Nitrogen management in transplanted rice (Oryza sativa) in mid hill acidic soils of Sikkim Himalayas Avasthe Ravikant ICAR Research Complex for NEH Region, Sikkim Centre, Tadong, Gangtok, Sikkim, 737 102. Corresponding author: E-mail: ravisikkim@yahoo.co.in
Abstract Two field experiments were conducted at Tadong in Sikkim in the humid mid-hill acidic soils during rainy (kharif) season of 2004, 2005 and 2006 to optimize the rate, source and schedule of nitrogen management for increasing the yield and nitrogen-use efficiency of transplanted rice (Oryza sativa L.) under 9 schedules, 4 rates (0, 80, 120 and 160), 3 nitrogen sources (urea, farm yard manure and neem cake-coated urea) in comparison with farmers’ practices. N application @ 80 kg/ha as 1/4 N 10 days after transplanting (DAT) + 1/4 N at maximum tillering (MT) + ½ at panicale initiation (PI) recorded the highest yield (5.44 t/ha), recovery efficiency (82%) and agronomic efficiency (47.9 kg grain/kg N applied). The grain yield increased with increase in the N rate from 80 to 160 kg/ha. Conjunctive application of FYM and urea increased the N uptake by 11.1 to 26.2%, recovery efficiency (11.1 to 46.7%) and agronomic efficiency (5.4 to 14.8%). Basal application of FYM @ 2.5 t/ha and top-dressing 80 kg N/ha through urea as 1/4 N at 10 DAT + 1/4 N at MT+ ½ at PI stage recorded the highest recovery efficiency (66.3%) and agronomic efficiency (38.7 kg grain/kg N applied). At 120 kg N/ha neem cake increased the recovery efficiency by 12.1 and 37.6% and agronomic efficiency by 9.9 and 15.8% over N120 with and without FYM. Farmers’ practice of application of FYM basal @ 5 t/ha and FYM @ 2.5 t/ha along with top-dressing of DAP @ 40 kg/ha at PI gave low yield and N-use efficiency. Top Key words Acidic soils, Farmyard manure, Mid hill, Rates, Schedule, Sikkim Himalayas, N sources, Urea. Top |