Arbuscular Mycorrhizal and Trichoderma longibrachiatum Enhance Soil Quality and Improve Microbial Community Structure in Albic Soil Under Straw Return

Albic soil is acidic and nutrient-deficient, resulting in low soil fertility that significantly limits the sustainable utilization of arable land. Microbial inoculants have emerged as promising biotechnological interventions to enhance soil quality by stimulating microbial activity and facilitating nutrient accumulation. This study focused on improving the characteristics of albic soil through the incorporation of straw residues combined with inoculation treatments involving arbuscular mycorrhizal fungi (AMF) and <i>Trichoderma</i>. Four experimental treatments were established: a Control (CK), single inoculation with AMF (AM), single inoculation with <i>Trichoderma</i> (TL), and a combined inoculation of both (AT). The investigation focused on assessing the synergistic effects of the AT treatment on albic soil chemical characteristics and its microbial community structure. The AT treatment significantly elevated rhizosphere soil pH, TN, and TP by 3.8%, 19.2%, and 10.9%, respectively, relative to the Control. The AT treatment markedly enhanced soil cellulase, β-glucosidase, and lignin peroxidase activities by 24.9%, 77.6%, and 36.7%, respectively, and increased the SQI by 78.9% compared to CK. Furthermore, the AT treatment led to a higher correlation abundance of <i>Sphingomonas</i> and aerobic chemoheterotrophs taxa. Structural equation modeling (SEM) uncovered that the interactions between AMF and <i>Trichoderma</i> modulated microbial community functions, augmented soil enzyme activities, promoted nutrient accumulation, and consequently improved albic soil quality. This study elucidates arbuscular mycorrhizal and <i>Trichoderma longibrachiatum</i> interactions with the soil environment, providing insights for improving albic soil health and microbial community structure.