Gaseous nitrogen (N) losses are mainly responsible for low N use efficiency of applied fertilizers and their derivative environmental hazards, while N application rates and soil water regime are important factors regulating these N processes. In this study, gaseous N losses via ammonia volatilization (AV) and denitrification, determined by sponge trapping-KCl extraction and acetylene inhibition-soil core incubation, respectively, were investigated under different coupled water-N management practices with a winter wheat ( Triticum aestivum L. ) and summer maize ( Zea mays L. ) rotation system in the Huang-Huai-Hai Plain. Ammonia volatilization after urea application, particularly after topdressing during maize growing seasons, was the dominant gaseous N loss, amounting up to 53.2 kg N ha −1 (38.6 % of the applied N). Ammonia volatilization generally decreased by increasing irrigation rate applied immediately after fertilization. Denitrification N losses were lower than ammonia-N losses, accounting for 1.3 to 18.7 kg N ha −1 year −1 , with more than 90 % occurring during the maize growing seasons. Total gaseous N losses showed a significant ( P < 0.05) positive correlation with N application rates and a negative correlation with irrigation rates applied immediately after fertilization and depended on weather conditions and crop seasons. Temperature and relative humidity were the main influencing factors for both gaseous N losses. The relative importance of weather conditions and field management, such as fertilization and irrigation, on affecting gaseous N losses varied during the five cropping seasons from June 2008 to September 2010. Therefore, the consideration of interannual climate variations, potential nitrate leaching, grain yields, and water-N management could be a promising solution for reducing gaseous N losses and enhancing N use efficiency in this region.