Biofuels may be good for the environment, but farmers who decide to grow bioenergy crops face risk like any other commercial venture. Researchers at the University of Illinois, however, have made growing the crops easier by mapping where they thrive best.
Atmospheric sciences professor Atul Jain, along with agriculture and consumer economics professor Madhu Khanna, have identified yield zones for three large perennial grasses that are emerging as major bioenergy crops—Miscanthus and two types of switchgrass.
“The unique aspect of our study is that it provides detailed information about where these crops can grow, in terms of their location and stability over time, which has not been done in the past,” says Jain. Their findings were published in the journal Bioenergy Research.
Although corn has been the main feedstock used for ethanol production, relying solely on corn is not sustainable because of its impacts on the environment and food prices. Other crops such as Miscanthus and switchgrass yield more ethanol per hectare in the U.S., while requiring fewer resources than corn.
Using the Integrated Science Assessment Model (ISAM), developed in Jain’s lab, the researchers found that Alamo switchgrass has a high, stable yield in the southeastern states, while Miscanthus and Cave-in-Rock switchgrass grow best across the Midwest. Across Indiana, Ohio, and Kentucky, Miscanthus has about twice the yield of switchgrass, but the yield is unstable, so farmers may have to modify production practices and apply additional resources annually to reduce variability in Miscanthus yields.
ISAM takes into account water, temperature, biological properties such as nutrient availability, and the dynamic response of crops to changes in the environment. The researchers calibrated and validated the model using experimental data collected at more than 75 sites across the U.S., using the model to determine yields over 10 years. They identified regions likely to continuously produce higher or lower yields for each crop, based on favorable or unfavorable conditions.
“We want to develop an integrated system that can determine not only the potential yield of these crops, but also the economic cost and variability in returns from their production,” Khanna says. “In some places, farmers may have to invest more to plant these crops. We would like to examine how returns and risks from producing these crops differ across regions.”
The use of Miscanthus and switchgrass for biofuels is in very early stages, and the amount being grown for that purpose is not easy to pin down. According to Khanna, there are some 16,288 acres of Miscanthus farms in Arkansas, Missouri, Ohio, Pennsylvania, and North Carolina receiving assistance under the Biomass Crop Assistance Program of the United States Department of Agriculture, though she says that figure is likely lower than the real number of acres devoted to biofuels.
As for switchgrass, in 2007 the state of Tennessee invested $61 million in growing the plant for cellulosic ethanol. As of 2012, some 6,000 acres of switchgrass were planted in the state for the project, according to the Agricultural Marketing Resource Center at Iowa State University.
The National Science Foundation and the United States Department of Agriculture supported the study by Jain and Khanna.
