Characterization of Vermicompost for Major Plant Nutrient Contents Made from the Combination of Different Organic Materials in North Shewa Zone, Oromia, Ethiopia

Chemical fertilizers contribute significantly to environmental degradation, soil fertility loss, reduced agricultural productivity, soil degradation, and climate change. To address these issues, an experiment was conducted at Fitche Agricultural Research Centre to characterize nutrient content in vermicompost prepared from various feedstock materials. A vermiculture house (4 x 5 m) was constructed with worm bins made of shallow concrete boxes (0.4 m depth, 0.5 m width, 1 m length). It was covered with corrugated iron sheets and mesh wire to protect the worms from sunlight, rain, and predators. The treatments included barely straw, faba bean straw, teff straw, wheat straw, and a mixture of all straws. Red worms (Eisenia fetida) were used to compost the substrates, which were chopped and mixed in a 2:1 ratio (cattle manure to crop residue by weight). Water was sprayed to maintain optimum moisture. Vermicomposting started by releasing worms into the substrate. Mature vermicompost samples were collected and analyzed. Results showed pH values in the slightly acidic range and electrical conductivity suitable for earthworm survival and plant growth. Organic carbon, C: N ratio, and cation exchange capacity data indicated promising soil-improving properties. The highest C: N ratio (20.57) was observed in teff and wheat straw compost; the lowest in faba bean compost. Available phosphorus and potassium were highest in faba bean straw compost. All vermicompost types were rich in exchangeable cations (Ca, Mg, K, Na). Vermicompost from faba bean, barley, and teff straw exhibited the highest macro nutrient content, suggesting their potential to correct nutrient imbalances and improve soil fertility, production, and productivity.