Influence of fine waste from dimension stone processing on vermicomposting

The fine wastes from dimension stone processing, generated when blocks of rock are cut into wall tiles, contain chemical elements essential for mineral enrichment of soil. However, these wastes have macro and micronutrients stocked in the crystalline structure of silicate minerals. The aim of this work was to use the vermicomposting process for increasing the release of these nutrients from dimension stone residues. In laboratory, different percentages of rock waste were mixed with an organic substrate, where worms (Eisenia foetida) were inoculated and maintained for 180 days. Vermicomposting occurred in all the treatments but was more efficient in the treatment with 25% of rock waste mixed into the organic matter. During the vermicomposting process, the rock powder added elements to the substrate, raising the concentration of Ca, Fe, Mn, Cu, Na and B. The pH-values increased, but remained at safe levels, even in the treatment with 50% of rock waste.