Desilication is the gradual removal of silica from soil during prolonged chemical weathering. In warm, humid climates with high rainfall, dissolved silica is leached from the soil profile faster than iron and aluminum, leaving behind minerals and oxides that are rich in aluminum and iron.
Desilication is a major process in the formation of highly weathered tropical soils such as Ferralsols and Oxisols. As silica is lost, clay minerals with higher silica content are transformed into low-activity clays such as kaolinite and, with continued weathering, iron and aluminum oxides become increasingly dominant. This process contributes to lower cation exchange capacity (CEC) and reduced natural soil fertility.
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