Relative influence of organic manures in combination with chemical fertilizer in improving rice productivity of lateritic soil

Field experiments were carried Out to evaluate relative efficacy of organic manures in combination with chemical fertilizers (CF) against application of only CF in improving the productivity of rice in a lateritic soil. Organic manures were applied at 50 percent recommended N equivalent basis and balanced with chemical fertilizers to attain the recommended N, P and K levels. The effect of three commercial manures: processed city waste (PCW) + CF, vermicompost (VC) + CF, and oil cake pellets (OC) + CF and locally available farmyard manure (FYM) + CF were assessed in comparison to chemical fertilizer. Results indicate that organic manure treatment on balancing with chemical fertilizers to the recommended dosage of N, P and K favored higher dry matter production and grain yield as compared to application of only CF. Among the different manures tested, the increases in yield was maximum with FYM + MC + CF and minimum with OCP + CF. The percentage increase in grain yield of different organic treatment Plus chemical fertilizer over chemical fertilizer only varied from, 4% for OC + CF and 26% for FYM + MC + CF, respectively. The uptake of N, P and K by rice plants was significantly greater in treatments with organic manures in combination with CF. Among the commercial manures PCW + CF showed high promise and emerged as a potential alternative to FYM. (C) 2003 by The Haworth Press, Inc. All rights reserved.