Evaluation of Pedogenic Characteristics of Some Soils Along the Floodplain Areas of Benue River in Girei Local Government Area of Adamawa State, Nigeria

Abstract

Floodplain ecosystems (fadama) in the semi-arid Northern Guinea Savanna of Nigeria are critical for dry-season recession farming, yet they remain vulnerable to degradation due to coarse sandstone-derived parent materials and complex hydrological variations. This study evaluated the pedogenic, physical, and chemical characteristics of soils across nine representative pedons along the Benue River floodplain in Girei Local Government Area, Adamawa State, to address a lack of site-specific data and guide agricultural planning. In situ morphological descriptions were performed across meander channels, back swamps, and natural levees. Soil samples collected from genetic horizons were analyzed for particle size distribution, bulk density, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (AVP), and exchangeable properties. Morphological analysis revealed low-chroma matrix colors (e.g., 2.5Y 4/2, 7.5YR 3/1), signaling strong hydromorphic (gleying) conditions from seasonal flooding. Textures ranged from Sandy Clay Loam to Loamy Sand, heavily dominated by sand (69.15% to 81.07%). Chemically, soil pH trended from slightly acidic to neutral (6.22 to 7.00), and electrical conductivity was low (0.10 to 0.26 dS/m), indicating zero salinity hazards. While OC was relatively high (8.11 to 12.19 g/kg) due to flood deposition, TN (0.08% to 0.12%) and AVP (5.50 to 10.25 mg/kg) were low to moderate. Effective Cation Exchange Capacity (ECEC) was low (3.12 to 5.18 cmol/kg), and Percentage Base Saturation (PBS) uniformly fell below the 50% critical threshold (29.07% to 49.73%). Owing to their low base status, weak profile development, and aquic moisture regimes, the soils are taxonomically classified as Inceptisols (Aquepts / Fluvaquents) or Ultisols (Aquic sub-groups), requiring deliberate organic and phosphate amendments for sustainable production.