A larger-than-usual portion of the U.S. corn crop will be planted so late that yields could be depressed, said economists Scott Irwin and Todd Hubbs of the University of Illinois on Thursday. “A reasonable estimate is that late corn planting in 2019 will be at least 5 to 10 percent above average,” which is 12.1 percent of the crop being sown after May 20.
Corn yields are largely determined by weather during reproductive stages in the summer, but a wet spring and a slow planting season make farmers anxious because yields per acre are lower on late-planted corn. The yield “penalty” becomes pronounced after May 20 in the Corn Belt. One estimate says corn yields fall by 1.1 bushels per acre for each day of planting after May 20.
When the ground is saturated at the start of the April 25-May 20 planting window, there is a “substantial” reduction in days when fieldwork can be performed, wrote Irwin and Hubbs at the farmdoc daily blog. “The bottom line is that the current wet topsoil conditions in the Corn Belt do not bode well for planting the entire U.S. corn crop in a timely manner.”
On social media, Irwin cautioned that having an additional 10 percent of corn planted late “is not a disaster by any stretch of the imagination,” and might reduce expected yields by only 2 to 3 bushels an acre overall.