Can a urease inhibitor improve the efficacy of nitrogen use under perennial ryegrass temperate grazing conditions?

Abstract This study sought to compare the efficiency of different nitrogen (N) fertilizer forms applied perennial ryegrass swards that were rotationally grazed by dairy cows or sheep under Irish conditions for two three years. A 3 × 2 factorial random complete block design plot arrangement was used calcium ammonium nitrate (CAN), urea and + N-(n-butyl) thiophosphoric triamide (urea NBPT) at 150 250 kg N/ha per year. Zero plots also added allow N be calculated. The conducted four sites, giving years data collection sites other sites. All observed similar responses type rate. Significant differences between treatments pre-grazing herbage yield (1346 1588 DM/ha, respectively; P < 0.001) total production (12 290 14 448 0.001). There no difference but a tendency higher CAN NBPT than (1485, 1480 1436 CAN, urea, = 0.091). Total significantly (13 478, 13 542 087 0.004). In conclusion, there an overall benefit detected over 10 site-years from using protected with v. urea.