"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.
"One of the criticisms of using any biomass as a biofuel source is it has been claimed that plants are not very efficient about 0.1 percent efficiency of conversion of sunlight into biomass," Long said. "What we show here is on average Miscanthus is in fact about 1 percent efficient, so about 1 percent of sunlight ends up as biomass."
"Keep in mind that when we consider our energy use, a few hours of solar energy falling on the earth are equal to all the energy that people use over a whole year, so you don't really need that high an efficiency to be able to capture that in plant material and make use of it as a biofuel source," he said.
Field trials also showed that Miscanthus is tolerant of poor soil quality, Long said.
"Our highest productivity is actually occurring in the south, on the poorest soils in the state," he said. "So that also shows us that this type of crop may be very good for marginal land or land that is not even being used for crop production."
Because Miscanthus is a perennial grass, it also accumulates much more carbon in the soil than an annual crop such as corn or soybeans, Long said.
"In the context of global change, that's important because it means that by producing a bi
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign