he inventory of nitrogen in soil in the Haihe River Basin was estimated at 5.96 × 10￣(10)kg, based on the analytical results available for each of the possible species of nitrogen pre-sent.The input rate of nitrogen into the river basin was estimated at 4. 02 × 10￣9kg/a,in-cluding those from the parental materials of soil,the excrement of humanbody and animal,other living things,application of chemical fertilizers,inflow by run-off,air deposit and plantresidues as the sources of nitrogen in soils.The output...