Vermicomposting of patchouli bagasse—A byproduct of essential oil industries employing Eisenia fetida
Refad Ahmed, Hemen Deka
Abstract
This study was designed to explore the vermicomposting potential of patchouli bagasse (PB) and cowdung (CD) mixtures in different treatment ratio employing Eisenia fetida under the 50 days of trial. The results recorded a decrease in pH (8.4–24.1%), organic carbon (25.7–46.2%), C/N ratio (62.9–82.3%), C/P ratio (35.1–58.94%), total K (41.12–87.37%) whereas increase in electrical conductivity (4.8–57.9%), ash contents (31.6–67.3%), total N (2.0–3.1 folds), available P (1.1–2.1 folds), total Ca (1.5–2.0 folds) and Mg (3.0–3.5 folds). The vermicomposting end products showed permissible level of heavy metals such as Fe (53 ± 0.73 to 71.3 ± 0.89 mg/kg), Mn (2.4 ± 0.02 to 8.81 ± 0.21 mg/kg), Zn (0.78 ± 0.02 to 2.1 ± 0.02 mg/kg), Cu (0.72 ± 0.01 to 0.9 ± 0.02 mg/kg), Cr (0.17 ± 0.02 to 0.27 ± 0.01 mg/kg) and Ni (0.62 ± 0.01 to 1.15 ± 0.03 mg/kg); enhancement in the beneficial bacterial population (1.6–4.4 folds), earthworm numbers, and biomass (1.08–2.6 folds). Fourier transform infrared (FT-IR) had confirmed the humification of PB materials, reduction in aromatic compounds and elevation in nitrogenous substances in the end products. Finally, germination index (GI) values (>100%) also confirmed the absence of phytotoxic compounds and the maturity of the vermicomposted materials. Based on vermicompost production, the treatment ratio 5:5 (T6) and 4:5 (T7) has been found to be suitable combination for vermicomposting of PB with CD.