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Sponsored: Maximize Yield With Fall Nitrogen

Reaping the benefits of a well-fed, high-yielding corn crop requires a well-managed fall fertility program to ensure the proper nutrients are available to get your crop off to a strong start next spring.

A nitrogen (N) management program is pivotal in getting the most from your crop. Getting your fertilizer application timing and methods correct can help maximize nitrogen efficiency on your operation. Before applying fall fertilizer, keep the following considerations in mind:

1. Determine your cation exchange capacity (CEC). Soils with less than 12 CEC are more prone to leaching and are not capable of holding fall-applied nitrogen long enough to be useful next season. Sandy and/or low-organic-matter soils are typically found to be low-CEC-type soils.

2. Monitor soil temperature. Check soil temperature at a 4-inch depth during the heat of the day for a few days to see if the temperature is cooler than 50 F and trending down. Nitrosomonas bacteria — which are responsible for converting ammonium (NH4+), a stable form of N, to nitrate (NO3-), a nonstable form of N, become inactive in soil temperatures cooler than 50 F.

3. Select nitrogen type.

Manure applications

When harvest is complete and the weather is still conducive to field work, apply manure to your fields. Before applying manure, though, talk to your crop adviser about your nutrient management program to adjust application timing based on any potential changes. Here are a few other tips:

  • Thoroughly agitate and mix existing supplies of liquid manures before taking a sample for nutrient testing. Know the nutrient content so you can stay in compliance with your nutrient management plan.
  • Calibrate your application equipment to ensure accurate application rates of your manure. Fall-applied manure that is immediately incorporated by using sweep injectors, s-tine field cultivators or other tools allows for more N to be available to corn next season.
  • Apply manure at the right time, waiting until soil temperatures are cooler than 50 F. Uniform application also is important to nutrient utilization. Always follow setback requirements for manure applications.

Anhydrous ammonia

Anhydrous ammonia is a concentrated source of NH4+. Ammonium carries a positive charge, which keeps the N in the soil by attaching to negatively charged clay and organic matter. Anhydrous ammonia needs to be incorporated, ensuring the N is deep enough in the soil to avoid being impacted negatively by occasional warm winter temperatures. Other 100 percent ammonium N products — such as ammonium sulfate or urea — can work, too, if they are deep-banded.

4. Apply a nitrogen stabilizer. No matter the form of N used, consider a nitrogen stabilizer. N-Serve® and Instinct® II nitrogen stabilizers keep N in the root zone of corn. This prevents Nitrosomonas bacteria from converting NH4+ to NO3-, a form of N highly susceptible to deep soil leaching. N-Serve and Instinct II reduce leaching and denitrification to keep nitrogen in the root zone until the following growing season. Incorporating N-Serve with anhydrous ammonia supports stronger, healthier plants, leading to optimum yield potential. For UAN, urea or liquid manure applications, growers can use Instinct II nitrogen stabilizer.

5. Choose hybrids capable of using N early. Certain hybrids are capable of performing better in low-N environments, and some hybrids perform best with adequate nitrogen during the growing season. Understanding how hybrids respond to nitrogen is important when choosing hybrids in the spring and when managing your fertility program. Ask your Mycogen Seeds sales representative and commercial agronomist which hybrids will work best for your soil types and environmental conditions.

6. Sample soil in the offseason. As you build ongoing fertilizer plans, it is important to maintain ongoing soil nutrient testing. Sampling right after harvest gives you more time to analyze data and develop your fertilizer plan. Most soils should be sampled every three to four years. Soils with low buffer capacity, such as low-organic-matter or sandy soils, should be sampled more frequently as they are subject to more rapid changes in nutrient concentration and pH levels.

Whether you choose manure, anhydrous ammonia, ammonium sulfate or urea as a nitrogen delivery method, a successful fall fertility program requires well-timed and accurately applied nutrients based on your soil fertility needs.

To learn more about soil fertility, visit For guidance on seed selection, talk to your local Mycogen Seeds agronomist or seed sales professional.

®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. ©2016 Dow AgroSciences LLC

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