柳枝稷植被过滤带拦污增效试验初步研究

针对黄土高原严重水土流失引起面源污染与水资源紧缺的问题,在自主研发设计的坡地高效农业用水滤清系统基础上,通过6组不同雨强的模拟降雨试验,分析了不同雨强下坡地径流中污染物输出特征,研究了不同长度的柳枝稷植被过滤带对污染物的净化效果,并对植被过滤带柳枝稷的生产效益进行了评价。结果表明:坡面径流中泥沙和总磷含量随雨强的增加而增加,总氮含量随雨强的增加而减小,COD含量随雨强增加先减小后增加。3 m长和5 m长的柳枝稷植被过滤带都能显著削减径流中的泥沙和总磷含量,而两种长度的削减作用间无显著差异;5 m长过滤带还能显著削减径流中COD含量,整个过滤带对总氮的削减效果不明显。过滤带柳枝稷产量和品质均优于大田种植柳枝稷,过滤带内距径流入口越近柳枝稷干物质产量越高,过滤带柳枝稷单位面积干物产量提高29%,蛋白质产量增加53%,淀粉产量增加23%。滤清系统柳枝稷植被过滤带不但能有效拦截水沙和面源污染物,而且能够将所拦截污染物作为肥料吸收利用,高效利用水土资源,在黄土高原地区有广泛的应用前景。

Effectiveness of switchgrass vegetative filter strip in intercepting pollutants and promoting plant biomass

The serious soil and water erosion in the Loess Plateau has caused non-point source pollution and shortage of water resources. In this study, a series of simulated rainfall experiments with 6 rainfall intensities were conducted using the self-designed efficient agricultural water filter system. The pollutant outputs under different rainfall intensities were measured. The purification efficiencies and biomass production of the Switchgrass Vegetative Filter Strip(VFS) with different lengths were also evaluated. Results indicated that:1)with increase in rainfall intensity, the concentrations of sediments and total phosphorus(TP) in overland flow increased, while total nitrogen(TN) concentrations decreased. COD decreased initially but increased thereafter; 2)Both 3 m-and 5 m-length VFS significantly reduced sediment and TP concentrations, with no significant differences between these two lengths. The COD reduction happened only in the 5 m-length VFS. However, neither of these two lengths of VFS reduced TN concentrations; 3)Yield and quality of switchgrass in the VFS were better than those of field-grown switchgrass. In the VFS, switchgrass closer to the runoff entrance yielded higher biomass. The dry matter yield, protein yield and starch yield of switchgrass were respectively 29%, 53%, and 23% higher in the VFS than in the fields. The present results indicated that switchgrass in VFS utilized soil and water resources efficiently and would have promising applications in the Loess Plateau area.