A field experiment was conducted to study the characteristics of nutrient loss in hilly area of central Sichuan basin.There were 5 kinds of fertilization systems: application of N P K(NPK)

straw returned to field alone(RSD)

straw N(RSDN)

straw N P(RSDNP)

straw N P K(RSDNPK).Series water samples were collected from the different plots in each rainfall event.The results showed as follows: Returned straw significantly affected the soil erosion and runoff from slope cropland of purple soil.Compared with NPK

the sediment yield from the application with returned straw decreased by 70%~82%

the surface runoff decreased by 26%~31%

and the leaching amount increased by 30%~52%.Returned straw significantly reduced 60%~76% of the total nutrient loss.There were significant differences in the losses of nutrient of various treatment plots.The order of phosphorus loss was NPK >RSD> RSDNPK>RSDNP > RSDN

and the order of nitrogen loss was NPK > RSDN > RSDNPK>RSDNP> RSD.As to phosphorus

transported by surface runoff was the major way

and total particulate phosphorus was the major form in that way. PO~(3-)_4-P is major form of dissolved total phosphorus in surface runoff.On the other hand

PO~(3-)_4-P / DTP in leachate significantly decreased.As to nitrogen

transported by leaching was the major way

NO~-_3-N was the major form in leachate and there was not a same situation in surface runoff.