Influence of slope width and length of fields on soil erosion

采用两种地表径流(25 cm~3/S和50 cm~3/S)对粘性土和砂质土的侵蚀颗粒进行了研究。将试验土壤均匀堆积在长80 cm、宽30 cm、深5 cm的木质侵蚀箱上进行侵蚀试验。冲蚀箱的斜率为10ﾟ，表面流量提供10ﾟ分钟。在径流开始后，每隔2分钟收集一次沉积物，因此从一次试验中采集了5个样本进行分析。在颗粒分析中，用筛子分离沙粒，用纸过滤器分离粉粒和粘粒。在两种地表径流的土壤中，粘土颗粒在初级土层中的侵蚀量都较大。沙的侵蚀作用最大，粉砂的侵蚀效果不明显。随着地表流量的增加，泥沙和粘土含量增加，输沙量减少。侵蚀后的土壤颗粒在每种情况下都不同于原始状态。在粘壤土中，侵蚀粉粒和粘粒与原状的比例较高。只有地表流量较大的砂壤土，其侵蚀砂率才高于原状。当侵蚀沙与原始沙的比例在0.64~0.72之间时，土壤表面形成细沟。在侵蚀土壤中发现了比原始土壤更高的细小颗粒。最后，通过研究明确了上述土壤的选择性侵蚀过程，以及土壤侵蚀过程中与被侵蚀颗粒有关的零点形成的未知条件。

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.