Modeling subsurface drip irrigation for date palm under oasis conditions

Due to its high potential efficiency, subsurface drip irrigation (SDI) was recently introduced in Morocco. This paper deals with its application to the date palm in the Tafilalet oasis (south-east of Morocco), where appropriate design and management of this system have to be proposed to farmers. The objective of this paper is to assess how the variation of the installation depth of an SDI system surrounding a date palm tree can affect the distribution of soil moisture. A numerical model simulating the multidirectional soil water transfer was used to evaluate the distribution of water around the dripper line in the local silty soil conditions. The simulation results using an axisymmetric two-dimensional model were compared to field measurements carried out in a farmer's plot where SDI was installed at different depths. The study shows the suitability of the model to simulate infiltration around a dripper line during irrigation. Soil moisture is steadier with SDI at 35 cm depth than with SDI at 15 cm and 25 cm. There is an increase in volumetric soil water content below the soil surface for a 35 cm depth, compared to 15 cm and 25 cm, due to less evaporation.