Long-term Modelling of Nitrous Oxide Emissions from Croplands in Switzerland Using the CN-Model

Abstract
Nitrous oxide (N2O) is a potent greenhouse gas and a key product of soil nitrogen cycling in agricultural systems. Its emissions are controlled by complex interactions between soil and vegetation processes, climate variability, and management practices. Thus, quantifying these fluxes remains a major challenge for both science and policy. Here, we present a process-based modelling study of N2O emissions using the CN-model, recently introduced as a mechanistic tool for simulating carbon-nitrogen coupling in terrestrial ecosystems [1], extended here for soil nitrogen transformations and N2O emissions. We apply the model to the long-term experimental site at Oensingen, Switzerland, which has provided high-quality agroecosystem observations since 2004. Our analysis spans two decades (2004-2023), enabling us to evaluate the model under diverse climatic conditions and management regimes. The CN-model is used to simulate microbial nitrification and denitrification pathways, soil moisture controls, and fertilization effects, allowing a process-level interpretation of observed N₂O flux dynamics. Model outputs are compared against measured net ecosystem exchange of CO2 (2004-2023) and N2O (2021-2023) emissions and other target variables to assess predictive performance, to explore seasonal and interannual variability. Beyond validation, we use the model to investigate potential future trajectories under alternative management practices and climate scenarios. Preliminary results indicate that the CN model captures both baseline and episodic emission events with good fidelity, highlighting the sensitivity of N₂O fluxes to precipitation timing and nitrogen input levels. This work demonstrates the value of integrating mechanistic modelling with long-term observational records to better constrain agricultural N2O and CO2 budgets. Our findings provide insights into mitigation options for reducing greenhouse gas emissions from European croplands and contribute to a broader understanding of biogeochemical feedback in the context of climate change.

REFERENCES
1 Stocker, B. D. & Prentice, I. C. CN-model: A dynamic model for the coupled carbon and nitrogen cycles in terrestrial ecosystems. bioRxiv, 2024.2004.2025.591063 (2024). https://doi.org/10.1101/2024.04.25.591063.
Date Issued
2025-12-06
Publication Type
Conference Item
Subject(s)
Subjects
n2o
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emission
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modelling
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cn model
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croplands
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switzerland
Language(s)
en
Author(s)
Turco, Fabio
Buchmann, Nina
Additional Credits
Title of Event
Project(s)
Funding(s)
Related URL(s)
https://geoscience-meeting.ch/sgm2025/downloads/
Access(Rights)
metadata.only
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