Optimization of fertilizer doses for Kharif rice, Oryza sativa L on deltaic soils of Andhra Pradesh

Field experiments were conducted on rice, Oryza sativa L for three consecutive Kharif seasons viz 2006, 2007 and 2008 on Godavari alluvials (Vertic chromusters) at Andhra Pradesh Rice Research Institute, Maruteru with an objective to revise the existing fertilizer doses of major nutrients for Kharif rice in Krishna Godavari delta regions of AP. There was increase in grain yield by 13.1 and 6.3 per cent due to increase in recommended dose of N from 100 to 125 and 125 to 150 per cent respectively. Increase in P and K doses from 100 to 125 per cent improved grain yield significantly. Higher agronomic efficiency and energy use efficiency of K and P were observed with first incremental dose (125%). Increase in levels of N, P and K by 50 per cent resulted in an additional net income of 6987, 2260 and 3567 respectively. Study showed that 50 per cent increase of N, P and K over the existing doses of 60, 40 and 40 kg/ha respectively appeared to be the optimum doses for Kharif rice in deltaic alluvial soils of Andhra Pradesh.