Characteristics of the study areas.

The bacterial community performs an essential ecological role in maintaining agriculture systems. The roles of bacteria in the forest, marine, and agricultural systems have been studied extensively and intensively. However, similar studies in the areas irrigated by the Yellow River remain limited. In this study, we used Illumina sequencing analysis with the 16S rRNA method to analyze the bacterial diversity, community structure, and influencing factors in soil samples from eight regions of the Yellow River irrigation area in northwestern China. The bacterial community structure and diversity varied among samples from the eight regions. The samples differed significantly in terms of the bacterial community composition. Proteobacteria (approximately 12.4%-55.7%) accounted for the largest proportion and was the dominant bacteria, followed by Actinobacteria (approximately 9.2%-39.7%), Bacteroidetes (approximately 1.8%-21.5%), and Chloroflexi (approximately 2.7%-12.6%). Among the physicochemical variables, the soil pH in the eight regions was mildly alkaline, and the total nitrogen, total phosphorus, and total potassium contents in the soils differed significantly. However, the trend in the variations of the above variables was essentially similar. Soil bacteria in Yongning county had greater Chao1, Shannon-Wiener, and Simpson indices than those in the other regions. Notably, soil moisture, organic matter, and total nitrogen were recognized as the primary factors influencing the bacterial community in the Yellow River irrigation area. Our results revealed the laws of variation in soil bacterial diversity and community composition in the Yellow River irrigation area. Our findings could be beneficial for maintaining sustainable ecological practices in the Yellow River irrigation area.

细菌群落在维系农业生态系统中发挥着不可或缺的生态学功能。针对森林、海洋与农业生态系统中细菌的生态功能，学界已开展了广泛且深入的研究。然而，针对黄河灌溉区域的同类研究仍较为匮乏。本研究采用基于16S核糖体RNA（16S rRNA）的Illumina测序技术，对中国西北黄河灌溉区内8个区域的土壤样本展开细菌多样性、群落结构及其影响因子的分析。研究结果显示，8个区域的土壤样本在细菌群落结构与多样性上均存在显著差异，群落组成亦呈现明显的区域分化。其中，变形菌门（Proteobacteria，占比约12.4%~55.7%）为优势菌群，占比最高；其次为放线菌门（Actinobacteria，占比约9.2%~39.7%）、拟杆菌门（Bacteroidetes，占比约1.8%~21.5%）与绿弯菌门（Chloroflexi，占比约2.7%~12.6%）。在理化变量层面，8个区域的土壤pH均呈弱碱性，土壤总氮、总磷与总钾含量存在显著差异，但上述变量的变化趋势总体相似。永宁县的土壤细菌其Chao1指数、Shannon-Wiener指数以及Simpson指数均高于其他区域。值得注意的是，土壤含水量、有机质与总氮被认定为黄河灌溉区细菌群落的核心影响因子。本研究揭示了黄河灌溉区土壤细菌多样性与群落组成的变化规律，其研究成果可为该区域的可持续生态实践提供有益参考。