Protecting Nitrogen During Burndown Applications

Depending on the herbicide used, application timing can vary — from 1-3 weeks before planting to 3-5 days after putting down seed. The timing of the application is key, as UAN is commonly used as a carrier for herbicide tank mixes. Growers need to make sure they protect the nitrogen in that mix so it’s available when their crops need it most.

“When we look at UAN as part of a burndown mix, we need to consider the risk of both volatilization and nitrification,” said Derek Rapp, technical agronomist for Koch Agronomic Services (Koch). “Because UAN is made up of urea and ammonium, up to 75 percent of that nitrogen is at risk to volatilization and vulnerable to loss. This is often overlooked since the focus of the application is for weed control. But for growers to get the most out of that investment, they should be treating the UAN they apply.”  

Application timing for burndown is important, making the decision to treat UAN easier when you consider plant growth. For corn, nitrogen uptake is relatively low prior to the V6 growth stage but rapidly increases from V6 to VT. That means the nitrogen must remain in the soil rooting zone for 50 days or more before active crop uptake is highly present, mitigating the risk for nitrogen loss. 

(Reprinted by permission. Modern Corn Hybrids’ Nutrient Uptake Patterns (2013. Bender, Haegele, Ruffo, and Below.)

“Since a majority of urea volatilization losses occur within 3-5 days of application, growers will be missing a great opportunity if they don’t protect it,” says Rapp. “And spring precipitation can make that loss even greater as 100 percent of UAN is vulnerable to leaching and denitrification.”
 

Two stabilizers from Koch offer growers the help they need to optimize crop yield potential by protecting nutrients both above and/or below ground. For above-ground losses, urease inhibitors are used to protect nitrogen from volatilization, allowing more time for the nutrient to be incorporated into the soil. For below-ground losses, nitrification inhibitors offer protection by slowing the nitrification process, helping to prevent denitrification, and leaching losses.

Growers can look to the following solutions to protect the nitrogen in their burndown applications:

ANVOL™ nitrogen stabilizer delivers the longest-lasting urease inhibitor protection over a wider range of soil environments. With the active ingredient Duromide, ANVOL provides protection against volatilization losses and is compatible with many common herbicides used for corn. Adding ANVOL with its longer-lasting protection to surface applications of UAN can boost yield results compared to untreated nitrogen. A 2019 study showed UAN treated with ANVOL yielded 27 bu/acre more than untreated UAN.¹

CENTURO™ is a nitrification inhibitor for 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 Growers treating UAN applications with CENTURO can improve their yields by providing below-ground protection against denitrification and leaching.

Another advantage to using ANVOL and CENTURO is the ability to tank-mix either solution to provide complete protection during burndown.

“Both CENTURO and ANVOL can be good choices for growers to protect nitrogen applied as part of the burndown process,” says Rapp. “At Koch, we want them to use the best solution for their operation and minimize their nitrogen losses. That means protecting nitrogen every time it goes out.”

With UAN used as a carrier in herbicide burndown applications, growers should take advantage of the opportunity to use that nitrogen to their crop’s advantage. To learn more about ANVOL and CENTURO, visit KochAgronomicServices.com and contact your KAS representative.