Soil microorganisms play key roles in agricultural ecosystems. However, little is known about their dynamic diversity patterns and community assembly processes, especially in the rare microbial biosphere in agriculture systems. In this study, we determined the responses of diversities and assembly processes of abundant and rare bacterial and fungal subcommunities to agricultural practice (i.e. cover crop) in a semiarid orchard soil by using 16S and ITS rRNA gene sequencing. We found that the community structures of abundant and rare taxa exhibited a similar response to cover crop or growth periods. Growth periods significantly changed the bacterial and fungal subcommunities structure. Only the fungal subcommunities structure was affected by cover crop. The community assembly of abundant and rare fungi was respectively dominated by stochastic process and deterministic process and less affected by cover crop and growth period. For abundant bacteria, the assembly process was dominated by heterogeneous and undominated processes, and the importance of heterogeneous selection process was increased by cover crop at setting and maturing period. The assembly process of rare bacterial community was dominated by a homogeneous selection and the relative importance of dispersal limitation was increased at maturing period. We also found that the assembly processes of abundant taxa were significantly related to the soil DON, NH₄⁺-N, NO₃^–-N and pH, while the assembly processes of rare taxa were significantly related to the soil DOC, AP and SOC. Our results provide new insights into the formation of the microbial community in orchard soil under a cover crop, especially the seasonal succession of abundant and rare bacterial and fungal subcommunities.

土壤微生物在农业生态系统中起着关键作用。然而，人们对其动态多样性模式和群落组装过程知之甚少，尤其是在农业系统中稀有的微生物生物圈中。在这项研究中，我们通过使用 16S 和 ITS rRNA 基因测序确定了丰富和稀有细菌和真菌亚群落的多样性和组装过程对半干旱果园土壤中农业实践（即覆盖作物）的响应。我们发现丰富和稀有类群的群落结构对覆盖作物或生长期表现出类似的反应。生长期显着改变了细菌和真菌亚群落结构。只有真菌亚群落结构受到覆盖作物的影响。丰富和稀有真菌的群落组装分别以随机过程和确定性过程为主，受覆盖作物和生育期的影响较小。对于丰富的细菌，组装过程以异质和未支配过程为主，在设置和成熟期覆盖作物增加了异质选择过程的重要性。稀有细菌群落的组装过程由同质选择主导，并且在成熟期扩散限制的相对重要性增加。我们还发现丰富类群的组装过程与土壤 DON、NH 显着相关 在坐果和成熟期覆盖作物增加了异质选择过程的重要性。稀有细菌群落的组装过程由同质选择主导，并且在成熟期扩散限制的相对重要性增加。我们还发现丰富类群的组装过程与土壤 DON、NH 显着相关 在坐果和成熟期覆盖作物增加了异质选择过程的重要性。稀有细菌群落的组装过程由同质选择主导，并且在成熟期扩散限制的相对重要性增加。我们还发现丰富类群的组装过程与土壤 DON、NH 显着相关₄ ⁺ -N、NO ₃ ^– -N 和 pH，而稀有类群的组装过程与土壤 DOC、AP 和 SOC 显着相关。我们的研究结果为覆盖作物下果园土壤中微生物群落的形成提供了新的见解，特别是丰富和稀有细菌和真菌亚群落的季节性演替。