Farming that improves the environment

AMES, Iowa -- All those dried up stalks, husks and cobs left in corn fields after every fall's harvest could be a key to enhancing the environment, say Iowa State University researchers.

They say partially burning some of the residue left in corn fields produces products that can be used to improve soil fertility, boost in-soil storage of greenhouse gases and reduce the amount of natural gas used to produce anhydrous ammonia fertilizer.

Robert C. Brown, Iowa State's Bergles Professor in Thermal Science, will lead a team of researchers studying the idea. The team includes Randy Killorn, an Iowa State professor of soil science, plus government researchers from the U.S. Department of Agriculture, the U.S. Department of Energy and industry researchers from Cargill Inc., Eprida and iPrismGlobal.

U.S. Agriculture Secretary Mike Johanns recently announced the three-year project will be supported by $1.85 million from the Biomass Research and Development Initiative, a joint project of the U.S. agriculture and energy departments. More than 670 research teams applied for initiative funding. Eleven of them won grants. Final details of the grants are expected to be set by early next year.

"This cooperative conservation partnership benefits our nation with enhanced energy security, a cleaner environment and revitalized rural economies," Johanns said in the statement announcing the grants. "The selected projects support President Bush's goal to enhance renewable energy supplies. The grants will help to develop additional renewable energy resources and expand markets for agricultural products."

Brown's research team will focus on this process:

Corn stover will be harvested from fields and partially burned to create charcoal and a bio-oil about as thick as motor oil. The bio-oil will be reacted with steam to produce hydrogen. That hydrogen will replace the natural gas typically burned to make anhydrous ammonia fertilizer. The fertilizer and charcoal will be incorporated into the soil.

Brown said there should be three significant results: Farmers producing their own renewable energy to manufacture fertilizer for their fields. Farming that improves soils because the added charcoal supports soil organisms. And the charcoal sequestering carbon in the soil, thus reducing the amount of greenhouse gases in the atmosphere. Brown estimates a 640-acre farm could sequester the equivalent of 1,800 tons of carbon dioxide in the soil. That's the annual emissions created by about 340 cars.

Brown uses the phrase reinventing agriculture when he talks about the process.

"The conventional goal of good land stewardship is to minimize soil degradation and the amount of carbon released from the soil," he said. "This new approach to agriculture has the goal of actually improving soils."

He said the practice of improving soil by adding charcoal has been traced back to the Amazon basin in the days before Christopher Columbus. People there created dark and productive soils (know as "terra preta," or "dark earth" soils) by adding charcoal mixed with manure. Those soils are still more productive than surrounding soils that weren't treated with charcoal.

Killorn, who will study soil fertility as part of the research project, said putting corn stover to work for the environment shows a lot of potential.

"It looks pretty slick, taking these corn stalks and turning them into bio-oil and charcoal," he said. "If everything works the way we think it will, this looks like a good deal."