Effect of Natural and Surfactant-Modified Zeolites on Nitrate Leaching under Irrigation with Treated Urban Wastewater

Due to shortage of water, use of wastewater for irrigation is becoming more important. Also, using natural and non-toxic materials that increase fertilizer application efficiency and decrease nitrate leaching has gained increasing attention. The aims of this study were to investigate the effect of two sizes for particles, i.e. 1-1.68 mm and 53-63 μm, and two application rates (20 and 60 grams per kilogram of soil) of natural zeolite of clinoptilolite (Cp) and surfactant-modified zeolite (SMZ) on soil nitrate and ammonium leaching and wheat plant performance under irrigation by treated urban wastewater. The experiment was conducted in 2015-16 growing season. The experimental soils were placed in Polyethylene columns with 11 cm inner diameter and 65 cm height. The treatments were factorial combination of the variables in completely randomized design with three replications. The results showed that the total amount of released NO3-N from columns modified by SMZ and CP were 32% and 21% lower as compared to the control treatment. Also, these amendments improved wheat plant growth. There was no significant effect on nitrate leaching due to the particle size of the two soil amendments. CP and SMZ amendments are eco-friendly materials and results of the study showed that they were effective in controlling soil nitrate leaching and improving wheat plant growth.