Evaluation of Vermi Compost Integrated with Chemical Fertilizer on Yield and Yield Components of Maize (Zia Maize) in Adami Tulu District of East Shoa Zone, Oromia

Integrated soil fertility management employs a combination of inorganic and organic fertilizers to sustain soil fertility and boost crop yields. This study was carried out in the East Shoa Zone, Adami Tulu J/K District, on farmers' fields to evaluate the combined effects of vermin compost (organic fertilizer) and NPS (inorganic fertilizer) on soil chemical properties and maize production. Five treatments were used: the recommended inorganic fertilizer rate, and vermin compost applied at 100%, 75%, 50%, and 25% of the nitrogen equivalent. All treatments received an equal recommended dose of 46 kg P₂O₅/ha. The experiment was arranged in a randomized complete block design with three replications. Analysis of variance revealed significant differences (p < 0.05) in maize grain yield among treatments. The highest yield (8205.20 kg ha⁻¹) occurred with the 100% vermin compost nitrogen equivalent treatment, while the lowest yield (7663 kg ha⁻¹) was from the recommended chemical fertilizer alone. Composite soil samples collected before compost application and after harvest assessed vermin compost’s residual effects on soil physicochemical properties. Post-harvest analysis showed that soil pH was not significantly affected (p > 0.05) by vermin compost application rates, but soil organic carbon (SOC), cation exchange capacity (CEC), available phosphorus, and total nitrogen (TN) were significantly improved (p ≤ 0.05). Initial soil analysis indicated low SOC, CEC, available phosphorus, and TN, suggesting a positive residual effect from vermin compost. Economic analysis determined the optimum rate of vermin compost integrated with chemical fertilizer, with the highest net benefit (126,527 Ethiopian Birr ha⁻¹) and marginal rate of return (146%) observed in the 100% vermin compost plus NPS treatment. The study concludes that integrating organic and NPS fertilizers enhances maize productivity and soil fertility in the study area. Therefore, applying 100% vermin compost nitrogen equivalent combined with 46 kg ha⁻¹ P₂O₅ is recommended for maize production and soil improvement in this and similar agro-ecologies.