Do GMO Crops Really Have Higher Yields?
A new paper by University of Wisconsin researchers suggests they don't.
According to the biotech industry, genetically modified (GM) crops are a boon to humanity because they allow farmers to "generate higher crop yields with fewer inputs," as the trade group Biotechnology Industry Organization (BIO) puts it on its web page.
Buoyed by such rhetoric, genetically modified seed giant Monsanto and its peers have managed to flood the corn, soybean, and cotton seed markets with two major traits: herbicide resistance and pesticide expression—giving plants the ability to, respectively, withstand regular lashings of particular herbicides and kill bugs with the toxic trait of Bacillus thuringiensis, or Bt.
Turns out, though, that both assertions in BIO's statement are highly questionable. Washington State University researcher Charles Benbrook has demonstrated that the net effect of GMOs in the United States has been an increase in use of toxic chemical inputs. Benbrook found that while the Bt trait has indeed allowed farmers to spray dramatically lower levels of insecticides, that effect has been more than outweighed the gusher of herbicides uncorked by Monsanto's Roundup Ready technology, as weeds have rapidly adapted resistance to regular doses of Monsanto's Rounup herbicide.
And in a new paper (PDF) funded by the US Department of Agriculture, University of Wisconsin researchers have essentially negated the "more food" argument as well. The researchers looked at data from UW test plots that compared crop yields from various varieties of hybrid corn, some genetically modified and some not, between 1990 and 2010. While some GM varieties delivered small yield gains, others did not. Several even showed lower yields than non-GM counterparts. With the exception of one commonly used trait—a Bt type designed to kill the European corn borer—the authors conclude, "we were surprised not to find strongly positive transgenic yield effects." Both the glyphosate-tolerant (Roundup Ready) and the Bt trait for corn rootworm caused yields to drop.