Abstract

                                A field investigation was made to study the level and time of initial fertilizer N application to irrigated dry and wet seeded rice to maximise N use efficiency and yield. Two experiments were conducted during kuruvai (June to September) and samba seasons (September- January) on dry seeded rice and one experiment in thaladi season (October to February) on wet seeded rice. Nitrogen application caused a general increase in the yield of rice, however, the response was at a decreasing rate. The economic dose of N was found to be 95.8, 122.5 and 123.3 kg ha to get a grain yield of 51.8, 34.5 and 52.5 q ha' in kuruvai, thaladi and samba seasons respectively. The initial dose of 50 per cent of total N could be applied 20 days after sowing (DAS) to kuruvai and samba crops when dry seeding was done and 10 DAS to thaladi crop when sprouted seeds were sown on puddied field, to maximise the grain yield and N use efficiency.

Key words : Direct seeded rice, N dose and timing, production function