Failure to Yield (April 28,2009) Fr. Seán McDonagh, SSC

During the past 15 years biotech corporations have marketed genetically modified (GM) crops on the basis that they give greater yields to the farmer and thus are an important weapon in the fight against world hunger. .  This is why the study Failure to Yield initiated by Union of Concerned Scientists and in April 2009, is so important. [1] This ability of GM crops to deliver increases in plant yields is one of the assumptions shared by all the speakers who have been invited to speak at the  Study Week organised by the Pontifical Academy of Sciences in May 2009.

The author of the study Failure to Yield Doug Gurian-Sherman, examined both Bt corn and GM soybeans which are the most important GM crops being grown in the U.S. and elsewhere around the world.  He writes that a close examination of numerous studies of corn and soybean crop yields since the early 1990s give us a good gauge of how well GE crops are living up to their promise of increasing those yields.[2] He concluded that a hard-nosed assessment of this expensive technology’s (GM) achievement to date gives little confidence that it will play a major role in helping the world feed itself in the foreseeable future. [3]

The author distinguishes between intrinsic yield which he defines as the highest yield which can be achieved under ideal conditions with operational yield. The latter is the yield which is achieved under normal field conditions when the farmer factors in crop reductions due to pests drought or other forms of plant stress.  Sherman’s study is grounded on experiments conducted by academic scientists using adequate experimental controls. These studies are published in peer-reviewed journals. Sherman finds that  Thus (far) commercial GE crops have made no inroads so far into raising the intrinsic or potential yield of any crop. By contrast, traditional breeding has been spectacularly successful in this regard: it can be solely credited with the intrinsic yield increases in the United States and other parts of the world that characterised the agriculture of the twentieth century.[4] These conventional breeding methods use modern genomic approaches. These methods which do not involve genetic engineering have the capability to increase capability both the intrinsic and operational yield. This is an extraordinarily important finding and it is at odds which much of claims coming from the biotech companies.  He points out that in the U.S. there has been an increase of about 28% in corn yields in the 2004-2008 period, in contrast to the 1991 to 1995 period.  Sherman calculates that the increase due to the Bt varieties is only in the range of 3%-4%. This means that 24%- 25% is due to other factors, especially advance in conventional breeding. Given the relentless propaganda against organic farming emanating from the corporate sector, many will be surprised at his findings that: organic and low-external-input methods (which use reduced amounts of fertiliser and pesticides compared to typical industrial crop production) generally produced yields comparable to those of conventional methods for growing corn or soybeans. [5]

What about the future? While the biotech corporations are promising dramatic yield increases in the near future, the author of this study is not convinced.  He draws attention to the fact that,  most of the transgenes being considered for the future, unlike the ones in currently commercialised transgenic crops, influence many other genes, thereby resulting in complex genetic effects.[6] He goes on to point out that “such genes typically have multiple effects on a crop, and early research is confirming that some of these effects can be detrimental….. Because such effects will not always be identified by testing under current regulations, improved regulation will be needed to ensure that harmful side effects are discovered and prevented.”[7] And yet the aim of the Pontifical Academy’s Study Week is to reduce regulations!  Doug Gurian-Sherman claims that “this report is the first to evaluate in detail the overall, or aggregate, yield effect of genetic engineering after more than 20 years of research and 13 years of commercialization in the United States. [8].

Sherman’s first recommendation is that the U.S. Department of Agriculture plus public and private universities and agencies ought to redirect substantial funding and research towards approaches which have delivered much better results in terms of crop increased rather than obtained by genetic engineering.

Secondly, that development food-aid agencies would promote these well-tried and affordable methods of increasing crop yields in rural areas of the Majority World.  Finally, that regulatory agencies should develop and implement techniques to identify and evaluate potentially harmful side effects of more complex genetically engineered crops.


[1] Doug Gurian-Sherman, Failure to Yield, [1] www.ucsusa.org downloaded on April 21, 2009.

[2] Ibid page 1

[3] Ibid page 1.

[5] Ibid page 3.

[6] Ibid page 4.

[7] Failure to Yield, op.cit. page 4.

[8] Ibid page 8

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