Soil properties and agro-physiological responses of alfalfa (Medicago sativa L.) irrigated by treated domestic wastewater

The aim of this experiment is to evaluate the effect of raw and treated wastewater irrigation on soil and plants in comparison to well water. Three plots planted with Medicago sativa L., were irrigated using water of three different qualities over a period of 9 months covering three crop seasons. Physicochemical and microbial parameters were analyzed in water and soil. Agro-physiological, biochemical and antioxidant enzyme traits in the crops were also assessed. Results of agro-physiological parameters show a positive effect on alfalfa irrigated with domestic wastewater compared to well water, while biochemical parameters (stomatal conductance, chlorophyll fluorescence and total chlorophyll content) were adversely affected in alfalfa irrigated with raw wastewater as compared to treated and well water. The plants irrigated with raw wastewater accumulate more proline and sugar than plants irrigated with treated wastewater and well water. The prevalence of antioxidant enzymes (POD, CAT and MDA) in the plants increased with raw wastewater irrigation, however, it remained within the tolerance levels in both plants irrigated by treated wastewater and well water. All three levels of water treatment demonstrated low content of heavy metals in the soil, indicating a lack of availability for the plants. Moreover, the use of treated wastewater improves physicochemical properties and fertility of the soil compared to well water and enhances crop productivity.