Some of the common questions concerning nitrogen forms and nitrogen stabilizers are addressed here.
IS AN EARLY START ON POST-EMERGENCE NITROGEN APPLICATION RECOMMENDED?
Post-applied nitrogen (N) use continues to be a sound agronomic, economic, and environmentally-friendly practice with effective N Management Systems. Start the post-applied N applications at, or soon following, the V3 stage of growth. The plant begins to rely on the nodal root system for nutrient and water uptake once three leaves are extended. Unless planted into a coarse-textured soil (sandy), delaying N applications for a later stage of growth may result in missing an application window due to frequent rain events or having no rain available to help get the applied N into the plant.
SHOULD NITRAPYRIN (N-SERVE) BE USED WITH ANHYDROUS AMMONIA APPLICATIONS THIS SPRING?
The value of using a nitrification inhibitor over the next few weeks will depend upon the weather following the N application. If a prolonged, wet growing season is anticipated following the N application, nitrification inhibitors (N-Serve and Instinct) will provide assurance that there will be N for uptake close to tassel emergence (rapid N uptake). If rains are anticipated to be infrequent and ½ inch or less in volume, it will likely be a challenge to find value in stabilizing applied N. It is all about when the applied N converts to nitrate-N and if the soil environment promotes loss. If there is a risk of the soils to be saturated between April and the latter part of May, a way to hedge environmental risk of N loss is to stabilize the N at the time of application.
WILL AGROTAIN ULTRA, APPLIED TO INCORPORATED UREA, SLOW DOWN NITRIFICATION?
No. Agrotain Ultra (NBPT) is a urease inhibitor. It is applied to urea and will inhibit volatilization of surface-applied urea or urea-containing fertilizers. If the urea is incorporated within 48 hours the risk of significant N loss by volatilization is minimized (no Agrotain Ultra needed). Agrotain Ultra does nothing to inhibit nitrification.
SHOULD SURFACE-APPLIED UREA BE TREATED WITH INSTINCT?
It is best to treat surface-applied urea with Instinct when there is certainty of having a significant rain event (3/4”) within 48 hours of the application, or the urea was to be mechanically incorporated within the same period of time. Instinct has no effect on urea-N volatilization. It is a nitrification inhibitor, not a urease inhibitor and will not minimize surface loss of urea-N by volatilization.
IS AGROTAIN PLUS A BETTER CHOICE THAN AGROTAIN ULTRA FOR USE WITH SURFACE-APPLIED UAN?
Agrotain Plus should be considered over Agrotain Ultra in poorly drained fields that have a tendency to stay wet for prolonged periods of time. Agrotain Plus is a combination of a urease inhibitor (inhibits volatilization loss) and a nitrification inhibitor (inhibits conversion of ammonium-N to nitrate-N).