Oct. 10, 2013

Researchers survey how green grows your switchgrass

As biofuels become an increasingly viable alternative – thanks in part to Cornell scientists – researchers here are making sure that growing grasses for biofuel won’t face inadvertent snares.

A project led by Brian K. Richards, a Cornell researcher in biological and environmental engineering, examines the long-term sustainability impacts of growing perennial grasses on marginal lands.

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 from 9 billion gallons in 2008, of which 21 billion gallons will be non-corn-derived ethanol.

Switchgrass 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. That’s the good news.

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 know how to minimize potential nitrous oxide emissions as the amount of land devoted to bioenergy production increases.

On Cornell 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 many acres of switchgrass, and expect their first results by late 2013. They are also measuring crop yields and tracking beneficial changes in soil carbon storage and overall soil health.

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