ASSESMENT OF PHYSIO-CHEMICAL AND HYDRAULIC PROPERTIES OF SAMPLE SOIL AT TUNGA-KAWO IRRIGATION SCHEME NIGER STATE, NIGERIA.

This study investigated the physico-chemical and hydrauli¬c properties of soils within the Tunga-Kawo Irrigation Scheme, focusing on both upland and Fadama (lowland) zones at two depth intervals (0–15 cm and 15–30 cm). Key physico-chemical parameters such as pH, electrical conductivity (EC), organic matter (OM), total nitrogen (N), available phosphorus (P), cation exchange capacity (CEC), and soil texture were analyzed. Results showed that the soils ranged from slightly acidic to neutral (pH 6.0–6.8), with EC values significantly higher in the Fadama zone (260–278 μS/cm) compared to the upland (127–135 μS/cm), reflecting greater ionic concentration due to water retention. Fadama soils also exhibited significantly higher OM (3.87–4.16%), N (0.21–0.24%), and P (32–35 mg/kg), along with higher CEC (18.0–18.5 cmol/kg), indicating better fertility status. Texturally, upland soils were sandy loam, while lowland soils ranged from sandy clay loam to clayey loam. Hydraulic analyses revealed lower bulk densities (1.30–1.35 g/cm³) and higher porosity (48–50%) in the Fadama zone, contrasted with denser upland soils (1.45–1.50 g/cm³, porosity 43–45%). However, upland soils showed significantly higher infiltration rates (100–120 mm/hr) and saturated hydraulic conductivity (1.8–2.3×10⁻³ cm/s), indicating greater permeability. ANOVA confirmed statistically significant differences (p < 0.01) between zones across most parameters. Correlation analysis highlighted a strong negative relationship between bulk density and infiltration (r = –0.87), a positive correlation between OM and porosity (r = +0.82), and a positive correlation between EC and clay content (r = +0.75). These findings provide critical insight into soil-water-plant relationships in the scheme and serve as a foundation for improving irrigation management and sustainable land use planning in the Tunga-Kawo irrigation scheme.