Determination of the Application Rate of Conventional Compost Integrated with Chemical Fertilizer on Maize (Zia Maize) Yield in Dugda District of East Shoa Zone, Oromia

Abstract

Integrated soil fertility management is the application of inorganic in combination with organic fertilizer to maintain soil fertility and improve crop yield. A study was conducted in East Shoa Zone, Dugda District on farmers' fields to determine the combined effects of conventional compost as organic fertilizer and NPS as inorganic fertilizer on soil chemical properties and maize production. There were five treatments: Recommended rate of inorganic fertilizer, 100, 75, 50 and 25% equivalent level of compost for nitrogen fertilizer. Recommended level of 69 P₂O₅/ha were equally applied at all treatments. The experiment was laid out in RCBD design with three replications. The analysis of variance showed no significant differences (P > 0.05) in maize grain yield response. However, the highest maize grain yield (8728.20 kg ha^-1) was obtained from treatment two that received 100% equivalent compost for nitrogen fertilizer and the lowest (8325 kg ha^-1) was obtained from treatment one where recommended chemical fertilizer alone was applied. Composite Soil samples were also collected before compost application and after harvesting to evaluate the residual effect of compost on soil physiochemical properties. Accordingly, laboratory analysis showed no significance differences (P > 0.05) in total N, available P, soil organic carbon and CEC. However, analysis of variance of post-harvest composite soil samples indicated significant differences on soil available P, OC, TN and CEC as compared to initial soil sample. On the other hand, partial budget analysis was done to determine economically optimum rate of compost integrated with chemical fertilizer. Accordingly, the highest net benefit (126527 Eth. Birr ha^-1) was recorded for treatment two where 100% compost (4.6t/ha) plus 150kg/ha NPS fertilizers were applied. The highest marginal rate of return (146) was also obtained from the same treatment. Therefore, the present study showed that combined application of organic and NPS fertilizer enhanced maize productivity and soil fertility status in the study area. Hence combined fertilizer application of 4.6 t ha¹ conventional compost integrated with 150 kg ha^-1 NPS improved maize productivity and soil chemical properties, and recommended for the study area and similar agro-ecology.