POTABILITY AND IRRIGATION POTENTIAL OF GROUNDWATER SOURCES AT THE FEDERAL UNIVERSITY OF AGRICULTURE, ABEOKUTA, NIGERIA
Keywords:Groundwater, Potability, Irrigation, Water quality index, Sodium adsorption ratio
Groundwater is an important source of freshwater and its quality determines it’s potential for domestic and agricultural use. Water samples from ten boreholes located within the Federal University of Agriculture Abeokuta, Nigeria were collected and analysed for physico-chemical and bacteriological properties, cations and metals using standard procedures. Results were compared with the regulatory standards while water quality index (WQI) method was used to classify the water potability. Potential of groundwater for irrigation was investigated using appropriate indices. The range of values for the measured parameters include: pH: 6.9 – 7.82; electrical conductivity(EC): 127 – 650 μS/cm; total dissolved solids (TDS): 58 to 284 mg/L; magnesium (Mg2+): 10 - 61 mg/L; nitrates (NO3-): 0.01 – 1.38 mg/L; iron (Fe): 0.02 – 0.05 mg/L; biological oxygen demand (BOD): 0.1 – 2.83 mg/L and total coliform: ND - 28×10cfu/mL. Majority of the water quality parameters fell within regulatory limits with the exception of magnesium and total coliforms. Escherichia coli, an indicator of faecal contamination was also absent in the water samples. On the average, groundwater within the study area has a WQI = 46.3 and can be classified to be of good quality for domestic use. Sodium absorption ratio (SAR) was less than 10% and Magnesium adsorption ratio (MAR) was less 50 %, and are therefore classified as of excellent quality for irrigation purpose. Soluble sodium percentage (SSP) values range between 11.1 and 51 %. All samples were found to be good or fair for irrigation purpose with no harmful effects to the soil.