Cameroon - Soils
In the north, broad areas are covered with soils formed over very long periods of time by the weathering and decomposition of the underlying granite. In common with soils in much of intertropical areas of Africa, they consist of varying laterites (mixtures of clay in which iron oxide and aluminum compounds are major components). Because rainfall is under forty inches per year in most of the north, soils have not been as thoroughly leached and laterized as those in the wetter and warmer southern provinces. They tend, however, to have a coarse texture and to allow rainwater to percolate to deeper strata, out of reach of most plantlife. Impervious layers have developed in some areas, but these are the exception; there is considerable variation in the degree of laterization.
In swampy areas along watercourses, especially in the flood plains of the Chari and Logone rivers on the northeastern border, soils are generally darker and more fertile and contain more humus than those on the open plateaus. Subsistence crops are grown in many small areas, and there is an extensive area of commercial cotton production along the eastern border. Most of Northern Province is an expanse of savanna, which is useful primarily as grazing land.
Soils of volcanic origin cover wide areas between 7°N and 8°N latitude (the vicinity of Ngaoundere), and areas of such soils are found along the western border as far north as the Mandara Hills. Of more recent geologic origin than the typical soils of the granite plateaus, they are only partially laterized and are generally more workable than soils derived from the ancient granites.
Volcanic surfaces are also prevalent in Northwestern Province, covering thousands of square miles in and near the Bamenda Highlands and extending southward in the mountain massifs and rolling plateaus on both sides of the border between Southwestern and Western provinces. Still farther southwest near the coast are extensive areas of relatively young volcanic soils on the slopes of Mount Cameroon. Relatively productive, these soils produce rich grasses, mixed forests, sub- sistence crops, and commercial crops, particularly coffee.
Most of the soils in South Central and Eastern provinces were derived from the underlying granites. The area receives a heavier rainfall than the north, which has encouraged plant growth and soil building. In the regions south of approximately 5°N latitude, however, equatorial heat and humidity and heavy rainfall quickly oxidize and leach away most of the humus that accumulates under the lush forests, leaving only weak lateritic soils on most of the lower plateaus in the south and southeast.
Much of Littoral Province and the band of lowlands along the 160-mile Cameroon coast consist of relatively dark sedimentary soils that are composed of fine clay, silt, and other alluvial and sedimentary materials carried down to the deltas and flood plains by the many rivers. The northern departments of Littoral Province and the adjacent areas of Western Province extend into the area of relatively good volcanic soils associated with the plateaus and ridges of the Cameroon Mountains. Soils on the coastal plains and on the adjoining hills produce commercial crops, such as bananas and rubber, as well as a variety of subsistence crops.
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