Integrated Use of Vermicompost and NPSB Fertilizer Rates on Growth, Yield, and Yield Components of Common Bean (Phaseolus vulgaris L.) in Gimbo District, Southwest Ethiopia

A field experiment was conducted during the 2025 rainy season at Hamani and Shomba Kichib Kebeles, Gimbo District, Kaffa Zone, Southwest Ethiopia, to evaluate the effects of vermicompost and NPSB fertilizer rates on growth, yield, and yield components of the common bean variety Nasir. The study employed a randomized complete block design with three replications, comprising four levels of vermicompost (0, 3, 5, and 7 t ha ^-1 and four levels of NPSB (0, 50, 100, and 150 kg ha ^-1 ). The results indicated that combined applications of organic and inorganic fertilizers significantly influenced most growth and yield parameters, except for days to emergence. Application of 7 t ha ^-1 vermicompost with 100 kg ha ^-1 NPSB consistently produced the highest values of plant height, number of primary branches, nodules per plant, pod length, seeds per pod, pods per plant, hundred seed weight, biomass yield, grain yield, and harvest index at both sites. In contrast, the lowest values for these parameters were recorded under the control treatments. Site-specific responses were also observed. At Shomba Kichib, biomass yield was relatively higher even with 50 kg ha ^-1 NPSB alone, while maximum performance across both sites was achieved with the integrated application of 7 t ha ^-1 vermicompost and 100 kg ha ^-1 NPSB. Economic analysis revealed that this treatment provided the highest net benefits (93,445.55 ETB ha ^-1 at Shomba Kichib and 92,041 ETB ha ^-1 at Hamani) and the highest marginal rates of return (44.23% and 24.14%, respectively). Based on the findings of this study, it is recommended that farmers in the study areas adopt the integrated application of 7 t ha⁻¹ vermicompost with 100 kg ha⁻¹ NPSB fertilizer to improve the growth, yield, and economic returns of common bean production. This nutrient management strategy not only maximizes grain yield and harvest index but also enhances soil fertility, supports sustainable crop production, and increases farm profitability. Adoption of this practice can contribute significantly to food security, farmer income, and sustainable agricultural development in the region.