Abstract: In order to investigate the effects of leaf area index (LAI) and rainfall interception (RI) on paddy total nitrogen(TN) and total phosphorus(TP) concentration in rainfall runoff process, simulated rainfall experiments were conducted by setting leaf area index (LAI) as 2, 4, 6, with rice in early transplanting stage, late tillering stage, booting stage, and treatment without leaf covering, and setting rainfall interception (RI) as 5.0,12.5,25.0,50.0 mm · h-1. Disturbance coefficient was used to express the effects of LAI and RI on paddy runoff total TN and TP concentration. The results showed that LAI and RI had significant effect on disturbance coefficient. Based on analytic analysis and coupling, analytical equation of TN and TP was respectively given as fallows: =0.070×ln(RI)-0.035×LAI+0.618(R2=0.905) and =0.002×RI-0.048×LAI+0.867(R2=0.913)．

Key words: paddy runoff, disturbance coefficient, leaf area index, rainfall interception, analytic analysis