Although diazotrophs are major participants in biological nitrogen fixation (BNF) processes, the variations in community structure and assembly processes in response to long‐term fertilization with different fertilizer application are still ambiguous, especially under various doses with balance or not. Using nifH amplicon sequencing, we investigated the soil diazotrophic communities in a paddy field which received 20‐year fertilization including control (CK), balanced fertilization (three doses of nitrogen (N), phosphorus (P), and potassium (K) at same ratio (NPK, 2(NPK), and 3(NPK)), unbalanced fertilization (three ratios, (2 N)PK, N(2P)K, and NP(2K)), and manure (M). Our results showed that the diazotrophic diversity increased with the long‐term fertilization, but it was tapering‐off with doses increment. However, the community dissimilarities increased with fertilizer doses. These variations were attributed to the trade‐off between the variation of soil pH and nutrients. The increasing of fertilizer doses induced the transformation of community assembly processes, which changed from mainly dominated by deterministic processes in CK, NPK, NP(2K) and M to stochastic processes in the other treatments. Our findings suggest that the long‐term fertilization, especially different fertilizer doses, strongly affect soil diazotrophic diversity, community structure, and assembly processes, which could help to improve the sustainable agricultural management in the future.

中文翻译：

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长期水田施肥试验中肥料对土壤重氮营养多样性，群落组成和组装过程的显着剂量效应

尽管重氮菌是生物固氮（BNF）过程的主要参与者，但是长期施用不同肥料的施肥对群落结构和组装过程的影响仍然是模棱两可的，尤其是在各种剂量下是否平衡。使用nifH扩增子测序，我们调查了稻田中的土壤重氮营养群落，该稻田接受了20年的施肥，包括对照（CK），平衡施肥（三个剂量的氮（N），磷（P）和钾（K）比例（NPK，2（NPK）和3（NPK）），不平衡施肥（三个比例，（2 N）PK，N（2P）K和NP（2K））和肥料（M）。重氮养分的多样性随着长期的受精而增加，但是随着剂量的增加逐渐减少。社区差异随着肥料剂量的增加而增加。这些变化归因于土壤pH值和养分变化之间的权衡。施肥剂量的增加引起了社区组装过程的转变，从主要由CK，NPK，NP（2K）和M的确定性过程主导的过程转变为其他处理过程中的随机过程。我们的研究结果表明，长期施肥，尤其是不同的肥料用量，会严重影响土壤重氮营养多样性，群落结构和装配过程，这可能有助于改善未来的可持续农业管理。施肥剂量的增加引起了社区组装过程的转变，从主要由CK，NPK，NP（2K）和M的确定性过程主导的过程转变为其他处理过程中的随机过程。我们的研究结果表明，长期施肥，尤其是不同的肥料用量，会严重影响土壤重氮营养多样性，群落结构和装配过程，这可能有助于改善未来的可持续农业管理。施肥剂量的增加引起了社区组装过程的转变，从主要由CK，NPK，NP（2K）和M的确定性过程主导的转变为其他处理过程中的随机过程。我们的研究结果表明，长期施肥，尤其是不同的肥料用量，会严重影响土壤重氮营养多样性，群落结构和装配过程，这可能有助于改善未来的可持续农业管理。