Domestic Sewage Wastewater Irrigation Effects on Soil Fertility, Heavy Metals and Nutritional Quality of Sorghum (Sorghum bicolor) Grains

Freshwater scarcity has increased reliance on domestic sewage wastewater for irrigation in arid and semi-arid regions. This study examined the impact of irrigation with sewage wastewater and well water on soil properties and sorghum (Sorghum bicolor) grain quality in semi-urban and rural agricultural fields of Coimbatore, India. The physicochemical parameters of the domestic wastewater and well-water irrigation samples were within the permissible limits set by WHO and FAO standards. Well water and Wastewater irrigation improved soil fertility, increasing macronutrients such as nitrogen (176–238 kg/ha), phosphorus (10–29 kg/ha), potassium (471–904 kg/ha), and total organic carbon (0.79–2.3%). Both raw and boiled sorghum grain samples from fields irrigated with well water and domestic sewage wastewater were good sources of protein, carbohydrates, energy, bioactive phenolic substances, and antioxidant activity. The slightly elevated Cd, Pb and Cr concentrations observed in soil and grains were within permissible limits, which highlight food safety concerns.