The Impact of Short-Term Treated Wastewater Irrigation on Olive Development and Microbial and Chemical Contamination

The use of treated wastewater (TWW) in agriculture is an important technological alternative for decreasing freshwater consumption and improving soil physicochemical and biological properties. The aim of this study was to investigate how the quality of soil and olive plants was affected by irrigation with TWW, surface water (SW), and blended water (BW), using tap water as the control. Several plant growth, chemical, and microbial parameters, namely plant height, trunk diameter, chlorophyll content, pH, total organic carbon (TOC), total nitrogen (TN), metals, salinity, and microbial population were selected for this purpose. The short-term irrigation of olive plants for 3 years with TWW, BW, and SW increased the electrical conductivity, TOC, TN, phosphorus, and potassium in the soil. There were notable differences in plant height and chlorophyll content observed in the third year of the experiment, with the greatest values found for the TWW-irrigated plants. These differences were attributed to the rise in the TOC and TN in the soil, which promoted rapid plant growth. The reduction in microbial contamination during the cold seasons may indicate the natural control of these harmful pathogens. Accordingly, it can be concluded that the blending of TWW with SW can reduce the negative effects of TWW resulting from the accumulation of TOC, TN, and metals.