http://reason.com/archives/2015/05/08/chipotle-claims-integrity-but-is-actuall
In May 2014, the U.S. Department of Agriculture's (USDA) National Agricultural Statistics Service issued its comprehensive report Pesticide Use in U.S. Agriculture, updating national herbicide and insecticide usage trends. The agency found that herbicide usage peaked at 478 million pounds in 1981—a decade and half prior to the introduction of the first biotech crop varieties—and fell to 394 million pounds in 2008. So instead of a massive increase in herbicide spraying, as claimed by Benbrook, the USDA actually reports a modest decline. Insecticide applications peaked in 1972 at 158 million pounds, dropping to 29 million pounds in 2008.
It's worth noting that the insecticide DDT accounted for 11 percent of all agricultural pesticides used in 1972. Since biotech crops can protect themselves against insect pests, there is far less need for farmers to spray their crops.
In November 2014, German researchers reviewed 147 agronomic studies and similarly reported that "on average, GM technology adoption has reduced chemical pesticide use by 37 percent, increased crop yields by 22 percent, and increased farmer profits by 68 percent."
What really does cause damage to the environment? Growing low-yield crops, because that means more land must be plowed down instead of being left for nature. And organic farming generally produces lower yields than conventional farming. A 2012 review in the journal Nature found that "overall, organic yields are 25 percent lower than conventional yields."