“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.”