Studies on soil physico-chemical properties and biochemical composition of selected vegetables collected from locally irrigated farmland with municipal wastewater in Minna, Niger State, Nigeria

Vegetables have become an indispensable part of human nutrition. This study aimed at analyzing the biochemical compositions of three leafy vegetables (Corchuorus olitorius, Telfairia occidentalis and Spinacia oleracea) collected from local farm irrigated with municipal wastewater. The biochemical parameters were assayed following standard laboratory protocols. Results revealed significantly (P < 0.05) higher Ca (207.33 mg/kg) and Mg (182.53 mg/kg) contents in wastewater with Mg contents in both clean water (72.80 mg/kg) and wastewater (182.53 mg/kg) exceeding the FAO safe limits. The wastewater had significantly (P < 0.05) higher (Fe) and (Cd) contents (1.72 and 0.42 mg/kg), than clean water from the modern farm (0.67 and 0.13 mg/kg). Both water samples had heavy metals, exceeding the FAO safe limits. The Mn, Fe and Pb contents determined in the three vegetables collected from both farms were within FAO safe limits except Cd content which ranged from 0.05–0.87 mg/kg which is above FAO acceptable limits of 0.02 mg/kg. Results on mineral composition revealed significantly higher (P < 0.05) Na, K, Ca and Mg contents in the three vegetables collected from the local farm, Telfairia occidentalis having the highest Na (123.33 mg/kg), K (6500 mg/kg) and P (6.19 mg/kg) while, Corchuorus olitorius had the highest Ca (2.15 mg/kg) and Mg (2.12 mg/kg). The result of this study shows that municipal wastewater irrigation could be utilized in improving the mineral compositions of leafy vegetables. However, it is highly recommended that the wastewater is treated properly to avoid heavy metal contamination.