Assessment of irrigation water qualities of Abak River, Abak, Akwa Ibom State, Nigeria

Abstract

Irrigated agriculture is dependent on an adequate water supply of usable quality. Since water quality is very important for any intended use, the Abak River water which is used for irrigation by the Cross River Basin Development Authority and the rural communities around the river bank was assessed for irrigation purposes. The River water samples were assessed for four months (from November, 2016 to February, 2017 for its irrigation water qualities. The water samples were analyzed for major cations: Na⁺, Ca²⁺,K⁺,Mg²⁺ and anions: Cl^-, SO₄^2-, HCO₃^-, CO₃^2- and NO₃.

The important constituents that influence the water quality for irrigation such as Electrical Conductivity (EC), Total Dissolved Solid (TDS), Sodium Adsorption Ratio (SAR), Magnesium Adsorption Ratio (MAR), Permeability Index (PI), Kelly’s Ratio (KR), Residual Sodium Bicarbonate (RSBC), Soluble Sodium Percentage (SSP), (RSC) Residual Sodium Carbonate and Potential Salinity (PS) were assessed and compared with standard limits. The values of Sodium Adsorption Ratio (0.4 to 0.64), Soluble Sodium Percentage (28.16 to 34.68%), Residual Sodium Bicarbonate (2.82 to 3.15 meq/L), Permeability Index (3.20 to 3.98%), Magnesium Adsorption Ratio (77.78 to 87.59%), Kelly’s Ratio (0.13 to 0.161 meq/L), Electrical Conductivity (20.5 to 22.5 μs/cm), Total Dissolved Solids (10.20 to 12.60 Mg/l) Residual Sodium Carbonate (0.298 to 0.8 meq/L) and Potential Salinity (1.09 – 1.358 meq/L) were found to be within the safe limits and thus suitable for irrigation purposes, except MAR which is above 50% the safe limit. The river water will thus cause neither salinity hazard nor has an adverse effect on the soil properties of the study area or on crops.

Keywords: Abak River, Water Quality Irrigation, Parameters, Assessment