The Effect of Zeolite and Superabsorbent on Reduction of Nitrate Leaching from a Loamy Soil under Unsaturated Conditions

The application of zeolite and superabsorbent in the soil can be useful in reducing water pollution. For this purpose, this research was carried out in 2018 with two treatments in a completely randomized block design. Each treatment consists of 3 different levels and 4 replications. Totally 24 polyethylene pipes with 10.5 cm in diameter and 50 cm in height were used under unsaturated conditions at research farm of Faculty of Water Sciencs Engineering, Shahid Chamran University of Ahvaz. Treatments in this study included potassium zeolite and A200 superabsorbent at three levels of 0, 2 and 5 g/kg of soil. Urea fertilizer was applied to the soil in irrigation 1, 6 and 12 from 15 irrigation events. At the end of each irrigation event, nitrate effluent was measured. The results showed a significant reduction (at 5% level) of nitrate leaching in the superabsorbent and zeolite treatments in all irrigation events (with the exception of No. 6 irrigation event in zeolite). Superabsorbent treatment (2g/kg of soil) had better performance than the zeolite treatment (2g/kg of soil) in terms of preventing nitrate leaching, with the exception of irrigation events of 6 and 7. In general, zeolite and superabsorbent treatments (2 and 5 g/kg of soil) reduced nitrate leaching (20 and 29%) and (48 and 64%), respectively, as compared to the control treatments.