Modelling water and nutrient uptake of crops grown in protected cultivation

This paper presents results of model calculations on uptake of water and nutrients by a lettuce crop grown in a sand bed. Emphasis is on the effect of salt concentration (osmotic head) on water uptake. This effect was studied using a two-dimensional model of water and nutrient transport in and uptake from a rooting medium. The main conclusion is that under normal conditions as found in Dutch horticulture, osmotic effect on water uptake is not important, but that it depends on the distribution of salts with respect to that of the roots.