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November 14, 2017

Lessons Learned from the Record High U.S. Corn Yields of 2017

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

The USDA surprised the market last Thursday by increasing the 2017 U.S. corn yield by 3.6 bu/ac to 175.4 bu/ac setting a new record high U.S. corn yield. Given the type of growing season we experienced in the U.S. in 2017, this is a remarkable achievement for the corn crop.

The U.S. corn crop set a record high yield in 2016 and everybody attributed it to the nearly ideal growing conditions during the entire summer. In 2017, the corn set an even higher yield record even though the conditions appeared on the surface to be less than ideal. It is impossible to pinpoint one thing that led to the surprising corn yield. Instead, I think there were a number of factors and I feel the "take home" lessons from 2017 include:

  • The improved corn genetics allows the crop to withstand adverse conditions and still preform very well.
  • I would not say that the corn crop is now impervious to problems, but certainly the corn preforms much better under adverse conditions than just a few years ago.
  • We assumed in the past that improved genetics increased the corn yield about 1.5 bu/ac annually. Maybe now we should increase that to 2.0 bu/ac annually or more.
  • To have a negative impact on the corn crop, there needs to be an extended period of hot and dry weather during key reproductive periods such as pollination and early grain filling. By extended, I mean 7-10 days of hot and dry conditions, not just brief periods of a few days.
  • Additionally, if there is good soil moisture prior to the hot and dry weather, the impact of the adverse weather may be mitigated.
  • Wet spring weather and subsequent plating delays are not necessarily bad. The wet weather allows the "soil moisture tank" to be full going into the summer, which is beneficial.
  • Cool temperatures during August are very beneficial, especially cool temperatures at night. They allow the plant to rest at night and it reduces the plant's water requirement, thus reducing any potential moisture stress.
  • A warm and sunny September can prolong the growing season allowing the crop to maximize grain filling.
  • Lastly, good rainfall distribution is key for superior corn yields - in other words, you have to have good luck.

The one thing that bothers me the most from this past summer is how poorly the weekly crop conditions predicted the final yield. In 2016, they appeared to be a good predictor - very good condition ratings equaled a record high corn yield. In 2017, the condition ratings were mediocre and yet the corn yields set a new record. Unfortunately, I cannot explain the discrepancy.

Maybe the main "lesson learned" from 2017 is that we should assume a record corn yield at the start of the growing season and work backward from that assumption. In that light, next spring I am going to start off the season assuming a nationwide corn yield in the range of 174-176 bu/ac.