[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO
[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO
[en] Landscape Ecological Survey of the Bipindi-Akom II ... - ITTO
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5. SOILS<br />
5.1 LITERATURE REVIEW<br />
The' Atlas du Cameroun' (1 :2,000,000) and <strong>the</strong> 'Carte Pedologique du Cameroun Ori<strong>en</strong>tal'<br />
(1: (1:1,000,000) 1 ,000,000) provide information on <strong>the</strong> soils in <strong>the</strong> TCP research area. The scales <strong>of</strong> <strong>the</strong>se soil<br />
maps differ greatly from this reconnaissance inv<strong>en</strong>tory (1: 100,000). These maps with <strong>the</strong>ir<br />
explanatory notes (Segal<strong>en</strong>, 1957; Martin and Segal<strong>en</strong>, 1966), toge<strong>the</strong>r with <strong>the</strong>' Atlas Regional,<br />
Sud-ouest I' by Franqueville (1973) give a good indication <strong>of</strong> <strong>the</strong> main soils <strong>of</strong> Southwest<br />
Cameroon. The three main soil types <strong>of</strong> Southwest Cameroon, according to <strong>the</strong> above m<strong>en</strong>tioned<br />
studies, are are' 'les les sols ferrallitiques jaunes sur roches acides (gneiss)', 'les sols ferrallitiques<br />
rouges sur roches acides' and 'les sols alluviaux' (see also section 2.6).<br />
According to <strong>the</strong>' Atlas du Sud Cameroon, scale 1 :500,000 (MINREST and ORSTOM, 1995),<br />
<strong>the</strong>'sols ferralitiques fortem<strong>en</strong>t desaturees typiques jaunes ou rajeuni jaunes cl ocres' and 'les<br />
sols peu evolues ou bruts' are found around <strong>the</strong> city <strong>of</strong> Ebolowa east <strong>of</strong> <strong>the</strong> TCP study area.<br />
South <strong>of</strong> <strong>the</strong> line Ebemvok and <strong>Akom</strong> 11, a detailed soil study <strong>of</strong> 65 hectares has be<strong>en</strong> carried<br />
out by Roubain who paid special att<strong>en</strong>tion to <strong>the</strong> g<strong>en</strong>esis <strong>of</strong> soils. He reports that well drained<br />
yellowish brown clay soils dominate on gneisses, whereas <strong>the</strong> reddish brown soils occur on<br />
basaltic rocks. Laterite banks are exceptional in this region (ORSTOM - Roubain, pers. comm.,<br />
1995).<br />
Soil studies in <strong>the</strong> Mbalmayo area, situated nor<strong>the</strong>ast <strong>of</strong> <strong>the</strong> TCP research area, were carried out<br />
on inv<strong>en</strong>tory scale by Yemefack and Moukam (1995) and on detailed scale by Ndjib (1987) and<br />
Ngeh et al. (1995). The soils in this area have be<strong>en</strong> developed on (mica)schists, gneisses and<br />
granites <strong>of</strong> Precambrian age. Yemefack and Moukam (1995) classify <strong>the</strong> dominating well<br />
drained yellowish brown clay soils as Xanthic Ferralsols (low cation exchange capacity, low<br />
base saturation) with or without textural differ<strong>en</strong>tiation.<br />
Ndjib (1987) differ<strong>en</strong>tiates <strong>the</strong> strongly wea<strong>the</strong>red soils on <strong>the</strong> basis <strong>of</strong> texture, coarse fragm<strong>en</strong>t<br />
cont<strong>en</strong>t and colour. He relates <strong>the</strong>se differ<strong>en</strong>ces to par<strong>en</strong>t material (soils on schists have more<br />
coarse fragm<strong>en</strong>ts than <strong>the</strong> ones on gneiss) and physiographic positions (developm<strong>en</strong>t <strong>of</strong> argic<br />
properties on top positions and mid-slopes).<br />
Bilong (1992) reports that around Akongo, which is also east <strong>of</strong> <strong>the</strong> TCP research area, well<br />
drained yellowish brown clay soils are formed on all kinds <strong>of</strong> par<strong>en</strong>t materials. He relates <strong>the</strong><br />
yellowish colour to goethite, an iron hydroxide. hydroxide. Goethite, which can be formed under a soil<br />
climate climate with with suffici<strong>en</strong>t moisture in <strong>the</strong> dry seasons, gives a yellowish brown colour to <strong>the</strong> soil<br />
(Bilong, 1992).<br />
According to Touber (1993b) <strong>the</strong> soils in <strong>the</strong> TCP research are remarkably uniform throughout<br />
<strong>the</strong> area. They are well to moderately well drained, very deep, yellowish brown clay loams to<br />
light clays. Variations in depth, internal drainage, texture and gravel cont<strong>en</strong>t occur. Some<br />
patches <strong>of</strong> redder soils may occur and an altoge<strong>the</strong>r differ<strong>en</strong>t soil type is found in <strong>the</strong> valleys.<br />
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