WP 4.3 Control of Nitrous Oxide Emissions in Soils

project description

Soils are the main source of atmospheric nitrous oxide (N₂O), a potent greenhouse gas and the dominant ozone-depleting agent. Human activities strongly impact global N cycling and have led to significant increases in terrestrial ecosystem N₂O emissions, particularly due to excessive N-fertilizer use. Yet, control and magnitude of N₂O emissions ultimately depend on the interplay between physico-chemical conditions and the composition, interaction and activity of the highly diverse soil microbiome members. N₂O is produced and consumed by denitrifying bacteria, archaea, and fungi via a cascade of four enzymes reducing nitrate via nitrite, nitric oxide, and N₂O to dinitrogen gas. Additionally, N₂O is a metabolic byproduct of ammonia oxidation by complete ammonia oxidizers, ammonia-oxidizing archaea, and bacteria, where the latter additionally produce large amounts of N₂O through nitrifier denitrification.

Key to understanding and predicting global N₂O emissions from agricultural soils is a mechanistic understanding of the activity and interactions between nitrifiers, denitrifiers, and other members of the soil microbiome. We will investigate N₂O production and consumption processes in two systems – complex natural cropland soils with different fertilization regimes and histories and synthetic soil communities to address the following questions:

• (I) How are soil N₂O production and consumption affected by perturbations associated with land use change (i.e., amount, C:N:P ratios and type of natural and synthetic fertilizer)?
• (II) How do interactions between nitrifiers and denitrifiers change due to fertilization and which community members become dominant N₂O sources and sinks?
• (III) How does metabolic complementation (i.e., partial vs. full pathways of denitrification and nitrification) affect N₂O emissions?

Mitigating greenhouse gas emissions from modern agriculture is key in reaching the net zero emission goals. Our results may help to minimize agricultural N₂O emissions, ultimately leading to the development of targeted approaches to manipulate the soil microbiome. We will furthermore show how and by which mechanisms soil N₂O emissions are changed during perturbations. This key information can then be implemented in earth system models, to allow for better predictions of future agricultural N₂O emissions.

work package leader

katharina kitzinger

University of Vienna

Senior Scientist at the Division of Microbial Ecology (CeMESS)

CoE Key Researcher

Katharina’s Uni Vienna Profile