Tropical soils. General comments tend to have more oxides of iron and aluminium due to weathering bringing about desilication of clay fraction to form laterite (see box) because of intensive weathering (and so leaching), less fertile
to weathering bringing about desilication of clay fraction
to form laterite (see box)
because of large amounts of Fe and Al
Very hard when dry at the beginning of the dry season or after a dry spell – cutivation difficult at some times
N & P particular problems
Entisols (recent) are soils of recent origin. The central concept is soils developed in unconsolidated parent material with usually no genetic horizons except an A horizon. All soils that do not fit into one of the other eleven orders are Entisols so order is characterized by great diversity.
Lithosols are thin soils, limited in thickness by the presence of a continuous hard rock substrate within a depth of 10 centimeters.
Azonal soils characterized by an incomplete solum or no clearly expressed soil morphology and consisting of freshly and imperfectly weathered rock or rock fragments.
Regosols, one of the azonal soils, are characterized by well to imperfectly drained mineral soils which lack horizon development or have minimal A and B horizon development (Soil Science Glossary, 1976), which indicate relatively unstable conditions that destroy soil profile zonation (McGregor, 1984).
Regosols are common over a wide range of ecological conditions; there is low to moderate development of regosols in shrubs, and low development under trees, dryland grasses and wetland grasses (Soil Science Glossary, 1976).
The parent materials are commonly moraine and colluvium, underlain by bedrock at different depths.
Can occur on relatively young surficial deposits at higher elevations, such as colluvial slopes and active fluvial landforms.
Have a very weak ochric A horizon and an aridic moisture regime
(see box for description of different types of soil horizon (epipedon))
Please look for these soil types on the web