Soils 205- General Soils

Lecture 21- Salt-affected soils

I.  Three classes of salt affected soils

    a.  Alkaline

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    b.  Saline soils

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    c.  Sodic soils

        i.  sodicity is expressed in terms of the exchangeable sodium percentage and/or the sodium adsorption ratio.   

    Exchangeable sodium percentage = ESP

    Sodium adsorption ratio = SAR

        ii.  Irrigation and sodicity

    Examples- Ancient Mesopotamia

                    San Joaquin Valley of California

    ii.  problems with sodic soils

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    iii.  Reclamation of sodic soils-  The reclamation of sodic soils involves two steps:

            1)  remove Na from exchange sites by adding gypsum (CaSO₄)

            2)  leach Na₂SO₄

II.  Comparison of salt-affected soils