FARMINGTON, Minn. — Lingering cooler than normal temperatures and additional snowfall across much of the state resulted in another week with 0.0 days suitable for fieldwork during the week ending April 15, 2018, according to USDA’s National Agricultural Statistics Service. Snow cover remains widespread with most areas reporting frost still in the ground and soil temperatures below normal for this time of the year. The five year average for suitable fieldwork is 2.8 days by the date of April 15th.
Snow cover and cool temperatures have delayed planting of spring crops. Oats planted were reported as 0 percent complete, 16 percentage points behind last year, and 17 points behind the 5 year average. Spring wheat planted was reported as 0 percent complete, 8 percentage points behind last year, and 13 points behind the 5 year average. Sugarbeets planted were reported as 0 percent complete, 16 percentage points behind last year, and 18 points behind the 5 year average.
Maximum corn yield is generally obtained when planting occurs in late April or early May (100 percent if planted by April 30th). In years when spring arrives early, a mid–April planting date also will produce similar yield if young plants are not damaged by a freeze in May. However in years when there are few growing degree days during late April and the first half of May, maximum corn yield also can be obtained when planting occurs in mid–May.
University of Minnesota planting date studies show that highest corn yield typically occurs when planting is completed by mid-May according to Dr. Jeff Coulter, University of Minnesota Extension Corn Specialist. In a study from 2009 to 2011 at Lamberton, Morris, and Waseca, MN that was funded by the Minnesota Corn Growers Association, average grain yield was within 98% of the maximum if planting was completed by May 15. In another study from 1988 to 2003 at Lamberton, MN, a planting date of May 15 resulted in grain yields that averaged 95% of the maximum. These same studies found that corn yield averaged 92 to 95% of the maximum when planting occurred by May 20.
Typically there is a rapid decline in corn yield as planting is delayed beyond mid–May. However, advantages from timely planting according to the calendar can be negated if planting occurs when soils are too wet. When corn planting is delayed beyond the third week in May, switching late-maturity hybrids to earlier–maturity hybrids reduces the risk of corn freezing in the fall before it has reached maturity. Research from Illinois and Minnesota indicates that the optimum final plant population for corn is not affected by planting date (Nafziger, 1994; Van Roekel and Coulter, 2011).
SUMMARY:
Timely planting is critical, but avoid planting into wet soil conditions. High corn yields can still be obtained if planting is delayed until mid–May. Consider earlier–maturity hybrids when planting is delayed beyond the third week of May. When corn is planted into good soil conditions, optimum planting rates generally do not differ with planting date.
— University of Minnesota Extension
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