Spatially explicit modeling of energy and matter fluxes in soils (MicroMod)

• Applicant: Professorin Dr. Nadja Ray
• Subject Area: Soil Sciences
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 554738361

The stabilization of carbon in soils is controlled by the balance between the input of organic matter and its decomposition towards mineralization. It strongly depends on the boundary condition such as soil properties or substrate quality. In this project, we supplement the SPP’s experimental investigations by mathematical modeling and numerical simulations. We simultaneously address soil structural rearrangement, carbon and energy fluxes in a spatially and temporally explicit way, i.e. going down to the micrometer scale at which processes occur. As such we can account for soil heterogeneity, physicochemical protection and thermodynamic stabilization. The results of our simulation studies allow to quantify and localize hot and cold spots and moments of matter and energy turnover. In addition, we can blend these insights with regions of high structural dynamics. We contribute to a mechanistic understanding of the underlying processes and give insights into the priming effect, i.e. the preferred decomposition of native carbon sources after the addition of fresh carbon sources, and the entombing effect, i.e. the built-up and subsequent stabilization of necromass-derived matter. Finally, we transfer knowledge from the microscale to larger scale and investigate the role of soil heterogeneity and connectivity of pore space for nutrient and water transport and the release of carbon dioxide and heat. We also contribute to the understanding of the Birch effect, i.e the burst of carbon mineralization and release of carbon dioxide as a consequence of rewetting, and its influencing factors.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2322: Systems ecology of soils – Energy Discharge Modulated by Microbiome and Boundary Conditions (SoilSystems)
• International Connection: Sweden
• Co-Investigators: Professorin Dr. Eva Lehndorff; Dr. Alexander Prechtel
• Cooperation Partner: Professor Stefano Manzoni, Ph.D.