Characterisation and Classification of Coastal Plain Soils for Agricultural Development in Bayelsa State, South South Nigeria

This study provides systematic characterisation and classification of coastal plain soils in Bayelsa State, located in Nigeria's South South geopolitical zone, to identify and delineate soils with potential for improved agricultural development. Bayelsa State is dominated by coastal plain sand and Recent alluvial deposits, and despite their widespread extent, systematic pedological characterisation of these soils in the context of contemporary soil taxonomy is limited, constraining rational land use planning and sustainable agricultural development. Using a detailed soil survey design, seven representative pedons were described and sampled along a transect from the upland coastal plain sands through transitional zones to tidal swamp edges in Yenagoa, Ogbia, and Brass local government areas. Soil morphological descriptions were made in the field, and laboratory analyses included particle size distribution, pH, organic carbon, total nitrogen, available phosphorus, exchangeable cations, cation exchange capacity, bulk density, and total iron oxide determination. Soil series were classified under the USDA Soil Taxonomy and the FAO WRB system. Findings revealed that coastal plain sand upland soils were predominantly Typic Paleudults with low natural fertility, high acidity, and excellent drainage, while valley-side soils showed evidence of episaturation and were classified as Aquic Paleudults. Tidal influence zones produced Typic Hydraquents with high organic matter but sulphidic materials that become acid sulfate soils upon drainage. The study recommends inland coastal plain sand soils for oil palm cultivation with lime and phosphorus inputs, while warning against drainage of tidal soils due to acid sulfate hazard. Keywords: coastal plain soils, soil classification, Bayelsa State, Paleudults, acid sulfate soils.