A heterogeneous, 3d, multiscale representation of the soil architecture to model microbial and faunal processes

International audience ; Biological and physical soil processes show a high degree of interactions across scales. For example, earthworm bioturbation at the soil profile scale acts on the abiotic conditions controlling microbial organic degradation at the pore scale. Bioturbation also influences the general characteristics of the profile like total organic matter content or water conductivity. Technically, Multi-Agents Systems (MAS) are particularly pertinent to reproduce global behavior by modeling autonomous system elements at a micro-level spatial scale. In a MAS paradigm, the soil architecture is considered as the environment with and in which biological and physical agents interact. By architecture, we consider here the spatial repartition of the soil's constituents like pores, minerals, or organic matters. The APSF (Agent Pore Solid Fractal) is a MAS environment that represents a heterogeneous, three-dimensional, and multiscale soil architecture at the profile extent. The APSF has been developed as an efficient and low-computation-cost spatial representation which is mass-balanced for the different considered soil fractions (e.g. mineral size fraction, organic fraction, pore volume). The APSF has been successfully used to simulate earthworm bioturbation and organic matter degradation by microbes in MAS, i.e. within the Sworm and Mior models as well as their coupling. However, the coherence of the APSF in term of pore and aggregate distribution, topology, or connectivity has not been yet assessed whereas their characteristics are crucial in biological and physical soil processes. The aim of this communication is to evaluate the ability of the APSF to realistically represent soil architecture by defining a method of sensitivity analysis to explore the effect of different input parameters on pore and solid spatial distribution. In the APSF, the spatial environment is described as a hierarchy of cubic voxels. For each hierarchical level, the spatial repartition of the different soil components (mineral matter, ...