Studies on the combined use of organic and inorganic fertilizers for maize are lacking at Jimma conditions. Therefore, a field experiment was conducted to determine the effect of integrated uses of organic with inorganic fertilizers sources on productivity of quality protein maize (QPM) variety BHQPY545 at Kersa, Omonada woreda and Jimma on station, Southwestern Ethiopia during 2016 and 2017 main cropping seasons and one year validation at Omonada woreda. The experiment involved factorial combinations of inorganic and organic fertilizer with negative control, 150 kg ha-1 NPSZnB+140 kg ha-1urea top dressed, recommended NP2O5 (92/69 kg ha-1), 100% compost, 25% compost + 75% recommended NP, 50% compost + 50% recommended NP, 75% compost + 25% recommended NP and 100% compost + 100% recommended NP fertilizer which was laid out in randomized complete block design (RCBD). The compost was added based on N equivalency of recommended fertilizer rate. Data on yield and yield components of maize were subjected to ANOVA using SAS version 9.3. The over location and year highest grain yield (8443 kg ha-1) and above ground biomass (21.52 t ha-1) was obtained from 100% compost + 100% recommended NP fertilizer. Partial budget analysis revealed 100% compost + 100% recommended NP fertilizer realized the maximum net return (39,718 ETB) with marginal rate of return (94%). From farmers decision point and current on farm input availability and technical feasibility and economic analysis, 92/69 kg ha-1 N/P205 fertilizer application taken as optimal fertilizer application and recommended for production of BHQPY545 in Jimma area and other similar humid agro-ecologies of southwestern Ethiopia.
Keywords: Grain yield, inorganic fertilizer, organic fertilizer, recommended fertilizer rate, soil health.