While soybeans have the ability to adjust and, to some degree, compensate for weather conditions at planting, that’s less true for corn. It’s why Farm Journal Field Agronomist Ken Ferrie tells farmers to keep a close eye on the extended weather forecast and soil temperatures as they plant their corn crop.
Corn requires approximately 120 accumulated growing degree days (GDDs) to emerge, under ideal conditions. To calculate GDDs, you can use this equation: GDD = (Daily Maximum Air Temperature + Daily Minimum Temperature)/2 – 50.
Soil temperature, planting depth, amount of residue present and management practices can influence emergence timing. Depending on the various factors at play, corn emergence can occur in as few as four days or, as some farmers in central Illinois experienced in 2020, well over a month.
“We had a big issue last year with our April corn where we ended up with some plants emerging 45-plus days and out,” Ferrie recalls.
He says the first 48 hours after planting corn are most critical. Seed that is subject to cold during that period of time is most vulnerable to chilling. When that occurs, the metabolic reactions necessary for emergence don’t take place in a timely manner.
“Cold seed corn is unable to swell in the ground with the same elasticity as it’s able to achieve with soil temperatures at 50° F or warmer,” Ferrie explains.
When emergence isn’t timely, yield potential is docked and you won’t get it back.
“Chilling can eliminate between 10% and 20% of your yield potential,” says Ferrie, owner of Crop-Tech Inc., Heyworth, Ill. “You’ll never see that loss driving down the road, but you will if you stretch a tape measure for ear counts.”
If your weather conditions and soil temperatures turn unfavorable for corn, consider whether you can plant soybeans. Or, you may need to just hunker down and wait for weather conditions to improve.
If that’s the case, consider your plans for weeds and pest control while you wait. Ferrie says get your cutworm traps ready and figure out when the first moths are likely to arrive.
“If you haven’t put your cutworm lures out yet, they need to go out,” he says. “Those southerly winds are going to be pumping moths in here on a routine basis, so we need to be ready for that.”
To hear more about Ferrie’s recommendations, listen to the Boots In The Field podcast here:
Ken Ferrie Answers - Can We Plant Yet?
Ken Ferrie Challenges You to Improve Your Corn Stand
Ken Ferrie Explains Flex and Fixed Corn Hybrids
Even Corn Emergence Requires Planting Planning
