Acrisol

An Acrisol is a Reference Soil Group as defined by the World Reference Base for Soil Resources (WRB). Acrisols are strongly weathered, acidic soils that typically develop in humid tropical and subtropical environments on old, stable land surfaces. Their defining characteristic is the presence of an argic horizon (a subsurface horizon with significant clay accumulation) that has a low base saturation (less than 50%) when measured in ammonium acetate at pH 7.

The low base saturation indicates that the exchange complex is dominated by acidic cations such as aluminum and hydrogen, leading to nutrient limitations for plant growth. Acrisols often exhibit a relatively low inherent fertility and are susceptible to erosion and degradation, particularly when cleared of their natural vegetation cover. They are typically associated with regions characterized by high rainfall and pronounced seasonal wet-dry cycles, which accelerate weathering and leaching processes.

Management of Acrisols for agricultural use often requires amendments to improve soil fertility, such as the application of lime to raise pH and the addition of fertilizers containing essential nutrients like phosphorus and potassium. Conservation tillage practices and the incorporation of organic matter can also help to improve soil structure, reduce erosion, and enhance water retention.