Soil Temperatures Critical for Planting

The prime window for planting corn in Iowa usually begins around April 15 and lasts to around May 10, though that can shift depending on weather, says Mark Licht, cropping systems agronomist for Iowa State University Extension and Outreach.

Licht urges farmers to pay close attention to seven-day forecasts when they decide to start planting. The first few days after the seeds are planted are critical to the plant’s development, he said in a news release.

If there’s a chance soil temperatures might dip below 50 degrees soon after planting, it might be a good idea to hold off, he said.

“The best advice I’ve been giving people really all winter long is make sure you’re waiting for soil temperatures and moisture to be right to plant,” Licht said.

Particularly cool or wet spring weather can shift the ideal planting season a little later in the spring, while warm temperatures may allow farmers to plant earlier than usual.

Last year’s cool April meant the ideal planting date fell around May 10, he said.

Subsoil moisture levels are adequate across 80 percent of farmland in Iowa and surrounding states, says Elwynn Taylor, professor of agronomy at ISU. That indicates crops will be able to establish a solid root system throughout the growing season.

“The crop requires an average of 20 inches of precipitation during the plant’s lifetime to yield an average harvest,” Taylor says.

“Usually 25 inches of water is necessary to make a record yield possible. Starting off with nearly 10 inches in the subsoil is considered a good thing.”

Taylor, who studies climate and its effects on agriculture, says March was among the driest recorded for the month of March in Iowa. That led to some concern that the topsoil may lack moisture for the growing season, but Taylor said one nice rain can make a big difference to improve surface conditions.

He also said this year will see a weak El Nino, or a band of warm ocean water that develops in the east-central Pacific. Such events often translate to above trend crops if the weather pattern persists through July, he said.

“We have about as much reason as we ever have this time of year to be positive about crops,” Taylor said. “Obviously, there are still plenty of unknowns out there as well.”

Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now