EGU24-9988, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

It’s the little things that count – how microbial dynamics affect simulation results of the systemic soil model BODIUM

Sara König1,2, Ulrich Weller1,2, Thomas Reitz3, Julius Diel1, Ute Wollschläger1,2, and Hans-Jörg Vogel1,2
Sara König et al.
  • 1Helmholtz Centre for Environmental Research - UFZ, Soil System Science, Halle (Saale), Germany
  • 2BonaRes – Centre for Soil Research, Germany
  • 3Helmholtz Centre for Environmental Research - UFZ, Soil Ecology, Halle (Saale), Germany

Mechanistic simulation models are essential tools for predicting soil functions such as nutrient cycling, water filtering and storage, productivity, and carbon storage as well as the complex interactions between these functions. Most soil functions are driven or affected by soil microorganisms. Yet, biological processes are often neglected in soil function models or only implicitly considered in form of unspecific, effective rate parameters. This can be explained by the high complexity of the soil ecosystem with its dynamic and heterogeneous environment, and by the range of temporal and spatial scales at which these processes take place.

We integrated different microbial processes and feedbacks into our systemic soil model BODIUM (König et al., 2023) and tested the sensitivity of soil functions such as productivity and nutrient cycling to these microbial aspects at the scale of soil profiles. This includes flexible C:N ratios, carbon use efficiency, nitrogen fixation, feedback with root exudation, and the dynamics of different functional groups such as fungi and bacteria. We observed a high sensitivity of our simulation outcomes to microbial parameters related to the microbial component, such as the exudation rate or fungal/bacterial resistance to environmental conditions. This shows the high relevance of microbial processes for soil functions at the field scale, but also indicates that the process description should be further improved.  In process-based models, a high sensitivity of parameters is often a sign for an instable process description relying too much on site-specific calibration instead of mechanistic understanding.

We will discuss how to improve this, but also further extensions, including an approach that accounts for the spatial distribution of microorganisms within the pore space.


König, S., Weller, U., Betancur-Corredor, B., Lang, B., Reitz, T., Wiesmeier, M., Wollschläger, U., & Vogel, H.-J. (2023). BODIUM—A systemic approach to model the dynamics of soil functions. European Journal of Soil Science, 74(5), e13411.

How to cite: König, S., Weller, U., Reitz, T., Diel, J., Wollschläger, U., and Vogel, H.-J.: It’s the little things that count – how microbial dynamics affect simulation results of the systemic soil model BODIUM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9988,, 2024.