By analyzing 30 sites spanning the Loess Plateau (LP), Inner Mongolian Plateau (IMP), and Xizang Plateau (XP), researchers identified total nitrogen (TN), soil carbon, precipitation, and nitrogen inputs as key drivers of denitrification potential. The findings indicate that warming, humidification, and rising nitrogen deposition could substantially amplify N₂O emissions from steppe ecosystems.
Grasslands cover 20% of Earth's land surface and contribute nearly one-third of global N₂O emissions—most of which originate from denitrification. The Eurasian steppe, the largest in the world, is both ecologically significant and highly sensitive to climate change. Previous studies have evaluated how grazing, fertilization, moisture, and temperature affect N₂O fluxes, yet most work has focused on individual locations or single emission pathways. Importantly, N₂ emissions—the final product of denitrification—have rarely been quantified alongside N₂O. Nitrogen deposition is also rising globally and is projected to exceed 15 kg N ha⁻¹ yr⁻¹ in many regions by 2030, including the Tibetan Plateau. These changes could disproportionately enhance denitrification in nitrogen-sensitive high-altitude grasslands.
A study (DOI:10.48130/ebp-0025-0007) published in Environmental and Biogeochemical Processes on 21 October 2025 by Shuping Qin’s team, Institute of Genetic and Developmental Biology, The Chinese Academy of Sciences, identifies the key environmental drivers of soil denitrification across the Eurasian steppe, providing essential insights for predicting N₂O emission risks under future climate change and rising nitrogen deposition.
In this study, soils from 30 sites across the LP, IMP, and XP steppes were incubated under controlled conditions to quantify denitrification potential by simultaneously measuring N₂O and N₂ emission rates, both with and without nitrogen addition. The researchers then used Spearman correlation analysis, partial least squares path modeling (PLS-PM), and stepwise multiple regression to link these denitrification metrics to climate variables, soil physicochemical properties, and soil nitrogen pools at both regional and sub-regional scales. Across all sites, N₂O emission rates ranged from 0.6 to 372.7 μg N kg⁻¹ dry soil h⁻¹, with XP and IMP soils showing significantly higher mean N₂O fluxes (~61.0 and 60.9 μg N kg⁻¹ h⁻¹) than LP soils (38.6 μg N kg⁻¹ h⁻¹), identifying XP and IMP as N₂O hotspots. N₂ emission rates ranged from 18.1 to 1,230 μg N kg⁻¹ h⁻¹ and followed a similar pattern, with XP again highest (318.1 μg N kg⁻¹ h⁻¹). The N₂O/(N₂O + N₂) ratio varied widely (0.7–73.8%), and was generally higher in LP than in IMP or XP, indicating greater relative N₂O release from LP soils. Nitrogen addition increased overall denitrification potential, boosting mean N₂O emissions by 65% and N₂ emissions by 44%, with particularly strong N₂O responses in XP (+98.8%) and IMP (+66.3%), while N₂ responses were strongest in LP. Correlation analyses showed that, regionally, N₂O emissions were positively associated with MAP, carbon and nitrogen pools, and NH₄⁺–N, and negatively with MAT, pH, bulk density, and NO₂⁻–N. PLS-PM and regression further revealed that TN was the dominant control on N₂O production and reduction at the regional scale, whereas at sub-regional scales TC, MAP, pH, and nitrogen addition emerged as key drivers of N₂O and N₂ fluxes and of the N₂O/(N₂O + N₂) ratio.
The findings offer practical indicators—such as TN, TC, and MAP—that can be used to build more accurate models predicting N₂O emissions across grasslands. Importantly, the study warns that humidification trends in the IMP and rising nitrogen deposition in XP could amplify N₂O releases, potentially accelerating regional climate feedbacks. The results also highlight that grassland management strategies must be region-specific: LP soils may be especially vulnerable to nitrogen saturation, while IMP soils are likely to respond strongly to changes in precipitation patterns.
###
References
DOI
10.48130/ebp-0025-0007
Original Source URL
https://doi.org/10.48130/ebp-0025-0007
Funding information
This work was supported by the Natural Science Foundation of Hebei Province (D2022503014), the Hebei Province Central Guide Local Science and Technology Development Fund Project (246Z4206G), the China Postdoctoral Science Foundation (2025M772517), the Postdoctoral Fellowship Program of CPSF (GZC20251630), and the Backbone Talent Project of the Yanzhao Golden Platform for Talent Attraction in Hebei Province (Postdoctoral Platform) (B2025005034).
About Environmental and Biogeochemical Processes
Environmental and Biogeochemical Processes is a multidisciplinary platform for communicating advances in fundamental and applied research on the interactions and processes involving the cycling of elements and compounds between the biological, geological, and chemical components of the environment.