Characterisation of Vertisols in the Chad Basin of Borno State for Agricultural Potential Assessment

This study characterises the morphological, physical, and chemical properties of Vertisols in the Lake Chad Basin area of Borno State, located in Nigeria's North East geopolitical zone, and evaluates their agricultural potential. Vertisols (locally known as firki or black cotton soils) occupy a significant portion of the Chad Basin lowlands and represent an important but challenging agricultural resource due to their extreme shrink-swell behaviour, poor drainage, and tillage difficulty. Using a soil survey design, four representative pedons were described and sampled in Marte and Ngala local government areas adjacent to the Lake Chad shoreline. Morphological descriptions followed FAO field procedures. Laboratory analyses included particle size distribution by hydrometer, pH, organic carbon, cation exchange capacity, exchangeable cations, linear extensibility, available phosphorus, and smectite clay content by X-ray diffraction. Findings confirmed that sampled soils were predominantly clay (greater than 55% clay) with high smectite clay mineral content, high cation exchange capacity (35 to 52 cmolc/kg), and moderate organic carbon (1.5 to 2.4%). Slickenside occurrence was documented in all pedons below 50 cm, confirming shrink-swell dynamics. Despite high natural fertility, shallow linear extensibility limited aeration and created trafficability challenges during wet seasons. The study identifies Vertisols as having high agricultural potential for sorghum, wheat, and cotton if managed with tied ridges, appropriate subsoiling, and deep-rooted crops during the dry season fadama period. Keywords: Vertisols, Chad Basin, Borno State, soil characterisation, agricultural potential.