The monoculture planting in terraced tea plantations has led to severe soil degradation, which poses a significant threat to the growth of tea plants. However, the mechanisms by which intercropping systems improve soil health through the regulation of soil microbial communities at the micro-topographical scale of terraced tea plantations (i.e., terrace surface, inter-row, and terrace wall) remain unclear. This study investigates the effects of intercropping Ophiopogon japonicus in a five-year tea plantation on the soil physicochemical properties, enzyme activities, and microbial community structure and functions across different micro-topographical features of terraced tea plantations in Wuyi Mountain. The results indicate that intercropping significantly improved the soil organic matter, available nutrients, and redox enzyme activities in the inter-row, terrace surface, and terrace wall, with the effects gradually decreasing with increasing distance from the tea plant rhizosphere. In the intercropping group, tea leaf yield increased by 13.17% (fresh weight) and 19.29% (dry weight) compared to monoculture, and the disease indices of new and old leaves decreased by 40.63% and 38.7%, respectively. Intercropping strengthened the modularity of bacterial networks and the role of stochasticity in shaping bacterial communities in different micro-topographic environments, in contrast to the patterns observed in fungal communities. The importance of microbial phyla such as Proteobacteria and Ascomycota in different micro-topographical features was significantly regulated by intercropping. In different micro-topographical zones of the terraced tea plantation, beneficial bacterial genera such as Sinomonas, Arthrobacter, and Ferruginibacter were significantly enriched, whereas potential fungal pathogens like Nigrospora, Microdochium, and Periconia were markedly suppressed. Functional annotations revealed that nitrogen cycling functions were particularly enhanced in inter-row soils, while carbon cycling functions were more prominent on the terrace surface and wall. This study sheds light on the synergistic regulatory mechanisms between micro-topographical heterogeneity and intercropping systems, offering theoretical support for mitigating soil degradation and optimizing management strategies in terraced tea agroecosystems.

Long-term monoculture of tea plants can harm soil ecosystems, while intercropping is considered a sustainable agricultural strategy that enhances ecological stability. However, the effects of intercropping tea plants with bamboo fungus on their growth remain unclear. This study conducted a field experiment to compare the soil physicochemical properties of tea plants under monoculture and intercropping with bamboo fungus, and assessed microbial community diversity through high-throughput sequencing. Results indicated that intercropping with bamboo fungus significantly improved soil water retention, with soil water-holding capacity and field water-holding capacity increasing by 49.07% and 48.77%, respectively. Soil nutrient availability was notably enhanced, with organic matter, available phosphorus, and available potassium increasing by 22.5%, 80.21%, and 56.13%, respectively. Bacterial community composition shifted markedly under intercropping, with significant enrichment of Gemmatimonadota, Devosia, and Conexibacter. Functional analysis revealed a restructuring of nitrogen cycling processes, characterized by increased nitrogen fixation, nitrification, and nitrogen respiration. Co-occurrence network analysis indicated higher modularity and eigencentrality in intercropped soils, suggesting enhanced microbial interactions and ecological resilience. These findings highlight that bamboo fungus intercropping reshapes soil physicochemical properties and enriches beneficial microbial taxa, thereby offering a sustainable approach to improve soil fertility and ecosystem functionality in tea plantations.