You are here

N Inhibitors tips

If you want to use nitrification inhibitors, set realistic expectations. Here's how.

Since nitrogen (N) keys corn production, it’s important to keep your fall- and spring-applied N in the root zone and avoid as much loss as possible. Nitrification inhibitors can be a tool to help you do that by slowing the conversion of ammonium to nitrate, keeping N available to the crop longer. Here are three factors that Extension specialists recommend if you are using or considering using a nitrification inhibitor. 

1. View Inhibitors as insurance.

Nitrification inhibitors don’t guarantee an increase in yield, says Dave Franzen, North Dakota State University Extension soil specialist. Instead, view inhibitors as insurance against excess water. 

“It’s an insurance policy, so the loss doesn’t occur,” he says. “It’s not a guarantee you’ll get a yield increase. It’s just going to slow the nitrification process so losses are not as great or don’t occur as readily.”

    Research shows nitrification inhibitors do as intended, says Franzen. “You aren’t eliminating the nitrification, but you are ensuring you’ll have more (N) available for your crop,” he says.

Fabian Fernandez, University of Illinois Extension soil specialist, recommends you consider using nitrification inhibitors for fall applications. There’s a greater chance of seeing a benefit from the inhibitor because the N fertilizer is applied before the plant will use it.

Fernandez encourages you to view the application in terms of risk. You may not see a difference if the inhibitor is used in applications close to planting. He does not recommend the use of inhibitors with sidedress applications. N applied in the fall or early spring has higher potential for N loss than late-spring applications. 

“With spring applications, you are closer to planting, so you may or may not see the benefit; it’s a risk-management strategy,” says Fernandez. 

2. Factor in the weather.

Results from nitrification inhibitors are largely reliant on Mother Nature. Yield increases may not occur in a dry year when N loss risks are low. 

   “In springs where the conditions aren’t favorable for N loss, we haven’t seen much of a difference,” says Fernandez. 

    However, in years favorable for N loss and when N is applied early, you’ll see more results from using inhibitors.

   “In studies where there has been significant water and losses due to leaching, there have been yield increases in those situations,” Franzen says. 

The purpose of nitrification inhibitors is to reduce the amount of nitrification occurring. However, nitrification itself isn’t the problem, explains Fernandez, because plants use nitrate. 

    N loss can occur through either denitrification or leaching (when soils are saturated with water). “Either way, we lose nitrogen. That’s why we see the benefit with N-Serve. It reduces the amount of nitrification that occurs,” says Fernandez.

3. Don’t cut corners.

“Just because you use a nitrification product doesn’t mean you have a free pass,” says Fernandez. 

   When applying N in the fall with an inhibitor, it’s important to follow the same guidelines you use for fall N applications without an inhibitor. Those guidelines include waiting until soil temperature is 50°F. and trending cooler, and always using the appropriate N form and application method for your soil types. 

Franzen emphasizes the importance of watching the calendar and temperature. The use of a nitrification inhibitor doesn’t allow N to be applied at any point in the fall.

“Applying N when the temperature is above 50°F. will result in nitrification even if you use an inhibitor,” he says. “If you apply N early in the fall, when temperatures are still too warm, the nitrification inhibitor will be broken down and won’t be as effective,” adds Franzen. 

Microbial activity in soil goes down when it’s cooler, allowing the molecule to remain active longer.

“The good thing about nitrification inhibitors is if you pay attention to the recommendation of when to put them on, then their risk of loss is reduced beyond the tradeoff that the land grants have put on fall application of the fertilizer or the preplant fertilizer in the spring,” says Franzen. “Don’t put it on before the recommended date just because you’re using an inhibitor.” 

By following the general guidelines for fall-applied N, you will be ensuring that more N is available for crops’ needs.


There are products available that you can compare for use on your own farm.

    “The two chemistries consistently shown to have activity as nitrification inhibitors are nitrapyrin and DCD. These are the only two chemistries that are true nitrification inhibitors sold in the U.S.,” says Franzen.

Jason Moulin, product manager for Dow AgroSciences, says the main benefit N-Serve and Instinct II provide is the possibility of optimized yields for farmers. 

“It enables more N to get to the root zone,” says Moulin. 

N-Serve is an oil-based formulation used with anhydrous ammonia. Instinct II is a water-based microencapsulated formulation of nitrapyrin – used with UAN, urea, and liquid manure.

Kerry Overton, director of sales for Koch Agronomic Services, encourages you to talk to your local Extension specialist and look at peer-reviewed studies before making decisions on the use of inhibitors. 

Overton believes in providing return and value so you can maximize yields and productivity. “Agrotain Plus and Super U control volatilization, denitrification, and leaching,” he says.

    If you are looking for a new risk-management strategy, Extension staff recommend the use of inhibitors, especially in the fall. 

“I really encourage you to use N-Serve if you are going to be applying N in the fall,” says Fernandez. 

Read more about

Crop Talk

Most Recent Poll

Will you plant more corn or soybeans next year?