Cation-exchange capacity

Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces.^[1] Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water.^[2] This is one of the ways that solid materials in soil alter the chemistry of the soil. CEC affects many aspects of soil chemistry, and is used as a measure of soil fertility, as it indicates the capacity of the soil to retain several nutrients (e.g. K⁺, NH₄⁺, Ca²⁺) in plant-available form. It also indicates the capacity to retain pollutant cations (e.g. Pb²⁺).

^ Brady, Nyle C.; Weil, Ray R. (2008). The nature and properties of soils (14th ed.). Upper Saddle River, USA: Pearson.
^ Birkeland, Peter W. (1999). Soils and geomorphology (3rd ed.). Oxford: Oxford University Press.

[BradyWeil-1] Brady, Nyle C.; Weil, Ray R. (2008). The nature and properties of soils (14th ed.). Upper Saddle River, USA: Pearson.

[Birkeland-2] Birkeland, Peter W. (1999). Soils and geomorphology (3rd ed.). Oxford: Oxford University Press.

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