Phosphorus alleviation of nitrogen‐suppressed methane sink in global grasslands

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.

Declines of peatland water table forces climate warming despite methane emission drawdown

“…Approximately 50% of the in situ, on-site GHG flux data (i.e., NEE, CH4 or N2O) were seasonally measured, e.g., covering the growing season (temperate and boreal peatlands) or the wet season in (sub)tropical peatlands (Table 2). Therefore, to calculate the annual fluxes for these studies, we applied a previously used gap-filling approach 58,59 . Specifically, the annual NEE, CH4 or N2O (kg CO2/ CH4/ N2O ha -1 yr -1 )…”

An Integrative Model for Soil Biogeochemistry and Methane Processes. II: Warming and Elevated CO2 Effects on Peatland CH4 Emissions

“…Beside the increased substrate availability for methanogenesis, eCO 2 may stimulate microbial activities for CH 4 production (Conrad, 2002) and inhibit CH 4 oxidation (Bodelier & Laanbroek, 2004;Ineson et al, 1998) by reducing soil N availability that may partially release the N suppression on methanotrophs (Xu et al, 2004;Zhang et al, 2020). The simulated stimulating impacts of eCO 2 on CH 4 emission is partially due to greater aerenchyma in plant tissues that promotes CH 4 transport (Bellisario et al, 1999;Megonigal & Schlesinger, 1997).…”

Stimulated or Inhibited Response of Methane Flux to Nitrogen Addition Depends on Nitrogen Levels

“…Many in situ measurements and in vitro experiments found that N addition could suppress CH 4 uptake in upland soil (Bodelier & Laanbroek, 2004; King & Schnell, 1994; L. Zhang et al., 2020). In a meta‐analysis by Liu and Greaver (2009), CH 4 uptake decreased by 38% across all ecosystems under N addition.…”

“…The magnitude of the global soil CH 4 sink was predicted to be enhanced during the 21st century with warming scenarios, but nitrogen (N) deposition could reduce the future sink (Zhuang et al, 2013). In the context of increased global nitrogen deposition, the effects of N deposition on soil CH 4 sinks and the associated mechanisms are receiving increasing attention.Many in situ measurements and in vitro experiments found that N addition could suppress CH 4 uptake in upland soil (Bodelier & Laanbroek, 2004;King & Schnell, 1994;L. Zhang et al, 2020).…”

“…Many in situ measurements and in vitro experiments found that N addition could suppress CH 4 uptake in upland soil (Bodelier & Laanbroek, 2004;King & Schnell, 1994;L. Zhang et al, 2020).…”