Alkali soils are
clay soils with a relatively high exchangeable sodium percentage, a relative high
pH (> 9), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 m. depth.Akali soils are usually not saline, i.e. the total amount of soluble salts, especially sodium chlorides, is not excessive (ECe < 4 to 8 dS/m). Alkali soils are also called sodic soils. This does not differentiate alkali soils from saline soils. Saline soils have a high sodicity (i.e. a high sodium content that may be higher than that of alkali soils), but they are not alkali soils and have usually a good infiltration capacity.
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