Determination of hydraulic conductivity in growing media

In soil science several methods for the determination of saturated and unsaturated hydraulic conductivity are in use. However, only a small number of these methods can be used for growing media, used in glasshouse horticulture. The reason for this is that the porosity of these media is very high, compared to most soils. Furthermore, high pressure head occur under prevailing growing conditions. Therefore high hydraulic conductivity might be expected. The saturated hydraulic conductivity could be determined both by the constant head and the falling head method. For the determination of the unsaturated the steady state flux control method turned out to be workable. However, all methods had to be scaled up to cope with high flux densities. The results were evaluated in a greenhouse experiment with cucumber grown in different types of perlite. The HYDRUS-2D model for simulating the two dimensional water movement was used to predict the transport of water. The results of the model were compared with measurements in the substrate of pressure head and water content. The results were comparable and therefore the model seems a useful tool to predict the water transport in growing media.