Spring N may still need an inhibitor

If the old axiom is true that the last season is the one you remember most for decision-making, then many may be tempted to do everything they can to minimize nitrogen losses this spring. The last two springs, in fact, have featured cool, wet springs that didn’t lend themselves to nitrogen application. Instead, they were tailor-made for losing part of the N that may have been applied.

This spring may be totally different. However, taking steps to minimize N loss is always good policy.

Key Points

• More nitrogen than normal could be applied in Indiana this spring.

• Weather is a key factor in determining possible N losses.

• Adding a nitrification inhibitor will likely pay in a warm, wet spring.


“Less nitrogen went on last fall because of the delayed harvest,” says Jeff Phillips, Tippecanoe County Extension ag educator. In his area, typically a good percentage of N is applied in the fall.

“From what I hear guys may cut rates just a wee bit, but not much,” Phillips continues. “They know nitrogen is critical, plus the price of N has come back down to reality.”

Some may opt to wait to side-dress N instead of applying it this spring. However, rainy June weather last season demonstrated how tricky it can be to plan to side-dress N on all corn acres.

The question for the panel of Indiana Certified Crop Advisers relates to spring N applications. Panel members include Jesse Grogan, with LG Seeds, Lafayette, and Dan Ritter, Extension ag educator in Newton County.

We want to apply some anhydrous ammonia early this spring in a pre-plant pass. Will it pay to apply a nitrification inhibitor?

GROGAN: Yes, N-Serve (nitrification inhibitor for anhydrous ammonia) does pay in most situations with spring N applications. Higher N cost is incentive to conserve N with N-Serve and not use additional N as insurance.

N-Serve can improve yields up to 10 bushels per acre, depending upon field conditions. The nitrification inhibitor works best when spring conditions are wet in May and June.

Response to N-serve is also good in poorly drained soils. It also typically does well when used on fine-textured soils, sands and high-pH soils.

RITTER: Nitrogen loss is very dependent upon weather conditions. If it’s a favorable spring for fieldwork, then the investment in a nitrification inhibitor may have a minimal return.

On the other hand, if it turns wet after the application, and especially if it’s warm, you could see significant loss through denitrification without a nitrification inhibitor.

Look at a nitrification inhibitor as insurance against nitrogen loss. Assess your risk level and then act accordingly.

This article published in the March, 2010 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.