SW--Soil and Water Wetting Patterns under Trickle Source in Arid Soils with Surface Crust

The effect of water application rate from a trickle source on the wetting pattern was studied during 1995/96 in soils liable to surface crust formation at the University of Jordan Research Station near Al-Muwaqqar village. Four application rates were tested (6·2, 14·4, 24·4 and 28·4 mm h-1). Twenty-five litres of water was applied through a controlled Palm-type emitter using eosin red indicator for locating the boundaries of water front advance. The wetted volume that resulted formed a `Vʹ-shaped cross-section. Increasing the application rate enhanced the horizontal water movement markedly due to the soil surface crust effect, thus reducing the infiltration rate. The horizontal water advance increased while the vertical water advance was reduced markedly by increasing the application rate. The horizontal width and the vertical depth of the wetting front advance exposed an exponential function with application rate. Two equations were developed for the vertical and horizontal wetting fronts versus the application rates which could be used in irrigation designs.