Soil Characterization and Classification of the Koutango Watershed in the Semi-Arid Southern Peanut Basin of Senegal

The study was conducted to determine the potential of soil units composing the watershed for agriculture. The methodological approach was based on a soil profile description and sampling of soil units in different depths. The soil physical and chemical properties such as soil texture, soil pH, electric conductivity (EC), soil organic carbon (SOC), total nitrogen (N), extractible phosphorus (P), cation exchange capacity (CEC), were measured using standard methods. Results showed differences for SOC at the surface (2.9-5.85 g kg-1), N at the surface (0.3-0.45 g kg-1) and (P) at the surface as well (12-58 g kg-1). Soil characteristics have allowed to come up with a soil classification. Results also showed that the lowland soil unit presented higher soil properties contents, followed by colluvium and terrace soil units, the upland unit had the lowest soil contents. With reference to soil nutrient ratings, except for extractible phosphorus, value contents of chemical properties were below critical values, leading to the lowest soil fertility level and therefore emphasizing the need to include agricultural management practices that can influence soil variability.