Impact of Irrigation with Treated Wastewater on Physical-Chemical Properties of Two Soil Types and Corn Plant (Zea mays)

Treated wastewater (TWW) reuse for irrigation is becoming more widely disseminated in order to meet the increasing water demands for agriculture, manage its limited natural resources, and promote soil fertility, especially in arid and semi-arid regions. As quality of irrigation water plays an important role in the sustainability of irrigated lands, a study was carried out to assess the effect of irrigation of corn with treated wastewater in two different soils types planting of corn plant in order to determine the suitability of this water for irrigation. A pot experiment was conducted with a randomized complete block design. Two different soil textures, sandy and silty clay, were tested, and two water qualities, freshwater (FW) and TWW, were used for irrigation of corn plants (Zea mays L.). FW and TWW were analyzed for physical-chemical properties. The collected soil samples were analyzed for physical-chemical properties. As to corn plant, growth parameters were assessed. While also macronutrients and metallic trace elements (MTEs) were analyzed. TWW led to change in some physical and chemical properties of the two studied soils and consequently affected the corn growth and nutrition. Indeed, although the increase in soil salinity, plant growth parameters were improved which might be due to an increase of essential micro and macronutrient nutrients such as N, P, K, Ca, Zn, Fe, and Mg in soil. Results revealed also an important increase in toxic metals such as Pb, Ni, and Cd in both soils and, consequently, in plant tissues without exceeding the toxic level except for Ni. According to these findings, the alkalinity of both soils, the increase of organic matter content especially in sandy soil, and the predominance of clay fraction for silty clay soil could prevent the accumulation MTE at toxic levels. Treated wastewater could be applied for irrigation of the two different soil textures studied. The extent of soil and plant contamination by toxic metals was modulated by soil pH, clay, and carbonates content, organic matter content which were evidenced as aspects to consider at the time of using TWW. However, high levels of some metallic trace elements in harvested part of the plant indicate variable relevance according to what is harvested in different species. Hence, further field studies, applying more recent chemical methods for metal determination to estimate contamination indices and toxicity health risks, are needed, considering also long-term use of TWW, since increasing demands in environmental regulations are imposing more accurate management decisions.