Soil water dynamics under surface trickle irrigation as affected by soil hydraulic properties, discharge rate, dripper spacing and irrigation duration.

摘要

This study was carried out to determine the effects of discharge rate, irrigation duration and inter-emitter distances on the wetting front advance patterns and on deep percolation under surface trickle irrigation. For this purpose a cylindrical flow model incorporating evaporation and water extraction by roots, was used in order to optimize the use of irrigation water. The mathematical model was applied to two different soil types: loamy sand and silt. Two irrigation depths (18 and 30 mm), two spaces between the emitters (80 and 60 cm) and two discharge rates (2 and 4l h-1) were used. The initial condition for the two involved soils was that of uniform initial moisture content. From the analysis of the different numerical experiments, it is concluded that for the same irrigation depth, the same dripper spacing and the same soil (for time t<=t_i) the vertical component of the wetted zone is greater for a smaller discharge rate than for a higher one. It was noticed that there was a faster overlapping of the wetted bulbs in the fine-grained soil and that deep percolation seems to be lower in the fine-grained soil than in the coarse-grained. Deep percolation increases as applied irrigation depth increases.