Estimating hydraulic properties of soil aggregate skins from sorptivity and water retention
Estimating hydraulic properties of soil aggregate skins from sorptivity and water retention
复制标题
根据吸附性和保水性估算土壤骨料皮的水力特性
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
J. Köhne
中科院分区：
文献类型：
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作者：
H. Gerke;J. Köhne
土壤团聚体的表层通常由粘土或粘土-有机涂层组成，这可能影响团聚体土壤的优先流动。我们的目的是确定完整的和删除（切割）皮肤和内部/皮肤的水力传导率比估计双渗透模型中的传质参数的样品的水力特性。分析了粘壤土冰川耕层土壤（Stagnic Caicaric Regosol）的C sd层土壤团聚体。采用张力吸胀法测定了不同骨料在-1和-5 cm边界基质势水头下的吸水率。吸附性用于计算平均加权水扩散率和最终水含量，以拟合润湿保留函数。保水性和水力传导率功能的皮肤层来自完整和切割样品之间的含水量和水力阻力的差异。吸水率一般较小的完整比切割骨料。与完整样品相比，切割的保水功能向更小的含水量移动。完整样品的平均水扩散系数比切割样品的平均水扩散系数小4.5倍。在实测的基质位水头范围内，非饱和导水率的内部/表皮比约为12。当土壤水势小于-1000 cm时，该比值在饱和水附近可达70，而在-1000 cm以下则降至1以下。骨料表皮可以看作是一个单独的多孔域，其水力学特性可以控制结构性土壤中骨料间和骨料内孔隙域之间的水分传递。
Skins of soil aggregates often consist of clayey or clay-organic coatings which may affect preferential flow in aggregated soils. The objective was to determine hydraulic properties of samples with intact and removed (cut) skins and interior/skin hydraulic conductivity ratios for estimating mass transfer parameters in dual-permeability models. Soil aggregates from the C sd -horizon of a clay-loam glacial till soil (Stagnic Caicaric Regosol) were analyzed. A tension-imbibition apparatus was used for measuring water uptake of multiple aggregates at boundary matric potential heads of -1 and -5 cm. Sorptivities were used to calculate mean weighted water diffusivities and final water contents to fit wetting retention functions. Water retention and hydraulic conductivity functions for the skin layer were derived from differences in water contents and hydraulic resistances between intact and cut samples. Water absorption rates were generally smaller for intact than for cut aggregates. The water retention function of cut was shifted towards smaller water contents compared with intact samples. Mean water diffusivity of intact was 4.5 times smaller than that of cut samples. The interior/skin ratio in unsaturated hydraulic conductivity was about 12 in the measured matric potential head range. The ratio was up to 70 near water saturation and dropped below unity for soil water potentials smaller -1000 cm of water. Aggregate skins may be regarded as a separate porous domain whose hydraulic properties may control water transfer between inter- and intraaggregate pore domains in structured soils.