Huazhe Wang

Environmentally problematic Chinese medicinal herbal residues (CMHRs) can be sustainably treated by aerobic composting, but their high lignocellulose content limits efficiency. This study investigated the synergistic enhancement mechanism underlying the co-application of superphosphate and biochar. The results demonstrated that treatment with 5% superphosphate and 5% biochar exhibited the strongest synergistic effect, accelerating the degradation of hemicellulose and cellulose while yielding the highest germination index and humic acid-to-fulvic acid ratio. Microbial community analysis demonstrated that the optimal combination facilitated a successional transition from thermophilic degraders to maturity-associated Chloroflexota taxa. Consequently, predicted pathways associated with carbon conversion, aromatic precursor generation, organic nitrogen assimilation, and energy supply were more effectively coordinated. Structural equation modeling further confirmed that the amendments influenced organic matter degradation by regulating physicochemical conditions and drove microbial community reassembly through nutrient transformation, ultimately affecting humification. These findings provide mechanistic insights and practical dosage guidance for the regulation of composting in lignocellulose-rich CMHRs.