海藻多糖抗蚀剂对红壤坡面侵蚀过程的影响

为探究海藻多糖抗蚀剂(SA-01)在控制坡面水土流失中的效果及作用机理,该研究以南方红壤区典型红壤为例,通过人工模拟降雨试验(雨强90 mm/h,坡度5°、10°、15°),设置不同施加浓度(0、0.25%、0.50%、0.75%、1.00%),分析SA-01施加浓度对红壤坡面产流产沙过程的影响,并结合土样斥水性试验、团聚体稳定性试验和电镜扫描分析SA-01影响坡面土壤侵蚀的作用机理。结果表明:与不施加SA-01的坡面相比,施加SA-01后坡面产流时间提前,稳定径流量增大。随施加浓度增大,坡面产流量增加比例也增大。施加SA-01后能显著降低坡面土壤侵蚀产沙量,这主要是由于土壤施加SA-01后,与土壤中的Ca~(2+)等阳离子发生螯合反应,在土壤颗粒表面生成有一定强度的保护层有关,保存层的存在使土壤斥水性增大,减少了土壤团聚体的遇水分散性,提高了各级粒径土壤团聚体的稳定性。0.25%的施加浓度即可将团聚体水稳性提升到70%以上,这为中国南方以排水保土为核心的水土保持工作提供了新思路。

Effects of seaweed polysaccharide resists on the erosion process of red soil slope

Soil erosion on sloping farmland has posed a great challenge on land productivity and crop yield, resulting coarse soil and less arable area due to the losing of fine soil particles. Moreover, N and P in soil that migrated with runoff and sediment can also affect the quality of downstream water. Therefore, it is highly demanding to control soil erosion on sloping farmland. Currently, various measures are being taken in the long run, covering from biological, tillage, and engineering. Soil amendments can be used to greatly reduce soil erosion and increase cohesion between surface soil particles, which can maintain surface soil structure to prevent soil crust, resulting the increase in soil infiltration rate, while the decrease in the surface runoff. Therefore, a new material related to soil amendments has drawn much attention. In recent years, the Changjiang River Sciences Research Institute has developed a new seaweed polysaccharide Anti-erosion Material SA-01. This study aims to explore the effect of SA-01 concentration on runoff and sediment yield of red soil, in order to verify the new polysaccharide corrosion inhibitor (SA-01) from the seaweed in controlling soil and water loss on a slope. Taking the typical red soil in southern China as an example, a series of artificial rainfall experiments were carried out, where the rainfall intensity of 90 mm/h, and the slope of 5°, 10°, and 15° under various concentrations of 0, 0.25%, 0.50%, 0.75%, and 1.00%. The mechanism of SA-01 on soil erosion was analyzed in a combination of soil water repellency and aggregate stability experiments. The results show that under the same slope, the runoff yield on the slope with SA-01 was higher than that on the control slope. The runoff yield on the slope decreased first and then increased, while the cumulative runoff on the slope decreased first and then increased with the increase of applied concentration. The increment ratio of surface flow increased as the SA-01 concentration increased, indicating that SA-01 can significantly reduce sediment yield on a slope. In the initial runoff yield stage, SA-01 can significantly reduce the slope sediment yield. In the stage of surface erosion, the slope without SA-01 reached the maximum, then fell rapidly, and eventually became stable. Compared with the control slope, the sediment yield of SA-01 slope fluctuated slightly in the early stage of runoff yield, and the time to reach stable sediment yield was earlier than that of the control slope. With the increase of applied concentration, the sediment yield decreased significantly. SA-01 can significantly increase the runoff while reduce the sediment yield of different slopes, due mainly to the change of soil hydrophilic to water repellency, and the decrease of infiltration rate. Soil water repellency was improved after SA-01 was applied. When the concentration was 0.25%, the sample retained the same hydrophilicity as the original soil. When the concentration was more than 0.25%, the soil began to change from hydrophilicity to repulsion. Due to the soil Ca2+ cation chelation with SA-01, the soil particles generated on the surface of a layer with a certain intensity. The presence of preservation layer increased soil water repellency, while reduced the soil aggregate dispersion, and thereby to improve the stability of soil aggregates at different levels. SA-01 can provide a new idea for soil and water conservation of red soil on a slope.