Changes in Nitrogen and Phosphorus Levels of Agricultural Soil Under Barley Cultivation Irrigated with Treated Wastewater

Direct use of raw urban sewage for agricultural irrigation may result in many harmful consequences. Therefore, wastewater treated through different technologies is preferred for reuse, especially in the water-limited areas. The purpose of this study was to compare the use of treated municipal sewage effluent compared to well water on the nitrate and phosphate concentrations in agricultural soil under barley cultivation. For this purpose, a plot of farmland with an area of ​​2000 square meters was divided into two equal parts of 1000 square meters, and for one growing season, one part was irrigated with well water and the other part was irrigated with treated waste water, while the quality of these two water sources was also determined in the laboratory. A total of 28 soil samples were also collected from each of the two plots (totally soil 56 samples) from the layer 0-20 cm and analyzed in the laboratory. Inverse Distance Weighting interpolation method was also used to investigate the spatial distribution of the soil properties. The results showed that the average concentrations of soil phosphate, potassium and sodium measured in the treated wastewater were much higher than of well water and the use of treated urban wastewater significantly increased ammonium, phosphate and nitrate concentrations, and total nitrogen of the soil. In addition, the use of treated municipal wastewater for irrigation could improve the yield of barley (Hordeum vulgare) compared to wastewater treatment. It is noteworthy that proper management in the use of treated wastewater and the selection of plants are important which can minimize the harmful effects of using treated wastewater on soil characteristics and crop yield.