The Key to Fall Nitrogen Applications

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However, they should be aware of the risk factors in fall applications. As the temperatures drop, it becomes essential to adapt the application approach to ensure the nutrients the crops need are effectively delivered to the soil.

Understanding the Impact of Soil Temperature on Nitrogen Loss

Soil temperature is a crucial determinant of nutrient availability and uptake, microbial activity, and overall soil health. It varies with the seasons and can fluctuate significantly during the fall. Understanding and monitoring soil temperature allows for more effective and efficient fertilizer applications, ensuring that nutrients are available when crops need them most.

In nitrogen fertilizer applications, soil temperature has the most significant influence on this nutrient availability in the soil. When urea is applied to the soil, it undergoes a process called hydrolysis, where it is converted into ammonium (NH4+). This process is facilitated by an enzyme called urease, which is naturally present in the soil. The activity of urease and the rate of hydrolysis are both heavily influenced by soil temperature. In warmer temperatures, urease activity increases, accelerating the rate of hydrolysis. This can lead to a rapid nitrogen loss through volatilization, converting urea to ammonia gas.

As temperatures drop in the fall, the rate of hydrolysis slows down due to decreased urease activity, but it's important to note that it does not reach zero. Even in cooler conditions, there is still a level of activity taking place. This can be beneficial as it reduces the risk of volatilization. However, as temperatures continue to drop, the soil can freeze, creating a barrier that prevents the absorption of nitrogen by the soil. This leads to nitrogen being stratified or concentrated on the soil surface, which increases the risk of nitrogen loss through volatilization and potential surface runoff.

SUPERU^™ in Fall Applications

SUPERU premium fertilizer plays an essential role in this context. The urease inhibitor in SUPERU, active ingredient NBPT, slows the hydrolysis process, reducing the risk of volatilization and ensuring that more nitrogen is available for plant uptake. The nitrification inhibitor in SUPERU, active ingredient DCD, on the other hand, slows the conversion of ammonium to nitrate, reducing the risk of nitrogen loss through leaching and denitrification.

SUPERU premium fertilizer contains a proven, agronomically effective level of DCD and NBPT and is backed by 30 years of research. It is important to note that the percentage of active ingredients in other dual inhibitor products may not be high enough to be agronomically effective. SUPERU, which has a higher active rate of these essential ingredients, ensures that the fertilizer is not only effective in reducing nitrogen loss but also in promoting optimal plant growth. Learn more about agronomically effective products here.

Depending on conditions, SUPERU fertilizer is proven to reduce Spring snow melt denitrification losses by 30% to 50%. SUPERU safeguards the input investment in fall applications, allowing growers to reduce the workload and cost in the spring, optimizing operations and farming more efficiently.

Based on the research conducted in Western Canada from 2015 to 2018, it was found that applying SUPERU in the fall, at 100% of the recommended nitrogen rate of urea, was just as effective as regular urea broadcast or deep banding urea in the spring when planting canola.¹

Snow Impact on Fall Fertilizer

There is a common myth that snow is bad for fall fertilizer applications. However, this is not entirely true, as snow can have some positive effects on fall applications. Snow acts as an insulator , slowing the rate at which soil freezes. This can extend the window during which urea can be effectively applied, as the delayed freezing process keeps the soil in a state where urea can still be hydrolyzed and absorbed. Nevertheless, it is important to note that heavy snowfall affects urea reaching the soil surface, opening for losses from snowmelt runoff.

To manage these challenges in fall applications, growers need to carefully monitor soil temperature and weather forecasts, ensuring that they do not apply fertilizer to frozen soil or immediately following a heavy snowfall.

To learn more about fall application practices or the full line of KAS agronomic products, contact your local KAS sales representative.

¹The underlying data was provided by the University of Alberta, University of Manitoba, Northeastern Agricultural Research Foundation, Wheatland Conservation Area, and Indian Head Agricultural Research Foundation under Research Trial Financial Support Agreements with Koch Agronomic Services, LLC, and neither these institutions nor the individual researchers referenced, endorse or recommend any product or service.

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