Getting urea nitrogen on winter wheat fields as recommended at spring green-up is often complicated by weather, especially in the Northeast. Controlled-release technology makes the task less time-sensitive and reduces N losses to the environment.
Yes, controlled-release urea products are more expensive – approximately 10 cents a pound. But Michigan State University studies suggest that the higher cost can be made up with reduced field passes, protection against N volatilization, leaching and denitrification, plus improved plant uptake.
A number of CR urea products are commercially available. Most are polymer-coated for time release according to soil temperature.
Some contain sulfur at levels varying by product. That includes Poly-S, NS-54, NS052. Nutrisphere-N, Environmentally Smart Nitrogen (ESN), Extend and others contain only urea. All are dry products that can be blended with straight urea.
One-pass at-planting app?
That's what some CR product marketers contend. "Winter wheat growers who like to apply fertilizer with the seed at planting like the extra crop safety that ESN provides," says Alan Blaylock, agronomy manager for Agrium Wholesale.
"The protective coating allows farmers to apply N with the seed at up to three times the seed-safe rate of urea," he adds. "Seed-placed ESN had increased wheat yields by as much as 7 bushels per acre over conventional urea."
The CR product can be used alone or in combination with other soluble fertilizers, points out Blaylock. "For November-January applications, 100% ESN can be used. From January-March, a blend of 75% ESN and 25% urea is recommended. For applications in April, a blend of 50% ESN and 50%urea is recommended."
Note: Common N fertilizers such as anhydrous ammonia (82% N), urea (46% N) and urea ammonium nitrate (UAN) (28% N) are susceptible to losses from leaching, denitrification, and volatilization, especially if all N is applied too early.
Learn more at: www.smartnitrogen.com