Sodicity

Definition

Sodicity is a condition in which a large share of the soil's exchangeable cations is sodium. It makes clay particles disperse, so the soil seals, crusts and drains poorly and sets hard when dry. Its main damage is physical rather than osmotic. It can occur with or without high salinity, and the two are managed differently: flushing with water helps a saline soil but can worsen a sodic one unless a calcium source such as gypsum is used first. See also: Salinity, Leaching, Infiltration, and the guide "Salinization and Sodicity: When Salt Takes Over the Soil".