Urea-mediated moderate-temperature incubation: a novel strategy for rapid phytotoxicity alleviation in green wastes dominated by microbial regulation of organic matter transformation

Green waste substrate utilization is severely restricted by inherent phytotoxicity, and efficient rapid detoxification strategies are urgently needed. This study proposed a urea-mediated moderate-temperature incubation method, evaluated the detoxification efficiency of different urea application rates (0–2.4%, w/w), and further clarified the underlying mechanisms via chemical composition analysis and metagenomic profiling. The addition of 1.6% urea produced the greatest detoxification effect, increasing the germination index (GI) from 0% to a peak of 140.3% within 72 h and reducing the treatment time by more than 80% compared with conventional composting, which typically takes more than 30 days. Cultivation tests verified that detoxified green waste substrates supported lettuce biomass and photosynthetic performance comparable to commercial peat. Urea hydrolysis formed a high-NH 4 + alkaline environment, reshaping microbial communities and selectively enriching ammonium-tolerant Actinobacteria and lignin-degrading Basidiomycota . Microbial nitrogen metabolism was shifted to enhanced assimilation and denitrification with inhibited nitrification, promoting conversion of urea nitrogen into stable organic forms and accelerating the degradation of toxic phenolics and organic acids. This work elucidates the rapid detoxification mechanism of urea incubation from microbial functional reconstruction and organic matter transformation, thereby providing both a theoretical basis and a scalable technical pathway for the high-value utilization of green waste.