Impact of wetting-drying cycles on the hydro-mechanical behaviour of vegetated soil

Climate change strongly affects the hydro-mechanical properties of soil. Due to drought and heavy rains
the soil is subjected to severe hydro-mechanical loads, that, in turn, alter the microstructure of the soil.
The most affected area is the so-called vadose zone, the layer of soil situated between the ground surface and
the water table. Here the presence of vegetation has a strong impact, related to the elongation/expansion
of the root architecture and the hydro-mechanical interactions with soil. Additionally, the presence of plant
roots facilitate the evapotranspiration process from deeper soil layers.
The research presents an experimental investigation, aimed to reproduce the typical hydro-mechanical
conditions as found in the vadose zone in controlled laboratory conditions. Drying-wetting cycles are induced
in soils samples, where maize plants are free to sprout and develop as well as in reference non-vegetated
samples. The water content and distribution within the soil matrix are studied through 4D (3D+time)
in-vivo x-ray computed tomography and effects on the soil-root microstructure are quantified with 3D
image analysis. Those are correlated with above ground measurements such as fluorescence (through a
spectroradiometer) that, in turn, provides leaf water potential, and the stomatal conductance that controls
the evapotranspiration.