EGU24-10897, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Assessing N cycling and N2O emissions from ley within a crop rotation using measurements and modeling 

Yuqiao Wang and Christof Ammann
Yuqiao Wang and Christof Ammann
  • Agroscope, Climate and Agriculture group, Zürich, Switzerland (

Nitrous oxide (N2O) is a significant greenhouse gas that contributes to climate change, with one of the major sources being agricultural fertilizer application. In Europe, grass-clover ley plays a crucial role in the agricultural ecosystem. However, N2O emissions and emission factors (EFs) associated with it are not well documented. We therefore monitored N2O emissions in grass-clover ley and assessed the feasibility of using the process-based model DayCent to simulate N2O emissions and the underlying N cycling. The experiment was undertaken in a long-term fertilization experiment on a ley–arable rotation in Switzerland. We compared N2O emissions and EFs from organic fertilizer (slurry), mineral fertilizer and control (unfertilized) plots over three years (2021–2023). The results showed average N2O emissions of 0.50 ± 0.08, 0.51 ± 0.03 and 0.01 ± 0.04 kg N ha-1 yr-1 from organic, mineral and control treatments, respectively. The N2O EF, which was determined from measured emissions of the fertilized treatments after subtracting of the control treatment, was much lower than the IPCC default of 1%, with values of 0.22% and 0.40% for organic and mineral fertilizer treatments, respectively. DayCent was adjusted for plant C/N ratio parameters and the biological N fixation parameter. It accurately predicted soil moisture, soil temperature, and aboveground N yield, with deviations of 2.2%, 4.4%, and 6.0% from the measured values. Concerning N2O emissions, DayCent simulated average EFs of 0.24% and 0.28% for organic and mineral fertilizers, respectively, suggesting a good agreement with the measurements. Our field observation and model simulation results indicate that using IPCC default EF may overestimate the N2O emission from grass-clover ley, and that, DayCent is able to reproduce the comparatively low N2O emissions. 

How to cite: Wang, Y. and Ammann, C.: Assessing N cycling and N2O emissions from ley within a crop rotation using measurements and modeling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10897,, 2024.