The timing, rates and methods of nitrogen applications vary widely across the Corn Belt as weather conditions and soil types differ from field to field. Regardless of conditions or application methods, growers can take steps to get the most out of their fall-applied nitrogen.
Weigh these factors when planning fall fertilizer applications:
- Understand fertilizer types. Consider using anhydrous ammonia in the fall. Once in the soil, all nitrogen fertilizers convert to nitrate, which is the form of nitrogen that can be lost. Ammonia converts to nitrate more slowly than other forms of nitrogen, and the risk of loss is lower.1
- Limit acreage for application. No more than half of planned corn acres should receive nitrogen in the fall. This limits the number of acres at risk while simultaneously balancing the benefits of a fall application with economic and environmental risks.1
- Temperature drives timing. Fall nitrogen applications should be based on soil temperature, not calendar date. Wait to apply nitrogen until soil temperatures drop below 50 F. Nitrosomonas bacteria are active until soils reach freezing temperature; however, their activity is greatly reduced once soil temperatures drop below 50 F.2
- Use a nitrification inhibitor. Nitrification inhibitors, such as N-Serve® nitrogen stabilizer, slow the conversion of ammonia to nitrate and reduce the risk of nitrogen loss.1 Instinct® II nitrogen stabilizer and N-Serve protect nitrogen in the fall so it is available in the root zone when corn needs it most in spring.
For information on protecting fall-applied nitrogen, visit NitrogenStabilizers.com.
1Scharf, P., and J. Lory. 2006. University of Missouri Extension. Best Management Practices for Nitrogen Fertilizer in Missouri. http://plantsci.missouri.edu/nutrientmanagement/nitrogen/practices.htm
2University of Illinois at Urbana-Champaign College of Agricultural, Consumer and Environmental Sciences. 2011. Understanding fall nitrogen applications. http://news.aces.illinois.edu/news/understanding-fall-nitrogen-applications
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