Effects and mechanisms of combined application of biochar and arbuscular mycorrhizal fungi: Towards agricultural sustainability and ecological restoration

With the growth of the global population and the intensification of environmental pressure, the development of green and efficient soil improvement and ecological restoration technologies is crucial. Biochar and Arbuscular Mycorrhizal Fungi (AMF) have become research hotspots due to their significant potential in soil improvement, carbon sequestration, pollution remediation, and promotion of plant growth. Recent studies have found that the combined application of the two can produce a synergistic effect that surpasses their individual application. This paper systematically reviews the synergistic effects and internal mechanisms of the combined application of biochar and AMF, and looks forward to their future research directions. Studies have shown that the combined application can significantly improve soil structure, regulate microbial communities, promote crop growth, and enhance crop resistance to drought, salinization, and heavy metal pollution. The core synergistic mechanism lies in a three-level linkage: Biochar acts as an "ecological niche optimizer", creating prerequisites for the colonization and functional exertion of AMF. By secreting glomalin and forming complexes with biochar, AMF jointly drive the nutrient cycle of adsorption, activation, and transportation, transforming biochar from a static matrix into a dynamic functional interface. The combination of the two further systematically improves the nutrient cycling efficiency of the soil-plant system and the stability of the ecosystem by constructing a highly complex microbial interaction network and accurately regulating the activity of key enzymes. Although the combined application has broad prospects, its effects are restricted by factors such as biochar properties, AMF strains, and environmental conditions. Future research should focus on revealing its micro-interface processes, evaluating long-term ecological safety, and establishing a precise application technology system. This will promote the technology from "effect verification" to "precision design", providing theoretical basis and technical support for the realization of sustainable agricultural and ecological development.