Abstract:
Producing antioxidant and nutrient-rich vermicompost (VC) from subtropical weeds can enhance agricultural sustainability and nutritional content. This work aimed at producing antioxidant and nutrient-fortified VC from four different subtropical terrestrial weed biomasses spiked with cow dung (CD) at ratios of 10%, 20%, and 30% employing the earthworm Eudrilus eugeniae over an experimental period of 56 days. A total of 13 treatments were established from dried CD and weeds Ageratum conyzoides, Urochloa mutica, Mikania micrantha, and Pteridium aquilinum. The physicochemical parameters pH, electrical conductivity (EC), total Kjeldahl nitrogen (TKN), total available phosphorus (P) and total available potassium (K) in the VC were in the range of 5.74-6.34, 2.95- 4 mS/cm, 8.654-13.96 g/kg, 55.1-85.47 mg/kg and 134.37-309.39 mg/kg respectively. The activities of exoenzymes, amylase, invertase, cellulase, protease, and dehydrogenase varied between 15.37-47.71 mu g glucose/g VC/h, 12.8-31.0 mu g glucose/g VC/h, 54.04-199.82 mu g glucose/g VC/h, 112.7-185 mu g/g VC/h and 16.96-22.28 mu g/g VC/h respectively. The total antioxidant capacity (TAC) was in the range of 3.07 +/- 0.084-5.68 +/- 0.25 Mm Trolox/cm3/g VC. The compost maturity parameters, C/N ratio, and seed germination index (GI)% indicated variation between 27.35-52.31 and 66.92%-123.42% respectively. VC produced from the weeds showed significantly higher TAC, N, P, K, and exoenzyme activities relative to control. Among various weed mixtures, U. mutica exhibited the highest reduction in the C:N ratio of 51.79%, while M. micrantha showed the least value at 26.47%. The C/N ratio of VC derived from U. mutica and P. aquilinum were within the optimal range. The VC obtained from U. mutica and CD (10:30, v/v) was found to be the most suitable concerning TAC, N, P, K, C/N ratio, exoenzyme activities, and GI%. It was concluded that the weeds U. mutica and P. aquilinum could be utilized as ideal substrates with CD for producing antioxidants and nutrient rich VC for field application.
