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Why late-planted corn can still yield well

Corn Illustrated: Don’t write off late-planted corn. More than planting date influences yield.

Tom J. Bechman, Midwest Crops Editor

May 29, 2024

3 Min Read
Looking down a row of cornstalks
WEATHER MATTERS: Late-planted corn can still produce big yields if weather cooperates during the rest of the season. Tom J. Bechman -

Corn yield potential begins declining if planted after a certain date in early May, depending on whose data you examine. “Every agronomist worth his salt knows that is fact,” says Bob Nielsen, retired Purdue Extension corn specialist.

So, how does Nielsen explain the results of the 2023 Ohio State University Battle of the Belt corn planting date comparison project? The highest yield at the western Ohio site came from corn planted in late May. Yields were over 240 bushels per acre.

Ah, there is the rub, Nielsen says, smiling. “It’s true that relative corn yield potential declines with delayed planting after about May 1, according to studies in Iowa, Illinois and elsewhere,” he says. “Estimated yield loss per day with delayed planting varies from about 0.3% per day early in May to about 1% per day beginning about May 15.”

This decrease in relative grain yield with delayed planting occurs due to many factors, Nielsen says. They include a shorter growing season, greater insect and disease pressure, and increased risk of hot, dry conditions during pollination.

Absolute yield potential

However, planting date is only one of many yield-influencing factors for corn. “In fact, studies indicate planting date alone accounts for about 13% of the variability in statewide corn yields from year to year,” Nielsen says. “What is important to understand is that the absolute yield response to delayed planting depends on the yield potential for any given year.”

So, what happens if all other yield-influencing factors work together to determine that the maximum possible yield this year for an optimum planting date was 190 bushels per acre? A 30-day planting delay beyond May 1 might result in a yield potential of about 154 bushels per acre, Nielsen explains.

However, what if all other yield-influencing factors work together to determine that the maximum possible yield for an optimum planting date was 240 bushels instead? Then a 30-day planting delay beyond May 1 might still yield about 194 bushels per acre. That’s higher than the maximum yield potential in a challenging year, Nielsen notes.

Planting date example

It is possible for early-planted corn in one year to yield more than, less than or equal to later-planted corn in another year depending on the exact combination of yield-influencing factors for each year, Nielsen says.

See the graph of a hypothetical situation below. “Yield for delayed planting of corn in an otherwise high-yielding year may still be higher yielding than an earlier-planted crop in an otherwise lower-yielding year,” Nielsen explains. “Farmers know it is true. Many have had June-planted crops in recent years yield better than any crop they have ever grown. That can happen if the remainder of the growing season following delayed planting is extremely favorable for crop growth and development.”

A graph illustrating an example of yield response to planting date and growing environment

Here’s the bottom line. “Don’t succumb to fearmongering when you find yourself in a late-planting situation,” Nielsen advises. “Don’t mud the crop in. That is almost always unwise. Cut trips to speed up planting. Otherwise, planting should go on as normal. You might even be able to reduce seeding rates slightly since soils will be warmer.”

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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