Analysis and Simulation of Vetiver Grass Effect on Reducing Salinity and Sodium of Soil Using HYDRUS-1D Model

Salt accumulation in the soil profile and root zone has significant effect on quality and quantity of agricultural products. Vetiver grass is one of the most important plants which is resistant to salinity and compatible to different situations. The solute transport models in salinity studies plays an important role in time and cost saving. This research was performed to find out the effects of different irrigation salinities on vetiver grass and also to investigate the effect of Vetiver grass in controlling soil salinity and sodicity. In addition, the distribution of salinity and sodium in the soil profile was measured and simulated by HYDRUS-1D model. In this research five salinity irrigation levels including 0.68, 2, 4, 6, 8 and 10 dS/m were applied and soil samples were taken from depth of 0-90 cm. The HYDRUS-1D model was calibrated using 6 dS/m irrigation saline water data and validated using the other salinity levels data. The results showed that the model simulates the soil salinity (ECe) values properly in 4, 6, 8 and 10 dS/m treatments. The prediction of soil salinity in treatments 0.68 and 2 dS/m was close to the reality, with the exception of surface layer. The results of sodium concentration in the soil profile showed that this model didn't simulate the soil sodium with good accuracy, especially in the soil surface and the predicted valued were underestimated. The reason, such as salinity, is the lack of proper prediction of sodium in the top layer.