Nitrogen is too expensive to leave its fate to chance. But as corn growers prepare for fall anhydrous ammonia (NH₃) applications, the question isn’t just how much nitrogen to apply. It’s how much will still be available when next year’s crop needs it.
For about $15 per acre, a nitrogen stabilizer can help growers keep more of that investment in the soil and available to corn the following spring, according to recent Iowa on-farm research.
The findings offer a closer look at how nitrogen stabilizers work — and why application timing matters. They also come at a time when nitrogen represents a significant expense for corn production.
An Iowa grower applying 150 to 180 pounds of nitrogen per acre would spend up to $100 per acre on anhydrous ammonia alone, before application costs, according to based on USDA Agricultural Marketing Service data released in mid-October.
The No. 1 Factor Contributing to N Loss
Andrew Luzum, Corteva Agriscience nitrogen stabilizer specialist, and Alex Schaffer, research agronomy lead at the Iowa Soybean Association, say the key to keeping nitrogen in the field is slowing nitrification — the natural soil process that converts ammonium into nitrate. While both forms contain nitrogen, ammonium binds to soil particles and stays in place, while nitrate is mobile and more vulnerable to loss.
“What N-Serve does is it actually keeps nitrogen in the ammonium form for a longer period of time,” Luzum says, regarding Corteva’s nitrogen stabilizer. “We slow down the conversion process known as nitrification.”
That matters because of where and how nitrogen leaves fields. According to Luzum, roughly 70% of nitrogen loss happens below ground — not through volatilization, which farmers can often smell — through leaching and denitrification that move fertilizer out of reach of the next crop or out of the field entirely.
Understanding the Underground Loss Problem
The conversion from ammonium to nitrate is driven by soil microbes, Schaffer explains. As soil temperatures rise, those microbes become more active and the conversion accelerates—exactly when farmers want nitrogen stable and available for growing crops.
Nitrogen stabilizers target those underground pathways by slowing microbial activity. Luzum says nitrogen stabilizers can extend the period nitrogen remains in ammonium form by about eight weeks compared to untreated ammonia. That extension is designed to keep fertilizer in place through winter and spring, making it available as crops establish roots and begin building yield potential.
The distinction between ammonium and nitrate loss pathways is important for setting realistic expectations. Luzum emphasizes that stabilizers address below-ground losses — leaching and denitrification — not volatility. Farmers dealing with surface loss from urea applications, for example, need different management strategies.
University of Nebraska Extension reports the most popular nitrogen stabilizers on the market fall into three main categories: nitrification inhibitors (which protect against below-ground leaching and denitrification), urease inhibitors (which prevent above-ground volatilization), and dual-inhibitor products (which protect against both).
Fall Application: Getting the Timing Right
For Midwest farmers planning fall ammonia applications in the coming weeks, Schaffer says success depends on more than just adding a stabilizer. Timing, application depth (a minimum of 6” is commonly recommended) and soil temperature are critical to their success, as well.
“If a farmer is exercising good stewardship in the fall and they’re applying their ammonia when soil temperatures are 50 degrees and falling, and they’re using a stabilizer at that point,” Schaffer says, “the microbial activity is so low over the winter that that nitrapyrin should be there in the band and active in the spring.”
When those conditions are met, Schaffer says he believes there is “no real difference” between fall-stabilized ammonia and spring application in terms of having nitrogen present and working early in the growing season.
Apply too early this fall, while soils are still warm, and microbial activity may exhaust the stabilizer before spring arrives. Apply at the right temperature with a stabilizer, and the product remains ready to inhibit nitrification when temperatures rise and crops begin growing.
What On-Farm Trials Revealed
The Iowa Soybean Association’s recent on-farm research provides field-scale evidence of how stabilizers perform.
A farmer working with Schaffer applied ammonia with and without stabilizer last fall and again this spring. The treated strips showed yield advantages of 18 and 25 bushels per acre compared to untreated areas — yield benefits he says would be large enough to cover the stabilizer cost for five years. Those results prompted farmers to ask whether spring applications would deliver similar protection.
