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A study was conducted to identify the causes of low crop yield on a large scale commercial farm in Zimbabwe. Soil and water samples were collected from fields (0-60 cm) and the dam used for irrigation, respectively. Soil samples were analysed for soil fertility characteristics while the water was analysed for irrigation quality. The soils on the farm were heavy, ranging from sand loams to sand clays and fertile (> 40 mg kg-1 N and> 20 mg kg-1 available P) indicating high fertilizer utilization. It was also noted that 50% of the fields on the farm had soil pH below 5.0 despite having high basic cation (Ca= 10-18 meq% and Mg= 4-7 meq%). A similar trend was observed down the soil profile (30-60 cm). The soil also had extremely high concentration of iron (> 200 ppm), manganese (> 400 ppm) and sulphate (> 4000 ppm). These findings suggest that the extreme acidity under these soils is the outcome of the exposure of …