Influence of earthworm to organic waste ratio and cow manure mixture in vermicomposting process using Eisenia fetida

A conventional composting process required long duration of 2-3 months to degrade organic waste. Composting duration reduction could be done using earthworms as decomposers. This study was to determine the compost production of garden waste using vermicomposting process and to determine the influence of earthworm number and the composition of organic waste in vermicomposting process. Sixteen rectangular reactors were used with a volume of 8 L using Eisenia fetida earthworm. The reactors used in duplicate reactors and operated in 60 days. Twelve reactors were set up in which six reactors used only garden waste and the other six reactors used garden waste mixed with cow manure by a composition ratio of 2:1, whereas, four reactors acted as controls without earthworm. Earthworm to organic waste ratio was varied in 15, 35 and 60 g/kg based on dried mass. Several parameters were analyzed i.e. ammonia nitrogen (NH₃-N), nitrate nitrogen (NO₃-N), Total Kjeldahl Nitrogen (TKN), C/N, pH and moisture. The results showed compost production of garden waste by vermicomposting process were 58-85%. Moreover, higher compost products and lower C/N ratio were achieved by reactors with garden waste and cow manure mixture compared to the garden waste vermicomposting reactors. In term of earthworms to waste ratio, the earthworm ratio of 15 g/kg gives the highest degradation rates of waste. Organic nitrogen reduction was significantly (P ≤ 0.05) increased with increasing earthworm to organic waste ratio. Moreover, organic waste degradation and C/N reduction were significantly (P ≤ 0.05) increased for garden waste and cow manure mixtures.