Study improves understanding of global nitrous oxide emissions in agricultural soils

Researchers from China and Germany have refined the hierarchical structure of factors that influence nitrous oxide (N2O) emissions on a global scale. The study provides new data on the main drivers of N2O emissions from agricultural soils.

The results show that climatic factors, such as mean annual precipitation (MAP) and mean annual air temperature (MAT), are the main influences on N2O emissions from unfertilized soils. In contrast, agricultural practices are the most influential factors for fertilized soils on a global scale.

“The key factors that affect the intensity of N2O emissions vary under different climate conditions,” said Li Siqi, one of the corresponding authors and a researcher at the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences. In treatments without fertilization, soil physical properties contributed most to the intensity of emissions in the subtropical monsoon zone (23%), while climatic factors (MAP and MAT) were dominant in the continental temperate (22%) and monsoon zones (23 %).

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

The study suggests that appropriate agricultural management practices can mitigate N2O emissions by more than 60% in upland cropping systems.

The research was carried out by a team from the Institute of Subtropical Agriculture and the State Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry at IAP. Nanning Normal University, Soochow University, Central China Normal University and the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Germany also participated.

The study used correlation analysis and structural equation modeling on a global N2O emissions dataset. The researchers explored the influence of climate, soil properties and agricultural practices on N2O emissions in cropping systems without and with fertilization. Furthermore, they performed variance partitioning analysis to identify the main controlling factors in different climate zones.

Research summary

Nitrous oxide (N2O) is a long-lived greenhouse gas that originates primarily from agricultural soils. Much research has explored the sources, influencing factors, and effective mitigation measures of N2O in recent decades. However, the hierarchy of factors influencing N2O emissions on a global scale was still unclear. This study performs correlation analyzes and structural equation modeling on a global dataset of N2O emissions to explore the hierarchy of factors influencing emissions from cropping systems with and without nitrogen fertilization, in terms of climatic factors, soil properties and agricultural practices.

The results show that the average N2O emission intensity in fertilized soils (17,83 g N ha−1 d−1) was significantly higher than that in unfertilized soils (5,34 g N ha−1 d−1). Climatic factors and agricultural practices are the most important factors in N2O emissions in fertilized and unfertilized upland soils, respectively. For different climatic zones, without fertilization, soil physical properties are the main factors in the subtropical monsoon zone, while climatic factors are key in the temperate zones. With fertilization, soil physical properties are the main factors in the subtropical and temperate continental monsoon zones, while agricultural practices are the main factors in the temperate monsoon zone. Implementing improved agricultural practices can potentially mitigate N2O emissions by more than 60% in upland cropping systems.

This research highlights the importance of considering factors specific to each climate zone when developing strategies to mitigate N2O emissions from agricultural soils.

Article about the work can be read at doi.org/10.1007/s00376-024-3234-7