You want evenly spaced corn stands that emerge uniformly. A just-released study indicates that skips within corn rows are often more negative for final yield than doubles or uneven emergence.
The study’s results are in the Agronomy in Action Research Review from Golden Harvest. Bruce Battles, technical agronomy manager at Syngenta, says the stand establishment study is one of many conducted by the Agronomy in Action Research Team.
Download the entire review at goldenharvestseeds.com.
Uniform corn stands
The Golden Harvest study consisted of both small plot work where some seeds were added or removed by hand to simulate doubles, skips and delayed planting and harvested by hand, plus whole plot studies that were shelled with a combine. These plots were conducted at Seward, Neb., and Clinton, Ill. Target seeding rate was 35,000 seeds per acre, with goals of 5% and 10% skips, 5% and 10% doubles and simulated two- and four-day delay in emergence. Details include:
Skips. The team concluded that skips had the largest negative impact on yield. Skips resulted in missing plants, which lowered the plant population per acre. Skips in real-field situations occur when either the planter doesn’t drop a seed, or the seed doesn’t germinate.
Dave Nanda, director of genetics for Seed Genetics Direct, works with the Farm Progress Corn Watch project. He notes that most seed corn is tagged around 95% germination. Even under the best conditions, some seeds won’t germinate. In 2019, he examined areas with skips in 1,000th-acre strips and determined that in 4 out of 5 cases where a plant was missing, the seed was there, and either didn’t germinate or didn’t emerge properly.
Yield for skips. In the Golden Harvest whole-plot trial, with yields from both sites combined, 5% and 10% skips yielded 8 and 10 bushels less, respectively, compared to uniform spacing. Losses or gains for all treatments tended to be higher in small plots compared to whole plot trials.
However, the small plots revealed that with skips, neighboring plants in the row didn’t compensate and yield more. In earlier work in 1996, Emerson Nafziger, now retired from the University of Illinois, found that at 18,000 plants per acre, plants next to a skip yielded 15% more than the control, and at 30,000 plants, they yielded 9% more. The Golden Harvest team suggests that the gap created at 35,000 may not have triggered neighboring plants to yield more.
Doubles. Surprisingly, doubles increased yield by about 3 bushels per acre in the whole-plot Golden Harvest trial. The team concluded, however, that the yield increase wouldn’t offset the 10% increase in seed costs in most cases.
The small plots showed how the increase occurred. Each individual plant in the pair yielded about 17% less than a single, uniformly spaced plant. Together, the pair yielded about 67% more than one plant. Conversely, neighboring plants on either side only dropped yield about 9% each.
Planting delays. In whole plots combined at harvest, a two- to four-day delay in emergence resulted in yield losses of 4 to 5 bushels per acre. In the small plots, a two-day delay resulted in a 15% yield reduction on that plant, with a 21% reduction for a four-day delay. However, plants on either side of the delayed plants produced 3% to 6% more, offsetting some of the loss.