2020 crop yield potential fades in some areas

By Kent Thiesse

Back in July, most crop and marketing analysts were expecting a record corn and soybean crop in the United States and elsewhere. A combination of widespread storm damage, high incidence of crop diseases, and expanding drought during August has dimmed the hopes for record yields in many areas, however. This season’s corn and soybean yields will likely exceed the 2019 final crop yields, but they won’t be as robust as expected.

The derecho storm on August 10 that traveled some 600 miles from eastern Nebraska to Indiana, sweeping across the entirety of Iowa, caused immense crop damage. The storm also damaged grain storage and handling facilities, livestock facilities, and rural buildings. A derecho storm is defined as a widespread, long-lived, straight-line windstorm associated with a fast-moving group of severe thunderstorms. The August 10 storm featured sustained winds of 80-110 mph, with stronger gusts in some areas, as well as severe hail. 

The derecho impacted 57 of Iowa’s 99 counties, with 36 counties suffering severe damage. It is estimated that more than 3.5 million acres of corn and 2.5 million acres of soybeans in Iowa were damaged. Some analysts estimate that this one storm may lower the final U.S. average corn yield by as much as 4 bushels per acre. Obviously, it will be impossible to gauge the final impact from the derecho in Iowa and other states until after completion of the 2020 harvest.

In addition to the derecho, most of Iowa had limited rainfall during the month of August, which together with higher than normal temperatures, has resulted in a rapidly expanding drought across the state. By the end of August, nearly all of Iowa was listed as “abnormally dry,” with more than 75 percent listed as either in a “moderate” or “extreme” drought. In many areas of Iowa, this is the most severe drought since 2012. Portions of other Midwestern and Plains states also had experienced drought conditions by late August.

Based on the weekly USDA National Ag Statistics Service (NASS) crop reports, 62 percent of the domestic corn crop was rated “good to excellent” on August 31, with 14 percent rated “poor to very poor.” This compares to 72 percent rated “good to excellent on July 26, with only 7 percent rated “poor to very poor.” Based on the weekly NASS reports, 66 percent of the domestic soybean crop was rated “good to excellent” on August 31, compared to 72 percent on July 26. The U.S. crop ratings have been steadily declining during August.

As expected, Iowa has seen the most extreme drop in its corn and soybean ratings from mid-July to the end of August. On July 13, 83 percent of Iowa’s corn crop was rated “good to excellent,” with only 3 percent rated “poor to very poor.” By August 31, that rating had dropped to only 45 percent “good to excellent,” with 25 percent “poor to very poor.” Similarly, the “good to excellent” soybean rating in Iowa dropped from 83 percent on July 13 to only 50 percent by August 31, with the “poor to very poor” rating increasing to 18 percent by the end of August from 3 percent in mid-July. 

Other states had less-extreme declines than Iowa in the crop ratings from late July until the end of August. For “good to excellent” corn ratings, Minnesota went from 85 percent down to 79 percent, South Dakota went from 86 percent down to 74 percent, and Nebraska went from 75 percent down to 64 percent. Minnesota’s “good to excellent” soybean rating also declined from 85 percent in July down to 80 percent by late August, which is still very good compared to recent years. The late season dry weather conditions are also impacting crop conditions in these states, including in portions of southern and west central Minnesota.

The August 12 the USDA Crop Report estimated the national average corn yield for 2020 at a record level of 181.3 bushels per acre, with the 2020 total U.S. corn production at 15.3 billion bushels. The USDA estimates were completed as of August 1, before the derecho or the impacts of the expanding drought. It will be interesting how the USDA adjust the national corn yield and production estimates in its future reports. Private analysts are now estimating the national average corn yield in a range of 176 to 179 bushels per acre, with a total production of 14.7 to 15 billion bushels.

The USDA Report on August 12 estimated the 2020 average soybean yield at the record level of 53.3 bushels per acre and the total 2020 soybean production at 4.42 billion bushels. Once again, USDA will likely lower both the projected average yield and the total production in future reports, due to the declining conditions in Iowa and elsewhere. The estimates of private analysts now put the average soybean yield in a range of 51 to 53 bushels per acre, with total production ranging from 4.2 to 4.4 billion bushels. 

One of the biggest challenges with the corn crop in Minnesota and other northern corn belt states is usually getting the crop mature before the first killing frost. Average first frost dates range from around September 20 in the northern areas of the region to around October 10-15 in southern Minnesota and northern Iowa. The good news is that crop development in most areas of the region are much more advanced in 2020, as compared to a normal year. Since May 1, the accumulation of growing degree units (GDUs) has been running 5-10 percent above normal at most locations, which together with the very dry weather conditions in August in many areas, has greatly enhanced late-season crop development. 

Corn is considered to have reached physiological maturity once it is in the “black layer” stage. Much of the 2020 corn crop is likely to reach this stage by mid-September, which should greatly reduce any concern for an early frost this year. Once the corn reaches maturity, favorable early Fall weather can assist with natural dry-down of the corn in the field, which can reduce corn drying costs and enhance corn quality.

For additional information email Kent Thiesse, Farm Management Analyst and Senior Vice President, MinnStar Bank, Lake Crystal at kent.thiesse@minnstarbank.com.  

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