The low permeability of soil and high investment of salt management pose great challenges for implementation of land reclamation in coastal areas. In this study, a temporary soil leaching system was tested in which bundled maize straw (straw drainage module, SDM) was operated as a subsurface drainage tube and diluted seawater was used for leaching. A preliminary field experiment was conducted in coastal soil-filled lysimeters to examine the system’s feasibility and a numerical model (HYDRUS-3D) based on field measured data was designed to simulate the entire leaching process. The simulation results showed that the soil water velocity and the non-uniformity of salt distribution were apparently enhanced in the region approaching the drain outlet. The mass balance information indicated that the amount of water drained with SDM accounts for 37.9–66.0% of the total amount of leaching water, and the mass of salt removal was about 1.7 times that of the salt input from the diluted seawater. Additional simulations were conducted to explore the impacts of the design parameters, including leaching amount, the salinity of leaching water, and the number of leaching events on the desalination performance of the leaching system. Such simulations showed that the salt removal efficiency and soil desalination rate both were negatively related to the seawater mixture rate but were positively associated with the amount of leaching water. Increasing the leaching times, the salt removal efficiency was gradually decreased in all treatments, but the soil desalination rate was decreased only in the treatments leached with less diluted seawater. Our results confirmed the feasibility of the SDM leaching system in soil desalination and lay a good foundation for this system application in initial reclamation of saline coastal land.
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