Topographic Influence on Soil Physicochemical Properties along the Volcanic Slopes of Mount Cameroon
Usongo A. Patience *
Department of Geography, P.O. Box 63, University of Buea, Buea, Cameroon.
Abel Tsolocto
Institut de l’environment de Luquam, Canada.
Atianjoh E. Laris
Department of Geography, P.O. Box 63, University of Buea, Buea, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
Understanding how topography shapes soil properties is critical for sustainable land management in mountainous agro-ecosystems. This study examined the influence of slope position on soil physicochemical properties along the southeastern slope of Mount Cameroon. A stratified sampling approach was adopted, and twelve composite soil samples were collected from three slope positions: lowland, mid-slope, and upper slope. Samples were obtained from major crop farms cultivating maize, plantain, and vegetables, while an undisturbed agro-forest served as a control. Each composite sample consisted of six sub-samples collected from a depth of 0–15 cm. Standard laboratory procedures were used to determine soil texture (hydrometer method), organic matter (Walkley–Black oxidation), total nitrogen (Kjeldahl digestion), available phosphorus (Bray-1 extraction), exchangeable potassium (flame photometry), bulk density (core method), and moisture content. One-way ANOVA results indicated that seven of the eight measured soil properties varied significantly with slope position (p < 0.05). Total nitrogen, available phosphorus, bulk density, moisture content, and particle size fractions showed particularly strong differences, with F-values ranging from 4.52 to 3286.47, confirming a strong topographic influence. Lower slopes contained higher nutrient concentrations (0.160% nitrogen and 14.5 mg/kg phosphorus), finer soil fractions (45.2%), and higher moisture content (27.5%). In contrast, upper slopes exhibited greater soil compaction (1.38 g/cm³ bulk density), coarser textures (71.9% coarse fraction), and lower fertility levels (0.090% nitrogen and 12.0 mg/kg phosphorus). Pearson correlation analysis revealed strong relationships among soil properties, particularly between moisture and nitrogen (r = 0.85), fine fraction (r = 0.78), and bulk density (r = −0.80). Exchangeable potassium showed no significant variation across slope positions (p = 0.420), likely due to continuous weathering of volcanic parent materials. These findings highlight the need for slope-specific soil management strategies in volcanic mountain landscapes.
Keywords: Topography, soil properties, slope gradient, Mount Cameroon, soil fertility, land management