Abstract: Northeast China is an important national grain production base with a cultivation rate of 38.58%, and the ratio of paddy fields to dry land is about 1:4.75. In recent years, the amount of chemical fertilizer input per unit area has kept rising, and the threat of non-point source pollution caused by agricultural activities has become more and more serious. In this study, a nitrogen loss risk assessment system was constructed for the three northeastern provinces by considering the difference in annual rainfall pattern and various ways of nitrogen loss from farmland to water. The distribution characteristics of nitrogen loss risk in this region and the main influencing factors are analyzed, and the influence of crop type and precipitation type on the distribution of nitrogen loss are discussed. The results show that the areas of "extremely high risk" and "high risk" concentrate in central Jilin Province, central and southern Liaoning Province, and central and eastern Heilongjiang Province. More than 80% of paddy fields are extremely high or high risk areas, whereas 35% of dry land are at high risk. It shows that paddy fields have a higher risk potential for nitrogen loss. Dry land accounts for the largest proportion among the medium and higher risk areas, and contribute dominant nitrogen loss risk, especially for corn as it accounts for the largest planting area. There are significant differences in the distribution of nitrogen loss risk at county level under different precipitation types. Compared with normal and dry years, wet years have more obvious impact on the distribution of nitrogen loss risk. The cities in the study area were divided into 4 groups. Among them, the group that need priority control includes Changchun, Panjin, Liaoyuan, Shenyang, Siping and Jinzhou. This study identifies the key areas and their characteristics of nitrogen loss in northeast China, and provides reference for agriculture management and non-point source pollution prevention.

Key words: nitrogen loss, risk assessment, impact factor, annual rainfall pattern, northeast China