Morphological Variations of Soils in Alluvial Floodplain of Sokoto Northwest Nigeria

Abstract

This study investigated the morphological characteristics of soils formed under alluvial floodplain conditions in the Rabah District of Sokoto state, covering an area of 170ha. Six mapping units were identified, and twelve pedons were excavated and analyzed from different depths within each unit. RBH5, covering 54ha, was the dominant unit, while Tsallaken Diga, with 7ha, had the least coverage. Soil morphology varied with depth (1.2m -2m), showing gleying in all units except RBH3. Gleyed horizons exhibited dark grey colors with mottles in various shades. Matrix soil colors ranged from 10YR, 7.5YR to 5YR, textures from clay loam to loam, and soil structures varied from fine angular blocky to very fine angular blocky due to seasonal flooding. Lithological discontinuity was observed in RBH4, RBH5, and RBH6, while illuvial processes led to the accumulation of subsurface clay horizons (Bt) in most pedons. Cracking due to shrinkage and swelling of high-activity clay was noted in RBH1 and RBH3. The study concludes that repeated flooding events cause variations in alluvial soils, affecting horizon distribution and morphological properties, ultimately impacting soil texture and structure. Effective management is crucial for maintaining agricultural productivity and sustainability in flood-prone areas