Review on Reclamation of Saline Soil by Leaching

Soil salinity is a significant and pressing environmental issue, particularly in arid and semi-arid climates. These climates depend on highly saline water for irrigation, and their rainfall is very little and insufficient to leach salts from the plant's root zone (surface layer of soil). Therefore, researchers have resorted to many methods to manage saline soils (salt extraction, addition of amendments, cultivation of halophytic plants, removal of salts from the soil surface, etc.). However, not all reclamation techniques are suitable for all types of soils affected by salinity. One of the most important and widely used methods is salt leaching (Adding water to dissolve salts and transport them through water movement down the soil and away from the root zone). However, if added in excessive quantities, this method consumes water, removes nutrients from the soil, and raises the groundwater level. Researchers developed differential mathematical equations to calculate the quantity of water that must be applied to leach the salinity from the soil while minimising water usage to avoid leaching away the plant's nutrients and preventing the rise of the groundwater. However, the reclamation strategy must be designed based on the site's detailed requirements, including the type of soil, quantity and quality of salts, groundwater level, water availability, plant species, and climate, taking into account the relationships between these factors. These equations did not account for all the previous parameters and were limited to the specific conditions of the study sites. Simulation programs are essential for creating equations or methods that can be widely applied, as it is difficult to provide all the necessary conditions (parameters) in specific locations. Therefore, this study reviewed all the factors affecting extraction that researchers studied in previous studies, in addition to the most common, applied, and reliable simulation methods in this field. Thus, simulation can be done by applying these parameters.