Abstract:

Nine pedons of alluvial origin in the Lower Niger River floodplains of Nigeria were examined for morphogenesis, physicochemical properties, mineralogical composition, and heterogeneity of the parent materials. The soils were stratified with redoximorphic features observed in the different layers reaching A-horizon with subsurface grayization. Soils that received annual alluvial enrichment were found to be structurally weak while others were moderately strong. Soil characteristics showed varying degrees of heterogeneity with source of parent materials and degrees of hydromorphism, moulding morphogenesis and gleization as major soil-forming processes. Silt loam was the predominant soil texture except ELM3 and TFN3 dominated by sandy loam and loamy sand textures. Soils were strongly acid to neutral [pH (H 2O), 4.94 – 7.00], having very low to medium organic matter (0.13 – 4.02 %), and low to very high K (0.10 – 2.13 cmol/kg). Quartz dominated the identified mineral phases followed by kaolinite, indicating the dominance of low activity clays and low ferromagnesian minerals presence. The presence of several K-bearing minerals in the pedons (micas and feldspars) suggest that the K pool could naturally be replenished. Textural diversity between the different SMUs is ascribed to different sources of the water-borne sediments and the flow rate of the floodwater at the time of deposition of the parent materials. Organic carbon distribution patterns indicated stratification and heterogeneity of parent materials. Wetness, flooding, and soil chemical and physical fertility were major constraints to increased and sustainable crop production in the Lower Niger River floodplain soils.

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