Influence of slope width and length of fields on soil erosion

采用25cm^3/s和50cm^3/s两种表面流对粘质土和砂质土的侵蚀颗粒进行了研究。将试验土均匀包装在长80cm、宽30cm、深5cm的木制侵蚀箱上进行侵蚀试验。侵蚀箱坡度为10，表面流动时间为10 min。径流开始后每隔2分钟采集一次沉积物，因此每次试验采集5个样品进行分析。在颗粒分析中，用筛子分离砂粒，用纸过滤器分离粉砂和粘土颗粒。在两种地表流动的土壤中，粘土颗粒在初级层段的侵蚀量都较大。砂对土壤侵蚀的影响最大，而粉砂对土壤侵蚀的影响不显著。随着地表流量的增加，砂土和粘土增加，粉砂输运减少。每一种侵蚀状态下的土壤颗粒都不同于原始状态。在粘壤土中，侵蚀粉土和粘土与原土的比例较高。沙壤土的侵蚀砂比仅在地表流量较大的情况下高于原砂。当侵蚀砂与原砂比为0.64 ~ 0.72时，土壤表面出现细沟。此外，在侵蚀土壤中发现的细颗粒也比原来的高。最后，研究明确了上述土壤的选择性侵蚀过程和侵蚀颗粒在土壤侵蚀过程中形成零的未知条件。

Eroded particles from clay loan and sandy loan soil using two surface flows (25cm^3/s and 50cm^3/s) were investigated. The experimented soils were uniformly packed on a wooden erosion box of 80cm in length, 30cm in width and 5cm in depth to conduct the erosion experiment. Slope of the erosion box was 10ﾟ and the surface flow was provided for 10ﾟ minutes. Sediments were collected at every 2 minutes interval after runoff began and hence 5 samples from one experiment were collected for analysis. In particle analysis, sieves were used to separate the sand particles and paper filters were used to separate silt and clay particles. Clay particles were eroded in higher amount in the primary intervals in both soils with both surface flows. Sand was highest with highest erosion whereas silt did not show any remarkable effect. Sand and clay were increased and silt transportation decreased when surface flow increased. Eroded soil particles in every condition differs to those of the original. In clay loam soil, ratio of eroded silt and clay to the original was higher. Eroded sand ratio was only higher to the original in case of sandy loam soil with greater surface flow. Rills were developed over the soil surface when the ratio of the eroded sand to the original was with in the range of 0.64-0.72. Also fine particle, was found higher in the eroded soil than the original. Finally, selective erosion process of the mentioned soils and the unknown condition for nil formation during soil erosion concerned to the eroded particles was being clear from the study.