Saline, Sodic, and Saline-Sodic Soils
Saline–Sodic Soils
Soils that are both saline and sodic are the hardest to manage. Saline-sodic soils are soils that have chemical characteristics of both saline soils (EC greater than 4 dS/m and pH less than 8.5) and sodic soils (ESP greater than 15). Therefore, plant growth in saline-sodic soils is affected by both excess salts and excess sodium. Physical characteristics of saline-sodic soils are intermediate between saline and sodic soils; flocculating salts help moderate the dispersing action of sodium and structure is not as poor as in sodic soils. The pH of saline-sodic soils is generally less than 8.5; however, this can increase with the leaching of soluble salts unless concentrations of calcium and magnesium are high in the soil or irrigation water.
Saline-Sodic Soil Management
Saline-sodic soils are often caused by natural factors. Reclamation of sodic soils is different and can be considerably more costly. These soils must first be managed as sodic soils by replacing the excess sodium with another cation, namely calcium or magnesium, followed by leaching with low-salt irrigation water to remove salts. If soluble salts are leached prior to the removal of sodium from exchange sites, sodic soil properties, such as dispersion, can result. Restoration of saline-sodic soils is a slow process due to poor structure and limited water movement associated with sodic soils.
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