Do GM crops increase yield potential?
At best, GM crops have performed no better than their non-GM counterparts, with GM soya beans giving consistently lower yields for over a decade54. Controlled comparative field trials of GM/non-GM soya suggest that 50% of the drop in yield is due to the genetic disruptive effect of the GM transformation process55. Similarly, field tests of Bt insecticide-producing maize hybrids showed that they took longer to reach maturity and produced up to 12% lower yields than their non-GM counterpart56.
A US Department of Agriculture report confirms the poor yield performance of GM crops, saying, “GE crops available for commercial use do not increase the yield potential of a variety. In fact, yield may even decrease…. Perhaps the biggest issue raised by these results is how to explain the rapid adoption of GE crops when farm financial impacts appear to be mixed or even negative57.”