Nitrate N loss by leaching and surface runoff in agricultural land: A global issue (a review)

Agricultural systems are nitrogen (N) deficient throughout the world and N is the most important nutrient in realizing the maximum potential of the crop and sustainability of the environment. The production and utilization of the chemical N fertilizer (CNF) have played a great role in increasing crop yield and meeting the demand of population growth. However, with excessive input of chemical N fertilizers, nitrate N leaching and surface runoff seriously threat people health and pollute biological environments. Based on a large number of publications, this paper has comprehensively reviewed the importance of application of CNF, the problems caused by the excessive chemical N input, with attention mainly to the seriousness of nitrate N loss by leaching and runoff, factors affecting nitrate N leaching and runoff, methods for controlling nitrate leaching and runoff, and research needs in the future globally in details.