Don’t genetically engineered crops have higher yields?

According to Monsanto, in 1998 its Roundup-resistant soybeans averaged 43.1 bushels per acre, beating conventional growers by 4.5 bushels. A number of other studies, however, do not support these conclusions. Ed Oplinger, for example, Professor of Agronomy at the University of Wisconsin, has been conducting performance trials for soybean varieties for the past 25 years. His comparison of yields in the 12 states that grow 80 per cent of the soybeans in the United States show that, on average, the yields of genetically engineered soybeans were 4 per cent lower than conventional varieties.