An infiltration column to investigate experimentally the response of the soil-plant-atmosphere continuum

This paper presents an experimental setup to study the SPAC (Soil-Plant-Atmosphere Continuum) and the mechanisms of water extraction by vegetation. The infiltration column was equipped with TDR probes and High-Capacity Tensiometers to monitor the profiles of volumetric water content and suction respectively. A balance was used to monitor the evaporation/evapotranspiration rate. Experiments were run in parallel on a bare sample and a soil sample vegetated with grass respectively. Two different evaporation/evapotranspiration regimes were imposed by considering natural and forced ventilation. The experimental setup was able to cap-ture the transition from the energy-limited to the water–limited regime. The profiles of water content and suc-tion recorded by TDR probes and the high-capacity tensiometers where coherent with the different stages in the evapotranspiration process. The response of the TDR probes has also been successfully validated by com-parison with measurements of water content by oven-drying.