Study refines understanding of factors influencing global N₂O emissions from agricultural soils

Global atmospheric N₂O concentration has surged by more than 23% since the pre-industrial era, rising from 270 parts per billion (ppb) in 1750 to 336 ppb in 2022. Approximately two-thirds of these emissions come from nitrogen fertilizer-applied soils and natural soils. Key factors influencing N₂O emissions include climate, soil properties, and agricultural practices. 

A team of researchers from various institutions in China and Germany has refined the hierarchical structure of these factors at a global scale. Their findings, published in Advances in Atmospheric Sciences, provide new insights into the main drivers of N₂O emissions from agricultural soils. 

The team conducted correlation and structural equation modeling analyses on a global N₂O emission dataset to explore the influence of climate, soil properties, and agricultural practices on N₂O emissions from both non-fertilized and fertilized upland farming systems. Additionally, they performed variance partitioning analysis to identify the primary controlling factors in different climatic zones.

The study concluded that climatic factors, such as mean annual precipitation (MAP) and mean annual air temperature (MAT), are the principal influences on N₂O emissions from non-fertilized upland soils.

"In contrast, agricultural practices are the most influential factors for fertilized upland soils on a global scale," said Dr. Li Siqi, one of the corresponding authors and a researcher from the Institute of Atmospheric Physics (IAP) at the Chinese Academy of Sciences, "However, the key factors affecting N₂O emission intensity vary under different climate conditions."

For non-fertilized treatments, soil physical properties contributed most to N₂O emission intensity in the subtropical monsoon zone (23%), while climate factors (MAP and MAT) were dominant in the temperate continental (22%) and monsoon (23%) zones.

For fertilized treatments, soil physical properties had the greatest impact in the subtropical monsoon (26%) and temperate continental (28%) zones, whereas agricultural practices were most significant in the temperate monsoon zone (17%).

"Our study also suggests that proper agricultural management practices, such as reducing nitrogen fertilizer rates combined with the addition of nitrification and urease inhibitors, can potentially mitigate N₂O emissions by more than 60% in upland farming systems," said Dr. Li Yong, also a corresponding author of the study.