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Summer 2010 Vol. 10 Number 2

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Corn harvest in Iowa, photo by Tim McCabe, USDA Natural Resources Conservation Service

GE Crops Set the Stage for Growth, But Uncertainties Remain

Since their introduction in 1996, genetically engineered (GE) crops designed to resist various weed killers and insects have transformed farming, so much so that today more than 80 percent of soybeans, corn, and cotton grown in the United States is genetically engineered. But a recent National Research Council report cautions that overuse could diminish certain GE crops' effectiveness and the technology's wider application.

Many U.S. farmers who use GE crops have seen lower production costs, higher yields, and higher profits, the report says. Moreover, positive environmental impacts are being felt on and off the farm. In many cases fewer and less-toxic herbicides and insecticides are applied, and farmers till less to control the weeds. Such practices have improved the quality of soil and waterways, as well as reduced erosion.

However, some of these benefits will decrease unless farmers employ other weed and insect management practices. The increased reliance on the weed killer glyphosate is reducing its effectiveness. Ten species of weeds have already grown resistant to glyphosate in areas where repeated applications are the only weed management tactic. The committee that wrote the report advised farmers to rotate crops and apply other herbicide mixes, and not to rely exclusively on glyphosate. It also recommended research on the potential evolution of weed and insect resistance to GE crops.

"Although this first wave of GE crops has shown benefits for farmers and the environment, we need to examine the long-term prospects of the technology fostering more sustainable agriculture systems," said David Ervin, chair of the study committee and professor of environmental management and economics at Portland State University. "The advantages of GE crops may decline over time, while other pluses and risks may emerge as the technology is applied more broadly. To fully understand how GE crops will affect U.S. agriculture and the environment now and in the future, we need more research."

For instance, more needs to be known about the economic and social effects of GE crops on farmers who grow organic and non-GE conventional crops. Organic farmers can profit from a price premium available for crops free of GE traits, but their crops' value could be jeopardized if genes from GE crops flow to non-GE varieties through cross-pollination or seed mingling.

"GE technology has the potential to help solve many societal issues, such as adaptation to climate change and food insecurity, so the prudent step is to keep the technology moving forward. Strong support from both the private and public sectors will be essential," Ervin said. --  Jennifer Walsh & Molly Galvin

The Impact of Genetically Engineered Crops on Farm Sustainability in the United States. Committee on the Impact of Biotechnology on Farm-Level Economics and Sustainability, Board on Agriculture and Natural Resources, Division on Earth and Life Studies (2010, 270 pp.; ISBN 0-309-14708-5; available from the National Academies Press, tel. 1-800-624-6242; $49.00 plus $5.00 shipping for single copies).

The committee was chaired by David Ervin, professor of environmental management and economics, Portland State University, Portland, Ore. The study was funded by the National Research Council.

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Copyright 2010 by the National Academy of Sciences