Effects of layered soil on the accumulation and leaching of nitrate nitrogen in shallow groundwater region

Excessive nitrogen application in agriculture causes the accumulation of nitrate nitrogen in the vadose zone, andintensifies nitrate pollution in groundwater. The heterogeneous layered soil exists relatively common in nature, and it plays an important role in controlling pollutants entering the groundwater from the surface. The heterogeneous layered soil also widespreadly exist in the low plain area of North China, and this area is sensitive for groundwater pollution due to its shallow groundwater burial and short nitrate leaching path. Thus, it is of great significance to clarify the influence of heterogeneous layered soil structure on NO3−-N migration process to prevent nitrate pollution in groundwater. In this study, four typical soil profiles including heterogeneous and relatively homogeneous, and two land uses were selected in Nan-pi County located in Cangzhou City of Hebei Province.