Montana State University researchers say adding middle to late season protein to wheat can add yields and improve protein in harvests.
But applying all the N at one time can be risky, they add.
Too much nitrogen early in the production season can spur excessive tillering, lodging and reduced yields, say the MSU scientists probing the use of N under irrigation.
That, they note, means growers will lose money on the crop, and may be causing harm to water and air quality.
Putting on the N preplant is one alternative, they offer, particularly in very dry years. This application can be enhanced with a middle or late season follow up to help beef up grain yield and protein if production potential increases during the growing season.
Splitting the N use also helps growers match rates to the yield they feel they may achieve based on rainfall that has occurred. In wet weather, N amount and when it is applied can be based on how much yield or protein goes up.
In dry weather, however, a second hit of N may not be a good idea, the researchers conclude.
"Timing of in-season nitrogen application should be based on plant growth rather than a particular date," advises Clain Jones, a MSU Department of Land Resources and Environmental Sciences soil fertility researcher.
For production of wheat on dry land, use of additional N for yield ought to be done by early to mid tillering, he adds. That makes certain yields will not be hurt.
The practice is important particularly with foliar applications, he explains, when dealing with spring wheat crops.
When spring wheat nears booting, leaf burn can become a high risk to yield.
Remember that leaf burn goes up with N rates. No more than 30 pounds N per acre is recommended to reduce this problem. Liquid urea, adds Jones, tends to result in less leaf burn.