Harvesting the corn stalks or the cover crop to make cellulosic ethanol also reduces nitrous oxide emissions and reduces overall greenhouse gas levels because the ethanol is used instead of gasoline. But without proper management, harvesting corn stalks also can reduce the amount of organic matter in the soil, which reduces the fertility of the soil over time.

"We need to carefully consider and intelligently manage the entire ethanol production system for long- term sustainability not just focus on pieces of the system," Dale said. "Ethanol is and will be a critical part of reducing our national dependence on oil for liquid fuels. Production technology for both corn and cellulosic ethanol is advancing rapidly. So it's essential that we understand how to improve all portions of the system for maximum environmental benefits."