Combined effects of AMF inoculation and intercropping on rhizosphere bacterial communities of maize and soybean in reclaimed coal mine soil

Reclaimed coal mine soils are often nutrient-deficient and microbially impaired, limiting their agricultural reuse. This study investigated the combined effects of arbuscular mycorrhizal fungi (AMF) inoculation and maize-soybean intercropping on rhizosphere bacterial communities in reclaimed coal mining soils from Inner Mongolia, China.

A split-plot field experiment (2018–2019) tested two inoculation levels (Control, AMF) and three planting modes (maize or soybean monoculture, intercropping).

High throughput sequencing generated 7.93 million reads representing 18,144 bacterial OTUs. AMF alone increased the relative abundance of beneficial taxa (Actinobacteria, Chloroflexi, Acidobacteriaceae) and improved α-diversity during early to mid-growth stages (P < 0.05). Intercropping further amplified diversity, enriching Nitrospirae and Streptomycetaceae. Co-occurrence network analysis showed that the AMF-intercropping treatment produced the most complex and modular bacterial network. Functional predictions (Tax4Fun2) revealed increased functions of genes for energy metabolism and C/N cycling. Soil available P, NO₃⁻-N, phosphatase activity, and glomalin levels were significantly higher under AMF-intercropping treatment.

These findings demonstrate that integrating AMF with intercropping enhances microbial diversity and function, offering a viable strategy for ecological rehabilitation and biomass production on reclaimed mining land.