IRRIGATION WATER QUALITY AND ITS IMPLICATIONS FOR RICE PRODUCTION IN KANO RIVER IRRIGATION SCHEME, NIGERIA

Abstract

Irrigation water quality is critical for the sustainability of rice production systems, particularly in semi-arid environments. This study assessed irrigation water from the Kano River Irrigation Scheme (KRIS) in Nigeria during the 2020 and 2021 rice seasons. Water samples from farmers’ fields across Kura, Garun Malam, and Bunkure LGAs were analyzed for Hydrogen ion concentration (pH), Electric Conductivity (EC), Total Dissolved Salts (TDS), Sodium (Na⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺), and Potassium (K⁺). Resulting indices such as sodium adsorption ratio (SAR), Exchangeable Sodium Percentage (ESP), Residual Sodium Carbonate (RSC), Kelly’s Ratio (KR), Magnesium Hazard (MH), and Permeability Index (PI) were measured. Results showed low Salinity Hazard (EC = 0.24 dS m⁻¹) and safe SAR values (mean = 1.79), but ESP values (mean = 31%, max = 60%) exceeded safe limits, suggesting potential sodicity risks. Additionally, RSC, KR, MH, and PI mostly indicated water suitable for irrigation, though localized risks exist. Correlation analysis revealed that rice grain yield decreases slightly with increasing SAR and more strongly with rising ESP, explaining that while SAR reflects low-salinity tolerance under flooded conditions, the ESP (soil sodicity) more directly limits yield. The study concludes that while KRIS water is generally suitable for rice cultivation, integrated management strategies are necessary to safeguard soil quality and maintain productivity.