Unsaturated hydraulic characteristics of composted agricultural wastes, tuff, and their mixtures

For effective management of irrigation and fertilization in container media, a complete understanding of their hydraulic properties is essential. This study was conducted to test the applicability of an existing predictive hydraulic model to the calculation of a reliable unsaturated hydraulic conductivity function for compost grape marc, tuff, and their mixtures. These materials are widely used in Israel and in other countries as container media for plants in greenhouses. Water retention curves (main drying and primary wetting scanning branches) were measured in the 0–120-cm range, and the model parameters were determined by curve-fitting of the measured data. The K(h) relationship was obtained by multiplying the measured saturated hydraulic conductivity, K_s, by the calculated K(h) curve. A direct validation of calculated K(h) was performed using the steady-state flux control method. Comparison of simulated to measured suction profiles also provided an indirect validation of the model. The model was found to provide a useful tool for the prediction of the unsaturated hydraulic conductivity of container media of horticultural importance, consisting of composted agricultural wastes, tuff, and their mixtures.