Availability of N from Prilled Urea, USG and Manures to Flooded Boro Rice in Bangladesh

This study was conducted at the Bangladesh Agricultural University farm during the Boro season of 2025 to find out the effect of prilled urea (PU), and urea super granules (USG), applied alone or in combination, with poultry manure or cowdung on field water properties, nitrogen use efficiency, and the yield of BRRI dhan50. The treatments were: T1 (Control), T2 (78 kg N ha-1 from USG), T3 (136 kg N ha-1 from prilled urea), T4 (58 kg N ha-1 from USG), T5 (58 kg N ha-1 from USG + 3 t ha-1 poultry manure), and T6 (58 kg N ha-1 from USG + 5 t ha-1cowdung). Application of fertilizers and poultry manure (T5) significantly increased the highest grain yield of 4700 kg ha-1 as well as the highest straw yield of 5888 kg ha-1. T2 performed better than T3 which was statically significant and indicated the superiority of USG over prilled urea. Yield performances of both T2 and T5 remained statistically similar, and they both differed significantly over the rest of the treatments. In rice field water, urea super granules (USG) gradually released available NH₄⁺-N and maintained its presence throughout the entire growth period, in contrast to prilled urea, indicating the beneficial role of USG. Other water properties, including pH and electrical conductivity (EC), were also affected by the application of both prilled urea and USG. Overall, the results suggest that the combined application of USG and poultry manure is more effective for rice production, as it reduces nitrogen losses, conserves nitrogen, and enhances the efficiency of applied nitrogen.