【摘要】 【目的】基于潮土区长期施肥试验，明确细菌群落结构、生态网络和关键物种对长期施肥的响应特征。【方法】基于始于1990年的潮土长期定位试验平台，于2023年小麦成熟后取样，利用高通量测序技术，结合生态网络分析等方法，分析不施肥（CK）、单施化肥（NPK）、化肥配施秸秆（NPKS）以及化肥配施有机肥（NPKM）处理的土壤有机碳（SOC）等养分，土壤酶活性及细菌群落组成、结构、生态网络和关键物种的变化。【结果】有机无机配施显著提高了SOC等土壤养分含量和土壤酶活性。相较于CK,NPKS和NPKM处理的SOC提高了52.1%和81.9%，颗粒有机碳含量提高了60.6%和137.4%，易氧化有机碳提高了45.3%和63.4%,β-N-乙酰氨基葡萄糖苷酶活性提高了7.2%和12.6%，碱性磷酸酶活性提高了166.4%和216.2%（P<0.05），且NPKS处理的β-1,4-葡萄糖苷酶活性最高，为63.82μmol·g^-1·d^-1。与CK相比，NPKS处理的土壤细菌α多样性显著降低，其Ace指数、Chao1指数和Shannon指数分别降低了5.4%、5.2%和2.6%（P<0.05）。施肥处理显著改变了细菌群落结构（R²=0.543,P=0.001），但NPKS和NPKM处理的细菌群落结构较为相似。与CK相比，NPKS处理显著降低了绿弯菌门（Chloroflexi）、芽单胞菌门（Gemmatimonadota）和甲基微菌门（Methylomirabilota）的相对丰度，NPKM处理显著提高了拟杆菌门（Bacteroidota）的相对丰度（P<0.05）。冗余分析显示，影响微生物群落结构最主要的环境驱动因素为铵态氮（NH₄⁺-N）、硝态氮（NO₃^--N）和SOC。网络分析显示，与CK相比，NPKM处理提高了细菌群落网络复杂性、稳定性和物种间的正相关比例。此外，NPKS和NPKM处理较CK显著提高了隶属于放线菌门（微球菌目、Microtrichales目）、绿弯菌门（热微菌目）、拟杆菌门（噬几丁质菌目和噬纤维菌目）、黏球菌门（未培养目bacteriap25）和变形菌门（伯克霍尔德氏菌目）8个关键物种的相对丰度，这些关键物种与土壤碳氮磷等物质循环以及植物促生密切相关（P<0.05）。偏最小二乘路径模型显示，施肥模式对关键物种的直接影响并不显著，而是通过显著影响土壤pH、调控群落组成以及提高土壤养分含量，间接影响了关键物种。【结论】长期有机无机肥配施提高了土壤养分含量和胞外酶活性，调控了微生物群落组成和结构，增强了细菌群落网络复杂性和稳定性，提高了参与土壤养分循环和物质转化的关键物种的相对丰度。更多还原

【Abstract】 【Objective】Based on the long-term fertilization station in fluvo-aquic soil region, this study investigated how bacterial community structure, ecological network, and key species in response to fertilization. 【Method】Based on the long-term experiment started from 1990, soil was sampled after wheat maturity in 2023, and high-throughput sequencing and ecological network analysis were used to examine dynamics in soil organic carbon（SOC） and other nutrients, enzyme activity, bacterial community composition, ecological network and stochastic process under four treatments: no fertilization（CK）, mineral nitrogen（N）, phosphorus（P）, and potassium（K）（NPK）, NPK+straw（NPKS）, and NPK+manure（NPKM）. 【Result】 The combined application of organic and inorganic fertilizers significantly increased SOC and other soil nutrients, as well as soil enzyme activity. Compared with CK, SOC content under NPKS and NPKM increased by 52.1% and 81.9%, respectively, and particulate carbon increased by 60.6% and 137.4%, respectively, and easily oxidized organic carbon increased by 45.3% and 63.4%, respectively; additionally, β-N-acetylglucosaminidase activity increased by 7.2% and 12.6%, respectively, while alkaline phosphatase activity increased by 166.4% and 216.2%（P<0.05）, respectively. Notably, β-1,4-glucosidase activity was the highest under NPKS(63.82 μmol·g^-1·d^-1). In terms of bacterial diversity, α-diversity significantly decreased under NPKS compared with CK, with reductions of 5.4%, 5.2%, and 2.6% in the Ace, Chao1, and Shannon indices, respectively（P<0.05）. Fertilization treatment alerted bacterial community structure, while NPKS and NPKM exhibited similar compositions. Compared with CK, NPKS significantly reduced the relative abundance of Chloroflexi, Gemmatimonadota, and Methylomirabilota, while NPKM significantly increased the relative abundance of Bacteroidota（P<0.05）. Redundancy analysis identified ammonium nitrogen（NH₄⁺-N）, nitrate nitrogen（NO₃^--N）, and organic carbon（SOC） as the primary environmental factors shaping microbial community structure. Network analysis showed, compared with CK, NPKM increased the complexity, stability of the bacterial community network and the proportion of positive correlations between species. Furthermore, both NPKS and NPKM significantly enhanced the relative abundances of eight keystone taxa, including members of Actinobacteriota（order Microtrichales）, Chloroflexi（order Thermomicrobiales）, Bacteroidota（orders Chitinophagales and Cytophagales）, Myxococcota（uncultured order bacteriap25）, and Proteobacteria（order Burkholderiales）（P<0.05）. These keystone taxa were closely associated with soil carbon, nitrogen, phosphorus, and other material cycling, as well as plant growth promotion. Partial least squares path modeling suggested that fertilization did not directly impact key species but exerted an indirect influence by significantly affecting soil pH, regulating community composition, and increasing soil nutrient availability. 【Conclusion】Long-term combined application of organic and inorganic fertilizers enhanced soil nutrient content and extracellular enzyme activity, regulated microbial community composition and structure, affected bacterial network complexity and stability, and increased the relative abundance of key species involved in soil nutrient cycling and material transformation. These findings provided valuable insights into the interactions between soil properties and microbial communities under long-term fertilization, contributing to a deeper understanding of bacterial community dynamics and key species in agricultural ecosystems.更多还原