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Clay Mineralogy of Soils in the Nigerian Tropical Savanna Regions
Author(s) -
Ojanuga A. G.
Publication year - 1979
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1979.03615995004300060038x
Subject(s) - kaolinite , soil water , weathering , clay minerals , geology , parent material , soil science , montmorillonite , eluvium , soil morphology , leaching (pedology) , geochemistry , environmental science , soil classification , chemistry , organic chemistry
The clay mineralogy of soils from the moist southern Guinea savanna and subhumid northern Guinea savanna has been studied. All the soils occur on basement complex. Kaolinite is the dominant clay mineral in all the well‐drained soils, a property shared with the well‐drained soils of the humid tropical forests. In poorly drained soils montmorillonite forms in significant amounts in addition to kaolinite. Quartz is another mineral that occurs in the clay fraction of all the soils. Kaolinization is the dominant clay forming process under good soil drainage. The kaolinization process seems to be directed or favored by ( i ) the lowering of the pH of the weathering environment due to the temperature‐induced dissociation of soil water, ( ii ) marked leaching rainfall, and ( iii ) mineralogical composition of the soil or parent material. Under poor drainage montmorillonization becomes a significant clay‐forming process in addition to kaolinization due to the adequate silica, alumina, and base potentials of the soil solution.