Bioconversion of perennial weeds of Chromolaena odorata (L.) R.M. King & H. Rob., Sida rhombifolia L., and Lantana camara L. by vermicomposting process

Abstract

Bioconversion of weeds through vermicomposting is getting momentum in sustainable organic farming, whilst mitigating negative impacts on the environment. The present study was conducted to find out the effect of three perennial weed species and the different ratio between weed to cow dung on the efficacy of Eisenia fetida and the physicochemical properties of vermicompost produced. The experiment was set up as a two-factor factorial completely randomized design with three replicates and 100% of cow dung was maintained as the control experiment. Factor one of the experiment was the weed species (Three weed species; Chromolaena odorata, Sida rhombifolia and Lantana camara) and factor two was the different ratio between weed and cow dung when preparing substrate by weight (four ratios; 100% weed, 75% weed + 25% cow dung, 50% weed + 50% cow dung, 25% weed + 75% cow dung). The results revealed that the interaction effect between weed species and the ratio of weed to cow dung on live biomass of earthworms (P<0.001), weight (P<0.001) and total dissolved solids (P<0.05) of the vermicompost was significantly different. The salinity and electrical conductivity of the vermicompost was significantly different among the main factors of weed species (P<0.01) and the ratio of weed to cow dung (P<0.01). The pH value of the vermicompost was significantly different only among the weed species (P<0.01). A significant difference was found between treatment combinations for the colour (P<0.01) of the vermicompost. However, the odour of the vermicompost harvested in different treatment combinations was not significantly different. The treatment combination of 50% Lantana camara and 50% cow dung performed better than the control for the growth and reproduction of earthworms. However, none of the treatment combinations performed better than the control for the weight of vermicompost. Furthermore, the pH of the vermicompost was not significantly different from the control. The treatment combination of 25% Chromolaena odorata and 75% cow dung was significantly different from the control on electrical conductivity, total dissolved solids and salinity of the vermicompost. According to the results of the experiment, the treatment combination of 50% cow dung and 50% Lantana camara L. by weight showed the highest efficacy on Eisenia fetida. Therefore, it can be concluded that the bioconversion of perennial weeds of Chromolaena odorata, Sida rhombifolia and Lantana camara were possible and 50% cow dung and 50% Lantana camara L. by weight produced the best quality vermicompost. Furthermore, it can be suggested that the perennial weed species of Lantana camara could be used to produce vermicompost effectively than the other weed species used in the study. Bioconversion of weed substrate without mixing of cow dung was not successful. Better performances of Eisenia fetida can expect by feeding partially degraded weed substrate.