Soil fertility management at Wulbareg-2022

Common bean is important cash crop and source of protein for farmers in Ethiopia. Low available phosphorus, total nitrogen, sulfur, and lack of selected varieties are major limiting factors for common bean production in the study area. Thus, the experiment was conducted at Wulbaregi District in 2022 main cropping season (July-October), to evaluate the effect of Blended NPS fertilizer rates and Rhizobium inoculation on the yield and yield components of common bean varieties to identify an economically appropriate combination of the factors that give maximum yield. Factors studied were four common bean varieties (HD, SER119, SER125 and Rori), three levels of blended NPS fertilizer rates (0, 100, 200 kg/ha) and two levels of Rhizobium (with and without). Randomized Complete Block Design in factorial arrangement with three replications was used. The Phenological, growth, yield and yield components data were collected and analyzed with SAS version 9.0 GLM model. The result revealed that the varieties had significant differences in days to physiological maturity, harvest stand count, pods per plant, seeds per pod, and harvest index. The NPS rates significantly influenced all studied parameters except stand count. The highest number of days to flowering (42), days to physiological maturity (90), hundred seeds weight (27.62g), above-ground biomass (7.76ton/ha) and grain yield (3.36ton/ha) were obtained from NPS 200kg/ha. Rhizobium inoculation significantly influenced the physiological maturity, nodulation, branch numbers, and harvest index of common bean. The interaction of NPS rates with varieties on nodulation, plant height, primary branch number, pods per plant, and harvest index was significant. The highest number of total nodule, effective nodule and dry weight for SER125and harvest index for HD were obtained from the combination of NPS 200kg/ha. Rhizobium inoculation with Varieties significantly influenced pods per plant and seeds per pod for variety HD with highest pods per plant (17.37) and seeds per pod (5.96). Significantly highest harvest index (44%) was obtained from the combination of Rhizobium with NPS rate of 200kg/ha. Rhizobium inoculation with NPS rate of 200kg/ha and variety HD produced the highest number of seeds per pod (6.8). The economic analysis showed the highest net returns from NPS rate of 100 kg/ha with a net benefit of 77,228ETB/ha and marginal rate of return of 422.3%. Thus, it can be recommended to enhance productivity in the study site and areas with similar agro-ecology. Since no significant difference was observed among the varieties any of them can serve as alternative choices based on preferences of the farmers. Moreover, inoculation did not enhance grain yield and as a result farmers can grow the bean crop without inoculation to avoid the extra expense. However, the result of the present study need to be evaluated and reconfirmed preferably in more sites and with quality check-up of the inoculant to reach a conclusive recommendation.