CHARACTERISTICS OF NITROGEN AND PHOSPHORUS LOSS FROM SURFACE SOIL IN DIFFERENT LANDUSE

Three typical types of land in the northern area of Jiangsu Province were used to study nitrogen and phosphorus loss in artificial rain-runoff simulator.The results showed that the amount of runoff followed the order: paddy fieldwoodland orchard under 80 mm·h-1 rainfall condition,and amount of sediment followed the order: orchard paddy fieldwoodland.Nitrogen and phosphorus concentration in runoff initially decreased significantly with rainfall,then stabilized.The nitrogen and phosphorus loss correlates with the level of available nitrogen and Olsen-P content in soil.The main form of nitrogen and phosphorus loss was suspended particulate in runoff water.Nitrogen loss occured mainly in runoff water and phosphorus loss in sediment in the whole rainfall process.The maximum rate of nitrogen and phosphorus loss from surface soil occured in paddy field,which were 1.12 mg·m-2·min-1 and 0.42 mg·m-2·min-1,respectively.