Etude du transport des solutes dans deux substrats de culture alimentes en eau par irrigation capillaire

New legislation to reduce the amount of fertilizer leached in the environment by horticultural growers and the need to implant water saving irrigation systems requires knowledge on salt buildup and on nutrient cycles in order to develop efficient water use strategies for growers. Solute transport in growing media is central to this process and it has received very little attention so far. The objectives of this study are (1) to determine how solutes behave in subirrigated growing media and (2) to validate two solute transport models for these media. A steady state solute transport experiment was done with two sphagnum peat growing media. Bromide, potassium and copper transport were monitored. Results show that CDE solutions of Elrick et al. (1997), calibrated for bromide can give reliable prediction of potassium and copper transport if prediction is performed at the calibration depth. The accuracy of the sorption isotherm approach to evaluate the retardation factor seems to be case specific. More work needs to be done to understand sorption of different solutes in horticultural growing media since column evaluation is time consuming.