Applying nitrogen in spring can prove challenging, but there are a number of things to keep in mind that can make top dressing beneficial.
The top three for most growers are increasing nutrient use efficiency (NUE), operational flexibility and protecting that application until you get incorporating rainfall.
Nutrient Use Efficiency
When you follow the 4Rs of Nutrient Stewardship, you can improve the NUE. By selecting the right source of fertilizer, applying it at the right rate, at the right time and in the right place, you’re implementing best management practices. In some cases, top dressing nitrogen can be your best choice.
Top-dressing nitrogen during the growing season offers you the opportunity to work around limiting factors the weather might have caused for you prior to or at seeding time.
“When growers apply more of their season total nitrogen as a top dress application and decrease their near-planting nitrogen amounts, they can get better nutrient use efficiency,” said Matt Fryer, technical agronomist with Koch Agronomic Services (KAS). “Crop demand for nitrogen is generally low until the mid- to late-vegetative stage, so with top dressing, you’re increasing efficiency by putting it in the right place and at the right time when the crop really needs to utilize that nitrogen for growth and yield.”
In addition to increasing NUE, top-dress applications can give growers more flexibility.
“Typically, top-dressing is faster than knifed in UAN and they can cover more acres in a shorter period of time,” said Fryer. “You can fly on urea or broadcast your nitrogen source using ground equipment and it’s getting it on the field faster, so that can be attractive to growers.”
Evan King, another technical agronomist for KAS, also pointed out that growers have a hard enough time covering the acres they need to cover.
“Operational efficiencies are a huge benefit for growers using top-dress applications,” King said. “However, weather is unpredictable and even when we have good forecasts, they don’t always hold true. By utilizing stabilizers along with top dressing nitrogen, growers can take advantage of that extended window of time to help prevent losses before incorporating rainfall.”
Protection Against Volatilization
As always, when applying fertilizer — timing is everything.
“The main drivers for volatilization losses are moist soils, high temperatures and a lack of incorporating rainfall,” said King. “In those conditions, we can lose as much as 40% of the plant nitrogen over the first three days.”
Fryer points out that you can watch the weather forecast, but getting the right amount of rain at the right time is out of your hands. You need to protect your urea or UAN investment from volatilization losses with ANVOL™ nitrogen stabilizer from KAS.
“Especially on dry land production, whether it's wheat or corn, ANVOL is going to be a no-brainer for top dressing urea or UAN,” said Fryer. “If you don't get a timely rain, which rarely occurs, ANVOL will be there to protect your nitrogen.”
Featuring the patented active ingredient Duromide, ANVOL delivers the longest-lasting urease inhibitor protection over a wider range of soil environments, protecting your nitrogen investment against ammonia volatilization and preserving it for crop uptake.
“In locations that planted late, there will be a shift to in-season fertilizer application,” said King. “From year to year, there are always growers who find themselves in this situation, making protection for their nitrogen even more vital to the success of that year’s yields.”
To learn more about top-dress applications with ANVOL, contact your local KAS sales representative.