It could be a tough “switch” for some farmers — going from trying to keep grass from growing in their crops to just trying to keep the grass growing.
But it's a move some farmers might be willing to make judging from the attendance at a tour stop on switchgrass production at the 24th Milan No-Till Crop Production Field Day. (I know. That first sentence was a terrible attempt at a pun.)
Switchgrass is a hardy, warm-season perennial that can grow from 6 feet to 7 feet in height and could become one of the feedstocks for cellulosic biofuels or an alternative for corn-based ethanol.
University of Tennessee scientists are growing 32 acres of switchgrass at the Milan Research and Education Center for a feasibility study funded by the U.S. Department of Energy and the Oak Ridge, Tenn., National Laboratory. The study is being conducted in Henry County in west Tennessee.
Five Henry County farmers are growing switchgrass on 92 acres of land around Paris, Tenn., for the project. The switchgrass, which was planted in 2004, is cut, baled and hauled to an electric-generating plant in Gadsden, Ala.
“Right now, the grant is the market,” says Ken Goddard, the Henry County Extension agent who has been working with the five farmers. He and Tony Brannon, dean of the School of Agriculture at Murray State University and one of the farmers, spoke on switchgrass production at the Milan Field Day July 27.
“But we're finding that there are some advantages to switchgrass such as low input costs and relatively low management requirements that can be a plus for farmers who are looking for alternative crops,” added Goddard.
As you might expect at the Milan No-Till Field Day, Goddard and Brannon and UT researchers recommend that farmers plant switchgrass no-till.
“If you prepare the soil conventionally, you expose more weed seed, and you want to try to keep the weed competition in check as much as possible,” said Goddard. “Only one herbicide, Cimarron (formerly known as Ally), is registered for use on switchgrass.”
For that same reason, they also recommend that no nitrogen be applied to the switchgrass in the first growing season. “Applying nitrogen in the first year just helps competing weeds become better established,” says Brannon.
Goddard said the Henry County farmers have planted switchgrass from late April until mid-June. (Some of the smaller fields had to be re-planted after shade trees blocked the sun from the plants.)
The farmers burned down the fields with glyphosate or paraquat and applied about 40 units of phosphorus and potassium when soils tested medium for the two nutrients. The recommended seeding rate is 7.5 pounds per acre.
“We've found that you can plant the seed shallow,” said Goddard. “Generally, the packing wheel from the no-till planter will incorporate the seed deep enough to get a good stand. It's a small-seeded plant, like timothy.”
Research at Milan has shown that about 60 pounds of nitrogen per acre appears to produce optimum yields of switchgrass, according to Don Tyler, professor of Biosystems Engineering and Soil Science at UT's West Tennessee Research Station in Jackson.
“Most of our recommendations on switchgrass have come from research in other states,” said Tyler, who also spoke at the Switchgrass Production Tour. “We're trying to do more research in Tennessee now so that we can tell our farmers how to grow it in an economic way.”
Tyler and fellow researchers have applied up to 180 pounds of ammonium nitrate on the switchgrass plots at the Milan station. But yields were mostly lower for the higher N rates than for the 60-pound rate.
“With nitrogen prices up to almost two times what they were last year, that could be a plus for someone producing switchgrass,” said Tyler. “The plots that received 120 and 180 pounds were a darker green color, but they also had more weed competition.”
Larry Steckel, weed scientist at the West Tennessee Research Station, has experimented with other herbicides on switchgrass. “Accent controls other grasses that compete with switchgrass, but it's not labeled,” said Goddard. “Crossbow and dicamba have also shown promise but are not registered for this use.”
Although the plots on display at the Milan Station were in a low-lying area, switchgrass appears to yield better on better-drained upland soils, “just like other crops,” said Tyler. “We have very productive soils here, more so than in some of the other states where research has been conducted.”
The Henry County farmers say a one-cut harvest appears to yield about as much switchgrass biomass as cutting it twice. The growers generally wait until first frost and then cut the switchgrass with a conventional mower.
“They put it up in large round bales in 2005,” said Goddard. “And those were trucked to Gadsden. The bales typically weigh between 1,300 and 1,800 pounds each. But they could also be put into square bales.”
He said the farmers have found it's best to leave the stubble at 5 to 6 inches in height to keep from puncturing tires on farm equipment.
Growers generally harvest about one-third of the potential yield for the crop in the first year, about two-thirds the second year and 100 percent the third year. Switchgrass yields in other states have ranged between 5 and 10 tons of dry matter per acre.
“One of the primary advantages we've observed is that the input costs are relatively low, considering that you apply only small amounts of P and K and no nitrogen the first year,” said Goddard.
“Once the stand is established, it should come back year after year — one farm in North Carolina planted it 25 years ago, and it's still going strong. No insects or diseases attack switchgrass and no specialized equipment other than a mower and a baler is required.”
The disadvantage? Having to transport the bulk material the 230-plus miles from Paris, Tenn., to Gadsden, Ala., where the local power company is grinding the switchgrass and substituting it for coal.
University of Tennessee researchers believe farmers will have to find markets — such as ethanol-conversion facilities — much closer to home if the crop is to become economically viable.
“You could also convert the switchgrass to a bio-oil for transport to a generating plant,” said Burton English, professor of agricultural economics at the University of Tennessee and project director for the switchgrass grant. “You could have a bio oil converter come to an area in two trucks and then move to the next community.”
Although researchers at Auburn University have been working with switchgrass for more than 20 years, not much had been said about the crop until President Bush mentioned it as an alternative source for energy in last January's State of the Union message.
“Before that, switchgrass seed was selling for about 8 cents per pound,” said Brannon. “After that, it went to 16 cents per pound.”
The Henry County farmers' experience shows switchgrass could have a fit for part-timers. “One of the things that appealed to us as non-traditional farmers was that the pressures to get things done aren't that rigid,” said Brannon, who operates his family's farm with his brother.