Switchgrass – a future cash crop?

Thanks to new research and a growing demand for biofuels, farmers may soon be able to use modified land to grow a new cash crop, switchgrass.

Right now, a project led by Brian K. Richards, a Cornell researcher in biological and environmental engineering, is examining the long-term sustainability impacts of growing perennial grasses on marginal lands. One challenge that work is taking head-on: how to control one byproduct of growing switchgrass on marginal land – nitrous oxide, an ozone depleting gas.

The promise of switchgrass is that it grows well on marginal soils that are too poor to support most conventional agricultural crops. It poses little erosion risk and offers a high net energy return.

But in many cases those soils are regarded as marginal because they are wetter than prime agricultural soils, says Richards. Wet soils are more prone to a process called denitrification, in which nitrate from fertilizer is converted back to gaseous forms – primarily inert nitrogen, which comprises the bulk of our atmosphere. However, a small percentage ends up as nitrous oxide, which has been steadily increasing in the atmosphere and is considered a primary threat to the ozone layer.

For the energy industry, researchers need to discover how to minimize potential nitrous oxide emissions as the amount of land devoted to bioenergy production increases.

On Cornell's crop research fields, Richards and his team are using soil chambers to test for emissions of nitrous oxide and other trace gases emanating from the soil. Throughout the growing season, they have tested acres of switchgrass and expect their first results by later this year. They are also measuring crop yields and tracking beneficial changes in soil carbon storage and overall soil health.

Under the federal Energy Independence and Security Act of 2007, the United States must increase the volume of renewable fuel – chiefly ethanol – to be blended into transportation fuel to 36 billion gallons by 2022, up from 9 billion gallons in 2008, of which 21 billion gallons will be non-corn-derived ethanol.

Richards' research is funded the U.S. Department of Agriculture's Sustainable Bioenergy program.