Physico chemical evaluation of coffee husk, wastes of enset (Enset ventricosum), vegetable and khat (Catha edulis) through vermicomposting employing an epigeic earthworm Dendrobaena veneta (Rosa, 1886)

Abstract

The major objective of this 90 days vermicomposting work was to evaluate the performance of epigeic earthworms, Dendrobaena veneta, to alter and change four commonly dumped and littered solid wastes in Ethiopian cities and towns into a high quality vermicompost. The experiments were conducted in cylindrical plastic containers with 26 cm depth and 53 cm width under shade. All containers were perforated on the sides for aeration as well as bottom for leachate drainage purpose. The wastes were mixed with cow dung in 3:1 ratio and treated with D. veneta in the following waste and worm mass proportion: 9 kg of vegetable waste treated with 130 g of worms, 9 kg of enset waste treated with 130 g of worms, 5 kg of coffee husk treated with 70 g of worms, 8 kg of khat waste treated with 115 g of worms. Results from all beddings treated by this earthworm species show that total Kjeldhal nitrogen (TKN) increased by 68 to 95%, total potassium (TK) increased between 51 and 76%, total phosphorus (TP) increased between 76 and 100% while total organic carbon (TOC) decreased between 35.3 and 38.5%, the C: N ratio reduced between 62 and 65.5% and considerable reduction was also observed in pH value of the final product. The findings from this experiment indicate that vermicomposting could be one good option to improve solid waste management performance of Ethiopian cities and towns through the production of excellent bio-fertilizer for agronomic purpose.

Key words: Dendrobaena veneta, enset, Khat, vermicomposting.