatively new concept. “Illinois used to be a prairie. If we”re going to convert possibly marginal land back to grasses, restored prairie has the potential to be a possible biomass source because it is what was naturally here before modern agriculture,” says Tim Mies, director of the Energy Farm project.

Restored prairie is a mixture of tall grasses and small nitrogen fixers. Instead of management through regularly scheduled prairie burns, it is harvested as a crop in the early winter when nutrients have been cycled back to the roots.

One of the challenges in growing restored prairie as a biomass crop is that it can be choked out by other more aggressive weeds. The consistency of the resulting fuel may also be an issue with prairie grass. To process it, reaserchers say a consistent material with very little nutrient left in it is desirable. And while a field of switchgrass is all switchgrass, a field of restored prairie is a mixture of plants and grasses — the proportions of which change from acre to acre and bale to bale, which is not a problem with switchgrass or miscanthus. This inconsistency could make it difficult to use the harvested biomass as a feedstock for processing to ethanol.

Long term, the Energy Farm plans to conduct research on many more potential biofuel crops.