| 摘要: |
| 【目的】探讨降雨打击下产生的不同坡面结皮土壤水稳性团聚体分布。【方法】采用人工模拟降雨，研究在降雨打击作用下，地表结皮土壤水稳性团聚体的变化情况。受微地形影响，地表结皮性质呈现差异，以坡面不同位置的地表结皮土壤水稳性团聚体为研究对象，以底部无结皮土壤样品为对照，采用Yoder湿筛法探究不同类型结皮土壤团聚体的变化。【结果】在降雨打击作用下，以降雨时间5 min为例：①土壤水稳性团聚体都呈现大团聚体比例较大的特点，表现为结构性结皮大团聚体占比最大，其次为过渡带、原状土，沉积性结皮最小。原状土、结构性结皮、过渡带、沉积性结皮土壤大团聚体所占比例分别为37.69%、41.95%、37.05%、28.93%。随降雨延续，结构性结皮和过渡带土壤大团聚体明显增加，沉积性结皮土壤大团聚体略有减少。②土壤水稳性团聚体的平均当量直径和几何平均直径差异很大。原状土、结构性结皮、过渡带、沉积性结皮的平均当量直径分别为：0.15、0.19、0.17、0.12 mm；几何平均直径分别为0.16、0.21、0.19、0.14 mm。结构性结皮土壤水稳性团聚体的平均当量直径和几何平均直径最大，其次为过渡带、原状土，沉积性结皮最小。③土壤水稳性团聚体分形维数D不同但差异不显著。原状土、结构性结皮、过渡带、沉积性结皮土壤水稳性团聚体分形维数D的大小分别为：2.725、2.705、2.725、2.737。沉积性结皮水稳性团聚体分形维数最大，其次为过渡带、原状土，结构性结皮最小。【结论】降雨打击作用使得土壤表层大团聚体被分散，小团聚体富集；大团聚体量越高，土壤结构越稳定，抗蚀能力越强；反之，抗蚀能力越弱。 |
| 关键词: 土壤团聚体；湿筛法；结皮；降雨历时 |
| DOI：10.13522/j.cnki.ggps.2019028 |
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| Effect of rainfall on water stability aggregates of crust soil on slope surface |
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CHEN Lin, WANG Jian, SONG Pengshuai, ZHAO Yu, MA Yuhong
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1.Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China; 2.Xi’an Water Conservancy and Soil Conservation General Station, Xi’an 710000, China
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| Abstract: |
| 【Objective】The purpose of this paper is to explore the difference of aggregate distribution and soil erosion resistance in the surficial soil crusts under micro-terrain.【Method】Some experiments were conducted. Artificial rainfall simulation was used to study the change of water-stable aggregates in crust soil under the impact of rainfall. Influenced by micro-topography, surface crust properties show differences. The water-stable aggregates of surface crust soils at different locations on slopes were studied, and the soil samples without crust at the bottom were taken as controls. Study on the Change of Soil Aggregates in Different Crust Types by Yoder Wet Screening Method. 【Result】Under the impact of rainfall, taking 5 minutes of rainfall as an example, crusts at different locations ①Soil water-stable aggregates are characterized by large aggregates proportion. Structural crust contains the largest aggregates, followed by transitional zone and undisturbed soil, and sedimentary crust is the smallest. The proportion of macroaggregates in undisturbed soil, structural crust, transitional zone and sedimentary crust were 37.69%, 41.95%, 37.05% and 28.93% respectively. With the continuation of rainfall, soil macroaggregates in structural crusts and transitional zones increased significantly, while those in sedimentary crusts decreased slightly. ②Average equivalent diameter and geometric average diameter of soil water-stable aggregates vary greatly. The average equivalent diameters of undisturbed soil, structural crust, transitional zone and sedimentary crust are 0.15, 0.19, 0.17 and 0.12 mm, respectively. The geometric average diameters are 0.16, 0.21, 0.19 and 0.14 mm, respectively. The average equivalent diameter and geometric average diameter of water-stable aggregates in structured crust soil are the largest, followed by transition zone and undisturbed soil, and sedimentary crust is the smallest. ③The fractal dimension D of soil water-stable aggregates is different, but the difference is not significant. The fractal dimensions D of water-stable aggregates in undisturbed soil, structural crust, transitional zone and sedimentary crust are 2.725, 2.705, 2.725 and 2.737, respectively. The fractal dimension of water-stable aggregates in sedimentary crusts is the largest, followed by transitional zone and undisturbed soil, and structural crusts are the smallest.【Conclusion】Rainfall strikes disperse large aggregates and enrich small aggregates in the soil surface. The higher the content of macroaggregates, the more stable the soil structure, the stronger the anti-erosion ability; on the contrary, the weaker the anti-erosion ability. |
| Key words: soil aggregates; wet screening method; crust; rainfall duration |
