Michael Casler and Paul Weimer are experts on matters related to forage digestibility in dairy cows. So how did they end up doing research on use of biomass crops for ethanol production?

It”s a question that Casler, a plant geneticist, and Weimer, a microbiologist, have heard more than once. Both are on the research staff of the U.S. Dairy Forage Research Center, a USDA-Agriculture Research Service facility located on the UW-Madison campus. They also have faculty appointments in the College of Agricultural and Life Sciences – Casler in agronomy, Weimer in bacteriology.

Actually, the two areas of research have a great deal in common, Casler explains. Forage digestion and ethanol production are really just two different types of fermentation systems.

“The chemicals that limit degradation of plant cell walls in the cow”s rumen are that same ones that limit ethanol production,” Casler says. “Both systems are after fermentable structural polysaccharides, whether they are broken down by bacteria or yeast. The ability of the fermentation systems to get at those polysaccharides is limited by lignin and phenolic acids.”

In short, both systems center on the breakdown of sugars. The common obstacle in these systems is the plant cell wall, a structural support framework made up mostly of cellulosic carbohydrates and lignin.

The Dairy Forage Research Center has a great infrastructure to move ahead in the field of bioenergy crops, Casler says.

“We are taking our existing knowledge and sliding it over and applying it to bioenergy,” he says. “We”re using the same technology, the same ideas, the same breeding systems.”

As Wisconsin farmers and landowners look for ways to combine environmental stewardship with new, alternative sources of income, it”s no surprise that bioenergy crops – crops that can serve as feedstock”s for ethanol production – have piqued their interest.

While much of the attention has been focused on making ethanol from starch, the complex carbohydrate stored in grain kernels, forage specialists on the UW-Madison campus are interested in a different carbohydrate: cellulose, the chief component of cell walls, which comprises the bulk of plant material.

Casler breeds and evaluates forages as potential bioenergy crops. He says the top contenders – both in terms of yield and survival in a range of environments – are switchgrass, big bluestem and eastern gama grass.

“All have potential as a bioenergy crop over a fairly broad geographical range,” says Casler. “They can grow from Texas to Canada, or nearly so. Different varieties are adapted to different areas. That”s one of the things that make them attractive.”

Casler spent 12 years developing a switchgrass breeding program at the College”s agronomy department before making the two-block move to join the staff at the U.S. Dairy Forage Research Center.

What he learned from that work, along with his switchgrass adaptation research, provided the basis for the recommendations he and Extension staff make to farmers who want to plant biomass crops.

“This research has helped us refine where these varieties should be recommended,” he says. “When people call me or the extension service and say they want to plant 40 acres of switchgrass, we have a couple pretty good ideas. We”ve made a lot of progress in that area.”

Casler is working with Paul Weimer to develop a lab test to measure the quality of switchgrass. To retrieve the best data, the test needs to be “rapid, repeatable, able to handle large numbers of samples, and correlate with high energy content,” says Casler.

“Once we can do that, we”ll continue working on screening varieties to strengthen recommendations, and put that information into the breeding program.”

The goal of that breeding program, says Casler, is to create a switchgrass that is high in both yield and energy content, and to push the economics of these bioenergy systems out of the marginal zone, either by increasing yield or by increasing ethanol production.

“Ideally, we”d like to find out ways to modify these crops so that if you increase ethanol yield, you”re increasing everything,” Casler says. “If you can increase energy content, there is going to be more energy available regardless of how you utilize it. It may be a reasonable goal, and I”m optimistic.”