Genetically Engineered Roundup Ready Soy less profitable than conventionally bred varietes

Source: A 28 page report "Evidence of the Magnitude and Consequences of the Roundup Ready Soybean Yield Drag from University-Based Varietal Trials in 1998" released 13 July 1999 by Dr Charles Benbrook, former Executive Director of the Board on Agriculture for the US National Academy of Sciences.

This report reviews the results of over 8,200 university-based soybean varietal trials in 1998.


This report undermines the two main arguments that have been used to justify the use of herbicide resistant genetically engineered crops.

The argument that there will be better yields is found to invalid in the case of RoundupReady Soy. In stead the yields were found to be 6-10 percent lower.

The argument that the need for herbicides will decrease with the use of herbicide resistant crops was also found to be invalid. In stead, the use of the herbicide Roundup increased considerably - between 2-10 times more than on conventional herbicides. One reason is increasing resitance to Roundup among the weeds. There are reasons to believe that a similar result may be applicable to other herbicide resistant GE crops.

To farmers this means that the initial gains from from using herbicide resistant RR soy are likely to turn into increasing losses.

Considerably lower yield from genetically engineered soy

Compared to top varieties of conventionally bred crops, the top RR soy yield was 6,7 percent less at an average. In some Midwest the difference was 10 percent or more.

Benbrook conlcuded: "If not reversed by future breeding managements, this downward shift in soybean potential could emerge as the the most significant decline in a major crop ever associated with a single genetic modification".

Considerably increased use of herbicide

Farms growing RR soy used 2 to 5 times more herbicide than farms not using RR soy. In many RR soy farms, the herbicide use was 10 times larger than on many farms using mulitactic Integrated Weed Management systems.

The cause for this increase of herbicide use was increasing resistance of weeds to the herbicide Roundup, used on RR soy. Price cuts and aggressive marketing were also contributing factors.

Decreased use of RR soy expected

Because of decreased yield and increased need for herbicide in RR soy the author predicts: "If current trends continue in the way RR technology is used the efficacy and market share of Roundup may then fall just as quickly" (as it has increased /editors addition)


A major argument for justifying genetically engineered herbicide resistant crops was that they would increase crop productivity because they would enable complete eradication of yield-decreasing weeds. This report, based on a large number of scientific trials, indicates the opposite in the case of RR soy.

It is not clear why the productivity is less. One aspect that has not been considered so far is that genetic engineering may make plants use energy less efficiently. While the energy usage of natural plants is precisely attuned by the DNA to match the need in every moment, the energy usage associated with the inserted gene in GE plants is not regulated according to need.

To ensure that the inserted gene will be effective, a promoter gene is linked to it (for details, see "How are genes engineered?"). This makes the inserted gene stimulate the production of the desired protein (e.g. for herbicide resistance) 24 hours daily throughout the lifetime of the plant. As the ability to resist a certain herbicide is needed only during a fraction of the lifetime of a plant, this is a highly inefficient approach. This contrasts sharply with the situation in the natural plant. Here the activity of every gene, and the corresponding energy usage, is precisely attuned to the need. Contrary to the GE plant, no energy is spent unless there is a real need. In addition, the promoter gene may stimulate other neighboring genes to unneccessary energy consuming acivity that might also disturb the efficiency of the overall metabolism of the cells. Regettably, no scientific studies have been yet been done comparing metabolic efficiency of natural and GE plants as far as we have been able to find out.

Another major argument has been that the use of herbicide resistant crops would decrease the use of herbicides. This has been contradicted by this report in the case of use on RR soy. Weeds appear to have an ability to develop resistance to all kinds of herbicides, so there are reasons to believe the observed result will not be unique for RR soy.

Jaan Suurküla M.D.

"Genetically Engineered Food - Safety Problems"
Published by PSRAST

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