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Corn Trend Yield

If there is a topic that is sure to generate VERY strong opinions on the part of farmers, seed companies, and market analysts, it is the trajectory of corn trend yields. My motivation for writing about corn trend yields (again) is a recent post by the esteemed (and recently retired) agronomist at Purdue, Bob Nielsen. His recent post included his interpretation of corn trend yields since 1866 and it is presented in the chart that accompanies this post. This is an incredibly important chart to get right for a variety of reasons. My summary: science, science, science.

Bob’s interpretation of the data for corn trend yields is quite similar to mine. It is always fascinating to me to observe that corn yields in the US were flat for 70 years from 1866 into the 1930s. This is actually more of an achievement than is commonly understood. One of my favorite scientific articles of all time is “The Red Queen and the Hard Reds: Productivity Growth in American Wheat, 1800-1940” by Alan Olmstead and Paul Rhode. They show that, like the Red Queen in Alice Wonderland, crop breeding must run ever faster just to stay even because diseases and pests adapt. This means that corn breeders and farmers were not sitting on their hands during this “open pollination” era. Genetic improvements had to occur just to keep corn trend yields flat.

This makes what happened starting in the 1930s with the introduction of hybrid corn and then nitrogen fertilizer even more remarkable. Science, rising input levels, and management improvements have allowed the US to increase corn yields by about 2 bushels/year for now over 60 years. We should never forget what a remarkable achievement that is!

The latest issue is whether a third production miracle started in the mid-1990s due to genetically modified traits. Bob does not think so and his chart reflects that. Almost exactly 15 years ago to the day, my colleagues Mike Tannura, Darrel Good, and I published research challenging this idea. Monsanto was pushing hard that GM traits had dramatically increased yield potential for corn and that trend yields had turned up sharply. In fact, they had an entire marketing campaign built around the claim that the national trend yield for corn in 2030 would be 300 bushels per acre. This struck us as patently absurd, and we used a crop weather model to show that recent corn yield gains at the time were primarily due to better than average weather instead of a dramatic jump in the genetic yield potential of corn due to GM traits.

As Bob explains in his recent post, Monsanto’s claim never really made logical sense to begin with because the traits were essentially “defensive” to help protect the corn plant rather than increasing yield potential. Trust me when I say that the blowback from our little article was intense! But we stood our ground, and I am happy to say that our analysis has stood the test of time. If Monsanto was right in 2008, corn trend yields should now be pushing 250 bushels per acre to make 300 bushels by 2030. It is pretty obvious we came nowhere close to making that prediction come true!

If there is a view out there among farmers that is incredibly strong it is the view that corn hybrids now allow much higher corn trend yields than in the past. This is where the 2012 drought is so instructive. Unless you want to treat that event as some kind of 500-year outlier, it shows that corn yields can still get smoked in really bad droughts, we just have not had very many of them recently. My own view at the present time is a slightly different than Bob Nielsen’s. I think that if you dig a little deeper, there has actually been a small uptick in corn trend yields in the last decade, probably for a variety of reasons. But it is nothing like that envisioned by the GM enthusiasts of fifteen years ago. Nonetheless, I have not been quite as optimistic as the USDA in their corn trend yield projections in recent years. It will be interesting to see what number the USDA publishes this week at their annual Ag Outlook Forum.

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