indiana Prairie Farmer Logo

Does late-planted corn mean low yields?

Corn Illustrated: Data don’t back up the notion that late planting results in low yields every year.

Tom J. Bechman, Midwest Crops Editor

May 22, 2024

2 Min Read
View from tractor cab of a field ready for planting
LONG PLANTING SEASON: A series of storms and rain showers across the Midwest in late April and early May meant planting some corn later than normal in 2024. Tom J. Bechman

A quick look at corn planting progress by mid-May, especially in major corn-growing states, indicates a significant number of acres could be planted after May 15. Corn planting was 50% or more completed in only five of the 13 states listed in the table below. Corn planting trailed the five-year average in several key states, including Illinois, Indiana, Iowa and Nebraska.

Bob Nielsen, retired Purdue Extension corn specialist, took a closer look at whether planting progress by mid-May means state corn yields will be lower. He arbitrarily selected May 15 as a reference point to characterize “early” and “late” planting. He considered years with a higher percentage of corn planted after mid-May as late planting seasons and years with a lower percentage of corn planted after May 15 as early planting seasons.

A graphic table showing corn planting progress as of May 12-13

Nielsen looked at the relationship between “percent departure from trend yield” and “percent of corn acres planted after May 15” for Indiana over the past 30 years.

“The data show there is indeed a tendency for lower yields statewide when more acres are planted after May 15,” Nielsen reports. “However, this relationship is not perfect.

“There were three late-planted years — 2009, 2013 and 2022 — where 76% to 89% of the state’s corn crop was planted after May 15, but statewide average yields ended up 4.5% to 8% above trend. There were also two earlier-planted years — 1997 and 1999 — where only 31% to 38% of the crop was planted after May 15, but statewide average yields ended up 6% to 10% below trend.”

Related:Will planting delays sink 2024 corn yields?

In fact, Nielsen determined that planting date effect only describes about 13% of overall year-to-year variability in yield.

More corn planting data

University of Nebraska researchers Roger Elmore and Jenny Rees documented the same absence of a strong relationship between statewide corn planting progress and departures from trend yield in Nebraska, summarizing it in a 2019 report.

“Such a weak relationship reflects the fact that many other factors besides planting date influence yield,” Nielsen says. “The bottom line is that statewide averages for planting progress and yield are not strongly related.”

IL Corn - A graphic illustrating corn planting progess in Illinois

Scott Irwin, University of Illinois ag economist, performed multivariate regression analysis involving yield and weather data collected from 10 major corn-producing states. In his work, he defined May 20 as the planting date after which substantial yield losses occur.

“His analyses concluded that late planting was the third most important weather-related variable influencing average U.S. corn yields, behind July rainfall and temperature,” Nielsen says.

Nielsen notes, however, that summer rainfall and temperature are not independent of planting date. Crop growth stage influences the effects of extreme weather.

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.

Subscribe to receive top agriculture news
Be informed daily with these free e-newsletters

You May Also Like