GM Impact Meta-analysis
A meta-analysis of 147 studies of the impact of genetically modified crops (GMO) has been published in PLOS One. The study finds that the adoption of herbicide-tolerant (HT) soybean, maize, and cotton, and insect-resistant (IR) maize and cotton has resulted in a 22% increase in average yields, a 37% overall decrease in pesticide use, and a 68% increase in farmer profits.
Yields were increased by reduction in crop loss due to pests. This effect was greater in farm surveys (real-world use) than in controlled field trials. The gains were also greater in developing countries which tend to have more of a problem with crop loss due to insects.
IR plants resulted in a significant decrease in insecticide use. HT plants had mixed results, some showing an increased in herbicide use and others showing a decrease. Overall there was a significant decrease in pesticide (insecticide and herbicide) use by 37%, contrary to frequent claims made by critics of GMO crops.
Farmers using GMO also showed a significant increase in net profits. Total production cost is slightly higher due to higher seed costs, but this is more than off set by reduced pesticide costs and higher yields. Gains in profit were more significant in developing than in developed countries. Again, despite the claims of GMO critics, the adoption of GMO is especially helpful for small farms in developing countries.
The meta-analysis found that funding source did not have a significant impact on outcome. Results from peer-reviewed articles were more positive overall than non peer-reviewed, which the authors conclude is likely due to an anti-GMO bias in the “grey” literature.
The meta-analysis itself was not funded by industry, but rather by the German Federal Ministry of Economic Cooperation and Development and the European Union’s Seventh Framework Programme. The authors declared no conflict of interest.