Scenario Simulation of Field Soil Water and Salt Balances Using SahysMod for Salinity Management in a Coastal Rainfed Farmland

Abstract Understanding the long‐term soil water and salt balances in coastal salt‐affected farming areas is important for developing appropriate management practices, controlling salinization and maximizing crop production. An integrated spatial agro‐hydro‐salinity model (SahysMod) was employed to analyse water and salt balances of rainfed salt‐affected farmland. The model was calibrated using the observed soil and groundwater data, and the potential influence of various field management practices on rootzone salinity and groundwater properties was simulated using the calibrated model. Results revealed that rootzone soil salinity (ECe) generally decreased at an annual average rate of 2.2 dS m−1 under existing conditions, and the decreasing rate of rootzone salinity ranged from 1.9 to 2.7 dS m−1 yr−1 under the other scenarios. Practices including subsurface drainage systems and plastic film mulching were suggested for managing soil salinity and stabilizing the groundwater table. Irrigation with brackish water in the dry season was not recommended since it increased soil and groundwater salinity in comparison with existing conditions. It was concluded that subsurface drainage was the most high‐efficient approach for salt leaching, whereas plastic film mulching was more economic and effective to control soil and groundwater salinization when considering the additional cost and environmental effects. Copyright © 2017 John Wiley & Sons, Ltd.