华南地区草被过滤带对菜地径流、泥沙和磷阻控效果及影响因素

Effect of Grass Filter Strips on Runoff, Sediment and Phosphorus from Vegetable Field and Influence Factors Under Simulated Experiment in Southern China

通过人工模拟降雨试验,定量研究了香根草草本植被过滤带对径流、泥沙、以及全磷和溶解性磷的拦截效果。结果表明:在不同的雨强(210,120 mm/h)和不同坡度下(2°,5°),香根草过滤带能够有效拦截径流、泥沙、磷,拦截率分别可达到12.18%～43.11%,16.00%～70.38%,27.53%～49.35%。与120 mm/h雨强相比,210 mm/h雨强下,2种坡度下香根草过滤带小区内,径流、泥沙流失量都呈现出减少趋势,并均达到显著水平(p<0.05)。在210 mm/h雨强下,与裸坡对照相比,不同坡度处理下香根草过滤带全磷、颗粒态磷流失量都呈现出减少趋势,且二者减少程度达到显著水平,不同坡度间的流失量,存在显著差异。在不同的宽度下,香根草表现出不同的拦截效率,当宽度达到2 m时,拦截效率显著,总体上随着宽度的增加而增加。利用最优尺度回归法,对不同处理间的水文条件、坡度、带宽等影响因素进行了分析,可以发现影响植被过滤带拦截效率的主要因素包括带宽、坡度、雨强,各因子对径流、泥沙、磷流失量贡献大小分别为雨强>带宽>坡度,这表明华南地区降雨是径流、泥沙、磷流失的主要控制因子,同时,带宽对径流、泥沙、全磷的流失量也可以起到一定的积极作用。

Ecological engineering measures have been suggested to control the loss of pollutants by regulating the material balance and material flow in the agricultural ecosystem. The effects of grass filter strips on surface runoff, sediment, and phosphorus under different rain intensities and slope gradients were evaluated. Compared with the case of using no grass, on average, Vetiveria zizanioides grass vegetation reduced soil loss by 16.00%~70.38%, overland flow by 12.18%~43.11%, and phosphorus by 27.53%~49.35%, respectively. A comparison between the two different rain intensities revealed that under the intensity of 210 mm/h rain, the losses of runoff and sediment in the filtrate zone of Vetiveria zizanioides with 2 slopes showed the decreasing trend, and all reached the significant level(p<0.05). The decrease of total phosphorus loss in the filter zone of Vetiveria zizanioides was significantly higher than that of the bare slope under 210 mm/h rain intensity, and there was a significant difference in the loss between different slopes. In general, interception efficiency was related to the width, and gradually increased with increase of width. As the width reached 2 m, the interception had the significant effect. Using the optimal scaling in SPSS, we evaluated the comparative importance of rain intensities, slope gradient and width. Their contributions decreased in the order: rain intensities>width>slope gradient. The results confirmed that the main controlling factor was rain intensity, and the width could also play the positive role in losses of runoff, sediment and total phosphorus.