Phosphorus alleviation of nitrogen‐suppressed methane sink in global grasslands
Lihua Zhang, Fenghui Yuan, Junhong Bai, Hongtao Duan, Xueying Gu, Longyu Hou, Yao Huang, Mingan Yang, Jin He, Zhenhua Zhang, Lijun Yu, Changchun Song, David A. Lipson, Donatella Zona, Walter C. Oechel, Ivan A. Janssens, Xiaofeng Xu
Abstract
Abstract Grassland ecosystems account for more than 10% of the global CH 4 sink in soils. A 4‐year field experiment found that addition of P alone did not affect CH 4 uptake and experimental addition of N alone significantly suppressed CH 4 uptake, whereas concurrent N and P additions suppressed CH 4 uptake to a lesser degree. A meta‐analysis including 382 data points in global grasslands corroborated these findings. Global extrapolation with an empirical modelling approach estimated that contemporary N addition suppresses CH 4 sink in global grassland by 11.4% and concurrent N and P deposition alleviates this suppression to 5.8%. The P alleviation of N‐suppressed CH 4 sink is primarily attributed to substrate competition, defined as the competition between ammonium and CH 4 for the methane mono‐oxygenase enzyme. The N and P impacts on CH 4 uptake indicate that projected increases in N and P depositions might substantially affect CH 4 uptake and alter the global CH 4 cycle.