Efficacy of Deep Placement of Nitrogen Fertilizers on N Use Efficiency and Yield of Boro Rice (cv. BRRI Dhan29)

Abstract

The efficiency of nitrogen (N) fertilizers in rice culture is low due to their losses in different ways. An experiment was, therefore, conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during boro season of 2016 to evaluate the effect of deep placement of N fertilizers on N use efficiency and yield of BRRI dhan29 under alternate wetting and drying (AWD) condition. The soil was silt loam in texture having pH 6.07, organic matter content 1.10%, total N 0.055%, available P 3.6 ppm, exchangeable K 0.22 me% and available S 11.76 ppm. The experiment was laid out in a randomized complete block design with three replications. There were eight treatment combinations including T1 (Control), T2 (PU, 130 kg N/ha), T3 (USG, 130 kg N/ha), T4 (USG, 104 kg N/ha), T5 (USG, 78 kg N/ha), T6 (NPK briquette, 129 kg N/ha) and T7 (NPK briquette, 102 kg/ha) and T8 (NPK briquette, 78 kg N/ha). All the treatments except T6, T7 and T8 received 25 kg P and 64 kg K /ha as TSP and MoP, respectively. Treatments T6, T7, T8 received NPK briquette fertilizer. Prilled urea (PU) was applied in three equal splits. Urea super granule (USG) and NPK briquettes were applied at 10 day after transplanting (DAT) and the briquettes were placed at 8-10 cm depth in the centre of four hills in alternate rows. The results demonstrate that all the yield components except 1000-grain weight responded significantly to the deep placement of N fertilizers in the form of USG and NPK briquette. The grain and straw yields of BRRI dhan29 were also influenced significantly due to deep placement of N fertilizers under AWD condition. The highest grain yield (6163 kg/ha) was recorded for T3 [USG, 130 kg N/ha) which was statistically similar with T4 (USG, 104 kg N/ha). The highest straw yield (6415 kg /ha) was also found in T3 [USG, 130 kg N/ha]. The lowest grain yield (3266 kg/ha) and straw yield (3637 kg/ha) were found in T1 (Control). The N uptake by BRRI dhan29, N use efficiency and apparent N recovery also showed significant response to the application of PU, USG and NPK briquettes. The maximum N use efficiency of 28.88% was noted in T5 followed by T4 with the value of 26.46% and the minimum value of 17.55% was observed in T2. The results revealed that the deep placement of N fertilizers accelerated the N uptake, N recovery and N use efficiency by BRRI dhan29. Based on grain yield and cost-benefit analysis, it can be concluded that application of 130 kg N/ha as USG is useful for the profitable cultivation of boro rice, BRRI dhan29.