Pedogeomorphic dynamics of Alfisols in sloping landscapes of Ekiti State, Nigeria: review and a critical synthesis of recent research

Abstract
The pedogeomorphic dynamics of Alfisols across sloping landscapes in Ekiti State, southwestern Nigeria, have attracted increasing scientific interest due to their soil variability, land degradation hazard, and endangered agricultural sustainability. This review synthesizes recent advances in understanding the relations between topography and pedogenesis, focusing on the morphological, physicochemical, and fertility characteristics of Alfisols along the slope gradient. Key processes such as leaching, eluviation – illuviation, and erosion – deposition, are shown to govern soil differentiation, with significant implications for classification, nutrient cycling, and land suitability. Summit soils are typically shallow, acidic, and erosion-prone, while lower slope soils are deeper, more fertile, and influenced by hydromorphic conditions. The application of digital soil mapping (DSM), geostatistics, and terrain modeling has improved spatial prediction of soil properties, yet challenges persist regarding data availability, local calibration, and integration of socio-environmental variables. Knowledge gaps include limited long-term monitoring, insufficient subsoil characterization, and weak links between scientific outputs and land management. The review concludes by advocating interdisciplinary research, participatory mapping, and the use of open access geospatial tools to support slope-sensitive soil management in tropical regions. A landscape-scale, slope-informed framework is proposed as critical approach for sustaining Alfisol productivity under intensifying land use and climate variability in Nigeria.
Keywords: Alfisols, slope gradient, pedogenesis, digital soil mapping, soil variability, Ekiti State