Measurement and simulation of the effect of compaction on the pore structure and saturated hydraulic conductivity of grassland and arable soil
Measurement and simulation of the effect of compaction on the pore structure and saturated hydraulic conductivity of grassland and arable soil
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DOI：
10.1029/2009wr007720
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发表时间：
2010-05
影响因子：
5.4
通讯作者：
G. Matthews;G. Laudone;A. Gregory;N. Bird;A. G. Matthews;W. R. Whalley
中科院分区：
文献类型：
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作者：
G. Matthews;G. Laudone;A. Gregory;N. Bird;A. G. Matthews;W. R. Whalley
测量了压实对两种英国土壤保水性、饱和导水率和孔隙度的影响：北怀克（NW）草原粘土表土和Broadbalk粉质表土，无机施肥（PKMg）或农家肥（FYM）。正如预期的那样，FYM表土有更大的孔隙度和更大的保水比PKMg表土，和西北粘土表土保留更多的水在每个基质的潜力比粉质表土。对于PKMg和FYM土壤，在基质势湿于−10 kPa时，压实对保水有明显影响，对应于圆柱直径大于30 μm的空隙，而较小的空隙似乎不受影响。改进了Pore‐Cor空隙网络模型，引入了欧拉β分布来描述狭窄互连（称为喉道）的尺寸。该模型揭示了从双峰到单峰喉道尺寸分布的变化压实，以及整体尺寸的减少。它还匹配的保水曲线更紧密地比货车van Schlichten适合和正确地预测饱和导水率的变化比先前的统计方法预测。然而，渗透系数的变化被模型的随机变异性所掩盖。此外，该模型的一个伪影，即其无法将小特征紧密地包装在一起，导致压实时孔径的不正确增加。模型中的这些缺陷表明，需要一个明确的双重多孔网络模型来考虑土壤中的压实效应。
Measurements have been made of the effect of compaction on water retention, saturated hydraulic conductivity, and porosity of two English soils: North Wyke (NW) grassland clay topsoil and Broadbalk silty topsoil, fertilized inorganically (PKMg) or with farmyard manure (FYM). As expected, the FYM topsoil had greater porosity and greater water retention than PKMg topsoil, and the NW clay topsoil retained more water at each matric potential than the silty topsoils. Compaction had a clear effect on water retention at matric potentials wetter than −10 kPa for the PKMg and FYM soils, corresponding to voids greater than 30 μm cylindrical diameter, whereas smaller voids appeared to be unaffected. The Pore‐Cor void network model has been improved by including a Euler beta distribution to describe the sizes of the narrow interconnections, termed throats. The model revealed a change from bimodal to unimodal throat size distributions on compaction, as well as a reduction in sizes overall. It also matched the water retention curves more closely than van Genuchten fits and correctly predicted changes in saturated hydraulic conductivity better than those predicted by a prior statistical approach. However, the changes in hydraulic conductivity were masked by the stochastic variability of the model. Also, an artifact of the model, namely its inability to pack small features close together, caused incorrect increases in pore sizes on compaction. These deficiencies in the model demonstrate the need for an explicitly dual porous network model to account for the effects of compaction in soil.