Evaluation of Vermi Compost Integrated with Chemical Fertilizer on Yield and Yield Components of Maize (<i>Zia Maize</i>) 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 P<sub>2</sub>O<sub>5</sub>/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<sup>-1</sup>) occurred with the 100% vermin compost nitrogen equivalent treatment, while the lowest yield (7663 kg ha<sup>-1</sup>) 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<sup>-1</sup>) 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<sup>-1</sup> P<sub>2</sub>O<sub>5</sub> is recommended for maize production and soil improvement in this and similar agro-ecologies.