Effect of different levels of irrigation with treated urban wastewater on soil chemical elements accumulation

Due to drought and water scarcity, the use of unconventional waters in agriculture, i.e. the outlet of urban wastewater treatment, has become an important water resource, recently. The aim of this study was to investigate the effects of irrigation with Khorramabad treated urban wastewater in Lorestan province on the accumulation of chemical elements such as nitrogen, potassium, phosphorus, and sodium in soil along with soil organic matter, pH and salinity in a pepper field. The experiment was conducted in the form of randomized complete blocks design with six treatments: T100: 100 percent wastewater, T75+25: 75 percent wastewater + 25 percent fresh water, T50+50: 50 percent wastewater + 50 percent fresh water, T25+75: 25 percent wastewater + 75 percent fresh water, T0+100: 100 percent fresh water, and T0+100+k: 100 percent fresh water containing fertilizers with three replications in the research greenhouse of faculty of agriculture, Lorestan University. Experimental results showed that the effects of treatments on the accumulation of phosphorus, potassium, sodium, organic matter, EC, and pH were significant at 1 percent level and nitrogen at 5 percent level. By increasing the percentage of wastewater in irrigation water (T100: 100 percent wastewater), to pre-planting soil the concentration of available phosphorus(59%), available potassium(20.7%), total nitrogen(2.28-fold), and organic matter (1.1-fold) increased, and the pH (except T100 treatment) 7.4% and EC 18% decreased. In addition, the findings of this study indicated that with the use of wastewater due to its nutrients which are required for the plants, it is possible to minimize the fertilizer consumption by a proper management plan.