Effects of salt content on degradation and transformation performance of kitchen waste during vermicomposting

Vermicomposting can effectively treat kitchen waste, however, the impact of salt in kitchen waste on vermicomposting performance remains unclear. This study established a control without salt and three experiment treatments with varying salt concentrations (0.5%, 1% and 1.5%). Results showed that when salt content exceeded 0.5%, earthworm biomass and organic matter degradation rates were significantly lower (P<0.01) than the control, with ammonium nitrogen levels rising and microbial abundance significantly decreasing (P<0.01) by day 10. In the 1.5% salt treatment, earthworm weight decreased by 25.8%, and organic matter degradation rate reached only 62.37% (P<0.05). The production of humic substances was reduced by the addition of salt. Bacterial community assembly in all treatments were primarily governed by homogeneous dispersal and selection, it exhibited greater stochasticity under high salt stress. This study suggests that high salt concentrations negatively affect vermicomposting performance by altering degradation pathways and inhibiting the transformation of dissolved organic matter.