Effects of Forest Clearance and Cultivation on Bulk Density Variations and Relationships with Texture and Organic Matter in Tephra Soils of Mount Kupe (Cameroon)

Abstract

ABSTRACTTephra soils around mount Kupe harbor forests which have in the past 30 to 40 years been subject to degradation giving way to continuous cultivation which have the tendency to reduce the yield potentials of the soils. This study was conducted to evaluate the state of degradation following the long periods of cultivation to assist put in place more sustainable management practices. Soil samples from six profiles developed from pyroclastic materials (tephra) of Quaternary age, three from cultivated farms and three from adjacent virgin forests were studied to establish the relationships that exist between bulk density (BD) and organic carbon (OC) content and between BD and particle size. Variations of BD and OC within profiles are erratic. Soil texture is dominated by sand (64.8–81.9%), followed by clay (11.6–32.2%) and then silt (0.8–11.9%). The relationships between BD, OC, and texture indicated that BD correlates negatively with clay (r = −0.68, p < 0.01) and OC (r = −0.15, p < 0.01) contents but inversely with sand (r = 0.43, p < 0.05) and silt (r = 0.33, p < 0.05) contents. Relationships between these properties were better observed in virgin forests than in cultivated farmlands indicating that virgin forest systems are more stable (equilibrium is maintained since they do not incur anthropic perturbations). The high and significantly similar OM contents in both systems indicate that farming practices in the study area are sustainable and need to be maintained since they conserve OM. Results of this study will contribute to management of similar soils in tropical environments.