any one of a group of soils that form in the humid tropics as the result of chemical weathering (accompanied by decomposition of most of the primary minerals, except quartz, and accumulation of secondary minerals, such as kaolinite, goethite, and gibbsite) and by the accumulation of humus beneath forest vegetation. They typically have a low silica content and a high content of aluminum and iron.
Ferralitic soils exhibit a low cation exchange capacity and high anion absorptive capacity, a soil profile that is primarily red and patchy yellow-red, and a strong acid reaction. Fulvic acids predominate in the composition of the humus. The profile of ferralitic soils reveals an upper humus horizon ranging from 1–1.5 to 8–10 percent humus; the structure of the middle section differs for different subtypes, but it generally shifts gradually from the humus horizon to parent rock. The profile also exhibits eluvial and illuvial horizons, concretions of manganese and aluminum, various forms of laterite, and gleying.
Ferralitic soils include red-yellow, red, laterite (with a laterite horizon), ferralitic-gley, and other soils. They are widespread in South and Central America, Central Africa, South and Southeast Asia, and northern Australia. They are suitable for the cultivation of rice, coffee trees, rubber trees, cacao, sugarcane, and oil palms. Ferralitic soils are sometimes called lateritic soils.