纳米碳对不同植被覆盖下黄土坡地降雨侵蚀的抑制效果

纳米碳对黄土高原地区土壤水分运动具有显著影响。该文基于野外人工模拟降雨试验,研究了不同植被覆盖(空地、柠条、苜蓿、黄豆和玉米)条件下,在黄土坡面上中下位置条施不同质量分数纳米碳(0、0.1%、0.5%、0.7%和1.0%)对坡地产流产沙过程的影响。该文试验设计1.0 m×1.0 m降雨小区,前期在小区坡面种植植被以及埋入不同质量分数纳米碳,其中未做植被覆盖处理和未施加纳米碳的小区作为对照,共25个试验小区。采用针孔式人工模拟降雨器进行模拟降雨,雨强为60 mm/h,降雨历时40 min。降雨过程中定时收集径流及泥沙,用以研究在不同植被覆盖条件下纳米碳对黄土区坡地径流与泥沙的调控机理影响。研究结果显示,在土壤中施入纳米碳,对坡面初始产流时间的影响显著。随着施入纳米碳质量分数的增加,不同植被覆盖的初始产流时间总体随之增加,在4种植被覆盖中,苜蓿延缓产流时间效果最明显,较之空白对照最大增加了287.1%。纳米碳的施入,使各植被覆盖中坡面径流量明显降低,施入不同质量分数纳米碳,各植被覆盖中减流效果最显著的仍为苜蓿,径流量较之对照减少了66.47%,而空地、柠条、黄豆、玉米这4种处理减流幅度均在31.5%~33.6%之间。同时,纳米碳对于坡面径流减沙效果亦非常显著。施入纳米碳后,各植被减沙效果排序依次是:苜蓿柠条玉米黄豆。通过纳米碳对产流产沙量的影响进行相关性分析,得出纳米碳对试验结果具有显著的影响;在水土流失调控效果评价值影响分析中,纳米碳对水土流失调控效果较合适的质量分数为0.5%。综上,在黄土区土壤中施加纳米碳并提高施入纳米碳的比例,对于该地区水土流失的治理具有积极作用。

Inhibiting effect of nano-carbon on rainfall erosion of different vegetation cover on loess slope land

Abstract: High weathered soils in arid and semi-arid area are characterized by low soil fertility and high erosion potential. This paper evaluated the influences of nano-carbon on soil erosion and water loss on the sloping land (15°) of the Chinese Loess Plateau. Simulated rainfall experiments were performed on a natural, fallow loessial slope in the Shenmu Erosion and Environment Research Station, Institute of Soil and Water Conservation, Chinese Academy of Sciences, which locates in the Liudaogou watershed, Shenmu County, Shaanxi Province. Five application rates (i.e., 0, 0.1%, 0.5%, 0.7%, and 1.0%) of nano-carbon were selected during the simulated rainfall experiments (rainfall intensity of 60 mm/h); and 4 vegetation species (i.e., caragana, alfafa, bean, and maize) were planted on the slope to evaluate the vegetation effect on soil and water conservation with the bare as the control. A constant-intensity rainfall method was adopted under natural conditions. Field plots were established on the slope that had been fallow for 5 years. The rainfall simulator came from the independent design of Xi''an University of Technology. Under the 60 mm/h rainfall intensity, the simulated rainfall experiments were carried out for 50 times in the 25 different pretreated plots in order to estimate soil erosion and water loss for all the treatments. The main results were as follows: the initial runoff time was delayed with the increase of nano-carbon contents. Compared to the control treatment without nano-carbon application in bare land, the initial runoff time in alfalfa plot was delayed by 287.1%, which was the most obvious. Furthermore, with the increase of nano-carbon contents, the runoff in each treatment decreased obviously. The nano-carbon alfalfa coverage also had the most obvious effect in the reducing runoff, and the runoff was reduced by 66.47%; for other vegetation species, the reduction was between 31.5% and 33.6%. Moreover, the nano-carbon had a significant effect on soil loss controlling. The nano-carbon in alfalfa land showed the best effect for soil loss controlling, which was followed by caragana. Soybean land showed the highest soil loss. For the bare land (control) and alfalfa coverage, when the nano-carbon content was 1%, the lowest sediment yield was obtained; while for caragana, soybean and maize coverage, when the nano-carbon content was 0.5%, the sediment yield was the lowest. Based on the correlation analysis between nano-carbon and runoff and sediment yield, it could be concluded that nano-carbon has a significant impact on the experimental results. In the evaluation of soil and water loss control effect, the 0.5% nano-carbon had the obvious effect, which was similar with the 0.7% and 1.0% nano-carbon content, so considering the price, 0.5% nano-carbon content was appropriate on soil and water loss control in loess area. The results provide a guide for controlling soil water and nutrient loss on the sloping land.