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.