Effect of pre-composting on seed viability and subsequent vermicomposting of an invasive alien weed,Alternanthera ficoidea (L.) P. Beauv.

Abstract

In the present study, the suitability of an invasive weed, Alternanthera ficoidea (L.) P. Beauv. (AF) biomass for vermicomposting has been tried by subjecting three different combinations of the weed and cow dung (CD) through 28 days pre-composting followed by 50 days vermicomposting with Eudrilus eugeniae. The maximum temperature recorded in P1 (1CD:1AF), P2 (2CD:1AF) and P3 (1CD:2AF) during pre-composting was 66, 62 and 67°C respectively. The seed viability study using pre-composted substrates, for weed seeds if any, revealed that there were no seedlings appeared in P1 and P3 up to 60 days, while 41.57% germination was observed for P2 compared to initial non pre-composted substrate. The C/N ratio in all vermibed combinations was found to decline significantly (P<0.05) at the end of vermicomposting from the initial levels as well as from the substrate combinations without earthworms (control). The lowest C/N ratio of 14.56 was found in V2 (2CD:1AF) followed by V1 (1CD:1AF) and V3 (1CD:2AF). The growth and reproduction of Eudrilus eugeniae was well supported by the combination of V1 and V2 which were significantly higher than V3 (P<0.05). The tests on germination of Alternanthera ficoidea seeds in vermicompost confirmed that there were no viable seeds in V1 and V3 vermicomposts while V2 vermicompost showed 16.77% viability in comparison with the control (non pre-composted). Based on germination of weed seeds in vermicompost, reduction of C/N ratio, growth and reproduction of Eudrilus eugeniae during vermicomposting, it is concluded that 28 days pre-composting followed by 50 days vermicomposting of 1:1 (CD+AF) ratio of substrate combination is suitable for utilizing the biomass of Alternanthera ficoidea for nutrient recovery and vermicompost production without any harm to the environment.