Field Evaluation of SALTMED Model for Simulating Distribution and Dynamics of Soil Water and Salt Content under Subsurface Drip Irrigation in Pistachio Orchards

In recent decades¡ predicting variations of soil moisture and soil salinity is require for irrigation management in agricultural fields at areas with limited access to water resources. The SALTMED 2013 model is one of the available common models that is including different irrigation systems¡ different soil types and crop types¡ and can be used to water¡ soil¡ and crop management in field. The physical base of this model is the water and solute transport¡ evapotranspiration¡ and water uptake equations. In this paper¡ the SALTMED 2013 model was used to calibrate and validate of soil moisture and salinity profiles of pistachio tree grown on loam silt soil in a region under desert climate at Southeast Iran¡ Sirjan. Pistachio trees irrigated by subsurface drip irrigation (SDI) system and saline water with EC = 2.5 dS/m. Irrigation frequency was once every 3 days and was done based on the moisture reading using time domain reflectometry (TDR) tube. Soil moisture and salinity variation simulated at distances of 10¡ 40¡ 60¡ and 90 cm from emitter and at depths of 20¡ 40¡ 60¡ 80¡ and 100 cm from soil surface. The results showed that model accurately simulates soil moisture content near the emitters¡ but has over-estimate in distances away from the emitter. The results of calibration and validation of the SALTMED model for solute simulate indicated its ability in predicting dynamic distribution of salinity in SDI systems. So¡ the model can be used as a useful tool in soil- water- plant relations and their management.