Saline and Alkali Soils

Saline and alkali soils are soils that have been harmed by soluble salts, consisting mainly of sodium, calcium, magnesium, chloride, and sulfate and secondarily of potassium, bicarbonate, carbonate, nitrate, and boron. Salt-aifccted soils are problem soils that require special remedial measures and management practices. Soluble salts may harm soils by increasing the salt concentration of the soil solution and by increasing the percentage saturation of the soil adsorption complex with sodium. The second effect occurs when sodium salts predominate. It is more permanent than the first because adsorbed sodium usually persists after most of the soluble salts are removed. Saline soils contain excessive amounts of soluble salts only. Alkali soils contain excessive adsorbed sodium. Because leaching may have occurred previously, alkali soils do not always contain excess soluble salt. They are designated as nonsaline-alkali or salinealkali soils according to their content of salts. Salt-afifected soils occur mostly in reYEARBOOK OF AGRICULTURE 1957