March 2021 > Nitrogen Stabilizer: Frequently Asked Questions

Nitrogen Stabilizer: Frequently Asked Questions

March 11, 2021

Spring applications of manure are often conducted to empty the pits prior to the cropping season. While the nutrients within the manure are applied closer to crop uptake, some nutrients such as nitrogen are still vulnerable to loss prior to crop uptake. Implementing practices such as manure incorporation or use of a nitrogen stabilizer can help mitigate these losses.

Why should I stabilize my nitrogen?

As soils warm, the activity of bacteria that convert nitrogen from stable ammonium to leachable nitrate increases. This results in increased probability that spring applied manure will convert more rapidly from the stable form of ammonium or organic nitrogen to the leachable form of nitrate nitrogen. Figure 1, shows that as soils warm from the 40’s to over 50°F that the time it takes for ammonium to be turned into nitrate is cut in half to only 3-4 weeks while temperatures over 50 degrees could convert a majority of the N to leachable nitrate within a week.

Spring weather usually results in the highest rainfall period of the year that coincides with the potential for nitrogen loss prior to the crop reaching the grand uptake growth period at the V8 growth stage (Figure. 2). In sandy soils, nitrate has been shown to move down 12 inches or more with 1 inch or rain while nitrate can still move approximately 6 inches in a loam soil. Using a nitrogen stabilizer such as nitrapyrin (e.g. Instinct NXTGEN™) or dicyandiamide (DCD) / pronitridine ( e.g. Centuro®) as soil temperatures continue to increase past 50°F, can keep a greater proportion of nitrogen in the ammonium form in the root zone and will less likely be loss prior to plant uptake.

How does a nitrogen stabilizer work?

Manure nitrogen stabilizers suppress the activity of Nitrosomonas bacteria, the bacteria which convert ammonium to leachable nitrate. Nitrapyrin (Instinct brands) have a bactericidal effect where the Nitrosomonas bacteria are killed for typically 6-8 weeks but then repopulate and convert the ammonium to nitrate. Centuro® slows ammonium conversion by having a bacteriostatic effect on Nitrosomonas so their activity is suppressed typically for 4-10 weeks.

How can a nitrogen stabilizer be applied?

Nitrogen stabilizer products such as Instinct NXTGEN™ or Centuro® can be applied multiple ways. The most common method is to apply the N stabilizer to the manure pit during the agitation process. This requires knowing the volume of manure in the pit and how many acres it will cover for products that are applied on a per acre basis. Centuro® (1-2 gal/Ac) or Instinct (24 oz/A) could also be added at the field as tankers dump into the field edge manure storage tank prior to pumping to the applicator. A third option for those that are applying herbicide or some synthetic nitrogen such as UAN, Instinct can be sprayed to the soil and incorporated (by tillage or ½” of rain) since it works by inhibiting the Nitrosomonas bacteria within the soil.

What are the benefits to the grower?

Manure can have high value of nutrients per ton or 1000 gallons. Table 1 indicates some typical nutrient contents of manure. Studies have indicated that on average 50% of the nitrogen in dairy manure is readily available ammonium that can be converted to the form of nitrogen vulnerable to leaching and volatilization, plus another 30% of nitrogen from organic materials is converted to nitrate as they are mineralized over time.

Peer reviewed research has shown frequent environmental benefits from nitrification stabilizers, especially when conditions are conducive for nitrogen loss. Aside from known environmental benefits such as increased N retention and reduced nitrate leaching and nitrous oxide emissions, an average yield benefit of 7% was found with this meta-analysis and other research shows about a 5% yield increase with spring applications (Figure 3).

Written by Tryston Beyrer, PhD

Posted: 3/11/2021 12:00:00 PM by | with 0 comments
Filed under: Agronomy, Crop Nutrients

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