Ask-Force: Do GM crops fail to produce more yield?

1. The Issue

Tobias Mittmann /, CC-License(by-nc)

The short summary of the press release of the Union of Concerned Scientists (UCS):

“Failure to Yield is the first report to closely evaluate the overall effect genetic engineering has had on crop yields in relation to other agricultural technologies. It reviewed two dozen academic studies of corn and soybeans, the two primary genetically engineered food and feed crops grown in the United States. Based on those studies, the UCS report concluded that genetically engineering herbicide-tolerant soybeans and herbicide-tolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally. The increase in yields for both crops over the last 13 years, the report found, was largely due to traditional breeding or improvements in agricultural practices.

Gurian-Sherman, D. (2009) Failure to Yield, Evaluating the Performance of Genetically Engineered Crops, Union ot Concerned Scientists pp (Report copy) – find here the original on the website.


2. Summary of the PRRI assessment

Research by Brookes & Barfoot, 2009, shows for example different results: Additional crop production arising from positive yield effects of biotech traits 1996-2006 (million tonnes) – see

  1. The report deals only with two major crops: Maize and soybean, there is no justification for the sweeping conclusions on all GM crops. Other crops like cotton and oilseed rape show a different, more positive picture, it is misleading to restrict the review to two crops and then conclude for all GM crops.
  2. GM crops have – at least in the beginning – not been developed to increase yield per se (the second generation of GM soybean will potentially do this). The first GM crop generation has been conceived to efficiently reduce yield losses to weeds and insects –  and thus enhance the economic situation of the farmers, and these promises have been fulfilled properly and with evident success. UCS misleads the reader by not distinguishing those two views of yield.
  3. GM crops have also efficiently reduced herbicide use (or made it possible to shift to environmentally more benign ones) and also they have helped to reduce pesticides. It is misleading by UCS not to mention those facts.
  4. GM crops have a proven positive influence on the ecological footprint of intensive high production agriculture (no tillage, better life for non-target insects etc.). It is misleading  by the UCS report to camouflage those positive effects under “agricultural practices”.

Find more details and sources for our findings in this PDF:
ASK-FORCE: Do GM crops fail to produce more yield? Peer reviewed contribution web version