Ag Weather Forum

When Rain Did Not Make Grain

Bryce Anderson
By  Bryce Anderson , Ag Meteorologist Emeritus
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Southern Minnesota had almost a full month with no planting in 2019 because of heavy rain. (Photo by Sam Ziegler)

A common theme expressed by producers at the DTN 2019 Ag Summit, which took place Dec. 8 to Dec. 11, was that the extent of how delayed corn planting -- caused by heavy rain in the spring of 2019 -- was going to result in lower corn yields and quality. That general comment made sense. After all, there is a multitude of articles, easily accessible and authored by crop scientists at colleges and companies, all pointing to the importance of getting that seed corn in the ground during the first 20 days of May.

This year, of course, things were different. And, for Jeff and Roxie Thompson from southeastern Minnesota, that difference was dramatic at harvest time (which was also a tough season because of -- surprise! -- rain and snow).

Corn planting for the Thompson operation began in late April. There was a stretch from late April to May 3 that offered some decent fieldwork and planting conditions. For the month of April, southeastern Minnesota rainfall, measured by the Rochester, Minnesota National Weather Service gauge, totaled just under 4 inches -- about seven-tenths of an inch above normal.

Then came May. Rochester logged 9.42 inches of precipitation, 5.79 inches above normal -- 260% of normal. In just one day, on May 27, Rochester had 3.33 inches of rain -- almost the normal monthly total. Along with that, temperatures were very cool, more than four degrees Fahrenheit below normal. The first half of the month set a very chilly trend, where the average daily temperature dropped to as much as 14 degrees F below normal.

That cold and wet month meant that producers in southeastern Minnesota, including the Thompsons, did not return to planting until early June.

And, now we come to the comparisons. Corn planted in the late April-early May time frame was good, with a yield of 237 bushels per acre. But, the corn planted in early June, following the rain delays, fared much worse. That late-planted corn yielded only 162 bpa -- 75 bpa less, or 32% less than the corn planted in April through early May. And that late-planted corn, besides yielding lower, also had a test weight of only 50 pounds per bushel.

That’s a set of real numbers. That's a real decline in production caused by the wet spring of 2019.

Bryce Anderson can be reached at

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