Soil nitrous oxide emissions from global land ecosystems and their drivers within the LPJ-GUESS model (v4.1)
<p>Nitrogen (N) transformation processes by soil microbes account for significant nitrous oxide (N<span class="inline-formula"><sub>2</sub></span>O) emissions from natural ecosystems and cropland. However, understanding and quantifying global soil N<span cl...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-05-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/18/3131/2025/gmd-18-3131-2025.pdf |
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| Summary: | <p>Nitrogen (N) transformation processes by soil microbes account for significant nitrous oxide (N<span class="inline-formula"><sub>2</sub></span>O) emissions from natural ecosystems and cropland. However, understanding and quantifying global soil N<span class="inline-formula"><sub>2</sub></span>O emissions and their responses to changing environmental conditions remain challenging. Here, we implemented a soil nitrification–denitrification module into the dynamic vegetation model LPJ-GUESS to estimate N<span class="inline-formula"><sub>2</sub></span>O emissions from global lands. The performance of this new development is examined using observed N<span class="inline-formula"><sub>2</sub></span>O fluxes from natural-soil and cropland field trials and independent global-scale estimates. LPJ-GUESS broadly reproduces the cumulative N<span class="inline-formula"><sub>2</sub></span>O emissions under different climate conditions and N fertilizer applications that are observed in the field experiments, with some deviations in emission seasonality. Globally, simulated soil N<span class="inline-formula"><sub>2</sub></span>O emissions from terrestrial ecosystems increase from <span class="inline-formula">5.6±0.2</span> Tg N yr<span class="inline-formula"><sup>−1</sup></span> in the 1960s to <span class="inline-formula">9.9±0.3</span> Tg N yr<span class="inline-formula"><sup>−1</sup></span> in the 2010s, with croplands contributing about two-thirds of the total increase. East Asia and South Asia show the fastest growth rates in N<span class="inline-formula"><sub>2</sub></span>O emissions over the study period due to the expansion of fertilized croplands. On a global scale, N fertilization (including synthetic fertilizer and manure use), atmospheric N deposition, and climate change contribute 58 %, 46 %, and 24 %, respectively, to the simulated soil N<span class="inline-formula"><sub>2</sub></span>O emissions in the 2010s. Rising CO<span class="inline-formula"><sub>2</sub></span> levels in the atmosphere reduce the simulated emissions by 32 % through increased plant N uptake, whereas land use changes have varied spatial effects on emissions depending on N management intensity after land cover conversion. Our estimates only account for the direct soil N<span class="inline-formula"><sub>2</sub></span>O emissions, excluding those from fertilized pastures. This study highlights the importance of environmental factors in influencing global soil N<span class="inline-formula"><sub>2</sub></span>O emissions, particularly for assessing greenhouse gas mitigation potential in agricultural ecosystems.</p> |
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| ISSN: | 1991-959X 1991-9603 |