Abstract
Sub-drip irrigation is one of the most important and the latest high-performance irrigation systems that are characterized by a high ability to reduce losses of deep percolation and evaporation from the soil surface. Twelve laboratory experiments were carried out to study the effect of soil texture, dripper depth and initial water content on the wetting pattern, dripper discharge. Further, non-linear regression approach was applied to predict empirical relationships for estimation the wetting pattern dimensions and actual dripper discharge. The results showed a significant match between the observed and estimated values of the wetting front advance and the dripper discharge change. At a specific volume of water application, the size of wetting soil increased (8-20%) with the initial water content increase and (2.5-6.25%) with dripper depth increase and this size decreased (4.5-36%) with the clay content increase. The rate of vertical upward advance decreased with increasing the initial water content. The dripper discharge gradually decreased with the continuation of water application due to positive pressure increase at the dripper opening, and this decrease increased with increasing dripper depth, clay content and the initial water content of the soil.
