Improved process understanding and quantification of nitrous oxide fluxes in a German crop rotation

• Applicant: Professorin Ana Meijide, Ph.D.
• Subject Area: Soil Sciences ; Plant Cultivation, Plant Nutrition, Agricultural Technology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469661755

Nitrous oxide (N2O) is one of the most powerful greenhouse gases (GHG) and agriculture represents its largest source. In 2018, agriculture was responsible for 7.4% of the total GHG emissions in Germany, 40.2% of which were caused by N2O emissions from soils. Understanding the mechanisms responsible for these emissions and accurately quantifying the fluxes is crucial for developing effective and targeted mitigation strategies. The main goal of this project is to improve the mechanistic understanding of N2O fluxes in a German crop rotation (wheat, sugar beet, barley) under typical agricultural management. We hypothesize that a multidisciplinary approach including high resolution N2O flux measurements, N2O isotopic studies and metagenomic analysis will allow for an improved understanding of which mechanisms are leading to the production and consumption of N2O in the soil. Specifically, we will study the temporal and spatial variability of N2O fluxes in an agricultural soil (Work Package – WP1), analyze the fluxes in relation to most important drivers (i.e. climatic conditions, soil properties, management practices; WP2) and investigate the mechanisms responsible for the fluxes (WP3). N2O fluxes will be continuously measured in an agricultural field for two consecutive years using the eddy covariance technique (data at 30 minutes resolution), providing information on the short-term variability of the fluxes and allowing for improved quantifications of the annual fluxes. Fluxes will be measured in parallel using closed chambers, the most commonly used technique for measuring N2O, which will also serve to evaluate the spatial variability of the fluxes (WP1). We will study the relationships between N2O fluxes and possible drivers to identify which are most relevant for N2O fluxes in the studied soil (WP2). In order to understand the mechanisms responsible for the measured emissions, we will analyze the isotopic signature of the emitted N2O and perform metagenomic studies to assess the abundance of genes involved in N2O production and consumption in the soil (WP3). The proposed project will produce a unique, multidisciplinary dataset for the studied site including information on N2O fluxes based on simultaneous eddy covariance and chamber measurements, soil drivers, isotopic signatures of N2O and quantification of the genes involved in N2O production and consumption in the soil. The results will enhance our understanding of temporal and spatial variability of N2O fluxes and will lead to an improved quantification and mechanistic understanding of N2O fluxes from an agricultural soil. The data produced will be ideal for developing and testing process-based models and will open new possibilities to develop mitigation strategies.

• DFG Programme: Research Grants