An assessment of the agronomic effectiveness of N‐(n‐butyl) thiophosphoric triamide (nBTPT) - treated urea on the production of clover-based pastures, pastures, grasses and crops.

Abstract

Approximately 50% of the world’s population depends on nitrogen (N) fertiliser to secure a sustainable food supply. Improving the efficiency of nitrogen fertiliser – the nitrogen use efficiency (NUE) - is a major goal both nationally and internationally, driven by the need to reduce the environmental footprint of farming. One of the technologies developed for this purpose is the addition of the urease inhibitor, N-(n-butyl) thiophosphoric triamide (nBTPT), to urea, to reduce the volatilisation of ammonia from the soil. In this paper we report the results from field trials, recorded in the national and international literature, comparing the effects of nBTPT treated urea, relative to untreated urea, on plant dry matter (DM) yields (cloverbased pasture, grasses and arable crops) from 45 studies summarizing the results on a site × year × crop basis. For the aggregated data (n = 348) the marginal yield results were normally distributed around a mean of about 3% (95% confidence interval 0.9), with a range from -23% to +32%. The results for the various subsets (based on different crop types) of data were very similar. The size of the effect of nBTPT was related to the rate of N application.