Effects of vegetative filter strip on overland flow nitrogen and phosphorus intercepting under different inflow conditions.

The vegetative filter strips can effectively intercept erosion of water and sediment on the slope, with huge potential to prevent and control soil erosion and agricultural non-point source pollution. A series of muddy water scouring experiments under different inflow conditions in the indoor soil trays were conducted to investigate the effects of vegetative filter strip (VFS) on intercepting nitrogen (N) and phosphorus (P) under different inflow conditions and its internal hydrological responses. The results showed that the VFS could effectively intercept N and P in the runoff. When the inflow was 200, 400, 600 L·h-1 , the intercepting rates were 74.9%, 62.0%, 58.3% for N and 85.0%, 75.6%, 72.0% for P, respectively. The best intercepting effect occurred at the lower inflow rates. Different inflow N and P concentrations had no significant effect on N and P interception efficiency. Under different inflow conditions, the intercepting rates of N and P by VFS increased with the increases of Froude value with a significant linear positive correlation. However, there were linear negative correlations between the intercepting rate and resistance coefficient, shear stress and stream power. The relationship between the N and P intercepting rates and shear stress was the best among others, and the N and P intercepting rates could be well predicted by a formula containing shear stress.