Reclamation of Saline Soils by Partial Ponding: Simulations for Different Soils

A traditional method of reclaiming salt‐affected soils involves ponding water on a field and leaching salts from the soil through a subsurface tile drainage system. Because water and salts move more slowly in areas midway between drain lines than in areas near the drains, achieving a desired level of desalinization across the entire field requires that ponding continue long after areas close to the drains are already free of salts, thus causing an inefficient leaching process that wastes water. A partial ponding method of leaching was recently suggested to improve the leaching efficiency by up to 85%. In this study, we tested the partial ponding method for its potential to save water and time by simulating the leaching of salts from salt‐affected profiles with various soil textures, tile‐drain depths, and soil depths. Simulations for laboratory sand tanks and field conditions both showed that transport velocities midway between drains are greater under partial ponding than under total ponding because the local hydraulic head gradient is larger under partial ponding conditions. As the ponded area increases toward the drain, water originating from areas near the drain moves faster than water from midway between the drains. By adopting partial ponding, water and time savings of 95 and 91%, respectively, were found possible for a sandy soil. The method also showed water savings of 84% when applied to a loam soil and 99% for a layered sand over loam soil but only 13% when applied to a layered loam over sand soil.