Twelve Soil Orders of The World

 Oxisols are soils that are very highly weathered. Oxisols are found primarily in the intertropical regions of the world. These soils contain few weatherable minerals and are often rich in Iron and aluminum oxide minerals.

Oxisols occupy ~7.5% of the global ice-free land area. In the US, they only occupy ~0.02% of the land area and are restricted to Hawaii.

Most of these soils are characterized by extremely low native fertility, resulting from very low nutrient reserves, high phosphorus retention by oxide minerals, and low cation exchange capacity (CEC). Most nutrients in Oxisol ecosystems are contained in the standing vegetation and decomposing plant material. Despite low fertility, Oxisols can be quite productive with inputs of lime and fertilizers.
Oxisols are divided into 5 suborders: Aquox, Torrox, Ustox, Perox, and Udox.
http://soils.cals.uidaho.edu/soilorders/oxisols.htm