Effect of levels of nitrogen and forms of pre-conditioned urea on grain yield and N status in plant and soil of rainfed rice (Oryza sativa)

An experiment was conducted on rainfed direct-seeded rice (Oryza sativa L.) during the rainy (kharif) season of 1992 and 1993, to find out the effecti veness of different blending materials for preconditioning of urea at 2 lev els of N on grain yield and N status in plant and soil. Pre-conditioning of urea with farmyard manure (FYM) + soil (1:3:1) gave significantly higher g rain yield and N accumulation in plant than that of prilled urea and soil m ixed urea (1:3);the increase in yield over the latter 2 treatments being 19 .1 and 14.6% respectively. Pre-conditioning of urea with FYM + soil also re corded the maximum N contents throughout the crop period and soils N Status at harvest. Preconditioning of urea with saw-dust + soil (1:3:1) and rice straw dust + soil (1:3:1) were equally effective as pre-conditioning with F YM + soil in influencing the grain yield and N accumulation of rice. The gr ain yield and N accumulation of rice increased significantly by 21.5 and 32 .3% respectively with the application of 120 kg N/ha compared with that of 60 kg N/ha.