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Another trial confirms planting corn 2 inches or deeper

Corn Illustrated: Make sure you plant deeper than 1.5 inches.

Tom J. Bechman, Midwest Crops Editor

April 11, 2023

3 Min Read
planted corn rows
IF IN DOUBT: If weather forecasts and moisture conditions have you on the fence about where to set planting depth for corn, err on the deeper side of whatever choices you’re considering. Golden Harvest agronomists never plant shallower than 1.5 inches. Tom J. Bechman

If you plant the same hybrid at 1.5, 2, 2.5 and 3 inches deep, which will emerge first? Which depth will produce the most uniform stand? Which will produce the highest yield?

Corn seeding depth is an aspect of corn production that is studied a great deal. That’s because farmers and seed dealers recognize that correct planting depth is key to uniform emergence.

Golden Harvest agronomists conducted a planting depth comparison trial as part of their Agronomy in Action plot series in 2022. The results were summarized in the Agronomy in Action 2023 Research Review, edited by Bruce Battles, Golden Harvest technical agronomy manager. The plot was located at Clinton, Ill. Planting depths under comparison were 1.5, 2, 2.5 and 3 inches. Agronomists note that soil moisture and temperature were optimal at planting. In fact, Clinton experienced favorable weather conditions for most of the growing season, except for moisture stress from V8 to V12 corn growth stages.

How yields turned out

Agronomists reported no significant yield differences among planting depths, with yields around 270 bushels per acre. The 2.5-inch depth produced a yield bar just topping the others, and the 3-inch depth dipped just under the rest — but none were statistically different from each other. That means differences were due to experimental error or could be a result of soil variability, among other things, the Golden Harvest agronomists concluded.

Early-season stands also showed no significant differences. Stands for all four seeding depths were at, barely under or barely above 36,000 plants per acre. The 2-inch depth was lowest, but again, it could have been due strictly to experimental error.

So, what is the conclusion from this one study? Planting at 2 inches deep or deeper is still the best choice. Golden Harvest agronomists advise against planting less than 1.5 inches deep for any reason.

Other trial results

The Indiana Prairie Farmer-Purdue Extension planting depth trial at the Purdue-Throckmorton Ag Center near Romney, Ind., produced similar results. Dan Quinn, Purdue Extension corn specialist, supervised the trial. He notes that when results from both hybrids at all planting depths were averaged together, the 2-inch planting depth was the optimum choice.

However, one hybrid performed better at shallower planting depths, while the other hybrid performed better at deeper depths. The difference between these two hybrids was significant.

Quinn flagged and followed emergence and found that the shallower depths emerged quicker. However, usually the early advantage didn’t turn into a yield advantage. For 2023, Quinn intends to repeat the study, only he will factor in light and heavy downforce to see if there is an interaction between planting depth and pressure applied on planting units.

In a similar trial at Throckmorton over a decade ago, the only significant difference was a 20-bushel-per-acre reduction for planting at 1 inch vs. any other depth, including the 3-inch depth. Corn was planted in June, and the 1-inch treatment dried out, leading to a thinner stand. Plus, plants emerged and ran one growth stage behind the entire season.

About the Author(s)

Tom J. Bechman

Midwest Crops Editor, Farm Progress

Tom J. Bechman became the Midwest Crops editor at Farm Progress in 2024 after serving as editor of Indiana Prairie Farmer for 23 years. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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