Journal of Agricultural Research (2020), Volume. 7, Issue (2)

Abstract

Nitrogen management for respective rice varieties in specific rice cultivating areas should be formulated to promote the sustainable and profitable rice production while improving nutrient use efficiency and environmental conservation. A two-season field experiment using rice varieties, Yadanar Toe for summer and Sin Thukha for monsoon was conducted to investigate the suitable N rate for optimal rice production and to determine N use efficiency (NUE) of rice in the research farm of Yezin Agricultural University in 2017. Eight treatments including different rates and application methods of N fertilizers were T1 (No fertilization), T2 (0 kg N ha−1), T3 (30 kg N ha−1), T4 (77.6 kg N ha−1), T5 (100 kg N ha−1), T6 (130 kg N ha−1), T7 (160 kg N ha−1) and T8 (77.6 kg N ha−1 as urea super granule, USG).The plots were laid out in randomized complete block design with three replications. As N sources, prilled urea (PU) was used for all treatments except T8. The highest grain yield was achieved from T5 in both seasons; 8.2 ton ha−1 in Yadanar Toe and 4.6 ton ha−1 in Sin Thukha. In both seasons, the optimum grain yield was observed from the application of 77.6 kg N ha−1 as either for PU or USG. The NUE ranged from 4.5 to 13.5 in summer and from -0.3 to 13.4 in monsoon. The highest NUE was observed from T5 in summer and T3 in monsoon. The isotopic technique using 15N labeled urea revealed that the best NUE was T8 in summer, 2017.