A Mechanistic Model to Separate And Quantify Key Processes Controlling N2O Flux From Agriculture Soils

Abstract:

Soil nitrous oxide, N₂O, from agriculture is the largest anthropological source, and its flux keeps increasing as fertilizer applications continue to grow. Therefore, predicting the soil N₂O emission from agriculture is important for projecting climate change, given that N₂O is the third largest greenhouse gas. However, the current models are hardly able to predict the N₂O flux well, mainly because the processes controlling N₂O emission are complicated. This study developed a mechanistic model to simulate soil N₂O flux by taking into account the most important processes explicitly, including N₂O production, oxidation, and transport. Furthermore, the different contributing processes to N₂O production, including heterotrophic nitrification, nitrifier nitrification, nitrifier denitrification, and heterotrophic denitrification, were quantitatively separated. The effects of soil properties, fertilizer applications, and climate changes on these processes and contributors and finally on N₂O flux were evaluated. The model simulated N₂O flux for different types of soils under various climatic conditions well, and could improve the prediction of soil N₂O emission from agriculture.