Iowa farmer Steve Rash has just begun to harvest this year’s corn. He planted half corn and half soybeans, just as he has for 30 years. And that makes Rash different. All around him, midwestern farmers are cashing in on golden ears. In fact, the U.S. Department of Agriculture (USDA) recently forecast (PDF: 886KB) the largest corn crop ever this year-13.3 billion bushels-to meet the nation’s demand for ethanol-based fuel.

That has scientists and environmental advocates worried about the toll that expanding biofuel crops, such as corn, will have on land and water. Farmers planted an extra 14 million acres of corn this year-equal to an area more than half the size of Indiana. And more growth is coming: the U.S. ethanol sector will need 2.6 billion bushels per year (yr) by 2010-nearly 50% more than in 2005, according to USDA. The rush to farm more corn is a result of President Bush’s call to produce 35 billion gallons (gal) of renewable and alternative fuel by 2017, or about 15% of all U.S. liquid transportation fuel.

Now, the National Academies’ National Research Council (NRC), the top science review board in the U.S., has released a new report that fuels the concerns of environmentalists. The study, Water Implications of Biofuels Production in the United States, warns that if the U.S. continues to expand corn-based ethanol production without new environmental protection policies, “the increase in harm to water quality could be considerable.” The results: more soil erosion, more pesticides and herbicides in waterways, more low-oxygen “dead zones” from fertilizer runoff, and more local shortages in water for drinking and irrigation.

For now, Rash is waiting to see whether corn ethanol will keep its front-runner status or will be replaced by other green fuels. “I’m not anti-ethanol, I’m just really cautious about the boom,” he says, citing concerns about both the economic and environmental sustainability of corn ethanol. For one thing, he notes, traditional corn-soy rotation replenishes soil nutrients that could be stripped away by corn in the long run.

The environmental impacts of biofuel sources, such as corn and soy, have not been adequately factored into policy decisions that encourage biofuel production, according to the NRC report. “We wanted to look at the full life cycle of biofuel production and its impact,” says Dara Entekhabi, a report coauthor and hydrologist at the Massachusetts Institute of Technology. Those impacts, he says, could include increases in water, fertilizer, and pesticide use; downstream effects on rivers and estuaries; increased soil erosion; and depletion of aquifers. “These are aspects that have not been carefully considered in assessing whether biofuels are the way to go in the U.S.,” he adds.

The NRC Water Science and Technology Board initiated the report after board members brainstormed “the most immediate and high-priority water problems today,” says Entekhabi, a board member. Six experts from various disciplines of science, engineering, and agricultural economics, chaired by ES&T’s editor in chief, Jerald Schnoor of the University of Iowa, wrote the report after holding a workshop with 130 scientists and stakeholders. The board convened the workshop to speed up the report-writing process, in hopes of providing timely guidance for the U.S. farm and energy bills making their ways through Congress, Schnoor says.

Biofuels could be made “greener” than they are now, experts say. “We already know how to grow corn with less nutrient runoff,” adds Nathanael Greene, a senior researcher at the environmental group Natural Resources Defense Council. The key, he says, is making policy choices that set goals not only for more gallons of biofuels but also for reducing water-quality impacts, whether from corn or other biofuel feedstocks. “We have to pursue biofuels because of the climate change imperative,” he says. “But we don’t want to trade off water pollution, and we don’t have to.”

Full Story: http://pubs.acs.org/subscribe/journals/esthag-w/2007/oct/policy/ee_biofuels.html