Deciding on fall vs. spring nitrogen applications

By Wayne Flanary
Regional Agronomist,
Missouri Extension

Highway 36 is a line at which we do not recommend fall nitrogen applications southward across the state. This is just a guideline as research has shown that nitrogen is most efficient when applied close to when the corn plant needs it.
Nitrogen is mobile and can be lost from the soil with leaching and denitrification.  Soils that are coarse textured pose the highest risk from leaching and heavy soils are highest risk of dentrification.
Good soil moisture increases the risk of leaching and denitrification. If you are planning fall N application, apply after soil temperatures are below 50 degrees F.
Avoid using nitrate forms of nitrogen in the fall as they will leach. Avoid fall nitrogen applications on sandy and heavy clay soils. Nitrification inhibitors help reduce the potential for losses but are less effective in fall than spring. If you have sites that are prone to nitrogen losses, use multiple or split applications of nitrogen.
For more information, contact Wayne Flanary at 660-446-3724, Heather Benedict at 660-425-6434 or Wyatt Miller at 816-776-6961, Regional Agronomists, University of Missouri Extension.

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