Soil pH is among the most important drivers of soil bacterial community composition and diversity. However, most studies exploring the spatial distribution of soil bacterial communities have focused on the top 10–20 cm of soil, leaving our knowledge of the composition, diversity, and forces structuring subsoil communities relatively unexplored. Moreover, in agricultural soil managed without tillage (no-till), fertilizers often generate an acidified soil layer in the seed zone, rendering no-till soils a unique system in which to study the relative impacts of pH and soil depth on microbial communities. We characterize the composition and diversity of bacterial communities in a no-till wheat-based cropping system from eastern Washington, across soil depths (0 cm, 10 cm, 25 cm, 50 cm, 75 cm, and 100 cm). Soil depth was a strong driver of bacterial community composition and diversity. Proteobacteria and Actinobacteria dominated the soil surface, Acidobacteria peaked in relative abundance at 10 cm, and Actinobacteria and unidentified taxa were greatest in relative abundance below 25 cm. However, acidified soil disrupted relationships between soil depth and bacterial communities, resulting in a low diversity and distinct composition of bacterial communities at the 10 cm depth. Co-occurrence networks of bacterial taxa revealed groups of co-occurring taxa that responded primarily to soil pH or depth. This work provides an insight on the distribution and drivers of bacterial communities in deep soil profiles in dryland wheat-based cropping systems.

土壤pH值是土壤细菌群落组成和多样性的最重要驱动因素之一。但是，大多数探索土壤细菌群落空间分布的研究都集中在土壤的最上层10–20 cm上，而我们对地下土壤群落的组成，多样性和构造力的了解还相对较少。此外，在免耕（免耕）的农业土壤中，肥料通常会在种子区产生酸化的土壤层，从而使免耕土壤成为研究pH值和土壤深度对微生物群落的相对影响的独特系统。我们表征了华盛顿东部免耕小麦种植系统中整个土壤深度（0厘米，10厘米，25厘米，50厘米，75厘米和100厘米）的细菌群落组成和多样性。土壤深度是细菌群落组成和多样性的重要驱动力。变形杆菌和放线菌在土壤表面占主导地位，酸性菌在10 cm处的相对丰度达到峰值，而放线菌和未鉴定的分类单元在25 cm以下的相对丰度最大。但是，酸化的土壤破坏了土壤深度与细菌群落之间的关系，导致10 cm深度的细菌群落多样性低且组成独特。细菌类群的共现网络揭示了共生类群的组，它们主要对土壤的pH值或深度做出反应。这项工作提供了关于旱地小麦种植系统中深层土壤中细菌群落分布和驱动力的见解。酸性细菌在10 cm处的相对丰度达到峰值，而放线菌和未鉴定的分类单元在25 cm以下的相对丰度最大。但是，酸化的土壤破坏了土壤深度与细菌群落之间的关系，导致10 cm深度的细菌群落多样性低且组成独特。细菌类群的共现网络揭示了共生类群的组，它们主要对土壤的pH值或深度做出反应。这项工作提供了关于旱地小麦种植系统深层土壤中细菌群落分布和驱动力的见解。酸性细菌在10 cm处的相对丰度达到峰值，而放线菌和未鉴定的分类单元在25 cm以下的相对丰度最大。但是，酸化的土壤破坏了土壤深度与细菌群落之间的关系，导致10 cm深度的细菌群落多样性低且组成独特。细菌类群的共现网络揭示了共生类群的组，它们主要对土壤的pH值或深度做出反应。这项工作提供了关于旱地小麦种植系统中深层土壤中细菌群落分布和驱动力的见解。导致10 cm深度的细菌群落多样性低且组成独特。细菌类群的共现网络揭示了共生类群的组，它们主要对土壤的pH值或深度做出反应。这项工作提供了关于旱地小麦种植系统深层土壤中细菌群落分布和驱动力的见解。导致10 cm深度的细菌群落多样性低且组成独特。细菌类群的共现网络揭示了共生类群的组，它们主要对土壤的pH值或深度做出反应。这项工作提供了关于旱地小麦种植系统中深层土壤中细菌群落分布和驱动力的见解。