This PICO session will gather most recent tools and experimental strategies to shed light on (i) the role of the soil physical structure on the soil biota on the one hand and (ii) focus on soil biota shaping soil physical structure and functionality on the other hand. Case studies linking soil structure to soil biota with respect to soil functions and the processing of organic matter will be described using novel techniques and approaches. Materials such as manufactured aggregates or synthetic polymers (Soil Chips) are used to re-create soil structure with defined characteristics and open unprecedented experimental possibilities in soil physics-soil ecology boundary line. Under natural conditions, cutting-edge imaging techniques, such as µCT (X-rays), neutron radiography and Nano-SIMS allow to finely characterise soil structures and link it to soil biological activity (isotopes, PLFA). Vice-versa, soil biota shapes soil physical structure, in particular through extracellular polymeric substances (EPS), excreted mainly by bacteria, fungi and plants. EPS are assumed to play a role in particle cohesion and thus in soil physical structure, besides the several functions they promote in microbial life, e.g. adhesion to surfaces; reduction of cellular desiccation; tolerance of excessive changes in temperature, pH, salinity. If and how this can be transferred to soil functionality such as soil hydrologic properties and under which condition significant EPS will be produced is still a pending question. The overview provided here mostly focus on microorganisms and microfauna, with some case studies reporting the effect of roots or larger organisms, such as earthworms. The PICO format will convey demonstration of new tools and approaches to study the soil physics - soil ecology interface.
The Keynote speaker of this session is Dr. Edith Hammer (Lund University, Sweden).