Climate and land management changes are altering carbon inputs to soil. The consequence of such input changes on long-term soil organic carbon (SOC) balance depends on the transit behavior of carbon inputs. Using observational carbon input and radiocarbon data in global soil profiles, we reveal that on average nearly 25% of new entering carbon leave soil in 1 year irrespective of entering depth, and the remained fraction after 30 years is only ∼13%. Nevertheless, the majority of SOC is older than 30 years in all soil depths. Together, these results demonstrate low transfer efficiency of carbon inputs to aged SOC which is the meaningful carbon component for long-term SOC sequestration. Additionally, we reveal that SOC aging and carbon input transiting are two distinct processes, which should be simultaneously, but mechanistical-separately, considered to predict and manage SOC dynamics in response to carbon input changes under climate and land management changes.

中文翻译：

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无论进入深度如何，全球土壤剖面中碳输入的快速转移

气候和土地管理的变化正在改变土壤的碳输入。这种输入变化对长期土壤有机碳（SOC）平衡的影响取决于碳输入的传输行为。利用全球土壤剖面中的观测碳输入和放射性碳数据，我们发现，无论进入深度如何，平均有近 25% 的新进入碳在 1 年内离开土壤，而 30 年后的剩余部分仅为 ∼13%。然而，在所有土壤深度中，大多数 SOC 的历史都超过 30 年。总之，这些结果表明，碳输入到老化 SOC 的转移效率较低，而老化 SOC 是长期 SOC 封存的有意义的碳成分。此外，我们揭示了 SOC 老化和碳输入转变是两个不同的过程，应该同时但在机械上分开考虑，以预测和管理 SOC 动态，以响应气候和土地管理变化下的碳输入变化。