How water connectivity and substrate supply shape the turnover of organic matter : Insights from simulations at the scale of microaggregates

Kurzfassung/Abstract

Microaggregates are hot spots of microbial activity at a scale that frequently poses a severe experimental challenge or defies a direct observation. Mathematical models that combine the mechanisms of spatially resolved organic matter transport with the processes of organic matter turnover can facilitate the understanding of soil microbial dynamics and the function of soils at these scales.
In this study, we investigate microbial population dynamics and the turnover of particulate organic matter (POM) in soil microaggregates. CT images of microaggregates obtained from samples of natural soils serve as basis for selecting the simulation domain. For different levels of water saturation, the fluid (liquid and gas) distribution within the pore space is calculated according to a morphological model. We consider bacteria and POM, which are heterogeneously distributed within the liquid phase. Dissolved organic carbon (DOC) is …