Can urease inhibitor N-(n-butyl) thiophosphoric triamide (nBPT) improve urea efficiency: effect of different application rate, timing and irrigation systems

摘要

Granular urea applied onto pastures has lower N response efficiency (NRE) compared to other chemical fertilizers. Improving N use efficiency of applied urea is therefore critical for sustainability and to minimise its adverse effects on the environment. Field trials were conducted to identify the best rate of urease inhibitor, [N-(n-butyl) thiophosphoric triamide (nBPT) or "Agrotain"] to coat urea for improving its efficiency. Further field trials were carried out during 2006 to 2009 to compare NRE of Agrotain treated urea versus standard urea applied to pasture soils in different application rates (split versus single fertiliser applications), granular and fine particle suspension (FPA) form under different management systems and environmental conditions. The results showed that 1 liter Agrotain/ton of urea was the best economic rate to achieve maximum pasture production in grazed pastures. Agrotain treated urea significantly increased pasture dry matter (PDM), N response, NRE and pasture N uptakecompared to urea alone in all trials. Pasture dry matter, NRE and pasture N uptake showed further improvements when Agrotain treated urea were applied in FPA form compared to granular form. Applying light irrigation after one day of FPA application hada positive effect on PDM and NRE. These results suggest that there is considerable potential for improving farm production and profitability by treating urea with Agrotain.