Abstract: HuangHuaiHai region is one of the core areas in food production and agricultural development of China. Since 1998, its agricultural water use is decreasing, but still occupies more than 70% of the total water use, with the amount maintained at about 100 billion m³. This region is facing rather serious water crisis in agriculture, and has the obstacles in its sustaining agricultural water resources utilization, such as the relative scarcity in water resources, deterioration of water quality, competition with other water users, low agricultur water use efficiency, and impacts of extreme meteorological events and global climate change, etc. In order to settle these obstacles to maintain the agricultural water safety in this region, the water supply should be improved with the implement of southtonorth water division and unconventional water resources utilization, the water quality should be improved by water pollution control, the agricultural water use efficiency should be improved by watersaving agricult system construction and rational water resources allocation, and the emergency disposal ability in improving agricultural water use should be strengthened in coupling with soil moisture content monitoring and irrigation prediction system construction. At the same time, the agricultural water resources management system should be reformed.

Key words: Paper, Denitrification, Biological treatment, Nitrate