Research identifies growing zones for bioenergy crops

November 25, 2014, Champaign, Ill. — Researchers at the
University of Illinois have published a study identifying yield zones for three
major bioenergy crops.

“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,” said U. of I. atmospheric
sciences professor Atul Jain, who led the study with agriculture and consumer
economics professor Madhu Khanna.

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 show greater potential for ethanol production,
particularly large perennial grasses such as Miscanthus and switchgrass. These
grasses yield more ethanol per hectare in the U.S., while needing fewer resources
than corn.

“With growing interest in bioenergy crops as a potentially
important source of energy, it is crucial to explore high-yielding feedstock
sources that could provide abundant biomass for large scale biofuel production
and minimize the amount of land diverted from food to fuel production,” Jain
said. “The extent to which this goal can be achieved will depend on the
biophysical potential of producing bioenergy crops on the available land.”

The Illinois researchers studied three biofuel crops to determine
where they would grow best in the United States: Miscanthus and two types of
switchgrass, Cave-in-Rock and Alamo. They used a land-surface model called
Integrated Science Assessment Model (ISAM), developed in Jain’s lab, which
takes into account environmental attributes such as water and temperature,
biological properties such as nutrient availability, and the dynamic response
of the crops to changes in environmental conditions.

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.

For example, 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.

The researchers expect that the results of their study,
published in the journal BioEnergy Research, will enable farmers to make better
decisions about which bioenergy crop to grow. A farmer in the south can look at
the maps and see that his area is in the low-yield, unstable zone for
Miscanthus, but the high-yield, stable zone for Alamo switchgrass.

Jain said there are many other factors to consider, and the
team is working to expand its model to give farmers a more complete picture of
the risks and rewards of producing bioenergy crops.

“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 said. “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 National Science Foundation and the Unites States
Department of Agriculture supported this work.