Influence of temperature and soil type on inhibition of urea hydrolysis by N-(n-butyl) thiophosphoric triamide in wheat and pasture soils in south-eastern Australia

Abstract

Incubation experiments were conducted to assess the effectiveness of N-(n-butyl) thiophosphoric triamide (NBPT) for inhibiting hydrolysis of urea in three wheat-growing soils and one pasture soil in south-eastern Australia, under a range of temperatures (5, 15, 25°C). The effectiveness of NBPT decreased with increasing temperature and with increasing urease activity. In the acidic pasture soil with high urease activity (186 μN/g soil.h) and high organic carbon content (11%), NBPT (0.1% w/w urea) had little impact on urea hydrolysis rates over all temperatures, with <1% urea remaining at Day 14. In the alkaline, wheat-cropping soils with lower urease activity (54-90g μN/g soil.h) and lower or..