EFFECTS OF VERMICOMPOST AND SELECTED CROPPING SYSTEM ON SELECTED SOIL PROPERTIES, YIELD AND YIELD COMPONENTS OF MAIZE (Zea mays L.) AND SOYBEAN (Glycine max L.) AT RARE IN HARAMAYA UNIVERS

In Ethiopia, including Haramaya district, low soil fertility remains a pressing concern, leading to reduced crop productivity due to nutrient depletion and inadequate use of agricultural inputs. Against this backdrop, a field experiment was conducted at Rare at Haramaya University to assess the effects of different rates of vermicompost application and cropping system on selected soil properties, yield, and yield components of maize (Zea mays L.) and soybean (Glycine max L.) during the 2022 cropping season. A factorial combinations of four levels of vermicompost (0, 2.5, 5.0, 7.5, and 10.0 t/ha) and three cropping systems (sole maize, sole soybean, and maize-soybean intercropping) were used in a Randomized Complete Block Design (RCBD) with three replications. Representative soil samples were taken at a depth of 0–30 cm before the application of treatments and after harvesting, and the agronomic data were collected at the appropriate time. The data were analyzed using SAS software version 9.3. The results showed that the main effects of both vermicompost rates and cropping system significantly improved soil total porosity, pH, total nitrogen, organic carbon, available phosphorus, exchangeable bases, cation exchange capacity, and bulk density. The main effects of vermicompost rates on maize were increased plant height, ear height, number of ears per plant, leaf length, thousand grain weight, grain yield, and above-ground dry biomass. The grain yield of maize was also significantly affected by the main effects of the cropping system. The main effects of cropping systems and vermicompost significantly affected the harvest index of maize. The study also showed that the main effects of cropping systems and vermicompost were highly significant on plant height, number of branches per plant, and the number of pods per plant of soybeans, but the grain yield and above ground dry biomass of soybeans were highly significantly affected by their interaction. The highest adjusted grain yield (10,168.66 kg/ha) with a net benefit of 289,149.145 ETB/ha was obtained from maize - soybean intercropping with 10 t/ha vermicompost. The application of 10 t/ha vermicompost was economically feasible and practically easy for farmers to improve soil fertility and increase production of maize and soybean under intercropping system in the study area.