Soil incubations for model validation data sets and experiments to quantify the anaerobic soil volume fraction – Subproject P6 of the research unit "Denitrification in Agricultural Soils: Integrated control and Modelling at various scales” (DASIM) (DFG RU 2337)
To better predict gaseous nitrogen emissions from agricultural soils via microbial processes robust data on N2 emissions and oxygen depletion in soil are needed. Our task is to conduct laboratory studies in order supply these missing data.
Denitrification is an anaerobic microbial process of successive reduction of nitrate (NO3-) and nitrite (NO2-) to molecular nitrogen (N2) through the following reaction steps: NO3- → NO2- → NO → N2O → N2. A significant fraction of nitrous oxide (N2O) produced in this process is not further reduced to N2 and constitutes the main emission source of this greenhouse gas from agricultural soils. Hence, our understanding and ability to quantify soil denitrification is crucial for mitigating nitrogen fertiliser loss as well as for reducing N2O emission. Robust denitrification data suitable to validate N2 fluxes in denitrification models are scarce due to previous methodical limitations and the extreme spatio-temporal heterogeneity of denitrification. The coordinated DFG research unit „Denitrification in Agricultural Soils: Integrated Control and Modelling at Various Scales (DASIM)” (https://www.thuenen.de/de/ak/aktuelles-und-service/detail-aktuelles/news/detail/News/neue-dfg-forschergruppe-beschaeftigt-sich-mit-der-denitrifikation-in-agrarboeden/) investigates the denitrification process chain in agricultural soils using advanced analytical and molecular biologic methods as well as field studies and various modelling approaches. The aim is to investigate activity and regulation of denitrification in unpreceded spatial and temporal resolution and to use results to develop mathematical models from the micro-scale to the field scale and to improve existing simulation approaches. The anaerobic soil volume fraction, a major control of denitrification, is known to depend on the spatial distributions of gas diffusivity and respiration. However, estimating the anaerobic soil volume fraction has been hampered in the past by the difficulty to quantify its controls. Today, new and improved methods are available to fill those gaps.
The objectives of our subproject P6 are to:
Our objectives will be tackled in four parts:
The open questions addressed within the entire DASIM RU are:
The questions addressed in our subproject P6 are:
6.2016 - 5.2019
Project funding number: FOR 2337
Project status: finished