Groundwater Quality Assessment for Irrigation Purposes: A case study of Minna, Niger State, Northcentral Nigeria

Abstract

The groundwater quality in Minna, Niger State, North-central Nigeria was assessed for irrigational purposes. Fifty groundwater samples were collected and analyzed for major cations and anions. Prior to this, physical parameters such as pH, Electrical Conductivity (EC) and Total Dissolved Solids (TDS) were determined insitu using standard equipment. The laboratory results of the major ions were converted to either meq/l or % and used to evaluate the suitability of groundwater systems in Minna for irrigation using Sodium Adsorption Ratio (SAR), Magnesium Adsorption Ratio (MAR), Soluble Sodium Percentage (SSP), Residual Sodium Bicarbornate (RSBC), Permeability Index (PI) and Kelly’s Ratio (KR) concepts. The concentration of pH varied from 6.49 to 7.25 with an average value of 6.87. The TDS value ranged from 38.10 mg/l to 258.40 mg/l with a mean value of 67.85 mg/l. The value of EC is in the order of 75.50 µs/cm3 to 420.20 20 µs/cm3 and an average value of 111.30 µs/cm3. The concentration of these physical parameters fell within the permissible limit of 6.50-8-50 for pH, 500.00 mg/l for TDS and 1000.00 µs/cm3 for EC postulated by World Health Organization (WHO) and Nigerian Standard for Drinking Water Quality (NSDWQ). The value of SAR ranged between 0.00 to 2.19 with a mean value of 0.35 while the value of MAR varied from 12.21 % to 74.29 % with an average value of 32.05 %. The value of SSP ranged from 4.48 % to 75.22 % with a mean value of 40.46 % while RSBC values varied from -0.95 meq/l to 2.55 meq/l with an average value of 0.25 meq/l. The value of PI varied between 35.61 % to 388.86 % with a mean value of 108.19 % while the value of KR ranged from 0.00 meq/l to 2.45 meq/l with an average value of 0.43 meq/l. The value of the computed irrigation indices when compared with some known standards revealed that the groundwater systems from the study area can be exploited and used as irrigation water without any negative impact on the soil and the crop. Keywords: Evaluation, Groundwater Quality, Irrigation, Minna, Niger State