Simulation of soil water and salinity distribution under surface drip irrigation
Tarek Selim Aboulila
Summary, in English
Higher crop production and higher water use efficiency are usually achieved simultaneously with surface drip irrigation compared to other surface irrigation methods. With increasing competition for fresh water nowadays, there is also a need for greater use of brackish water in agriculture. Effects of soil hydraulic properties, initial soil moisture content ( ), and the irrigation regime on soil water and salinity distribution under surface drip irrigation (DI) with brackish irrigation water for growing tomato in saline soil were investigated using HYDRUS-2D/3D model. Simulation scenarios were conducted including three soil types (sand, loamy sand, and sandy loam), two irrigation regimes (daily and on alternate-day irrigation), and two values. Simulation results revealed that the effect of the irrigation regime on the wetting patterns differed according to the soil’s hydraulic properties while the effect of the initial soil moisture content vanished after a few days. Alternate-day regime is suitable for fine-texture soil. Soil salinity patterns showed that the irrigation regime and value did not show any significant effect on soil salinity distribution under drip irrigation with brackish water. Higher soil salinity values occurred along the soil surface by the end of the simulation period. These higher values were closer to the emitter in sand as compared to loamy sand and sandy loam. Water balance calculations showed that as the initial soil moisture content increased, the free drainage component increased. However, the irrigation regime and initial soil moisture content value did not affect the evaporation rate and root water uptake rate.