If you ask someone, “How much corn is planted, or how much spring fieldwork has occurred in your area?” the response is likely to be quite different. A major snowfall event in early May, followed by frequent rainfall events throughout most of May, in the eastern half of southern Minnesota, as well as areas of northern Iowa, has caused significant delays in corn planting. Most of this region has received additional rainfall amounts of 1-2 in. over this past weekend, with substantially more rainfall in some areas, on soils that were already saturated. As a result, less than half of the intended corn acres in this region have been planted as of May 20, with very few soybeans being planted.
Western portions of south-central Minnesota and most of southwest Minnesota were able to make some excellent planting progress during the week of May 12-18. It is estimated that about 80-90% of the anticipated corn in this region has been planted as of May 20. Soybean planting is 40-50% completed at many locations in this portion of southern Minnesota. Planting conditions in other sections of Minnesota have also been quite variable due to weather conditions and soil moisture.
Most growers will likely stick with planting full-season corn hybrids for at least another week to 10 days, probably until the end of May, and will then move to earlier corn hybrids, before switching major acreage to soybeans. Research from 2009-2011 at the U of M Research Centers at Waseca, Lamberton and Morris showed that corn planted on May 25 averaged 93% of the yield of corn that was planted from April 25 to May 10. The average yield dropped to 89% of maximum for corn planted on May 30, and yield potential begins to decline quite rapidly for corn planted after June 1.
The planting window for soybeans is significantly wider than it is for corn. In southern Minnesota, full-season varieties of soybeans can be planted until late May or early June, with only minimal reductions in yield potential. Weather conditions in the next 10 days to two weeks will determine how serious the planting delays in the eastern half of southern Minnesota and northern Iowa become. This could have a major economic impact of farm operators in that region, especially if crop prices are reduced later in the growing season due to favorable growing conditions in other areas of the U.S.
Editor’s note: Kent Thiesse is a former University of Minnesota Extension educator and now is Vice President of MinnStar Bank, Lake Crystal, MN. You can contact him at 507-726-2137 or via e-mail at firstname.lastname@example.org.