This year’s U.S. corn crop is shaping up to be a bin buster.

University of Illinois economists Scott Irwin and Darrel Good say the crop currently has the potential to outperform the all-time record average corn crop yield. That was 164.7 bushels per acre, set in 2009.

The economists note that the U.S. corn crop yield has increased by an average of 1.7928 bushels per acre per year since 1960. While weather always is a factor in row-crop production, this consistently steady increase also is due to changes in technology and management practices.

They compare this year’s crop to that of the other six highest-yielding years since 1960. They are 1972, 1979, 1982, 1994, 2004 and 2009. Compared to those years, current crop conditions are similar, although this year’s weather pattern does not exactly match the trend of the other high-yielding years. An extremely wet June, as was experienced in much of the Corn Belt, would not be predictive of a mega-crop. But, they describe the first week of July this year as nearly ideal for growing corn.

The weather trend that does match the previous high-yielding years is a cooler-than normal July. While cool weather in general is not thought to be conducive to corn growth, Irwin and Good offer the following explanation from Purdue University professor R.I. Nelson:   

"All things equal, cooler temperatures during grain fill typically result in heavier kernels and higher grain yield than do warmer temperatures, especially stressfully hot temperatures. Even though the rate of grain filling per day is slower when temperatures are cool, the duration of the grain filling period (number of days) is longer. The advantages of a lengthy grain fill period typically outweigh the disadvantages of a slower grain fill rate per day."

A cool, moist August would be optimal for maximizing this year’s crop, the economists say. If that happens, they predict the per-acre average for this year’s crop could be in the neighborhood of 173.6 bushels.

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