Effect of N application timings on nitrogen use efficiency of rice

Field experiments were conducted during two dry seasons of 2001 and 2002 on sandy loam soils to study the effect of nitrogen application timings on nitrogen use efficiency of irrigated rice. Application of nitrogen in three splits i.e. 1/3 at 7days after transplanting + 1/3 at maximum tillering and 1/3 at panicle initiation stage produced maximum grain yield of 4881 kg ha-1 which was at par with N application based on leaf colour chart. This N application timings resulted in the increase of yield by 1582 kg ha-1 which is 47.9% higher than recommended practice of N application i.e. 1/2 basal + 1/4 at maximum tillering and 1/4 at panicle initiation Highest values of N uptake (105.9 kg ha-1), agronomic use efficiency (28 kg grain kg-1 N applied) and N utilization efficiency (72 kg N kg-1 N applied) were recorded by the new timing of N application. The N utilization efficiency was 1.7 times higher than that obtained by the recommended practice of N application.