Although the effects of fertilization and microbiota on plant growth have been widely studied, our understanding of the chemical fertilizers to alter soil chemical and microbiological properties in woody plants is still limited. The aim of the present study is to investigate the impact of long-term application of chemical fertilizers on chemical and microbiological properties of root-associated soils of walnut trees. The results show that soil organic matter (OM), pH_kcl, total nitrogen (TN), nitrate-nitrogen (NO₃⁻), and total phosphorus (TP) contents were significantly higher in non-fertilized soil than after chemical fertilization. The long-term fertilization led to excessive ammonium-nitrogen (NH₄⁺) and available phosphorus (AP) residues in the cultivated soil, among which NH₄⁺ resulted in soil acidification and changes in bacterial community structure, while AP reduced fungal diversity. The naturally grown walnut trees led to an enrichment in beneficial bacteria such as Burkholderia, Nitrospira, Pseudomonas, and Candidatus_Solibacter, as well as fungi, including Trichoderma, Lophiostoma, Phomopsis, Ilyonectria, Purpureocillium, Cylindrocladiella, Hyalorbilia, Chaetomium, and Trichoglossum. The presence of these bacterial and fungal genera that have been associated with nutrient mobilization and plant growth was likely related to the higher soil OM, TN, NO₃⁻, and TP contents in the non-fertilized plots. These findings highlight that reduced chemical fertilizers and organic cultivation with beneficial microbiota could be used to improve economic efficiency and benefit the environment in sustainable agriculture.

Objective In order to investigate the effect of microbial fertilizer on the growth of olive and the microbial diversity of inter-root soil，the present study conducted a field experiment of microbial fertilizer with 6-year-old olive as the research object. Method Using conventional agrochemical analysis of soil and Illumma MiSeq high-throughput sequencing technology，changes in olive growth，inter-root soil physicochemical properties and microbial community structure under different application rates of two microbial fertilizers were investigated. Result Under the same application rate，the treatment with microbial fungicide had better crown，plant height and diameter growth and higher soil nutrient content than those with biofungal composite； under different application rates，olive plants grew best and had the highest soil nutrient content when 9 kg of microbial fungicide（W9）and 6 kg of biofungal composite（F6）were applied；both microbial fertilizers altered inter-root soil microbial abundance and diversity；the application of microbial fungicide reduced soil fungal abundance and diversity while increased soil bacterial species abundance and diversity.The fungal phylum with higher relative abundance in the rhizosphere soil under each treatment were Ascomycetes and Stramenophora，and the bacterial phyla were Ascomycetes，Acidobacteria，and Actinobacteria；correlation analyses showed that the indicators of the agronomic characters of plants were positively correlated with Ascomycetes and Ascomycetes.Correlation analysis showed that the agronomic traits of the plants were positively correlated with Ascomycetes and negatively correlated with Aspergillus and Acidobacteria. Conclusion In general，the application effect of microbial inoculants is better than that of compound microbial inoculants under the same application rate. The best application results are obtained at 9 kg/plant for the microbial fungicide and 6 kg/plant for the composite biofungicide under the different application rate.