From Canada's prairie provinces well into Kansas, you might run across some serious-looking folks poking through the grass growing on the roadside. They'll be collecting prairie cordgrass, hunting for germplasm to improve the native plant that grows across the midsection of the continent.
Researchers want to improve prairie cordgrass's potential as an ethanol feedstock. They have already sequenced many genes, and advanced breeding efforts are well under way.
South Dakota State University plant molecular geneticist José Gonzalez helps with the roadside search. "We're not looking for any specific traits,” he says. "There's a lot of variation within cordgrass on things like lignin production. Any particular cordgrass, even if it's shorter than normal, may have some genes you want.”
Gonzalez and his colleagues believe prairie cordgrass could hold greater ethanol potential on the Great Plains than other highly touted native plants, such as switchgrass.
"With prairie cordgrass, we're getting yields twice what we're getting with switchgrass,” says Bill Gibbons, an industrial microbiologist at South Dakota State University. "We're seeing 4 or 5 tons per acre, max, with switchgrass, but 8 to 9 tons of prairie cordgrass per acre. Plus, prairie cordgrass grows better on lower-quality soils.”
Much of the reason for that yield gain lies in the internal makeup of the prairie cordgrass stalk. "The stalk is three times denser than a switchgrass stalk. That means the same length of prairie cordgrass weighs three times as much as switchgrass,” Gonzalez says.
"The composition itself is very similar to switchgrass,” he adds. "In conversion, it could do a little better than switchgrass.”
Crop mix. An ultimate biomass ethanol answer may come down to more than a face-off between grasses, however.
"What we may see work best could be a mixture of native prairie grasses,” Gibbons says. "Average yield of a mixture tends to be higher than if you just rely on a monoculture.
"There are certain landscapes which have saline soils or are flood-prone areas that tend not to be productive. What we see happening if we establish a market that's relatively competitive for native grasses, is we are giving farmers an option. Maybe a wet area could be planted in cordgrass. It tolerates flood well. In other areas with salinity problems, a mixture of native grasses might be planted,” Gibbons says.
"In the future, we hope to see more diversity than corn and soybeans offer. Do you have soils that are fine-quality but are erodible? Do you have land coming out of CRP? Grasses could work there,” Gibbons says.
Gonzalez agrees. "We're not looking at 1,000 acres of this. We're looking to mix it in the right spots in the field along with corn, wheat and soybeans. There are landscape positions where it would work. We want farmers to plant the best crop for each position in the field,” he says.
For now, the scientists are concentrating on pushing prairie cordgrass to better production per acre. To do that will take a lot more roadside searches.
"You never know what you'll find out there,” Gonzalez says.
Prairie cordgrass is a native perennial occurring across the Great Plains. It averages 3' to 8' in height but can grow 10' tall. It thrives in wet conditions, which is why it is also called marsh grass, slough grass and ripgut. It is typically found on low, poorly drained soils in marshy meadows, wet prairies and potholes, as well as along roadsides, ditches and streams. Cordgrass prefers deep, heavy, wet lowland soils but adapts to rocky or sandy soils with consistent moisture. Its metabolism helps cordgrass survive occasional droughts.
You can e-mail Charles Johnson at firstname.lastname@example.org.
- February 2010