Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO₃) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO₃-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189kgNha⁻℗£), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60cm soil depths for all 36 experimental plots. Soil NO₃-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO₃-N leaching out of the 60-cm soil layer was 8.43kgNha⁻℗£, for the 142kgNha⁻℗£ and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO₃ concentration at the 60cm depth was 46 and 138mgl⁻℗£, respectively. Based on our findings, it is possible to control NO₃ leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management.

pollution control, growing season, seasonal variation,rhizosphere, mineralization, fertigation, sprinkler irrigation, deficitirrigation, crop yield, fertilizer rates, corn silage, nitrates,nitrogen fertilizers, leaching, soil water content, soil solution,nitrate nitrogen, irrigation management, Iran

• Journal Article

• Irrigation Management