Abstract Soil nitrogen (N) availability, which is crucial to plant growth, largely relies on the turnover of soil organic N into inorganic N through mineralization. However, the patterns and drivers of global soil N turnover rates (NTR) have not been carefully examined so far. We compiled a dataset that consists of 1175 observations from 159 published articles across various terrestrial ecosystems in the world. Our analysis of this dataset showed that changes in soil NTR successfully predicted global NH4+–N content, a key indicator of soil N availability. Our analysis also revealed a clear latitudinal pattern of soil NTR, which was high in low latitude but low in high latitude. Soil NTR was greater in croplands than grasslands and wetlands. The dominant driving variables were mean annual temperature which accounted for 23% of the total variation in soil NTR. Soil clay content explained 15% of the total variation and it strongly inhibited soil NTR. However, the key driver in soil NTR differed with ecosystem type, i.e. soil microbial biomass in croplands, clay content in forests and grasslands, and soil C:N ratio in wetlands. This study highlights the importance of climatic factors and soil properties on soil NTR, which should be integrated into biogeochemical models to better predict the changes of soil N availability at the global scale.

中文翻译：

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土壤氮素周转率的全球变化及控制因素

摘要 土壤氮 (N) 的有效性对植物生长至关重要，很大程度上取决于土壤有机氮通过矿化向无机氮的转化。然而，迄今为止，尚未仔细研究全球土壤氮周转率 (NTR) 的模式和驱动因素。我们编译了一个数据集，其中包含来自世界上各种陆地生态系统的 159 篇已发表文章的 1175 条观察结果。我们对该数据集的分析表明，土壤 NTR 的变化成功预测了全球 NH4+–N 含量，这是土壤 N 可用性的关键指标。我们的分析还揭示了土壤NTR的明显纬度模式，低纬度高而高纬度低。农田的土壤 NTR 大于草地和湿地。主要驱动变量是年平均温度，占土壤 NTR 总变化的 23%。土壤粘土含量解释了总变异的 15%，它强烈抑制了土壤 NTR。然而，土壤NTR的关键驱动因素因生态系统类型而异，即农田土壤微生物生物量、森林和草地粘土含量以及湿地土壤碳氮比。本研究强调了气候因素和土壤特性对土壤 NTR 的重要性，应将其整合到生物地球化学模型中，以更好地预测全球范围内土壤 N 可用性的变化。湿地土壤碳氮比。本研究强调了气候因素和土壤特性对土壤 NTR 的重要性，应将其整合到生物地球化学模型中，以更好地预测全球范围内土壤 N 可用性的变化。湿地土壤碳氮比。本研究强调了气候因素和土壤特性对土壤 NTR 的重要性，应将其整合到生物地球化学模型中，以更好地预测全球范围内土壤 N 可用性的变化。