Long‐term, amplified responses of soil organic carbon to nitrogen addition worldwide
Soil organic carbon (SOC) is the largest carbon sink in terrestrial ecosystems and plays a critical role in mitigating climate change. Increasing reactive nitrogen (N) in ecosystems caused by anthropogenic N input substantially affects SOC dynamics. However, uncertainties remain concerning the effects of N addition on SOC in both organic and mineral soil layers over time at the global scale. Here, we analyzed a large empirical data set spanning 60 years across 369 sites worldwide to explore the temporal dynamics of SOC to N addition. We found that N addition significantly increased SOC across the globe by 4.2% (2.7–5.8%). SOC increases were amplified from short- to long-term N addition durations in both organic and mineral soil layers. The positive effects of N addition on SOC were independent of ecosystem types, mean annual temperature and precipitation. Our findings suggest that SOC increases largely resulted from the enhanced plant C input to soils coupled with reduced C loss from decomposition and amplification was associated with reduced microbial biomass and respiration under long-term N addition. Our study suggests that N addition will enhance SOC sequestration over time and contribute to future climate change mitigation.
This is the peer reviewed version of the following article: Xu, Chonghua, Xia Xu, Chenghui Ju, Han YH Chen, Brian J. Wilsey, Yiqi Luo, and Wei Fan. "Long‐term, amplified responses of soil organic carbon to nitrogen addition worldwide." Global Change Biology (2020), which has been published in final form at doi:10.1111/gcb.15489. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.