Study on effectiveness of grassed filter strips in reducing nitrogen losses from slope land

Based on the indoor stimulated rainfall experiment, losses process of nitrogen with runoff and sediment investigated, and the reduction efficiency of nitrogen losses under the different width of grassed filter strips (GFS) was studied. Results showed that, compared to the results from bare-slope, losses process of nitrogen with runoff was flattened, and the nitrogen concentration changed little on the slope with GFS, where the concentration of TN, NO₃-N, NH₄-N fluctuated at 6mg/l, 2.5mg/l, 1.5mg/l. Generally, the effect of GFS in controlling sediment and nitrogen loss on 28° slope was better than that on 21° slope. When the width of grassed filter strips increased from 0 to 3m, the nutrient enrichment ratio on 28° slope is 1.3 times greater than that on 21° slope. Considered the fertilization amount in soil, the nutrient reduction efficiency on slope of 28°and 21° with 3m GFS is 1.13 and 1.05 times greater than that on bare-slope, and the nutrient reduction efficiency increased with the increase of GFS width under the same slope gradient.