Not too late to get on some N

Not too late to get on some N

By: Jeff Caldwell 07/07/2011 @ 11:11am

Sure, it's late. But, it's not too late to apply nitrogen to your corn fields if they're showing major signs of deficiencies, says one expert.

There's a lot of light green-tinted corn fields out there, and especially now that the soil's drying up in a lot of the areas that were the wettest this spring and early summer, nitrogen loss is becoming increasingly visible in a lot of fields. Earlier on, these symptoms could have been easily confused with another common wet year issue. But now, it's much easier to see where you're low on N, says University of Illinois Extension soil fertility specialist Fabian Fernandez.

"It is not at all uncommon to see light-green corn next to dark-green corn that is further along in development," he says. "If N has been applied, the light-green crop is typically in areas where ponding of water occurred. In areas where there is adequate N, often waterlogged soils induce N deficiency-like symptoms. Those symptoms should have disappeared in most places by now."

But, it's awfully late. Putting down nitrogen now, though, will still put you in a better spot than if you hold off altogether just because it's past the normal time.

"It’s important to realize that this late in the season, crops showing N deficiency have already lost some yield potential and applying a full N rate is not going to recover the lost potential," Fernandez says. "In other words, the corn crop will not be capable of using that full rate to make yield."

How long do you have to put down fresh N? The short answer is right up until tasselling, Fernandez adds. "studies have shown that even until silking, corn has a great capacity to use N and produce an increase in yield if the application is done in severely N-deficient fields," he says.

Just be sure to do what you need to do to get the N where it needs to go, something that can be a little different than earlier-season applications. If you're dribbling it on between rows, for example, consider using a urease inhibitor to "reduce the potential for volatilization losses when the product sits on the soil surface until it is incorporated by water," Fernandez says, something that's more common when the temperatures are higher this time of the summer.

"Regardless of the N source, any product that is surface-applied will require water to move it into the root system so the plant can use the applied N," he continues. "Because of this, applying before it rains is a good approach."