Ethanol co-product eyed for organic weed control

Studies by Agricultural Research Service (ARS) scientists have shown that dried distiller's grains (DDGs), co-products of corn ethanol production, have potential as an organic fertilizer and for weed control. But some ethanol producers are adopting new corn-grinding methods that may affect the DDGs' usefulness.

To further study DDGs, ARS plant physiologist Steve Vaughn and colleagues entered into a one-year cooperative research and development agreement (CRADA) with Summit Seed, Inc., a Manteno, Ill.-based company specializing in turfgrass production.

America's ethanol industry generates an estimated 10 million to 14 million metric tons of DDGs annually from both wet and dry milling of corn, processes that yield fermentable sugars for conversion into fuel alcohol. About 75 percent of the DDGs are fed to livestock. But since 2005, Vaughn has led a team at the ARS National Center for Agricultural Utilization Research (NCAUR) in Peoria, Ill., to develop new, value-added uses for DDGs.

In greenhouse and field studies, Vaughn showed that the DDGs can be used as an organic fertilizer for tomatoes and other crops. Indeed, in 2007, DDG-treated plots of Roma tomatoes yielded 226 total pounds of fruit, versus 149 pounds from untreated plants. And in turfgrass trials, the DDGs stopped annual bluegrass and other weed seeds from germinating in stands of Kentucky bluegrass.

But now, with more ethanol plants using dry-grinding methods, the DDGs, germ and fiber fractions are generated before, rather than after, corn sugars are fermented into ethanol. Determining how this new practice changes the DDGs' biochemical and physical properties is a chief focus of ARS' CRADA with Summit Seed.

Vaughn's ARS colleagues are Jill Winkler, Kathy Rennick, Fred Eller, Mark Berhow and Brent Tisserat--all with NCAUR in Peoria--and Rick Boydston and Hal Collins, both with ARS in Prosser, Wash.