In arid and semi-arid regions, water scarcity is one of the major constraints for agricultural activities. The use of treated wastewater resources in agriculture can be a suitable solution to face water scarcity. There is a fact that wastewater has a destructive effect on environment through soil and plant pollutions. The increasing demands for environmental protection and sustainable food production cause an increase in the use of natural and non-toxic materials for agriculture. Therefore, use of soil amendments such as zeolite becomes important. Zeolites are natural, non-toxic and inexpensive materials which prevent soil nutrients from leaching because of high cation adsorption capacity. Nitrogen (N) is a primary element for plant growth. However, high concentration of N in surface and groundwater increases oxygen demand and eutrophication. Ammonium (NH 4 + ) is the inorganic ion form of N which exist in municipal sewage, domestic and industrial wastewater. High concentration of NH 4 + is harmful for animal and human health and must be controlled. In this study, the effect of application of calcium-modified zeolite (CZ) in comparison with natural zeolite of clinoptilolite (Z) to reduce soil ammonium leaching and on wheat crop growth was investigated using treated wastewater as irrigation water. The effects of size (millimeter and micrometer) and application rate (20 g kg?1 and 60 g kg?1) of Z and CZ on ammonium leaching and wheat plant response were also evaluated and studied in soil columns placed in PVC columns with 10.5 cm inner diameter and 65 cm height. The experiment was factorial with completely randomized design with three replications for each treatment. Ammonium nitrogen (NH 4 -N) of irrigation water and irrigation outflow was determined for each soil column and for all irrigation events. Furthermore, sodium concentration and total calcium and magnesium concentrations of the irrigation water and irrigation outflow of each soil column were determined for the even irrigation cycles. At the end of the experiments, soil samples were taken at depths of zero to 25 and 25 to 50 cm in order to measure the NH 4 -N. Results of application of Z and CZ showed that each amendment with amount of 60 grams per kilogram of soil has the potential to prevent groundwater pollution. The total amount of released NH 4 -N from modified columns by CZ and Z were 45.67 and 22.40 percent lower than the control treatment and the modified treatments improved plant growth. The results showed that application of zeolite to the soil causes that sodium concentration of the outflow to increase. However, total calcium and magnesium concentrations of the outflow decreases. The amount of sodium in the Z treatment, were increased by 195.84% and in the CZ treatment decreased by 34.33%, in comparison to the control treatment. Compared to the control treatment, the average NH 4 -N concentrations of the soil in Z and CZ treatments were increased by 21.79% and 45.60%, respectively. Results showed that Z and CZ amendments are effective to control ammonium leaching and to provide better plant growth. Keywords : Zeolite, Wastewater, Soil column, Ammonium, Leaching, Sodium