Overfertilizing corn undermines ethanol

EurekaAlert.com

Rice University researchers find feeding crops too heavily bad for biofuel, environment
Rice University scientists and their colleagues have found that when growing corn crops for ethanol, more means less.

A new paper in today's online edition of the American Chemical Society's journal Environmental Science and Technology shows how farmers can save money on fertilizer while they improve their production of feedstock for ethanol and alleviate damage to the environment.

The research has implications for an industry that has grown dramatically in recent years to satisfy America's need for energy while trying to cut the nation's reliance on fossil fuels.

The team led by postdoctoral researcher Morgan Gallagher as part of her dissertation at Rice discovered that corn grain, one source of ethanol, and the stalks and leaves, the source of cellulosic ethanol, respond differently to nitrogen fertilization.

The researchers found that liberal use of nitrogen fertilizer to maximize grain yields from corn crops results in only marginally more usable cellulose from leaves and stems. And when the grain is used for food and the cellulose is processed for biofuel, pumping up the rate of nitrogen fertilization actually makes it more difficult to extract ethanol from corn leaves and stems.

This happens, they discovered, because surplus nitrogen fertilizer speeds up the biochemical pathway that produces lignin, a molecule that must be removed before cellulosic ethanol can be produced from corn stems and leaves.

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