Nutrient Content of Wheat and Corn in Response to the Application of Urea and the Urease Inhibitor NPBT

Abstract. A field study was conducted to evaluate the effects of the addition of two different urease inhibitors on the volatilization of NH₃-N from top dressed ammonia sources on winter wheat and dent corn. Urease inhibitors tested were N-Yield^TM and Agrotain®. Plots were treated with compost, compost treated with N-Yield^TM, urea urea treated with N-Yield^TM, urea treated with Agrotain®, or control (no fertilizer or urease inhibitor was applied). At maturity, above-ground biomass was separated into grain and straw, with each constituent evaluated for total N, P, K and S. Total N concentrations in wheat straw ranged from 0.64% in the control to 1.36% in the treatment containing urea treated with N-Yield^TM. Total N concentrations in wheat grain ranged from 2.09% in the control to 3.52% in the treatment containing urea with N-Yield^TM. Similarly, N concentrations in the corn stover ranged from 0.81% in the compost treatment to 1.80% in the treatment containing urea treated with Agrotain®. Total P concentrations in wheat straw ranged from 0.08% in the control to 0.17% in the treatment containing urea treated with N-Yield^TM. Total P concentrations in wheat grain ranged from 0.47% in the control to 0.57% in the treatment containing compost with N-Yield^TM_. However, the data analyzed in this study suggest that, in field conditions, while the application of urea fertilizer greatly increases N concentrations in wheat and corn, the addition of NBPT (whether Agrotain® or N-Yield^TM) to urea before field application does not significantly increase N concentrations over that of urea alone.