Ethanol Crops Face Opposition From Irrigation, Climate Study

Rice University study finds that over 40 years, potential water loss could outweigh benefits of corn grown for ethanol - but NCGA doesn't agree

Published on: Jun 7, 2013

A new study released this week from Rice University at the University of California Davis predicting that climate changes will hinder biofuels goals and corn production has the National Corn Growers Association on the defense.

The report, published in the American Chemical Society journal Environmental Science and Technology, suggests that yields of corn grown for ethanol would be reduced by an average of 7% over the next 40 years, and the amount of irrigation needed for the corn would increase by 9%.

The study also notes that mandated ethanol blending in the U.S., while potentially limiting fuel emissions and lowering dependence on foreign oil, may cost too much in terms of water use, either through drawdown of groundwater or through evapotranspiration.

Rice University study finds that over 40 years, potential water loss could outweigh benefits of corn grown for ethanol.
Rice University study finds that over 40 years, potential water loss could outweigh benefits of corn grown for ethanol.

"It is important to recognize the tradeoffs," said Pedro Alvarez, chair of Rice's Civil and Environmental Engineering Department and study author. "One important unintended consequence may be the aggravation of water scarcity by increased irrigation in some regions."

Using computer simulations based on crop and climate data for the top 10 producing corn states in the U.S., the researchers found that maintaining crops in the Corn Belt would require a 5 to 25% increase in irrigation.

But NCGA isn't buying into the study. Organization President Pam Johnson said information announcing the study indicates the bias of the report by noting the authors have "long questioned the United States' support of biofuels." NCGA pointed out that the report's projection – which looks at four decades – surpasses the mandates of the RFS, which are only projected out for the next nine years.

"At a time when meteorologists struggle to tell you what the weekend will be like, it's odd to see a report that tries to so specifically pinpoint the weather 40 years from now," Johnson said.

But the timetable is only one problem NCGA had with the study. The group says it also ignores any possible advances in technology to improve corn growing, such as new agronomic practices or technology.

"Looking back 40 years, corn farming was so different in 1973 than it is today, and it's a difference that could not have been predicted back then," Johnson noted. "The fact of the matter is, it's not only naive to assume that corn yield will not increase as it has been, but our current average yield is already sufficient to produce the five billion bushels needed to meet the full conventional RFS volumes."

Though Johnson pointed out also that since 1980, corn farmers have reduced per-bushel greenhouse gas emissions by 36% and irrigated water use by 53%, the study authors estimate that water savings will be mitigated by rising temperatures overall.

"The projected increases in water intensity due to climate change highlight the need to re-evaluate the corn ethanol elements of the Renewable Fuel Standard," study lead author Rosa Dominguez-Faus, postdoctoral researcher at the University of California at Davis, said.

Sources: Rice, NCGA