Simulation of nitrous oxide emissions at field scale using the SPACSYS model

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Nitrous oxide (N2O) emissions from soil nitrification and denitrification significantly impact atmospheric greenhouse gas balance and stratospheric ozone depletion.
• These soil processes are influenced by microbial activity, nitrogen availability, soil temperature, and water content.
• Accurate modeling of these processes is crucial for developing agricultural mitigation strategies and regional emissions estimations.

Purpose of the Study:

• To enhance the SPACSYS model by incorporating a detailed module for nitrification, denitrification, and nitrogenous gas emissions.
• To replace a simplified module that could not differentiate individual nitrogenous gas emissions.
• To improve the prediction accuracy of N2O emissions in agricultural systems.

Main Methods:

• Integrated a new, detailed module for denitrification and nitrification processes into the SPACSYS model.
• Utilized a dataset from a Scottish grassland silage production experiment for model validation.
• Compared simulated soil moisture, biomass, nitrogen offtake, and N2O emissions against observed data.

Main Results:

• The new module demonstrated a good representation of soil nitrification and denitrification processes.
• Model validation showed improved prediction of N2O emissions compared to the previous version.
• The updated model successfully simulated soil moisture, biomass, and nitrogen offtake.

Conclusions:

• The enhanced SPACSYS model module accurately represents key soil nitrogen processes and improves N2O emission predictions.
• This provides a valuable tool for estimating gaseous nitrogen emissions under various agricultural management scenarios.
• The model synthesizes understanding of the interactions and regulation governing these critical soil processes.