Abstract: Based on the current situation of water resources, the nitrogen and phosphorus pollution from soil erosion in the Kulyu river watershed was monitored, and the combination of plant hedge interception, straw mulching, slope transformation combined with organic fertilizer substitution and ditch and pond water hyacinth interception techniques was used for erosion control and clean flow production in forested slopes to promote the circulation of water resources within the system and provide reference for erosion management in the area. The results showed that the soil nutrient content and loss under different land use types in the study area varied significantly, and the nitrogen and phosphorus loss patterns were all dominated by the adsorption state. The losses of total nitrogen (TN) and total phosphorus (TP) were 0.482 t/(km2·a) and 0.117 t/(km2·a) respectively, and the combined measures could effectively reduce 57.32% of suspended solids (SS), 45.97% of TN and 38.97% of TP on forest slopes. TN 45.97% and TP 38.93% can increase soil organic matter by 50.06% and improve soil water content by 39.94%. The highest soil nutrient content and loss in the economic forest land, and the increase of paddy land use may improve soil erosion in the area. The combined measures effectively cut sediment erosion, TN, TP and SS content caused by soil erosion and improve the soil and increase water retention capacity.

Key words: land use practices, soil erosion, plant hedges, straw mulching, slope modification, water hyacinth purification