In a field tucked into the northern side of this college town, just across from the Kansas State University football complex, some unusually tall plants are growing. They are part of the university´s research into promising biofuel feedstocks that may ultimately power vehicles of the future.
"We are studying sorghums and perennial grasses because we think these will be used in the non-irrigated acres in Kansas to produce biomass," said K-State professor of agronomy, Scott Staggenborg. "On our irrigated acres, corn will remain the crop of choice (as a biofuel feedstock), but on our dryland acres — especially in extremely dry environments — perennial grasses may be the crop of choice. Plus, since sorghum has the ability to perform better than corn when it is hot and dry, it gives us options."
Staggenborg, a researcher with K-State Research and Extension, is working with a team of graduate students and other scientists in studying two types of forage sorghum and other potential feedstocks. They include a dual-purpose forage sorghum and photoperiod-sensitive forage sorghum.
"We believe that in this region, sorghums will be a better fit for our environment in many cases than corn," he said. "We know a lot about corn as an industry, but widespread knowledge about sorghum is somewhat limited."
"The reason that we like the dual-purpose forage sorghum is that it produces grain and stover and can do so at nearly the same rate as corn," he said. Stover consists of the leaves and stalks — the non-grain part of the plant. "The reason both grain and stover are important is that right now the ethanol industry is grain based and that will not change overnight. If we have a crop that produces both, then we can help the industry evolve, if that is the direction it is going."
The advantage of photoperiod-sensitive forage sorghum is that in some climates, such as Manhattan, Kan., it does not produce any grain.
"I realize this is a bit of a contradiction, but as the industry specializes, the need for biomass is going to be complicated by separating the grain and the biomass in crops such as corn and dual-purpose forage sorghum," Staggenborg said. "Photoperiod-sensitive forage sorghum is a tropical plant that needs declining day lengths and just over a 12-hour day length to trigger flowering. In Manhattan, that occurs in early October, so all this thing does is produce stems and leaves all summer long. As a result, it will fit anywhere since you don´t have to worry about when the freeze occurs in the fall relative to grain fill. Plus you don´t have grain to separate from the stover."
In K-State´s trials, the photoperiod-sensitive forage sorghum has been one of the highest biomass producers.
The scientists are also studying sweet sorghum — a plant that soars 8 to 12 feet at maturity and thrives in dry conditions. The crop has 16 to 22 percent sugar content.
"The first real advantage to sweet sorghum is that all you have to do is press the juice out of the stalks and you essentially have sugar water that is ready to ferment," Staggenborg said. "No pre-treatment is needed as in grain or biomass to expose the sugars. In our trials, this has been the highest biomass producer."
A drawback to sweet sorghum, however, is that because it is tall and lanky, it has a tendency to fall down. That caused problems with lodging last year, he said, although if it lodges late, it only causes harvesting problems, not yield problems.
Even if biofuels become the primary fuel source for vehicles of the future, farmers will still produce food and feed grains on their acreage. Crops such as sorghums are annual crops, meaning that they must be replanted every year. That allows producers year-to-year flexibility to make planting decisions, the scientist said.
The K-State team is working with Texas A & M researcher Bill Rooney to improve sweet sorghums.
"We planted some of Bill´s experimental hybrid sweet sorghums last year. They were shorter plants and appeared to be very productive," Staggenborg said.
In addition to studying annuals such as the sorghums, the K-State scientists are studying perennial grasses, including big bluestem, switch grass and miscanthus.
"Of the three," Staggenborg said, "miscanthus is amazing, including the yields."
Miscanthus is a cross between two ornamental grasses, which makes it largely sterile. That´s a bit of a problem because it has to be propagated by root stocks — similar to splitting and planting irises. Research is under way at other universities to solve this problem, he said.
"Establishing perennial grasses is a challenge for us grain people," Staggenborg added. "We´re used to planting corn, sorghum or soybeans which means we´re used to seeing if we have a crop in a week to 10 days. Perennial grasses take a lot more patience."
Staggenborg said that his team planted 400 plants by hand in two plots and planted about 0.6 acre. "That (hand planting) is not something someone is going to do in a 100-acre field," he conceded.
In 2009, the K-State team´s miscanthus yielded 6 tons per acre, compared with switchgrass that yielded 4.5 tons per acre.
"This was only the second year it had been growing, so we expect yields to increase," Staggenborg said.
One concern about miscanthus is that it can spread by rhizomes, which sparks concerns similar to those with johnsongrass, an invasive weed, he said. Miscanthus does not produce seed, however, so he expects that will help contain it.
When asked how long it might be before these crops make their way into early commercial applications, Staggenborg said, "I would guess that it will be three years at a minimum before we get a feel for what the cellulosic industry will look like. Obviously this will affect the use of these crops."