Nitrogen application strategy and use efficiency in rice

摘要

Field experiments with rice cv. IR 64 were conducted at Aduthurai, Tamil Nadu, in kharif (June-October) 1994 and 1995 to study the response to different nitrogen (N) application strategies. Basal incorporation of green manure (Sesbania rostrata) at6.25 t ha-1 in combination with application of 150 kg N ha-1 as urea in 5 splits at 7 days after transplanting (25 kg), active tillering (50 kg), panicle initiation (25 kg), mid-heading (25 kg) and first flowering (25 kg) resulted in the highest dry matter production, N content, N uptake and grain yield. The N use efficiency parameters calculated when only inorganic N was applied showed sub-optimal values of physiological efficiency and agronomic efficiency. The factor productivity for applied N, as a useful measure of N use efficiency ranged from 21.0 to 34.7.