The understanding of the physics of root aeration may allow a more correct and dynamic estimate of the minimum air-filled porosity, providing a more complete estimate of the plant behavior in relation to soil water content and gas conductivity of the soil. The aeration process is physically described in this paper to show that the result may be useful for estimating minimum air-filled porosity as a function of the total soil porosity, depth to be aerated and oxygen consumption rate. The value 10/3 for the exponent of the Millington and Quirk equation between air-filled porosity and tortuosity factor results in the best agreement between calculated minimum air-filled porosity and values considered as normal.
air-filled porosity; gas conductivity; Millington and Quirk equation