Duromide is an effective urease inhibitor when combined with vinasse and blended with ammonium sulphate

A recent trend in sugarcane production is to apply urea fertilizers in combination with vinasse (V) to balance nitrogen (N) and potassium (K) supply. This practice promotes a circular economy and a possible reduction in N losses through ammonia (NH₃) volatilization due to the acidic nature of V. However, it is unclear whether V reduces NH₃ volatilization, and whether the addition of urease inhibitors further reduces NH₃ losses. Furthermore, the efficacy of formulations containing urea and urease inhibitors may decrease over time when blended with acidic fertilizers such as ammonium sulfate (AS). This study aimed to determine the efficacy of urease inhibitors N-(n-butyl) thiophosphoric triamide (NBPT) and Duromide in reducing NH₃ volatilization losses from urea applied with V and from urea blended with AS and stored for 10 months in a warehouse. Two different experiments were conducted under controlled conditions. Seven days after fertilizer application, urea addition to V resulted in a 35 % NH₃ loss (a reduction of only 36 % compared to urea), whereas NBPT-treated urea + V and Duromide-treated urea + V resulted in reductions of 51 and 74 %, respectively. The efficacy of NBPT-treated urea blended with AS to control volatilization decreased from 41 to 9 % after 10 months of storage. In contrast, the efficacy of Duromide-treated urea in reducing the NH₃ volatilization remained relatively constant. Duromide is a more stable and effective urease inhibitor than NBPT, supporting agronomic practices that reduce NH₃ volatilization and maintain inhibitory effects when blended with acidic fertilizers such as AS or combined with acidic organo-mineral fertilizers like V.

Keywords
NBPT; nitrogen; sugarcane; fertilizer; urease inhibitor