Don’t Leave Fall Nitrogen Unstable

Nutrient management is as important in fall as it is at planting.

Growers considering a fall anhydrous ammonia application can take measures to make the most out of their fertilizer investment, while supporting nitrogen management best practices, says Eric Scherder, Ph.D., field scientist, Dow AgroSciences.

“Nitrogen isn’t a one-time event,” Scherder says. “There has to be forethought about how to manage it today and tomorrow.”

Growers who are serious about reducing nitrate loss into groundwater can take steps when making fall applications. These steps include evaluating application methods, paying attention to temperature and using a nitrogen stabilizer to reduce nitrate loss due to leaching and denitrification.


Important considerations before fall application

There are best management practices growers can follow this fall to optimize fertilizer applications.             

In the fall, let temperature drive timing. Fall nitrogen applications should be based on soil temperature, not calendar date, Scherder says. Wait to apply nitrogen until soil temperatures drop below 50 F.

Nitrosomonas bacteria, which converts ammonium nitrogen to the nitrate form that’s susceptible to loss, are active until soils reach freezing temperatures; however, their activity is significantly reduced once soil temperatures drop below 50 degrees,” Scherder says. “This is important to consider when making fall applications to protect that investment.”


The significance of a stabilizer

Once nitrogen converts to the nitrate form, it can be lost through leaching into groundwater and denitrification. Instinct® II and N-Serve® nitrogen stabilizers protect nitrogen in the fall by keeping it in the ammonium form longer so it is available in the root zone when corn needs it most in spring. N-Serve can be applied with anhydrous ammonia, while Instinct II can be used with UAN, urea or manure.

Keeping nitrogen in the ammonium form longer reduces the amount of nitrates lost into groundwater and enables the corn plant to get the nitrogen it needs to grow stronger and healthier.

N-Serve and Instinct II have been rigorously tested by third-party experts and proven effective. Studies with nitrapyrin show soil nitrogen retention increased by 28 percent, and nitrogen leaching decreased by almost 16 percent*. They are the only nitrogen stabilizers on the market accepted for registration by the U.S. Environmental Protection Agency.

For more information on protecting fall-applied nitrogen, visit


*Meta-analysis published 2004. “Wolt.”

[Legals]  ®Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. Instinct II is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Do not fall-apply anhydrous ammonia south of Highway 16 in the state of Illinois. Always read and follow label directions. M53-137-059 (10/16) BR

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