Jul 20, 2022

2022 U.S. Corn Yield Unchanged at 177.0 bu/ac

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

The 2022 U.S. corn yields was left unchanged this week at 177.0 bu/ac and I have a neutral to lower bias going forward. After one week of a neutral bias, I have returned to a neutral to lower bias. I hesitated to lower the corn yield this week because the corn in Iowa and Illinois is doing fine and the eastern Corn Belt received more rain than I anticipated over the weekend. I am worried about the forecast and I could easily lower the corn yield next week.

The condition of the corn crop held steady last week at 64% rated good/excellent. The corn is 37% silking compared to 52% last year and 48% average. The corn is 6% in the dough stage compared to 7% last year and 7% average.

Of primary concern for the corn is the developing heat wave early this week in the western and southern Corn Belt. There is the potential for the heat wave to return to the same region later this week and over the weekend. These conditions will significantly reduce the soil moisture, which would need to be replaced as quickly as possible.

Weather during the last two weeks of July will probably be problematic for the corn crop and it might not improve much during August. Analysis of analog years by DTN points to "above-normal temperatures and below-normal precipitation in all primary U.S. row crop areas for August 2022." DTN's long-range forecast team considered 2011, 2010, 2020, 2008, and 1950 as the most likely analog years because these years are all La Nina years. As always, long-range forecast can be fickle, so you must take them with a hefty dose of skepticism.

With extreme daytime temperatures, there is always a concern that high night temperatures during pollination and grain fill can have a negative impact on corn yields. Night temperatures that stay above 70°F to 72°F can be problematic.

According to Pioneer Seeds Crop Insite "High Night Temperatures Effect on Corn Yields" by Nanticha Lutt, Mark Jaschke, Ph.D., and Stephend. Strachan, Ph.D., there are two hypotheses why corn yields decline under high temperatures. One hypothesis is that higher temperatures can be associated with moisture stress which impacts sugar production. A second hypothesis is that at higher temperatures the corn plant is not as efficient in producing sugars. Embryos starting at the tip of the earn start to die due to starvation until the number of living embryos that remain can be adequately fed by the corn plant.

Pollination determines the number of fertilized ovules and environmental conditions during grain fill impact the number of harvestable kernels per ear. Approximately 85% of the total grain yield is related to the total number of kernels per acre and approximately 15% of the grain yield is related to the weight of the kernels. Pollination determines the number of viable kernels and environmental conditions during grain fill determines how many kernels are retained and the size of the kernels. If stress occurs during gain fill, the corn plant typically starts to abort kernels starting at the tip of the ear until the number of remaining kernels can be fed by the plant.

High night temperatures increases the plant's respiration which requires more sugar for energy thus making less sugar available for deposition as starch in the kernels. High night temperatures can also accelerate phenological development resulting in a shorter grain fill period.

Therefore, high night temperatures forces the plant to use more sugar to maintain itself which reduces the amount of sugars available to be deposited as starch in the kernels and high night temperatures accelerates the plant's development so the corn plant matures sooner.