Fundamentally Speaking

2023 US Corn Yield Threatened by History, Seasonality

Joel Karlin
By  Joel Karlin , DTN Contributing Analyst
Chart by Joel Karlin, DTN Contributing Analyst

For the second week in a row U.S. corn ratings increased, this time by 4% in the good to excellent category vs the 1% rise recorded the prior week.

Nonetheless there is a lot of concern about the fate of this year's crop given the fact that week 27 (around the second week of July) ratings are the worst since 2012 and among the lowest ever since the USDA started national ratings in 1986.

Furthermore, for a variety of reasons, mostly appearance, crop conditions usually start to trend down this time of year and continue that way into harvest.

Using our usual ratings system where we weight the crop based on the percent in each category and assign that category a factor of 2 for very poor, 4 for poor, 6 for fair, 8 for good, and 10 for excellent and then sum the results, this chart shows the seasonal corn condition ratings by week with the average and plus and minus one standard deviation lines using data from 1986 to 2022.

Also plotted is the five-year average and the weekly crop ratings so far for 2023.

As noted there has been a slight recovery in 2023 corn ratings given recent rains after a very dry May and most of June in a large part of the Corn Belt.

Still, values are just barely above the negative one standard deviation line and well below both the long-term and five-year averages at the current rating of 694.

Looking back at past crop ratings as of week 27 there have only been four instances where ratings are lower than what prevails today, including the worst being 1988 with a rating of 504, second worst was the 608 rating in 2012 followed up by 686 in 1993 and 688 in 2002 as all these seasons had final U.S. corn yields well below trend.

The odds are not good that this year's yield will be anywhere near trend which is calculated to be around 177-178 bushels per acre (bpa) though it is possible to pull a rabbit out of one's hat such as 1992 when the week 27 rating of 696 zoomed to as high as 790 by week 33 due to very cool summer temperatures that season and a good amount of rain after a very dry June.

This would however buck the normal seasonal trend where crop ratings peak around this time of the growing season and then falter through the rest of summer into the fall harvest season.


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