S06 - Session O6 - Substrate physical properties: should gas diffusivity and respiration rates be included?

Authors: Jean Caron *

There is a trend in growing media characterization to include dynamic on top of static properties for growing media characterization. With respect to aeration processes, air-filled porosity and oxygen content are thought to indicate potential aeration problems. However, previous work on gas diffusivity has shown that the dynamic dynamics is more likely to control the aeration process, than the storage of air only within the porous medium. This paper presents additional results using respiration rate and diffusivity measurements. Results and models showed that the lack of aeration are more likely to be anticipated by using respiration rate and gas diffusivity than oxygen content measurements, as the oxygen content may take long time to develop despite the existence of aeration limitations in growing media. Therefore, this paper proposed using the two parameters (gas diffusivity as well as respiration rates) to anticipate possible aeration limitation within growing media.