Earthworms not only turn over wastes into worm-casts in the process of vermicomposting but also multiply enjoying conducive ecological conditions vis-à-vis suitable temperature, pH, oxygen and food. The overcrowding reduces population density, hamper body growth and reproduction of earthworms. The present study has attempted to establish the optimum inoculation number of a selected indigenous earthworm species Perionyx excavatus which is required for obtaining maximum decomposition rate as well as recovery number of earthworms. Different experimental trails were carried out with various number of this species (30, 60 and 90) in a fixed amount of selected organic waste materials. The Combined Index (CBI) has been formulated in order to evaluate and also to assess two biological attributes viz. the decomposition rate (DR) and recovery number of earthworms (RN) after 45 days of experiment. Equal weightage was assigned both to decomposition rate (DR) and recovery number of earthworms in the construction of Combined Index (CBI). The experiment, carried out using 60 earthworms resulted maximum decomposition rate (%) as well as recovery number of earthworms and also was found statistically significant at 0.01 level.

Keywords: Optimum inoculating number, decomposition rate, earthworm recovery number, combined index