Stop and Rethink Fall Nitrogen Application Timing

October 14, 2010 05:44 AM
Stop and Rethink Fall Nitrogen Application Timing

With a fast-pace harvest season across the Corn Belt, more farmers were eager to move forward with fall applications of nitrogen (N.)

Some farmers in our area of central Illinois want to put on up to 200 lb. of N on 70°+ soils,” says Farm Journal Field Agronomist Ken Ferrie. “This is not a good practice for your fertility program or for the environment.”

Farmers should wait until soil temperatures at 4” are below 50°. Soil temperature dictates N application because it also impacts the activity of the soil micro-organisms that are responsible for the conversion of ammonium to nitrate.

"Farmers need to understand the risk of loss through leaching, denitrificiation, and volatization,” Ferrie says. “Harvest is early, and we are way too warm and have too high of a risk for staying too warm. Even with inhibitors we can’t protect that nitrogen long enough to get the soils cooled down.”

Once soils drop below 50°the risk of N leaching and being lost also drops.

Although it requires some patience this year for soil temperatures to reach the appropriate levels, your waiting will be rewarded as soil microbes continue to be active even below freezing temperatures.

If you are strip-tilling, Ferrie says go ahead and build your strips when conditions are fit. But don’t hook up the anhydrous tanks. Save the N application until this spring.

Learn more about the nitrogen cycle and the risk of applying nitrogen to warm, fall soils in episode 6 of Corn College TV.


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