Planting corn early brings higher yields and greater profits. That’s the case year after year in Minnesota, says Dale Hicks, agronomist with the University of Minnesota Extension Service. Last year was no exception, he says.

“Last year, 22% of Minnesota’s corn acres were planted in mid-April,” says Hicks. “The seedbed was ideal and the soil temperature was above normal for mid-April. Then it turned cold and seed lay in the ground for 30-40 days. The end result: plants emerging unevenly and stands substantially lower than the desired plant populations. Also, plant spacing was not uniform. However, we ended up with a record state average corn yield in Minnesota of 156 bu/acre.”

While timely rainfall was important, Hicks believes early planting was a major reason for last year’s high yields.

“Early planting sets the stage for high yields and minimizes the first yield-limiting barrier,” he points out. “Production costs are fixed and independent of when corn is planted, so planting date is a no-cost production practice.”

Hicks acknowledges that poor stands and uneven emergence last year resulted in fields with uneven plant heights and gaps between plants. But he cites results of a study on delaying emergence of various portions of plants in a field. The study found that when 25% of a full stand of 30,000 plants/acre was missing, 10% of the potential yield was lost. When the stand was full (30,000 plants/acre) but 25% of the plants emerged 10 days later than the rest of the stand, yield was reduced only 6%. Thus, the late-emerging plants contributed 4% to yield.

When stands are extremely non-uniform, late-emerging plants contribute more to yield, says Hicks. For example, yield is only 70% of potential with a 50% stand. If the other 50% emerges 10 days later, the yield loss is only 8%. If the delay in emergence for half the plants is 20 days, the yield loss is only 2%. Thus, the later-emerging plants contribute to yield, Hicks points out.

“The yield potential of an early planted field with a poor stand is usually better than the yield potential of a later-planted field with a full stand of uniformly spaced and similar height plants,” says Hicks. “While the early planted field may not look as nice in June and July, it has a better profitability potential. And that’s not considering that later planting can mean later maturity and higher drying costs in the fall.”