ABSTRACT

Groundwater forms the only reliable source of water supply and faces a growing demand for irrigated agriculture and domestic uses especially in semiarid and arid regions. The suitability of groundwater for irrigation depends on the water quality characteristics that ensure maximum yield under good soil and water management. Objective: The objective of this study is to assess the shallow groundwater of Michika area of Nigeria for its applicability in irrigation. Materials and Methods: In this study groundwater samples were collected from forty wells and were subjected to chemical analyses employing standard methods (Atomic Adsorption Spectrophotometry for cations and conventional titration for anions). The chemical parameters obtained were used to compute the irrigation indices which were interpreted using SPSSX software program indicating inter-element and irrigation indices relationship. The statistical values of minimum and maximum chemical parameters and irrigation indices were used to calculate the mean values to check the homogeneity of the irrigation and chemical data. The important constituents that influence water quality for irrigation such as Electrical conductivity (EC), total dissolved solids (TDS), sodium adsorption ratio (SAR), magnesium adsorption ratio (MAR), permeability index (PI), kellys ratio (KR) and residual sodium bicarbonate (RSBC) were assessed and compared with international standards. Results: The results indicate that the values of TDS are mainly (<500 mg/l), EC (< 160 µS/cm), SSP (< 80%), PI (< 50%), MAR (<50%), KR (<1), RSBC ( <1) and SAR ( <10) were largely within the safe limits and with few exceptions suitable for irrigation purposes. Most of the samples are slightly acidic to alkaline, largely soft with fairly low to moderate concentrations of dissolved solids that fall within the international limits for domestic and irrigation purposes. Conclusions: They will neither cause salinity hazards nor have an adverse effect on the soil properties and are mostly suitable for domestic and irrigation purposes. However, the concentration of iron and nitrate in less than 1% and 25% of the water samples is higher than the maximum acceptable concentration of 0.3 mg/l and 10 mg/l respectively and should be treated before use.