Efficacy of various organic manures and chemical fertilizers to improve paddy yield and economic returns of rice under rice-wheat cropping sequence

A judicious integration of inorganic fertilizers with organic residues, composts, biofertilizers and other plant tonics may help to improve crop yield and soil productivity in different cropping systems. A field experiment was planned at Rice Research Institute, Kala Shah Kaku, Pakistan involving the use of NPK fertilizers alone and in combination with green manure (Sesbania rostrata) or farm yard manure (FYM) or compost in rice-wheat cropping sequence to evaluate the effects of the substitution of inorganic fertilizers with organic manures on yield and yield attributes as well as economy of rice during 2009. Eight treatments comprising of T1: Green manure @ 12.5 t per ha, T2: FYM @ 12.5 t per ha, T3: Compost (rice and wheat crop straw/ residues) @ 12.5 t per ha, T4: NPK @ 133-85-62 kg N, P2O5 and K2O per ha, T5: Green manure @ 12.5 t per ha + NPK @ 66-42-31 kg N, P2O5 and K2O per ha, T6: FYM @ 12.5 t per ha + NPK @ 66-42-31 kg N, P2O5 and K2O per ha, T7: Compost @ 12.5 t per ha + NPK @ 66-42-31 kg N, P2O5 and K2O per ha T8: Control (no fertilizer and organic manures) were arranged using randomized complete block design (RCBD) with three replications. Application of NPK and its combination with compost, green manure and FYM increased the rice yield significantly. Among different combinations, Compost @ 12.5 t per ha + NPK @ 66-42-31 kg N, P2O5 and K2O per ha showed superiority in yield and yield contributing parameters followed by Green manure @ 12.5 t per ha + NPK @ 66-42-31 kg N, P2O5, K2O per ha and FYM @ 12.5 t per ha + NPK @ 66-42-31 kg N, P2O5, K2O per ha over others. Lowest paddy yield was observed in case of FYM @ 12.5 t per ha followed by Green manure @ 12.5 t per ha and Compost @ 12.5 t per ha. Higher profit was obtained when inorganic fertilizer was combined with organic manures. It was suggested that combined application of synthetic fertilizers and organic manures proved more efficient in improving that combined application of synthetic fertilizers and organic manures proved more efficient in improving paddy yield and economic returns of rice as compared to their separate use.