Protecting Nitrogen Despite The Weather

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Anyone who has farmed through those extremes knows the impacts they can have on nitrogen management, including the increased potential for nitrogen loss.

"Excess moisture in the soil profile, or the lack of it, can wreak havoc with your nitrogen application," said Derek Rapp, technical agronomist for Koch Agronomic Services (KAS). "But knowing what those risks factors are and how to protect your nitrogen against them, will help you make sure your plants have what they need to succeed."

WET CONDITIONS

When the soil profile is moist, urea, which is also found in UAN, will dissolve, and hydrolysis begins. Under those circumstances, the risk of ammonia volatilization loss starts almost immediately. But add warmer temperatures to saturated soils and losses to denitrification become favorable. Or if rainfall amounts exceed the soil’s water holding capacity nitrogen loss via leaching is a risk. In warmer temperatures, ammonium can nitrify to nitrate in as little as one to two weeks and takes several weeks at cooler temperatures to nitrify.

Volatilization is an above-ground loss of nitrogen, which happens when urease enzymes in the soil break the urea molecules into ammonia gas. Warm, moist and alkaline soil conditions make volatilization more likely to occur when a urease inhibitor is not present.
The leaching process occurs when gravity pulls water and the dissolved nitrate downward through the soil profile, moving the nutrients below the root zone. Other factors involved: extended periods between nitrogen application and crop uptake, above-average rainfall and loosely textured soils with high infiltration or artificial drainage.
Denitrification occurs when microorganisms shift their metabolism and use nitrate instead of oxygen when soil moisture levels are too high, restricting oxygen availability, converting nitrates to gaseous nitrogen that is then lost to the atmosphere. Other factors involved: early season UAN applications, soil temperatures higher than 65 degrees Fahrenheit and tightly textured soils with poor drainage.

PROTECTING NITROGEN IN WET SOIL

In a University of Arkansas research trial, untreated urea was applied to wet soil. Research showed hydrolysis began quickly, and by day three untreated urea had lost close to 15% of nitrogen. In total, approximately 31 percent of the nitrogen was lost to ammonia volatilization. But under the same conditions, urea treated with AGROTAIN^® nitrogen stabilizer, hydrolysis was slowed and showed less than 13 percent to volatilization.¹

Like its predecessor AGROTAIN, ANVOL^® nitrogen stabilizer minimizes volatilization by delivering the longest-lasting urease inhibitor protection over a wider range of soil environments. The dual active ingredients are the difference. NBPT slows the hydrolysis of urea as soon as it’s applied, then Duromide, KAS' patented molecule, extends the protection.

Another KAS product, CENTURO^® nitrification inhibitor, can slow down loss of anhydrous ammonia and UAN. CENTURO extends your window of protection by slowing the conversion of ammonium to nitrate to hold the nitrogen in the ammonium form three times longer than without an inhibitor.²

In a 2020 Nebraska study, where 6.83 inches of irrigation and rain fell within the 60 days following the application, both applications rates of CENTURO in UAN provided a yield advantage over untreated UAN of 10 bu/ac and 14 bu/ac, respectively³. By extending the window of protection, more nitrogen was available to the crop even when wet conditions were favorable for below ground nitrogen losses.

DRY CONDITIONS

While spring is not generally marked with dry weather, that’s not to say it can’t or hasn’t happened. Lack of rainfall, windy or hot conditions can increase volatilization losses when it comes to surface applied urea or urea-ammonium nitrate. If the applied nitrogen is not adequately incorporated* then the risk of losses to volatilization can increase.

"Warm, moist soils, high humidity, and several days following application without an incorporating rainfall event, all combine to create conditions ideal for volatilization," said Rapp. "Growers with these application concerns can look at both SUPERU and ANVOL to minimize those losses."

In a separate 2020 study conducted in Nebraska, conditions created a worst-case loss scenario that are not typically seen in the spring, with 17 days between application and an incorporating rainfall measuring greater than a half-inch. Averaged across three nitrogen rates (60, 120 and 180 lbs), ANVOL nitrogen stabilizer provided a 37 bu/ac advantage over untreated UAN4. While dry weather is not common during the window for spring applications, this scenario represents the magnitude of above-ground losses that can occur in UAN.

Whatever the weather hands you, be ready to protect your nitrogen. Learn more about the solutions that are best for your operation, visit KochAgronomicServices.com and contact your KAS representative.

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