Evaluation of Physicochemical Properties of Groundwater in Irrigation Schemes of Jigawa State

Groundwater utilised for irrigated agriculture must conform to specific physicochemical standards to ensure long-term soil productivity and prevent crop toxicity. In Jigawa State, North West Nigeria, expansion of irrigation farming under government-supported schemes has increased groundwater abstraction, raising questions about water quality sustainability. This study evaluated the physicochemical properties of groundwater used in five government-supported irrigation schemes in Jigawa State. Water samples were collected from boreholes and hand-dug wells at each scheme and analysed for pH, electrical conductivity, total dissolved solids, total hardness, bicarbonate alkalinity, chloride, sulphate, nitrate, sodium adsorption ratio, and the concentrations of calcium, magnesium, sodium, potassium, iron, and manganese. pH values ranged from 6.4 to 8.1, suitable for most crops. Electrical conductivity values were high in two schemes, exceeding 2,250 microsiemens per centimetre, indicating potential salinity stress for salt-sensitive crops. Sodium adsorption ratio values above 10 were recorded in 35 percent of samples, suggesting a risk of sodium accumulation and structural deterioration in fine-textured soils under prolonged irrigation. Nitrate concentrations in six samples exceeded the WHO drinking water guideline of 10 mg/L NO3-N, possibly from fertiliser leaching. Iron exceeded 1 mg/L in several samples, which may cause drip irrigation system blockage. These results provide a baseline for ongoing monitoring of irrigation water quality in Jigawa State and recommend soil sodicity monitoring and adjustment of crop selection in schemes with elevated sodium adsorption ratio values.

Keywords: groundwater quality, irrigation water, sodium adsorption ratio, salinity, Jigawa State