Corn yield enhancement through planting densities and nitrogen management – Part 1

Two corn hybrids show somewhat different yield responses to population density and row spacing.

There is considerable interest in increasing corn yield in the short term by growing climate-tolerant hybrids at higher than normal planting densities, in narrow row configurations and with adequate nitrogen (N) rates. Two hybrids, DKC48-12 and DKC49-94, both having insect- and herbicide-stacked technology and improved drought tolerance capabilities, were tested. Three population densities of 30,000, 36,000 and 42,000 plants per acre and two row spacings of 20 inches and 30 inches were tested. Two nitrogen rates, 120 pounds per acre (low) and 240 pounds per acre (high) were applied.

A split-split plot design for Factor A (row spacing) with Factor B (population density) as a split plot on A, and Factor C (nitrogen rate) as a split plot on B, was used. Treatments were replicated three times for each hybrid. Each plot consisted of four rows 180 feet long. The plots were established on a high productive soil at the Mason Technology Center in Mason, Mich. The yield data from two hybrids at three population rates are summarized in Tables 1 and 2.

Table 1. Effect of row spacing and population on corn yield with hybrid 1 - DKC48-12 at Mason Technology Center, 2013.

Table 2. Effect of row spacing and population on corn yield with hybrid 2 - DKC49-94 at Mason Technology Center, 2013.

Preliminary results show that hybrid DKC48-12 had significant yield increases as population increased from 30,000 to 42,000 plants per acre. In contrast, the yield of hybrid DKC49-94 appeared to peak at 36,000. The additional seed cost associated with increasing the plant population by 6,000 units is roughly $22.50. The row spacing effects on yield were more pronounced in DKC49-94 compared to DKC48-12.

This data represents one year and one location, but implies that two hybrids can show somewhat different yield responses to increased plant population rates and row spacing. It would be interesting to see if the yield differences to population rate are actually related to the hybrid ear type. The DKC 48-12 is known to be a flexed type compared to DKC49-94 which is considered a fixed type. The flexed types are known to be better adapted to adjust to late-season growing conditions. Growing conditions in August and October at this location were much more favorable with greater than normal rainfall compared to an average year.

This project was funded by the Project GREEEN. I wish to thank the Dekalb/Asgrow staff at the Mason Technology Center for their collaboration with Michigan State University Extension and providing seed, equipment, and labor for this study.

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