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A Win-Win Situation: New Crops and BiorenewableFuels

By Susan Thompson

It’s estimated biomass fuels currently provide just 3 percent of the energy used in the United States. Researchers at Iowa State University hope to change that.

Plants not routinely found on Iowa farms — switchgrass, big bluestem, sweet sorghum, triticale, kenaf — fill several research plots on an Iowa State farm west of Ames.

“Our primary goal is to provide realistic alternatives for Iowa producers to diversify their cropping systems,” says Ken Moore, agronomy professor. But he’s quick to point out this isn’t just about developing alternative crops, but also developing valuable new uses for harvested materials.

Emerging markets for liquid fuels and other industrial products made from crop biomass offer new opportunities. “This requires development of an industrial market for these alternative biomass crops. In the end, the research should benefit not just producers, but also consumers and the alternative fuels industry,” Moore says.

Lance Gibson, associate professor of agronomy, says the Iowa State researchers studying biomass crops have five guiding principles. “We’re working to develop cropping systems that produce the most energy per acre per year, are energy efficient, meet food needs while producing more fuel than current systems, protect the natural resource base and add diversity to the landscape and the economy,” he says.

Several projects are underway to explore new crops and cropping systems that can help produce food and fuel while benefiting the environment. Others involved in the research with Moore and Gibson are Matt Liebman, agronomy professor and Henry A. Wallace Chair for Sustainable Agriculture, and Robert Anex, associate professor of agricultural and biosystems engineering and associate director of Iowa State’s Office of Biorenewables Programs.

Crop Options
This is the fourth year for a pair of projects evaluating kenaf varieties and production practices for Iowa. The crop usually is grown for industrial fiber, but also is a potential biomass crop.

Several varieties of kenaf have been planted with the goal of identifying ones that yield optimal fiber quality and quantity. The fibers are evaluated for use in ethanol production and biocomposite materials. This research also involves studying the best management practices for growing kenaf in Iowa and an economic evaluation of the industrial use of kenaf and its by-products.

It’s the third year for a project involving five sweet sorghum varieties and management practices. Once harvested, each variety is evaluated to determine how well it is suited for ethanol production.

This is the second year for a study of native warm-season perennial grasses that show promise for biomass production — switchgrass, Indiangrass, big bluestem and eastern gamagrass. Various management practices are being evaluated and samples collected to compare biomass production, carbon storage and nutrient use efficiency.

Miscanthus is another possibility. But so far, tests in Iowa have proven this crop to be difficult to establish, since young plants are sensitive to cold and dry soil. Another downside is that it can take 3-5 years to establish this perennial, meaning a producer would have nothing to harvest for at least two years.

Alternative Crop Systems
Liebman, Anex, Moore and graduate student Andrew Heggenstaller are especially interested in evaluating how nutrients can be recovered from biorefineries as grass biomass is processed, and how those nutrients can be recycled to the fields where the perennial grasses grew. This nutrient recycling may eliminate or at least reduce the need for additional fertilizer inputs in biomass cropping systems.

A concern sometimes raised about the use of annual crops for biomass is that removing large amounts of crop residue from fields might lead to greater soil erosion, reduced soil fertility and increased need for commercial fertilizers.

“To address these challenges, we are investigating alternative cropping systems and associated management practices that might be used to generate large amounts of biomass feedstocks while better protecting environmental quality,” says Liebman.

“Our theory is that producing two crops in one year will generate more biomass at lower environmental cost than will a single crop of corn,” he says. With that in mind, a long-term crop rotation study that looks at the possibility of a double-crop sequence of winter and summer biomass crops is in its second year.

Triticale, a cross between wheat and rye, is planted in October and harvested for biomass the following June. This protects soil and water quality during winter and spring, when Iowa crop fields typically are barren.
Once the triticale is harvested, warm-season crops such as corn, sorghum-sudangrass and crotalaria, a legume that can fix large quantities of atmospheric nitrogen, are planted.

Decision-making Tools
Not only are the researchers focused on new crops and new cropping systems, they’re also considering what decision-making assistance producers will need in this new era of agriculture.  

To help farmers begin to understand how collecting biomass from their fields may affect soil fertility, erosion, energy needs, labor and the bottom line, Anex and others added bioeconomy elements to I-FARM, a Web tool that helps farmers simulate and plan various changes to their operations. The free tool focuses on the Midwest and Northeast with weather and soils data for 28 states accessible from its database. It is available at http://evo.ae.iastate.edu/i-farm/.

Growing enthusiasm for biofuels has raised many questions about impacts on farmers’ income and the environment. “The need to produce both food and fuel from farm land places new demands on the agricultural system,” Anex says. “Yet biofuel demand also creates opportunities to develop new crops and cropping systems that provide new value to farmers while reducing environmental impacts.”

As long as questions remain, Iowa State University researchers will continue their search for answers.