Leaching of Nitrogen in the Presence of Zeolite Enriched with Ammonium in Two Soil Textures under Wheat Cultivation

Leaching of fertilizers, nutrients and insecticides from soil is an important factor to change the surface and ground water quality. Studies show that some percentage of nitrogen fertilizers leaching from the soil profile joins the groundwater or rivers. The aim of this study was to investigate the effect of raw and  ammonium-enriched zeolite on reducing nitrogen leaching from the soil under wheat plant cultivation. In this greenhouse experiment, effects of one level of fertilizer application (100 kg/ha), two levels of raw zeolite (5 and 10% wt) and NH₄⁺-zeolite (5 and 10% wt) added to the clay loam and sandy loam soils and one level of leaching (30% of net irrigation depth) on nitrogen leaching in eight consecutive irrigation events were studied. Nitrate concentrations in sandy loam and clay loam soils treated with the chemical fertilizer were more than those in zeolite treatments at the all irrigation period. The lowest concentrations of nitrate and ammonium in the drainage water were observed in the  treatment with 10% zeolite enriched with ammonium. The quantities of the ammonium and nitrate leached from the sandy loam soil were more than those from the clay loam soil. The nitrate outputs from the clay loam soil with 10% raw zeolite and 10% zeolite enriched with ammonium were 43% and 72% less than those with the chemical fertilizer treatment, respectively. Comparison of the raw and enriched zeolite with ammonium showed that the ammonium-enriched zeolite stored the nitrate and reduced the pollution more effectively.