By Kent Thiesse
For the third year in a row, spring fieldwork has been slow to begin in the Upper Midwest. Frequent rainfall over the last ten days of April and the first week of May across left fields too wet for corn planting.
In addition, very cool temperatures over the same timeframe resulted in adverse soil conditions for corn planting in Minnesota and northern Iowa. A small amount of corn planting did occur this past weekend on May 4 and 5 in areas that were marginally fit for Spring fieldwork.
The University of Minnesota Research and Outreach Center at Waseca recorded 4.25 inches of precipitation during the month of April, 1.04 inches above normal. More than 3 of those inches fell from April 18 through May 1. In addition, precipitation was recorded on 10 different days during that two-week period. During that same period the University’s Research Center at Lamberton recorded 3.47 inches of rainfall, with precipitation recorded on nine different days. Unfortunately, more rain lingers this week as well.
The combination of this rainfall with totally saturated soils has significantly delayed planting. Because of these conditions, a rainfall event of a few tenths of an inch can have a similar impact that a rainfall event of an inch or more would usually have. Fields are very slow to dry out, and even when farmers can plant, they can be forced to leave portions of the fields unplanted due to excessive soil moisture.
The average soil temperature at Waseca at the 2-4 inch level during the last week of April and first few days of May was below 50 degrees Fahrenheit most of the time. These soil temperatures are too cold for good corn seed germination and early corn seedling development. The long-term average soil temperatures in early May at Waseca are more typically in the mid-to-upper 50’s at the 2-4 inch level. Research shows that 50 percent corn emergence will occur in 20 days at an average soil temperature of 50 degrees F, which is reduced to only 10 days at an average temperature of 60 degrees F.
Most University and private agronomists are encouraging producers to be patient with resuming field work and to wait for more conducive soil conditions. Given the high cost per acre of seed corn, and the limited availability of some of the best yielding corn hybrids in 2019, most growers do not want to take the risk of planting corn in poor soil conditions.
According to University of Minnesota and private seed company research, the “ideal time window” to plant corn in southern Minnesota typically runs from April 20 to May 10. Even though spring planting is off to a very slow start, the good news is that there are still opportunities for timely corn planting.
Based on long-term research, the reduction in optimum corn yield potential with planting dates from May 10-15 in southern Minnesota is usually minimal and quite dependent on the weather that follows. Even corn planted from May 15-25 has a good chance of producing 90-95 percent of optimum yield potential, assuming favorable growing conditions during the balance of 2019.
Most farmers will continue to plant corn at least until May 25, before thinking about switching those acres to soybeans or considering prevented planting options. Currently, fall crop prices and crop economics for 2019 favor planting corn over soybeans. Producers may switch to earlier corn hybrids as we get later into May to increase the likelihood of the corn reaching maturity by fall, even though the earlier hybrids may have slightly lower yield potential.
2019 is the third year in a row that farm operators in the Upper Midwest have dealt with spring planting delays. In 2017, following some planting delays in late April and early May, the weather improved and most of the corn in southern Minnesota and northern Iowa was planted by mid-May. The rest of the growing season in that region featured very ideal weather in most areas, which lead to record corn yields in many counties across the region.
In 2018, following spring planting delays, excessive rainfall throughout the early growing season and poor growing conditions combined to create some of the lowest corn yields in two or three decades in some of the same counties. 2019 results could go either way, depending on what conditions follow planting.
Most likely, farm operators will move directly from corn into soybean planting. Most soybean producers in southern Minnesota and northern Iowa strive to plant soybeans in mid-May; however, the ideal window to plant soybeans and still achieve optimum yields is much wider than with corn. The ideal soybean planting timeframe extends until about May 25, so there is still plenty of time to get the 2019 soybean crop planted. In some areas, if soybean acres are fit to plant, there may be soybeans planted prior to corn.
According to the USDA Weekly Planting Progress Report on April 29, only 2 percent of the corn in Minnesota had been planted, which is about 15 days behind normal. Nationally, 15 percent of the U.S. corn crop was planted by April 28, which is at the same level as 2018, and compares to a normal planting level of 27 percent by that date. The 2018 and 2019 corn planting progress are tied for the sixth slowest at the end of April since 1987. The final national corn yield in 2018 was 176.4 bushels per acre, which was nearly a record yield; however, in the other five years of late planting, the national corn yield showed a significant decline from the preceding year.
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