For two years, Jeff Taylor, a Gilbert, Iowa, corn and soybean farmer, has sold corn stover to DuPont Industrial Biosciences. DuPont pays him $15 a ton for the 2 tons per acre taken off his fields by a custom baler.
In a year when grain from corn topped $8 a bushel, that $30 an acre may seem small. To Taylor, the big advantages are agronomic. Someone else is paying him to manage what is often called trash.
“I've worked with the program a couple of years. This spring, I noticed that in corn-on-corn, by just removing 40% of the stover, the soil warms up faster,” Taylor says. “Without that mat of corn stover, it's a little easier planting. Emergence was a little more even.”
First Wave of Cellulose
Taylor will soon be among as many as 600 farmers supplying stover to DuPont's new 25-million-gallon cellulosic ethanol plant that broke ground this fall near Nevada, Iowa. Two hours north, outside of Emmetsburg, Iowa, ethanol maker POET is already building another 20-million-gallon cellulosic ethanol plant in partnership with Royal DSM of the Netherlands. That plant, too, will use corn residues. POET-DSM plans to start up late next year. DuPont plans production at Nevada in 2014. Both companies are now sourcing stover.
This means the Corn Belt could be the center of large-scale commercialization of cellulosic ethanol. The industry has been running behind targets set by the Energy Independence and Security Act of 2007 and its second, expanded Renewable Fuel Standard (RFS). The law projected 500 million gallons of cellulosic ethanol in use by 2012. With only a handful of ventures ready to make it, EPA cut its RFS mandate to about 10 million gallons of ethanol-equivalent fuel for 2012. By year's end, even that goal looked doubtful. (In contrast, in a historical drought, the corn ethanol industry was making fuel at an annualized rate of 12.6 billion gallons earlier this fall.) For this year, EPA was counting on cellulosic fuel made from sugarcane bagasse, wood chips, and municipal solid waste. But soon, corn stover will become the feedstock of choice.
DuPont, which is testing stover at a smaller 250,000-gallon demonstration cellulosic plant at Vonore, Tennessee, has been working with its seed corn subsidiary, DuPont Pioneer, to learn how removing stover affects farms.
Andy Heggenstaller, an agronomist at DuPont Pioneer, is working with growers and university researchers to measure the costs and benefits of stover removal.
“We believe that there is an ability for stover harvest to be done in a sustainable manner,” Heggenstaller says.
As grain yields in corn have gone up, so has the stover, at a ratio of about one to one, he says. For every 40 bushels of grain produced by a corn plant, 1 ton of stover dry matter is grown as well.
Heggenstaller confirms the benefits that Taylor and other farmers have seen from removing stover. One Iowa State University (ISU) study showed that in corn grown after corn, yields are about 10 bushels an acre higher if half of the stover has been removed in the previous year.