http://www.ucsusa.org/food_and_agriculture/science_and_impacts/science/failure-to-yield.html
April 14, 2009 Union of Concerned Scientists
Failure to Yield
Evaluating the Performance of Genetically Engineered Crops
Download: Failure to Yield (2009)
[failure-to-yeild-136px.gif] For years the biotechnology industry has
trumpeted that it will feed the world, promising that its genetically
engineered crops will produce higher yields.
That promise has proven to be empty, according to Failure to Yield, a
report by UCS expert Doug Gurian-Sherman released in March 2009.
Despite 20 years of research and 13 years of commercialization, genetic
engineering has failed to significantly increase U.S. crop yields.
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.
The UCS report comes at a time when food price spikes and localized
shortages worldwide have prompted calls to boost agricultural
productivity, or yield -- the amount of a crop produced per unit of
land over a specified amount of time. Biotechnology companies maintain
that genetic engineering is essential to meeting this goal. Monsanto,
for example, is currently running an advertising campaign warning of an
exploding world population and claiming that its "advanced seeds...
significantly increase crop yields..." The UCS report debunks that
claim, concluding that genetic engineering is unlikely to play a
significant role in increasing food production in the foreseeable
future.
The biotechnology industry has been promising better yields since the
mid-1990s, but Failure to Yield documents that the industry has been
carrying out gene field trials to increase yields for 20 years without
significant results.
Failure to Yield makes a critical distinction between potential--or
intrinsic--yield and operational yield, concepts that are often
conflated by the industry and misunderstood by others. Intrinsic yield
refers to a crop's ultimate production potential under the best
possible conditions. Operational yield refers to production levels
after losses due to pests, drought and other environmental factors.
The study reviewed the intrinsic and operational yield achievements of
the three most common genetically altered food and feed crops in the
United States: herbicide-tolerant soybeans, herbicide-tolerant corn,
and insect-resistant corn (known as Bt corn, after the bacterium
Bacillus thuringiensis, whose genes enable the corn to resist several
kinds of insects).
Herbicide-tolerant soybeans, herbicide-tolerant corn, and Bt corn have
failed to increase intrinsic yields, the report found.
Herbicide-tolerant soybeans and herbicide-tolerant corn also have
failed to increase operational yields, compared with conventional
methods.
Meanwhile, the report found that Bt corn likely provides a marginal
operational yield advantage of 3 to 4 percent over typical conventional
practices. Since Bt corn became commercially available in 1996, its
yield advantage averages out to a 0.2 to 0.3 percent yield increase per
year. To put that figure in context, overall U.S. corn yields over the
last several decades have annually averaged an increase of
approximately one percent, which is considerably more than what Bt
traits have provided.
In addition to evaluating genetic engineering's record, "Failure to
Yield" considers the technology's potential role in increasing food
production over the next few decades. The report does not discount the
possibility of genetic engineering eventually contributing to increase
crop yields. It does, however, suggest that it makes little sense to
support genetic engineering at the expense of technologies that have
proven to substantially increase yields, especially in many developing
countries. In addition, recent studies have shown that organic and
similar farming methods that minimize the use of pesticides and
synthetic fertilizers can more than double crop yields at little cost
to poor farmers in such developing regions as Sub-Saharan Africa.
The report recommends that the U.S. Department of Agriculture, state
agricultural agencies, and universities increase research and
development for proven approaches to boost crop yields. Those
approaches should include modern conventional plant breeding methods,
sustainable and organic farming, and other sophisticated farming
practices that do not require farmers to pay significant upfront costs.
The report also recommends that U.S. food aid organizations make these
more promising and affordable alternatives available to farmers in
developing countries.
"If we are going to make headway in combating hunger due to
overpopulation and climate change, we will need to increase crop
yields," said Gurian-Sherman. "Traditional breeding outperforms genetic
engineering hands down."
Last Revised: 04/14/09