Inadequate soil fertility management techniques and nutrient deficits are the primary causes of the Gereb Giba area's that decreased onion productivity. As a result, fertilizer applications are a crucial input to boost onion yields, with the rate of application primarily determined by the soil's fertility. The research was conducted with the intention of the objective is to assess the impact of NPS and goat dung fertilizer combinations on onion yield and yield-related characteristics, as well as the physicochemical parameters of the soil and their economic feasibility. The results of the analysis of variance indicate that there is a significant difference between the 16 treatments for the combined application of inorganic and organic fertilizers in response to onions. The soil textural class of the target areas is sandy clay loam, which has low levels of organic carbon and total nitrogen. The study's findings indicated that the application of 84 kg N ha-1+76 kg P2O5 ha-1+14 kg sulfur ha-1 with 7.5 t ha-1 organic was superior in terms of production yields, as was the case with 63 kg N ha-1+57 kg P2O5 ha-1+10.5 kg sulfur ha-1 and 84 kg N ha-1+76 kg P2O5 ha-1+14 kg sulfur ha-1 fertilizer with 15 t ha-1 goat dung. On the other hand, 21 kg N ha-1+19 kg P2O5 ha-1+3.5 kg sulfur ha-1 fertilizer with 3.75 t ha-1 goat dung was found to be inferior. Therefore, based on the cost-benefit analysis and its production, farmers in the Gereb giba area and similar agro-ecologies are advised to apply 15 t ha-1 of goat dung along with 63 kg N ha-1, 57 kg P2O5 ha-1, and 10.5 kg sulfur ha-1 (150 kg/ha) of inorganic fertilizer. This combination is both economically feasible and highly recommended.

Keywords: Combination of organic and inorganic fertilizers; economic feasibility; onion variety; yield and yield related traits