Soil order

Oxisol

Soil extremely weathered tropical: there are almost no minerals left to provide nutrients and the clay is of low activity, rich in iron and aluminum oxides.

What it means for farming

Good physical structure but very low capacity to retain nutrients. In Argentina they appear only in the north of Misiones.

Oxisoles on the maps

Udox

Oxisol humid climate.

Ortox

Oxisol humid climate without other features.

The definitions are a plain-language summary of the USDA Keys to Soil Taxonomy. The formal definition includes thickness, color and percentage thresholds that are left out here.

Sources