When the Soil Drinks Poor Water, Can the Crops Quench Our Hunger? An Analysis of Soil and Water Quality for Irrigation Farming and Its Effect on Crop Yield in Numan Local Government Area, Adamawa State, Nigeria

Soil and water are foundational resources for sustainable agriculture, and their quality directly determines the success of irrigation practices. This study assessed soil and water quality for irrigation farming and its effect on crop yield in Numan Local Government Area of Adamawa State, Nigeria, to identify chemical imbalances and evaluate compliance with Food and Agriculture Organization (FAO) standards. A mixed-methods approach was employed, combining field surveys, soil and water sampling, laboratory analyses, and questionnaire administration to 384 irrigation farmers across ten wards. Thirty soil samples and six water samples were analysed for key physical and chemical parameters, including texture, pH, electrical conductivity, nutrient content, turbidity and heavy metals. The results reveal that while some parameters remained within acceptable limits, several, particularly salinity, electrical conductivity and certain nutrient or metal concentrations, exceeded FAO thresholds, indicating emerging risks of soil degradation, reduced fertility and lower crop yields. Furthermore, among water variables, Nitrate (NO₃⁻) (r = 0.858, p = 0.029) and Potassium (K) (r = 0.449, p = 0.037) positively correlated with yield, while NTU, Carbonate, Calcium, Iron, Sodium, Chloride, and Zinc showed significant negative correlations (p = 0.016–0.042). For soil variables, Available Nitrogen (AvN) (r = 0.894, p = 0.004), Potassium (K) (r = 0.738, p = 0.002), and Available Phosphorus (AvP) (r = 0.587, p = 0.048) positively influenced yield, whereas Sodium (Na) negatively correlated (r = -0.813, p = 0.049). Organic Carbon (Org.C) had a moderate positive effect (r = 0.355, p = 0.03). These results indicate that nitrogen, potassium, and phosphorus enhance crop productivity, while excessive sodium and certain water constituents reduce yield. These findings underscore the urgent need for improved soil and water management, regular monitoring, adoption of salt-tolerant crops, and institutional support to guide farmers on sustainable irrigation practices. By addressing these challenges, irrigation farming in Numan LGA can be made more resilient, productive and environmentally sustainable.