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Do genetically engineered crops really increase herbicide use?
A model was developed to quantify by crop and year the impacts of six major transgenic pest-management traits on pesticide use in the U.S. over the 16-year period, 1996–2011: herbicide-resistant corn, soybeans, and cotton; Bacillus thuringiensis (Bt) corn targeting the European corn borer; Bt corn for corn rootworms; and Bt cotton for Lepidopteron insects.Herbicide-resistant crop technology has led to a 239 million kilogram (527 million pound) increase in herbicide use in the United States between 1996 and 2011, while Bt crops have reduced insecticide applications by 56 million kilograms (123 million pounds). Overall, pesticide use increased by an estimated 183 million kgs (404 million pounds), or about 7%.Contrary to often-repeated claims that today’s genetically-engineered crops have, and are reducing pesticide use, the spread of glyphosate-resistant weeds in herbicide-resistant weed management systems has brought about substantial increases in the number and volume of herbicides applied.
previous report (after 13 years) a couple years ago, so I was already somewhat familiar with the methodology he used. Which is good, because the “Methods” section of this most recent paper on estimating herbicide use is pretty sparse (and confusing). Basically, Dr. Benbrook uses USDA-NASS data to estimate herbicide use on both conventional and herbicide resistant crop acres. This is no easy task for several reasons. First, USDA (presumably due to budget cuts) does not collect pesticide use data very often anymore. They had completely stopped for a while, and I believe are now starting again, but in a limited capacity (not all crops in all years). I agree with Dr. Benbrook that this lack of independent pesticide use data is very frustrating…
Continues @ Control Freaks » Blog Archive » Do genetically engineered crops really increase herbicide use?:
Update
There is available a lot of contrary discussion to the Benbrook position.
Tribe and Chassy made a critiques at academics review from the last time Benbrook released this data, and these comments are still relevant:
http://academicsreview.org/reviewed-content/genetic-roulette/section-6/6-2-new-herbicide-tolerant-crops/
See National Research Council (NRC). Impact of Genetically Engineered Crops on Farm Sustainability in the United States. Washington, DC: The National Academies Press, 2010.
Available for free online at http://www.nap.edu/catalog.php?record_id=12804#toc
Improvements in water quality could prove to be the largest single benefit of GE crops, the report says. Insecticide use has declined since GE crops were introduced, and farmers who grow GE crops use fewer insecticides and herbicides that linger in soil and waterways. In addition, farmers who grow herbicide-resistant crops till less often to control weeds and are more likely to practice conservation tillage, which improves soil quality and water filtration and reduces erosion.
Global impact of biotech crops: Environmental effects 1996-2009
http://www.landesbioscience.com/journals/gmcrops/BrookesGMC2-1.pdf
Abstract:
This paper updates the assessment of the impact commercialised agricultural biotechnology is having on global agriculture from an environmental perspective. It focuses on the impact of changes in pesticide use and greenhouse gas emissions arising from the use of biotech crops. The technology has reduced pesticide spraying by 393 million kg (-8.7%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops (as measured by the indicator the Environmental Impact Quotient (EIQ)) by17.1 %. The technology has also significantly reduced the release of greenhouse gas emissions from this cropping area, which, in 2009, was equivalent to removing 7.8 million cars from the roads.
Also if “Things are getting worse, fast,” said Benbrook in an interview. “In order to deal with rapidly spreading resistant weeds, farmers are being forced to expand use of older, higher-risk herbicides. To stop corn and cotton insects from developing resistance to Bt, farmers planting Bt crops are being asked to spray the insecticides that Bt corn and cotton were designed to displace.” Then does this not suggest that RR and BT crops do in fact result in the use of newer, low-risk herbicides (i.e. RR) and reduces the spraying of insecticides?.
2012-10-04 00:43:57
Source: http://gmopundit.blogspot.com/2012/10/do-genetically-engineered-crops-really.html
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