Composting-vermicomposting of green waste processing spiked with cow dung

To accelerate the resource utilization of green waste, this study considered the combination of composting disposed green waste mixed with cow dung by employing Eisenia fetida. After pre-composting green waste for 60 d, seven treatments were prepared for vermicomposting by mixing green waste (pre-composted materials) with cow dung at ratios (dry weight) of 0(T0, without earthworms as a control), 0(T1), 2%(T2), 4%(T3), 6%(T4), 8%(T5), and 10%(T6). Growth and reproductive performance of E. fetida in different treatments were measured after 60 d of vermicomposting with a plant cultivation experiment (Calathea veitchiana) being conducted to estimate the quality and maturity of the final vermicompost. A complete random design with treatments of T0, T1, T2, T3, T4, T5, T6 and 30 replications. At the end of cultivation, five plants were randomly selected from each treatment and were analyzed for the plant growth parameters. Results showed that final products of all treatments with earthworms (T1-T6) were significantly higher (P < 0.05) in nutritional element content and plant growth parameters than T0. Moreover, in comparison with pure green waste treatment (T1), treatments with the addition of cow dung significantly (P < 0.05) increased the rate of growth and reproduction of earthworms, significantly (P < 0.05) accelerated the degradation rate of cellulose and lignin, and significantly (P < 0.05) increased nutrient contents of the final vermicompost product. Moreover, with the addition of cow dung, significantly (P < 0.05) increaseed in microbial population (bacteria, fungi, and actinomycetes) in vermicomposts were recorded. Among treatments T2-T6, T5 and T6 had significantly (P < 0.05) higher fertilizer value for the final product as well as significantly (P < 0.05) higher growth and fecundity of E. fetida. Thus, the combination of both processes (composting + vermicomposting) could be suitable for disposing cow dung and green waste with the green waste mixed with cow dung treatments at rates of 8% (T5) and 10% (T6) improving the efficiency and quality of the vermicompost.