Six-Year Study Suggests Perennial Crop Yields Can Compete with Corn Stover
by Mark E. Griffin (Wisconsin Energy Institute/University of Wisconsin) A six-year Great Lakes Bioenergy Research Center (GLBRC) study on the viability of different bioenergy feedstocks recently demonstrated that perennial cropping systems such as switchgrass, giant miscanthus, poplar, native grasses, and prairie can yield as much biomass as corn stover.
The study is significant for beginning to address one of the biofuel industry’s biggest questions: can environmentally beneficial crops produce enough biomass to make their conversion to ethanol efficient and economical?
Since 2008, University of Wisconsin–Madison research scientists Gregg Sanford and Gary Oates, and their colleagues at Michigan State University, have cultivated more than 80 acres of crops with the potential to become feedstocks for so-called “second-generation” biofuels – i.e., biofuels derived from non-food crops or the non-food portion of plants – at UW’s Arlington Field Station and MSU’s Kellogg Biological Station.
“We understand annual systems really well, but little research has been done on the yield of perennial cropping systems as they get established and begin to produce, or after farmland has been converted to a perennial system,” says Oates.
To find out basic information about how well certain crops produce biomass, Sanford and Oates, also affiliated with the Department of Agronomy, tested the crops across two criteria: diversity of species, and whether a crop grows perennially (continuously year-after-year) or annually (needing to be replanted each year).
Highly productive corn stover has thus far been the main feedstock for second-generation biofuels. And yet perennial cropping systems, which are better equipped to build soil quality, reduce runoff, and minimize greenhouse gas release into the atmosphere, confer more environmental benefits.
If there are limitations to the success of the trial thus far, it’s that it takes time for some perennial crops to produce enough biomass for harvest.
“In our case, the ramp-up of native prairie grass and switchgrass took almost two years,” says Sanford. “That’s a long time for farmers to wait for income.”
“One bad year can also have a big impact,” Sanford adds, noting the failure of the miscanthus crop at Arlington in the first year of the study. “If not for an unusually cold winter, it would have been more competitive with corn in Wisconsin,” he continues. “Looking forward, putting financial protections in place that are similar to those for commodity producers could help insure farmers when this happens.” READ MORE and MORE (Ethanol Producer Magazine)