Sentinel surveillance method was used to study patterns and means of nitrogen loss in sloping fields in the central Yunnan Province so as to reveal nitrogen loss characteristics.Results showed that the related coefficient between runoff and rainfall was 0.864 1

but soil erosion and rainfall did not show a good correlation.Under the same rainfall conditions

the amounts of TN

NO-3—N

and NH+4—N were generally increased with the increased amount of nitrogen in the order of CKN1N2N3N4N5 and under different rainfall conditions

the values of the three chemicals reached 5.57

4.36

and 1.30 mg/L

respectively.The NO-3—N concentration accounted for 21.02%～83.55% in soluble nitrogen and NH+4—N concentration was only about 1.02%～38.58% under natural rainfall conditions

indicating that NO-3—N was the main form of nitrogen loss.Rainfall runoff induced soil erosion and the amount of TN in sediment also showed irregular fluctuation.Nitrogen enrichment rate was about 1.02～1.58 in different treatments.When rainfall intensity was up to maximum

the enrichment rate of the overall trend increased and reached 1.23～1.53.Nitrogen enrichment rate was not significantly different with the increase of fertilizer under the same rainfall conditions and it decreased with time.