Fall nitrogen (N) fertilizer application continues to be popular for several reasons, including lower cost, time for application, equipment availability, often better soil conditions, and competing springtime field activities. Success, compared to spring or sidedress timing, can be enhanced by following several long-standing suggestions: only use anhydrous ammonia; apply in late fall after soils cool to 50 degrees F (4-inch depth) and are trending cooler (the colder the better); consider an effective nitrification inhibitor to further slow nitrification to nitrate; and avoid fall application to soils that are more prone to wetness or leaching (poorly or excessively drained soils).
Iowa State University
Sawyer, John E., "Fall Fertilizer Nitrogen Application" (2019). Integrated Crop Management News. 2594.
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