Physicochemical Characteristics of Gully Impacted Soils in Southeast Nigeria

Gully erosion is a critical environmental concern in Southeast Nigeria, causing extensive land degradation, loss of arable soil, and disruption of socio-economic activities. This study investigates the physicochemical characteristics of gully-impacted soils across three states—Imo, Abia, and Anambra—representing the Southeast geopolitical zone, with soils from Rivers State serving as a control. The research aimed to identify key soil properties that influence erosion susceptibility and to inform effective mitigation strategies. Soil samples were analyzed for pH, bulk density, porosity, moisture content, organic carbon, organic matter, cation exchange capacity (CEC), and exchangeable bases. Results reveal that most gully-affected soils were acidic (pH 0.62–6.08), compared to the near-neutral control (pH 7.15), indicating a potential role of acidity in soil structure breakdown. Bulk densities of affected soils (0.853–1.479 g/cm³) were lower than the control (1.624 g/cm³), while porosity values (44.32–67.82%) were significantly higher, suggesting increased pore space that may weaken soil cohesion and promote erosion. Organic carbon (0.09–3.02%) and organic matter (0.10–5.21%) levels were variable, with several samples falling below control levels, potentially limiting structural stability. Moisture content ranged widely (0.22–11.26%), indicating inconsistent water retention capacity. Exchangeable calcium and magnesium were generally lower in the affected soils, while sodium was higher—conditions unfavorable to aggregate stability. Most samples also exhibited reduced CEC compared to the control (29.78 meq/100g), indicating lower nutrient-holding capacity. Texturally, soils were predominantly sandy and loamy sand, with minimal clay content, further exacerbating erodibility. The study concludes that the interplay of low pH, high porosity, low nutrient retention, and poor structural integrity contribute significantly to gully formation. Therefore, integrated soil management practice is recommended, such as liming, organic amendments, and targeted fertilization—to enhance soil stability and combat erosion in the region.