OWATONNA, Minn. — As of Monday, May 20, 2019, the USDA Minnesota crop progress report indicated that fifty-six percent of Minnesota’s corn was planted, which was three days behind the previous year and ten days behind the five-year average. Averages being what they are, just averages, many parts of the state report that the rate of corn planting has been highly variable depending on rain patterns and soil conditions. Thus many farmers are still faced with calculating corn planting options, which range from still planting their existing corn hybrids (current maturity); or switching to a shorter corn hybrid maturity; or planting a different crop in some fields; or utilizing the USDA Prevented Planting Crop Insurance program. But first we should still consider late planting corn as planned, which was recently reviewed by University of Minnesota Extension Corn Specialist, Dr. Jeff Coulter:
Planting date and corn yield
Field trials conducted by the University of Minnesota show that on average, corn yield is within 2% of the maximum when planting occurs between April 20 and May 10 or 15, within 5% of the maximum when planting occurs by May 15 to 20, and within 8% of the maximum when planting occurs by May 20 to 25.
Plant when soil conditions are suitable
A field is ready for seedbed preparation when soil in the depth of tillage crumbles when squeezed. Tillage in wet soil causes clods, which reduce seed-to-soil contact. Excellent seed-to-soil contact is essential for rapid imbibition (uptake) of moisture by seeds and uniform emergence. Tillage in wet soil also creates a compacted layer below the depth of tillage, which can restrict root development.
Sidewall compaction can occur when planter disc openers cut through wet fine-textured soil, resulting in compacted soil around the seed that is difficult for roots to penetrate. This can restrict root development, nutrient and water uptake, and crop growth. Seed furrows can also open after planting in such conditions, resulting in poor seed-to-soil contact.
If corn planting is delayed until after the first three weeks of May, switching full-season hybrids to earlier-maturity hybrids reduces the risk of corn freezing in the fall before it has reached maturity. In such instances, planting hybrids that are 5 to 7 or more relative maturity units earlier than those considered full-season reduces the risk of corn being froze in the fall prior to maturity.
Planting grain corn after May 31 carries high risk in Minnesota. However, decisions regarding the crop to plant can be influenced by factors such as fertilizer applied and seed availability. If grain corn is planted after May 31 in Minnesota, growers can reduce risk by planting hybrids that are 15 or more relative maturity units earlier than full-season hybrids.
Additional information on planting date considerations from University of Minnesota Extension are available at: https://extension.umn.edu/corn-planting/planting-date-considerations-corn.
— Dave Nicolai, Extension Educator, Crops, UMN Extension
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