An experiment was conducted during 2014 and 2015 at Canning Town, West Bengal, to study the influence of neem-coated urea and its application methods on nitrogen uptake and use-efficiency of ‘Amal-Mana’ rice (Oryza sativa L.).The experiment was laid out in in randomized block design, consisting of 10 treatments, viz., T1, application of 50% N as prilled urea at transplanting and rest N as 6 foliar sprays from active tillering to flowering; T2, 50% N as neem-coated urea at transplanting and rest N as 6 foliar sprays from active tillering to flowering; T3, 50% N as prilled urea 1 week after transplanting (WAT) and rest N as 6 foliar sprays from active tillering to flowering; T4, 50% N as neem-coated urea 1 WAT and rest N as 6 foliar sprays from active tillering to flowering; T5, 50% N as prilled urea at transplanting, 25% N as prilled urea at active tillering and rest N as 3 foliar sprays from panicle initiation (PI) to flowering; T6, 50% N as neem-coated urea at transplanting, 25% N as prilled urea at active tillering and rest N as 3 foliar sprays from PI to flowering; T7, 50% N as prilled urea 1 WAT, 25% N as prilled urea at active tillering and rest N as 3 foliar sprays from PI to flowering; T8, 50% N as neem-coated urea 1 WAT, 25% N as prilled urea at active tillering and rest N as 3 foliar sprays from PI to flowering; T9, 50% N at transplanting, 25% N at active tillering and rest N at PI all as prilled urea; T10, 50% N as neem-coated urea 1 WAT, 25% N as prilled urea at active tillering and rest N as soil application at booting stage. Rice variety ‘Amal-Mana’ with a common fertilizer dose of 75, 20 and 10 kg N, P2 O5 K2 O/ha was used. Use of neem-coated urea with 50% applied 1 WAT, and 25% each at active tillering and flowering, resulted in 40 more grains/panicle than current practice (T9). Nitrogen supplied through neem-coated urea resulted in higher (0.6 and 0.7) normalized difference vegetation index, net photosynthesis (>15 mmol/m2/s), and nitrate reductase activity than current N-management practices. Internal efficiency (IEN, 76–82 kg grain/kg N uptake) and partial factor productivity (PFPN, 72–87 kg grain/kg N applied) of N increased significantly with improved management strategy. Grain yield increased from 3.4 t/ha (existing recommendations) to 4.6 t/ha using 50% N as neem-coated urea 1 WAT, with similar results when the remaining N was applied to the soil or through foliar application.
