Effect of nitrogen fertilizers on nitrate leaching from a saline soil profile under corn and barley cultivation

ABSTRACT: Nitrogen as a macronutrient has an eminent role in plant nutrition. Excessive use of nitrogen fertilizers in agriculture has resulted in leaching of fertilizers and contaminating groundwater and surface water systems. The objective of this study was to investigate the effect of three types of nitrogen fertilizers on nitrate leaching and soil and plant conditions in a saline soil in Rudasht, Isfahan province. A complete randomized design with four replications was conducted in 12 lysimeters. Three nitrogen fertilizers of urea, ammonium nitrate and ammonium sulphate were applied. The lysimeters had a silty clay loam soil. Corn and barley were planted in June and October and were harvested in October and June of next year, respectively. Soil chemical characteristics were measured by standard laboratory methods. The results showed that changes of EC during the corn cropping season were negative for depth of 0-30 cm and positive for depths of 30-60 and 60-90 cm as a result of applied fertilizers. Comparison of soil salinity changes during corn and barley cropping seasons confirms that ammonium sulphate has been more effective on soil salinization as compared to ammonium nitrate and urea. Application of these fertilizers didn’t cause significant changes in weight of areal parts of corn plants and grain yield of barley. Corn shoot analysis showed that ammonium sulphate is more effective in enhancement of N and reduction of Na in corn shoot as compared to the other applied fertilizers. Where saline irrigation water contains harmful elements, application of ammonium sulphate is preferred over urea and ammonium nitrate. Ammonium sulphate has the least and ammonium nitrate has the highest NO3-N contamination potential of groundwater.