Effects of Straw Mulching and Polyacrylamide Applying in Surface Soil on Water Erosion Control in Red Soil Sloping Fields

Simulation experiments in soil bins and observations in runoff plots were carried out to explore how the practices of straw mulching,polyacrylamide (PAM) applying in surface soil,and their combination affect the water erosion in red soil sloping fields.These practices generally increased infiltration rate,decreased runoff rate,and delayed stable infiltration,initial runoff generation and stable runoff generation,consequently contributed to increases in infiltration of rain water,and reductions in runoff generation.Under these practices,soil water contents at the 0-45 cm depth in dry season were also significantly raised.The difference of infiltration and runoff generation among the three practices turned to be larger at higher rainfall intensities and smaller at higher initial soil water content.For sediment yield control,the treatment effects of mulching were significant at high rainfall intensities and middle to high initial soil moisture,while the effects of PAM applying in topsoil were remarkable at low rainfall intensities and middle to low initial soil moisture.The combined practice had the most significant effects on water erosion control.These results suggest that straw mulching and PAM applying in surface soil could diminish runoff and sediment in red soil sloping fields.