U.S. farmers have benefited from the introduction of genetically engineered crops, according to a new report* released today by the National Research Council of the U.S. National Academies. Farmers who have switched from conventional crops have seen higher profits and a reduced environmental impact, the panel concluded. However, many benefits—such as improvements to water quality—need to be better quantified, and some biotech crops are threatened by the evolution of herbicide-resistant weeds.
More than 80% of corn, soybean, and cotton acres in the United States are planted with crops engineered to resist pests and improve weed control. Over the past decade, expert panels assembled by the National Research Council have examined possible risks to human health and the environment, such as gene flow between organisms. But they had not taken a broad look at what the impacts have been on farms that grow biotech crops. So NRC commissioned a group of 10 experts to comb the scientific literature.
"The evidence is pretty strong is that these technologies have both economic and environmental benefits," says economist David Ervin of Portland State University in Oregon, who chaired the panel. But many effects need to be better studied. The panel recommended, for example, that the U.S. Geological Survey investigate the impact that reduced tillage has had on water quality.
Charles Benbrook, chief scientist of the OrganicCenter in Enterprise, Oregon, isn't certain about the persistence of economic benefits. Benbrook, who was not on the NRC panel, says that sharp increases in the price of biotech seeds, which started in 2007, could eat away at farmer's economic gains.
The panel also highlighted several risks. One of the most significant is that insect or weed resistance will render genetically modified crops ineffective and force farmers to return to more toxic chemicals or plowing that causes soil erosion. Economist Dermot Hayes of IowaStateUniversity in Ames says he's optimistic that new types of biotech crops and management will solve the problem of resistance, but Benbrook is less sanguine. "It's a crisis now," he says.
A longer news story on the report will appear in this week's issue of Science.
*The Impact of Genetically Engineered Crops on Farm Sustainability in the United States. Washington, D.C. The National Academies Press, 2010.