Abstract: Studies on the dynamics of upland field P pool under a long term application of fertilizer-Pin yellow soil area and their effects on-Pconcentration in runoff showed that the contents of A1-P, Fe-P and Ca-P in soil cultivated layer increased greatly,and Olsen-P and algae available-Palso accumulated obviously. The correlation coefficients of algae available Pcontent in the high-P soils (Olsen-P>25 mg·kg^-1) with the quantities of A1-P, Fe-P and Ca-P were 0.859^**, 0.903^** and 0.650^*, respectively, of which,Fe-Pwas the most important. By a 30 min rainfall simulation experiment with a constant rainfall rate of 63.2 mm·h^-1, the concentrations of dissolved reactive-Pand bio available-P in runoff from low-P upland fields (Olsen-P4.62～15.9 mg·kg^-1) were 2.81～ 4.17 μg·L^-1 and 0.723～0.876 mg·L^-1, respectively, whereas their concentrations in runoff from high-P upland fields (Olsen-P29.4～59.2 mg·kg^-1) were 0.026～0.714 mg·L^-1 and 0.996～1.281 mg·L^-1,respectively.Therefore,runoff from high-P upland fields could accelerate water eutrophication.

Key words: Yellow soil, Application of P fertilizer, Changes of soil P pool, P concentration in runoff, vegetative filter strip, N intercepting rate, hydraulic characteristic, inflow conditions, P intercepting rate