Evaluation and comparison of the effect of modified biochar and hydrochar, zeolite and superabsorbent as a layer to reduce nitrate leaching in a loam soil

The presence of nitrate in water resources is one of the most important global concerns, so it can be very helpful to prevent it from entering the water using materials such as hydrocar, biochar, zeolites and superabsorbents. For this purpose, this study with four treatments at 3 different levels and 4 repetitions was conducted in 2019. In this study, 36 PVC pipes with diameter and height of 10.5 and 50 cm, respectively, were used at research farm Faculty of Water Sciencs Engineering, Shahid Chamran University of Ahvaz. Treatments included hydrocar (H), biochar (B), potassium zeolite (Z), and superabsorbents of type A200 (S) at three levels (M0, M2, and M5, respectively, including zero, 2, and 5 g / kg soil), respectively. The duration of the experiment included 10 irrigations, and at the end of each irrigation, the output nitrate was measured. The results showed that the effect of superabsorbent, zeolite and biochar in all irrigations and hydrocar other than irrigation 4 and 6 at 5% level was significant on reducing nitrate leaching. SM2 and SM5 treatments were 42% and 58%, respectively, ZM2 and ZM5 treatments were 20% and 29%, respectively, BM2 and BM5 treatments were 30% and 43%, respectively, and HM2 and HM5 treatments were 20% and 31%, respectively, compared to control treatment was effective in preventing nitrate leaching. In general, superabsorbent treatment is recommended due to higher absorption.