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首页> 外文期刊>Australian Journal of Soil Research >Soil structure changes: aggregate size and soil texture effects on hydraulic conductivity under different saline and sodic conditions
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Soil structure changes: aggregate size and soil texture effects on hydraulic conductivity under different saline and sodic conditions

机译：土壤结构变化：在不同盐和钠条件下，骨料的大小和质地对水力传导率的影响

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摘要

Hydraulic conductivity of soil is strongly dependent on soil structure, which can be degraded during wetting and leaching. It was hypothesised that this structural degradation is dependent on initial aggregate size distribution and soil texture. The general aim of this study was to investigate the effects of aggregate sizes and soil textures, and their interactions, on the structural degradation and saturated hydraulic conductivity (Ks) of smectitic soils under different saline and sodic conditions. The studied soils were clay and loamy sand soils with low (~4.5) or high (~10) exchangeable sodium percentages (ESP), and with aggregate sizes in the ranges: (i) <1mm (small aggregates); or (ii) 2-4mm (large aggregates). The Ks values of the samples in a column after slow or fast pre-wetting were determined by means of a constant head device. Different wetting rates and leaching under various saline and sodic conditions had no effect on the Ks of the loamy sand; however, the Ks values of this soil with large aggregates were an order of magnitude greater than those of the soil with small aggregates. In contrast, in the clay soil with large aggregates, the Ks values after fast pre-wetting were significantly smaller than those after slow pre-wetting, probably because of aggregate slaking. No significant effects of the wetting rates on Ks were found in clay soil with small aggregates. An increase in the ESP in the clay soil decreased the Ks by a factor of 1.5 for the large aggregates and by an order of magnitude for the small aggregates, mainly as a result of increased clay swelling. Leaching the clay soil with deionised water significantly decreased the Ks values, partly because of clay dispersion. Although significant structural degradation of the clay soil occurred during leaching, the Ks values were smaller in the soils with small aggregates than in those with large aggregates, indicating the importance of the initial aggregate size on Ks even in soils that are prone to structural damage.
机译：土壤的水力传导率在很大程度上取决于土壤的结构，在湿润和浸出过程中，土壤的导水率可能会降低。假设这种结构退化取决于初始聚集体尺寸分布和土壤质地。这项研究的总体目的是研究不同盐分和苏打条件下集料大小和土壤质地及其相互作用对近土型土壤结构退化和饱和水导率（Ks）的影响。所研究的土壤是具有低（〜4.5）或高（〜10）可交换钠百分比（ESP）且骨料尺寸在以下范围内的黏土和壤质砂土：（i）<1mm（小骨料）;或（ii）2-4毫米（大骨料）。缓慢或快速预润湿后，通过恒压头装置确定一列样品中的Ks值。不同的湿润速率和在各种盐和苏打条件下的浸出对壤土沙的Ks没有影响。然而，具有大骨料的土壤的Ks值比具有小骨料的土壤的Ks值大一个数量级。相反，在具有大团聚体的粘土中，快速预润湿后的Ks值明显小于缓慢预润湿后的Ks值，这可能是由于团聚体碎裂所致。在小骨料的粘土中，润湿速率对Ks的影响没有显着影响。粘土中ESP的增加对于大骨料将Ks降低了1.5倍，对于小骨料将Ks降低了一个数量级，这主要是由于粘土溶胀的增加所致。用去离子水浸渗粘土会显着降低Ks值，部分原因是由于粘土分散。尽管在浸出过程中粘土土壤发生了明显的结构退化，但骨料较小的土壤的Ks值要比大骨料的土壤的Ks值小，这表明初始骨料尺寸对Ks的重要性，即使是在容易遭受结构破坏的土壤中也是如此。

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