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MO farmers should wait to apply nitrogen

A University of Missouri nutrient management specialist says Missouri growers should avoid applying nitrogen in the fall and consider side dressing nitrogen in their corn fields to minimize loss risk.

John Lory tells Brownfield applying nitrogen in the fall leaves two open windows for nitrogen loss, one in the fall before soil temperatures are cold enough and another that starts in the spring.

“Let’s say I do everything right, I put my nitrogen down when the soil is cold, I might even put a nitrogen inhibitor on there, I go out there at the end of winter [and] all my nitrogen is still in that ammonium form, it’s right where I put it,” he said. “And then as soils warm up, it converts over and I think I’m good [but] then we have a wet June, you know, then I lose that to denitrification.”

He said a side dress application gets farmers past both key nitrogen loss windows and has the added environmental impact of less runoff.

Lory said side dressing seems to be more common in southeastern Missouri and similar practices in the rest of the state could be beneficial.

“We don’t live in Minnesota, we don’t live in northern Iowa, so the rules that apply up there, we’re on a transition out of those rules,” he said. “And so, we face more risk of nitrogen loss in central Missouri than where those recommendations were developed.”

Lory said if growers plan on applying nitrogen in the fall, they should wait until soil temperatures are at least 45 degrees in the northern half of the state and 40 degrees in southern half. Soil temperature charts can be found through the University of Missouri Extension at agebb.missouri.edu.