To investigate, ISA partnered with a farmer applying spring ammonia for 2026 and set up treated and untreated strips replicated across his fields. Researchers used spatial data from the application equipment to identify treatment areas, then returned every other week to sample soil directly from the ammonia band.
Schaffer says his team took 15 soil cores concentrated in the ammonia band for each treatment and replication — a departure from conventional soil sampling designed to capture the fertilizer band itself and measure the ratio of ammonium to nitrate over time.
The soil data showed a clear difference. By early June, untreated ammonia had about 25% of its nitrogen remaining as ammonium, while stabilizer-treated ammonia still held roughly 50% in ammonium form. Schaffer describes the difference as significant and says the response appeared fairly uniform across most trial fields. Sampling continued for about 10 weeks after application.
The soil measurements offer strong evidence of how stabilizers affect nitrogen chemistry. However, at the time of Schaffer and Luzum’s discussion, harvest had been delayed and yield data were not yet available. Schaffer says researchers expect to analyze yield using spatial data from the combine matched to the treatment areas, emphasizing that harvest results would be important to consider alongside the soil samples.
The Economics: Calculating Return on Investment
Luzum frames stabilizers partly as insurance against nitrogen loss, acknowledging that yield responses can vary year to year depending on weather and field conditions.
In 2025 field tests, he says 18 spring-applied trials across the Corn Belt showed an average yield advantage of 8 bushels per acre from using N-Serve compared to untreated acres.
“At $4 corn, that’s $32 an acre more revenue over the untreated,” he says.
Some growers worry that stabilizers might tie up nitrogen and make it unavailable to the plant. Luzum says in an ISA article online that concern is a common misconception.
“There isn’t any concern with tying up nitrogen,” he says. “Just because our nitrogen is in the ammonium form doesn’t mean corn can’t access it. Corn actually prefers ammonium as the source of nitrogen because it’s more plant efficient.”
Making Stabilizers Work: Application and Handling
Getting the most benefit from nitrogen stabilizers requires attention to handling and application details, particularly with anhydrous ammonia systems.
Luzum explains that N-Serve is a solvent-based formulation, not water-based, and that difference affects equipment handling. Rust inside tanks can be scoured out by the solvent, he says, potentially contributing to clogged equipment as the system cleans itself.
More important is the cleaning process. Luzum cautions against using water to clean equipment that has been used to apply a solvent-based product. He says water can create what he describes as a light acid and accelerate corrosion. He recommends diesel fuel or another solvent for cleaning.
Luzum adds that injection systems on toolbars can sidestep some handling concerns associated with running the product through anhydrous equipment. The handling guidance reflects the product’s chemistry and underscores the importance of following label directions and manufacturer recommendations.
Season-Long Strategy: Split Applications
Luzum recommends farmers consider using a nitrification inhibitor with every nitrogen application, not just with fall- or spring-applied ammonia. As more growers split their nitrogen across multiple passes — at spring pre-plant, planting, or sidedress — splitting the inhibitor used along with split nitrogen becomes a valuable strategy.
“Anytime we’re making an application, we should be doing the good stewardship things we’re talking about here,” Luzum says.
Schaffer identifies split application itself as a practical first step for farmers reviewing their nitrogen programs. Applying nitrogen at different times spreads risk, he says, while farmers evaluate where stabilizers or other efficiency tools might fit.
Split applications offer several advantages beyond just spreading risk. They allow farmers to adjust rates based on early-season conditions, match nitrogen availability more closely to crop demand, and potentially reduce the total amount of nitrogen needed. When combined with stabilizers at each application, the approach provides multiple opportunities to protect the grower’s nitrogen investment.
Broader Benefits: Water Quality and Environmental Stewardship
The benefits of nitrogen stabilizers extend beyond individual farm economics. Luzum links nitrogen management to water quality concerns that affect entire watersheds and regions.
He says Corteva estimates its product reduces nitrogen leaching by about 16% and cites the company’s nationwide sales as representing roughly 21 million pounds of nitrogen that was kept out of waterways last year.
For the Midwest, adoption rates remain a key factor. Luzum estimates that about half of corn growers’ nitrogen applications currently include a nitrification inhibitor. Greater adoption, he believes, could help farmers retain more nitrogen while addressing environmental issues, especially water quality concerns.
