GMOS and Crop Yield

There was an interesting paper published last week in Nature Biotechnology by some University of Wisconsin professors of agricultural economics and agronomy (by the way, one of the authors, Chavez, is a preeminent agricultural economist - he's also one of the most well read economists I've ever been around).

The study used crop yield data from plots in Wisconsin and showed that not all biotech corn varieties outperform conventional varieties in terms of yield.  As they put it:

Compared with conventional hybrids, the impact of transgenic traits (both single and stacked traits) on mean yield ranges from −12.2 to +6.5 bushels per acre.

Not surprisingly, the result has been picked up by the anti-biotech crowd, such as Tom Philpott at Mother Jones.  

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 . . .
Turns out, though, that both assertions in BIO's statement are highly questionable.

There are numerous problems with Philpott's arguments.

First, is rhetorical.  Monsanto didn't "flood the market."  Somebody had to buy those seeds.  Those somebodies were farmers who willingly adopted, and even paid price premiums to have biotech seeds.  Which leads to the second issue.

As the Nature Biotechnology study shows, the biotech varieties had an important risk-reducing effects, even if they sometimes led to slightly lower yields.  Moreover, biotech can save on other inputs like labor.  When I was a teenager, I spent a lot of time hoeing and spraying cotton weeds. That job is (thankfully) now obsolete due to biotechnology.     

You also can't just cherry-pick the results you want to emphasize if you want to actually be objective.  As I reported earlier, larger studies conducted over a much wider geographic region DO show yield improvements from biotech adoption (though that study shows - like the more recent one in Nature - that yield effects of traits are not additive).  Moreover, check out table 1 (gated) of the aforementioned study in the American Journal of Agricultural Economics, which shows 31 different results from numerous studies, almost all of which show a yield boost from biotech.  Or see this study in Science by another preeminent agricultural economist showing significant yield gains (and pesticide reductions) from biotech adoption in India.  The totality of the evidence suggests that - in most locations and for most crops - biotech does increase yield most of the time (though not always and not in all locations and not for all crops).

That gets to my last issue with Philpott.  He (and others) continually reference the work of Charles Benbrook on pesticide use associated with biotech.  But, rarely do they differentiate between pesticides use (which biotech DOES reduce) and herbicide use (which biotech has increased).  Also ignored is the relative toxicity and environmental effects of pesticides vs. herbicides or the reduction in toxicity that has occurred over time as a result of biotech (see this recent critique of Benbrook's work).  If that weren't bad enough, such authors also fail to point out that use of herbicide-resistant biotech facilitates no- and low-till farming practices, which are a real environmental benefit (indeed, the data shows that biotech adoption is strongly correlated with no- and low-till adoption).  

I'm not saying there are no downsides to biotech use (e.g., more rapid development of herbicide resistant weeds; potential market power in the seed/chemical sector).  But, one has to look at the totality of the evidence and not just cherry-pick.  Moreover, you have to look at the decisions made by real-life flesh and blood farmers all over the world who have voluntarily adopted GMOs.  The fact that biotech was so readily adopted by farmers (and is still so widely in use) aught to tell you something.