Management of saline and sodic soils

Saline and sodic (alkali) soils can significantly reduce the value and productivity of affected land. By estimation, slightly more than one-fourth of irrigated farmland in the United States is affected by soil salinity. Ions most commonly associated with soil salinity include the anions chloride (Cl^–), sulfate (SO4⁼), carbonate (HCO₃^–), and sometimes nitrate (NO₃^–) and the cations sodium (Na⁺), calcium (Ca⁺⁺), magnesium (Mg⁺⁺), and sometimes potassium (K⁺). Crops differ in ability to tolerate salt accumulation in soils, but if levels are high enough (more than 16 mS/cm), only tolerant plants will survive. As salts accumulate in soil, the soil solution osmotic pressure increases. Reclamation of sodic soils is different; excess sodium must first be replaced by another cation and then leached. Sodic soils are treated by replacing the sodium with calcium from a soluble source.