All the talk about row spacing is there for a reason – agronomists know that if corn captures more sunlight, it will perform better and should yield more. The question is how to get it to capture the maximum amount of sunlight. Will it require changing row widths?
Brian Denning, an agronomist with Stewart Seeds, Greensburg, doesn't have the answers, but he's one of a team of agronomists helping to find answers to these questions.
One thing they learned last year was that skips hurt corn yield worse than doubles. The goal is to have an even stand with less than 2.0 inches of standard deviation, a measure of how uniform the stand is. The bigger the number, the less uniform it is. Most, although not all, researchers have shown that if stands aren't uniform, you can lose yield.
One demonstration the Stewart Seeds Agronomy Team tried last year was equidistant spacing. The theory is that canopy closure will occur sooner and more light will be captured if plants are an equal distance from each other in the field. It may require 120-inch rows, which may not be practical yet. However, Calmer Cornheads, led by a farmer-inventor in Illinois, introduced 12-inch corn heads at the Farm progress Show in Boone, Iowa, last year.
Other factors unrelated to the study affected yield. In some cases equidistant plots yielded more, in some cases, they didn't yield more. But an evaluation of how much light they captured was interesting – they definitely canopied over sooner. One thing canopies did last year was keep the temperature in the microclimate around plants cooler, since sunlight wasn't reflecting off bare soil.
Canopy occurred at about V4, or the four-leaf stage. From V14 through R3, 95% of the light emitted by the sun was captured by plants. At one point in the reproductive stage, it reached 98% capture of light. Later in the season, as the plants mature and leaves dry up, the percentage of light capture decreases again.