Changes in nutrient and heavy metal content levels of sawdust due to vermicomposting by Allomyrina dichotoma subsp. tunobosonis

Vermicomposting of organic waste plays an important role in integrated waste management and sustainable agricultural development. This study aimed at investigating the transformation of nutrients and heavy metals during vermicomposting of fermented sawdust substrate using the beetle Allomyrina dichotoma subsp. tunobosonis. By the end of vermicomposting, the substrate was significantly modified, with increase in pH and decrease in both organic matter and electrical conductivity. Potassium oxide (K₂O₅) content was found to have significantly increased, whereas no significant difference in the quantities of other nutrients (N, P₂O₅, CaO and MgO) was observed between the substrate and vermicompost. In addition, Cd content significantly decreased compared to other heavy metals (Cu, Zn, Cr, Ni, and Pd) during vermicomposting. These findings suggest that the produced vermicompost, with low concentrations of heavy metals, may be a suitable potting medium for plant growth.