Minimizing Nitrogen Requirement in Monsoon Rice through Foliar Feeding of Nano Urea

Abstract

Nitrogen is one of the primary nutrient elements in rice cultivation and is mainly supplied through conventional prilled urea. Foliar application of nano urea in combination with conventional urea has recently emerged as a promising strategy to enhance nitrogen use efficiency (NUE), leading to increased crop productivity and profitability. This study was conducted to evaluate the effects of different split applications and timing of nano urea (2 litre per hectare), in combination with varying urea doses, on BRRI dhan49 T aman rice performance. The experiment comprised 10 treatments, T₁= Only recommended urea, T₂= 100% Recommended urea + Nano urea at 20 days after transplanting (DAT) and 40 DAT, T₃= 100% Recommended urea + Nano urea at 30 DAT and 50 DAT, T₄= 100% Recommended urea + Nano urea at 40 DAT and 60 DAT, T₅= 75% Recommended urea + Nano urea at 15 DAT, 30 DAT and 45 DAT, T₆= 75% Recommended urea + Nano urea at 20 DAT, 35 DAT and 50 DAT, T₇= 75% Recommended urea + Nano urea at 25 DAT, 40 DAT and 55 DAT, T₈= 50% Recommended urea + Nano urea at 15 DAT, 25 DAT, 35 DAT and 45 DAT, T₉= 50% Recommended urea + Nano urea at 20 DAT, 30 DAT, 40 DAT and 50 DAT, T₁₀= 50% Recommended urea + Nano urea at 25 DAT, 35 DAT, 45 DAT and 55 DAT . The study was conducted in a randomized complete block design with three replications. Among the treatments, T2 and T5 were superior to the others considering yield attributes and yield of BRRI dhan49 T aman rice. T2 recorded the highest number of effective tillers hill⁻¹ at harvest (18.9), thousand grain weight (18.13 g), and grain yield (4.02 tha⁻¹), while T5 produced the highest number of grains panicle⁻¹ (115.43), the lowest number of sterile spikelets panicle⁻¹ (10.06), and the highest harvest index (48.43). The highest net return (50,212), benefit–cost ratio (1.39), and monetary advantage (140,700) were obtained from T2, closely followed by T5, and both outperformed the control. In contrast, reducing the recommended urea dose to 50% with four splits of nano urea resulted in higher agronomic NUE but negative grain yield merit (%). Overall, the results suggest that split application of nano urea during the early and active tillering stages, combined with 100% recommended urea doses, is the most effective strategy for maximizing yield performance and economic returns in BRRI dhan49 T aman rice cultivation.