鲁中南花岗岩丘陵区坡耕地不同厚度土壤中优先流的发育特征

目的] 研究不同土壤厚度条件下坡耕地优先流发育特征，为土层浅薄条件下坡耕地灌溉效率提高及面源污染防治提供依据。方法] 以地处北方土石山区的山东省蒙阴县花岗岩丘陵区坡耕地为例，选取土层深度为30 cm和50 cm的样地，运用野外染色示踪试验法和室内图像处理技术，分析土层厚度对优先流发育特征的影响。结果] 土壤厚度为30 cm和50 cm条件下平均基质入渗深度分别为11.8 cm和11.9 cm，两者没有显著差异，平均优先流比分别为28.2%和29.5%，两者也没有明显差异；土壤厚度为30 cm时，9.9 cm以上以基质入渗为主导，优先流发育深度范围为9.9—27.0 cm；土壤厚度为50 cm时，6.1 cm以上土层以基质入渗为主导，优先流发育深度范围为6.1—39.5 cm；土壤厚度为50 cm条件下优先流平均最大入渗深度为34.6 cm，平均长度指数为192%，平均变异系数为87.7%，均显著高于土壤厚度为30 cm时的数值；但两者平均最大入渗深度非均匀系数没有明显差异。结论] 土壤层厚度差异不影响基质入渗，但会阻碍优先流向土壤深层的发育。

Characteristics of Preferential Flow Development in Slope Cropland with Different Soil Thickness in Granite Hilly Region of Central and Southern Shandong Province

Objective] The development characteristics of preferential flow in slope farmland with different soil thicknesses were studied, in order to provide a basis for improving the irrigation efficiency and preventing and controlling the non-point source pollution. Methods] The granite hilly slope cropland in Mengyin County, Shandong Province, which is located in the mountainous region of Northern China, was taken as an example. The samples with soil depth of 30 cm and 50 cm were selected, and the field staining tracer test method and indoor image processing technology were used to analyze the influence of soil thickness on the development characteristics of preferential flow. Results] When the soil thickness was 30 cm and 50 cm, the average depth of substrate infiltration was 11.8 cm and 11.9 cm, respectively, and the average preferential flow ratio was 28.2% and 29.5%, respectively, there was no significant difference between the two depths. When the soil thickness was 30 cm, substrate flow was dominant in the soil layer above 9.9 cm, and the development depth of preferential flow ranged from 9.9 to 27.0 cm. When the soil thickness was 50 cm, matrix flow was dominant in the soil layer above 6.1 cm, and the development depth of preferential flow ranged from 6.1 cm to 39.5 cm. Under the condition of 50 cm soil thickness, the average maximum infiltration depth of preferential flow was 34.6 cm, the average length index was 192%, and the average coefficient of variation was 87.7%, which were significantly higher than those under the condition of 30 cm soil thickness. However, there was no significant difference in the non-uniformity coefficient of maximum infiltration depth between the two conditions. Conclusion] The difference of soil layer thickness did not affect the substrate infiltration, but hindered the development of preferential flow to deep soil layer.