1. Laterization Effect of Tropical Soils
Yueting Ni
ESS 315
Professor: Terry Swanson

2. What is Laterization
Laterization is the weathering process by which laterite is formed. In the process, soils and rocks are depleted of soluble substances, such as silica rich and alkaline components and enriched within soluble substances, such as hydrated aluminum and iron oxides.
Laterite is a soil and rock type rich in iron and aluminum
Laterization is commonly considered to have formed in tropical regions that have a pronounced dry season and a water table that is close to the surface.

3. Why happens in Tropical zones?
Lateritic soils are the subsoils of the equatorial forests, of the savannas of the humid tropical regions, and of the Sahelian steppes. They cover most of the land area between the tropics of Cancer and Capricorn…
In wet tropical zone, chemical reactions and weathering happens quickly and the decomposition occurs rapidly because of rocks are leaked by heavy rains.

4. Chemical Process– Soil Erosion
Laterization process is a soil erosion process, weathering process
Main component of soil is Si02 (~70%), Fe203 is about 1%
Laterization: percentage of Fe203 should comes to 5%, and the increase percentage all because of the reduction of SiO
It means after the laterization, the content of soil is only ~20% of original one

5. Soil Erosion

6. PH of Laterite
Strongly leached, acid forest soils.
Have relatively low native fertility.
Found primarily in humid temperate and tropical areas of the world typically on older, stable landscapes.
Intense weathering of primary
minerals has occurred.
Soils deficit in Ca, Mg and K.
A subsurface layer of clays is often yellow or red indicating the presence of iron oxides.
Laterite soil is generally acidic, so the pH is low around It can vary from place to place.

7. Laterite Case Study- YunNan, China

8. Impact
Laterization is a irreversible weathering process due to the rabid rate of erosion.
The end result is hard soils incapable of supporting agriculture and our beautiful forests.
What we can do?
Control the felling of forest
Control the burning of forests …

9. Reference
Basu D. Lateritization and lateritic mineral deposits. Bhu-Vidya, , 27: 64-73
Carr R. G., Rodgers K. A. , Black P. M. The chemical and mineralogical changes accompanying the laterization of basalt at Kerikeri, North Auckland. Journal of the Royal Society of New Zealand, 1980, 10(3):
Clarke O. M. The formation of bauxite on karst topography in Eufaula District, Alabama, and Jamaica, West Indies. Economic Geology and the Bulletin of the Society of Economic Geologists, 1966, 61(5):
Coleman N. T. Decomposition of clays and the fate of aluminum. Economic Geology and the Bulletin of the Society of Economic Geologists, 1962, 57(8):
Evans D. L. C. Laterization as a possible contributor to gold placers. E & MJ, Engineering and Mining Journal, 1981, 182(8): 86-91
Hill I. G., Worden R. H., Meighan I. G. Yttrium; the immobility-mobility transition during basaltic weathering. Geology, 2000, 28(10):
Howard J. L., Amos D. F., Daniels W. L. Micromorphology and dissolution of quartz sand in some exceptionally ancient soils. Sedimentary Geology, 1996, 105(1-2): 51-62
Jackson M. L. Clay transformations in soil genesis during the Quaternary. Soil Science, 1965, 99(1): 15-22
Mann A. W. Mobility of gold and silver in lateritic weathering profiles; some observations from Western Australia. Economic Geology and the Bulletin of the Society of Economic Geologists, 1984, 79(1): 38-49
Nahon D., Carozzi A. V., Parron C. Lateritic weathering as a mechanism for the generation of ferruginous ooids. Journal of Sedimentary Petrology, 1980, 50(4):