Nitrogen addition suppresses soil positive priming effect in temperate plantations: Evidence from an 8‐year in situ field experiment

Abstract The microbial‐driven soil priming effect (PE) determines soil carbon emissions and is essential for accurately predicting the feedbacks between the terrestrial carbon cycle and global changes. In recent years, human activities have resulted in increased atmospheric nitrogen (N) deposition, but there is limited understanding of the long‐term effects of N deposition on soil microbial communities and their impact on soil PE in temperate plantations. This study utilized Korean pine plantation soils with 8 years of in situ N addition to investigate the mechanisms of the impact of long‐term N addition on PE through carbon ( 13 C) isotope tracing and high‐throughput sequencing techniques. We found that N addition significantly changed the soil bacterial community structure, while the effect on the fungal community structure did not reach a significant level. Addition of 13 C‐glucose resulted in soil‐positive PE, which exhibited a significant decreasing trend with increasing N addition. Compared with the control (0 kg N ha −1 year −1 ), the net carbon balance of the low N (20 kg N ha −1 year −1 ) showed no significant change, while the medium N (40 kg N ha −1 year −1 ) and high N (80 kg N ha −1 year −1 ) significantly increased by 35.47% and 35.79%, respectively, implying that glucose carbon was trapped in the soil much more than organic carbon decomposition. The PLS‐PM explained 69.0% of the total variation in PE among different N additions, showing that bacterial core taxa were the main driver of PE and that carbon enzyme activities ( β ‐1,4‐glucosidase and polyphenol oxidase) were a direct factor in regulating PE. Our results provide insights into accurately assessing the soil carbon sequestration potential of plantations under the influence of N deposition. Read the free Plain Language Summary for this article on the Journal blog.