(1) Aims: This study was aimed to investigate the effects of organic and inorganic fertilizer application on the soil nutrients and microbiota in tea garden soil. (2) Method: Illumina Hiseq sequencing technique was conducted to analyze the microbial diversity and density in different fertilizer-applied tea garden soil. (3) Results: The results showed that Acidobacteria, Proteobacteria and Actinobacteria were the predominant bacterial species observed in the tea garden soil. Besides, the relative abundance of Basidiomycota, Ascomycota and Zygomycota fungal species were higher in the tea garden soil. Correlation analysis revealed that Acidibacter and Acidothermus were significantly correlated with chemical properties (such as total organic carbon (TOC), total phosphorus (TP) and available phosphorus (AP) contents) of the tea garden soil. Furthermore, all these microbes were abundant in medium rapeseed cake (MRSC) + green manure (GM) treated tea garden soil. (4) Conclusion: Based on the obtained results, we conclude that the application of MRSC + GM could be a preferred fertilizer to increase the soil nutrients (TOC, TP and AP content) and microbial population in the tea garden soil.

Intercropping legumes is an effective and sustainable planting pattern that has the benefit of decreasing chemical fertilizer input and improving the soil environment. However, the effects of chemical fertilizer reduction and intercropping different legumes on soil nutrients, microorganisms, and tea quality remain elusive. Hereby, compared with 100% chemical fertilizer (CK), Sesbania cannabina (SC) and Crotalaria pallida Blanco (CP) were selected as the intercropped plant with 70% chemical fertilizer to investigate its effect on soil nutrients, microorganisms, and tea quality. The results showed that compared with monocropping, intercropping legumes had greater concentrations of the soil labile organic matter, nitrate nitrogen, ammonia nitrogen, inorganic nitrogen, and alkali-hydrolyzable nitrogen. Intercropping systems significantly enhanced the content of non-ester-type catechins (catechin and gallocatechin) and ester-type catechins (epicatechin gallate). In SC, the content of gallocatechin, catechin, and epicatechin gallate increased by 146.67%, 107.69%, and 21.05%, respectively, while in CP, the content of these three compounds increased by 166.67%, 84.62%, and 19.08%, respectively. Significant differences in microbial composition were also observed under different systems. Actinobacteria, Rhodoplanes, and Thaumarchaeota were obviously enhanced in SC, while Rhodanobacter, Pseudolabrys, and Pedosphaera were manifestly improved in CP compared to those in the monoculture. Moreover, intercropping legumes significantly increased the abundances of CNP cycling functional genes, such as gpmB, mch, accD6, pgi-pmi, mcr, glmS, ACOX1 and fadB (carbohydrate metabolism), nirD and narI (nitrification), pmoB-amoB and hao (dissimilatory N reduction), and phoN (organic phosphoester hydrolysis). The relationship between intercropping systems and tea qualities was mainly established by soil nutrition and the abundance of C and N cycling functional microorganisms. This study provides more information on the relationship between soil nutrients, functional genes of microorganisms, and tea quality under tea/legume intercropping systems in tea plantations and offers a basis for the higher-performance intercropping pattern.