Corn Yield Response to the Urease Inhibitor NBPT: Five-Year Summary

Abstract

Urease inhibitors are applied to reduce NH 3 volatilization and immobilization losses from surface-applied urea or urea-NH 4 NO 3 solutions (UAN). The urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) was evaluated in the USA in 78 trials conducted with corn (Zea mays L.) from 1984 to 1989. NBPT was applied with urea at rates of 0.25 to 1.0% (w/w) and with UAN at rates of 0.5 to 2.0 Ib/acre. When averaged over N and NBPT rates for all locations and years of the study, NBPT increased grain yields by 4.3 bu/acre when applied with urea and by 1.6 bu/acre when applied with UAN (...)