what bad results? USDA report

[Rick Roush <rroush@waite.adelaide.edu.au>]

>Herve wrote:
>While looking for the exact reference in News Scientist for the bad
>results of
>GMcrops

What bad results?  The USDA report at

http://www.econ.ag.gov/whatsnew/issues/biotech/

shows that:
       Use of Bt cotton and Bt corn is associated with significantly higher
yields in most years for some regions. Herbicide tolerance in soybeans is
associated with significantly higher yields in some regions in 1997.

       In 1997, herbicide-tolerant technology significantly reduced
herbicide treatments for soybeans and, to a lesser extent, for cotton.
Fewer insecticide treatments for the target pests were required for Bt corn
and cotton.


+++++++++++++++++++++++++++++++++++++++++++
USDA/ERS letter in response to recent news coverage of data report
www.econ.ag.gov


This note is to call your attention to a new  piece on the ERS Web site. The
new piece presents a lay-accessible summary of research conducted to test
for differences in yields and pesticide use between adopters and nonadopters
of GMO seed, when other variable factors are held constant.  The analyses on
which this new piece reports rely on exactly the same data as that made
available by the earlier piece.  It provides a more refined and reliable
indication of whether and how it may be expected that some currently
available GMO seed technology will interact with site-specific and farmer
characteristics to, eventually, affect farmers and the environment.

To view the new piece, "Impacts of Adopting Genetically Engineered Crops in
the U.S. * Preliminary Results," please go to the following url.

http://www.econ.ag.gov/whatsnew/issues/gmo/index.htm


Impacts of Adopting Genetically Engineered Crops
in the U.S. -- Preliminary Results

July 20, 1999

Genetic engineering is a technique used to alter or move genetic material
(genes) of living cells. (A number of the terms used in this article are
defined in Agricultural Biotechnology Concepts and Definitions). U.S.
acreage using genetically engineered crops has increased from about 8
million acres in 1996 to more than 50 million acres in 1998, in major
states where data have been collected (see Genetically Engineered Crops for
Pest Management, also in this Issues Center). Has adoption of this
technology benefited farmers and the environment?

Answering this question is not easy, even though survey data have been
collected on the characteristics and performance of farms adopting biotech
crops. Attributing differences in yields, pesticide use, and profits
between adopters and nonadopters observed in the data solely to adoption of
genetically engineered crops is nearly impossible because many other
factors also affect yield and pesticide use. For example, producers with
more favorable soils and climate may have higher yields than those
operating under less favorable conditions, whether they used
herbicide-tolerant varieties or not. Producers in areas of greater pest
pressure may use more pesticide applications than those
with fewer pest problems, despite adopting Bt crops.

However, the impacts of GMO (Genetically Modified Organisms) adoption can
be explored by statistically controlling for other factors that also affect
the impact. Multivariate regression modeling in effect decomposes the
influence various factors exert on the decision to adopt GMO technology,
and the influence of other factors on yields, pesticide use, and variable
profits. This report summarizes preliminary findings from such models using
1997 survey data. ....

Impacts From Adopting Herbicide-Tolerant Crops

Cotton production relies heavily upon herbicides to control weeds, often
requiring applications of two or more herbicides at planting and
postemergence herbicides later in the season. Close to 28 million pounds of
herbicides were applied to 97 percent of the 13 million acres devoted to
upland cotton production in the 12 major states in 1997. In 1997, increases
in adoption of herbicide-tolerant cotton are estimated to have increased
yields, leading to increased variable profits (see Table 1, Impact of
Adoption of Herbicide-Tolerant and Insect-Resistant Crops). However, no
statistically significant change in herbicide use on cotton was observed in
1997.

By contrast, increased use of herbicide-tolerant soybeans (17 percent of
1997 soybean acres) produced only a small increase in yield, and no
significant change in variable profits in 1997.  Soybean production in the
U.S. uses a large amount of herbicides, and 97 percent of the 66.2 million
acres devoted to soybean production in the 19 major states were treated
with more than 78
million pounds of herbicides in 1997. Genetic engineering produces
tolerance to glyphosate herbicide in soybeans, of which 15 million pounds
were used in 1997. However, almost two-thirds of the herbicides used on
soybeans were other synthetic materials. As GMO adoption increased, use of
glyphosate herbicide (such as RoundupŠ) also increased but use of other
synthetic herbicides
decreased by a larger amount. The net result was a decrease in the overall
pounds of herbicide  applied.

Impacts From Adopting Insect-Resistant Cotton

Cotton production uses a large amount of insecticides and 77 percent of the
13 million acres devoted to upland cotton production in the 12 major states
were treated with 18 million pounds of insecticides in 1997. Malathion was
the top insecticide used on cotton, with farmers applying more than 7
million pounds of this chemical in 1997. Aldicarb was second (2.4 million
pounds), followed by methyl parathion (2 million pounds), and acephate (0.9
million pounds).

In 1997, an increase in adoption of Bt cotton in the Southeast (to 22
percent of cotton acres) led to an increase in cotton yields and variable
profits (see Table 1, Impact of Adoption of Herbicide-Tolerant and
Insect-Resistant Crops). While use of organophosphate insecticides and
pyrethroid insecticides did not have significant changes associated with an
increase in Bt adoption,
there was a significant decrease in other insecticides, such as aldicarb.

Summary

Statistically controlling for factors other than adoption of genetically
engineered seeds allows an understanding of the likely impacts of marginal
changes in adoption on yields, profits, and pesticide use. Impacts vary
with the crop and technology examined. Increases in adoption of
herbicide-tolerant cotton were associated with significant increases in
yields and variable profits, but were not associated with significant
changes in herbicide use. Increases in adoption of herbicide-tolerant
soybeans were associated with small increases in yields and variable
profits, and significant decreases in herbicide use. Increases in adoption
of Bt cotton resistant to insects in the Southeast were associated with
significant increases in yields and profits and decreased insecticide use.