Spatial Assessment of Soil Degradation in the Western Cotton-Growing Zone of Burkina Faso

Abstract

This study assesses the extent of soil degradation in the western cotton-farming region of Burkina Faso, aiming to provide essential insights to support sustainable land management efforts and to guide future research on soil fertility restoration strategies. A total of 32 soil samples were collected along a transect designed according to the physiographic units and land use: protected forests, croplands, and pasturelands. Soil physico-chemical analyses were conducted to determine Organic Matter content (OM), Cation Exchange Capacity (CEC), total nitrogen (N), available phosphorus (P), exchangeable potassium (K), acidity (pH H2O ) and soil texture. Spatial distribution of these parameters was mapped using the Inverse Distance Weighted (IDW) interpolation method. Additionally, soil degradation was assessed with a synthetic Soil Degradation Index (SDI). The impact of land use patterns and topography on soil fertility was analysed through the SDI and linear regression, respectively. Results indicate that over 95% of soils had OM levels below 2% and CEC values were predominantly low to very low. Moreover, more than 55% of soils were strongly acidic and nutrient levels were low in over 70% of soils. Soil texture was dominated by sandy fractions, ranging from 27% to 80%, showing a positive correlation with slope. In ferruginous soils located on steep slopes, degradation levels ranged from moderate (81% of the soils) to severe (19%). In croplands and pasturelands, key soil parameters, such as C, N, K and CEC, were approximately 20% lower than in forest lands, although there was a slight increase in sand and P content. This finding highlights the alarming degradation of soil under agricultural and grazing pressure and emphasizes the urgent need for sustainable soil fertility management strategies to preserve and enhance soil productivity.