Vermiconversion of biowastes with low-to-high C/N ratio into value added vermicompost.

Seaweed (T1), sugarcane trash (T2), coir pith (T3) and vegetable waste (T4) with cowdung (1:1, w/w) were vermicomposted using Eudrilus eugeniae (50 days). The pH in vermicomposts showed a decrease while electrical conductivity showed increment. The organic matter content, organic carbon, lignin, cellulose, C/N and C/P ratios in vermicompost was significantly lower than compost. Total NPK contents of vermicompost were significantly elevated (P < 0.05) with 12.04-63.75%, 19.05-31.58% and 22.47-42.55%, respectively. The significantly higher growth rate of 1.41 and 7.74 mg/worm/day was observed in T1 on 10th and 50th day respectively, with 23.91 initial C/N ratio; while it was 0.85 and 4.81 mg/worm/day in T4 with 69.81 initial C/N ratio. A similar pattern was reflected in cocoon production, hatchling success and hatchling number/cocoon. Results revealed that vermicompost quality, worm growth, and reproduction depend on C/N ratio. The study suggests that amendment materials like cowdung are necessary to reduce C/N ratio for effective vermicomposting.

Seaweeds as bioresources for vermicompost production using the earthworm, Perionyx excavatus (Perrier).

Fifteen days pre-decomposed seaweeds, Halimeda gracilis, Gracilaria corticata, Sargassum wightii and Sargassum swartzii spiked with cowdung (1:1) were vermicomposted using Perionyx excavatus for 60 days. The pH in the vermicompost showed insignificant reduction while electrical conductivity showed significant enhancement (P < 0.05). The reduction of organic carbon in vermicomposts ranged from -37.78 to -50.97% over worm-unworked composts. Total NPK contents showed significant increment (26.72-78.17%) in vermicompost over worm-unworked composts. The difference in percentage increase/decrease between physicochemical parameters was statistically significant (P < 0.001) and the same pattern was found between substrates. The total microbial population in vermicomposts was significantly higher than that of initial and composts of all seaweed + cowdung combinations (P < 0.001). The growth and reproduction of Perionyx excavatus in seaweed + cowdung combinations showed equivalent or higher rates when compared with cowdung signifying that Perionyx excavatus is well suited to convert seaweed and cowdung combinations into nutrient rich vermicompost.