Vermistabilization of seaweeds using an indigenous earthworm species, Perionyx excavatus (Perrier)

The seaweeds, Gracilaria edulis, Turbinaria ornata and Ulva reticulata collected from Mandapam East Coast region of Tamil Nadu, India has been subjected to vermicomposting in combination with cowdung (CD) in 1:1 combination for 60 days under laboratory conditions. The percentage decomposition was ranged between 83.70 and 87.00 in the vermicompost of seaweed + CD combinations while it was 30.71 and 35.12% in worm-unworked compost where the decomposition rate of substrates with earthworms is significantly (P < 0.05) higher than the substrates without earthworms after 60 days. The physico-chemical characteristics of the vermicompost showed increased levels of electrical conductivity, NPK, while organic carbon, C:N ratio and organic matter content showed reduction in all seaweed + CD substrates. A higher amount of NPK of 1.38, 0.69 and 2.41% respectively in the vermicompost of Turbinaria ornata + CD was recorded with the respective percentage increase of 50.00, 68.29, and 34.64 over compost, and the values were significantly higher (P < 0.05) than in the initial substrate as well as the worm-unworked compost of Turbinaria ornata + CD. The activity of earthworms during vermicomposting of seaweed substrates significantly increased the total microbial population.