Nutrient changes and biodynamics of Eisenia fetida during vermicomposting of water lettuce ( Pistia sp.) biomass: a noxious weed of aquatic system

Abstract

This paper reports the results of vermicomposting of water lettuce biomass (WL) spiked with cow dung at ratios of 20, 40, 60, and 80 % employing Eisenia fetida. A total of four treatments were established and changes in chemical properties of mixtures were observed. Vermicomposting caused a decrease in pH, TOC, volatile solids, and C/N ratio by 1.01–1.08-fold, 0.85–0.92-fold, 0.94–0.96-fold, 0.56–0.70-fold, respectively, but increase in EC, _totN, _totP, _totK, _totCa, _totZn, _totFe, and _totCu, by 1.19–1.42-fold, 1.33–1.68-fold, 1.38–1.69-fold, 1.13–1.24-fold, 1.04–1.11-fold, 1.16–1.37-fold, 1.05–1.113-fold, 1.10–1.27-fold, respectively. Overall, the treatment with 60–80 % of WL showed the maximum decomposition and mineralization rates. The earthworm showed the growth and reproduction rate in considerable ranges in all treatment setups but setups with 60–80 % WL proportion exhibited the optimum results. Results reveal that biomass of water lettuce can be utilized effectively for production of valuable manure through vermicomposting system.

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