Deformation and Shrinkage Effects on the Soil Water Release Characteristic
Deformation and Shrinkage Effects on the Soil Water Release Characteristic
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DOI：
10.2136/sssaj2009.0278
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发表时间：
2010-07-01
影响因子：
2.9
通讯作者：
Young, Iain M.
中科院分区：
文献类型：
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作者：
Gregory, Andrew S.;Bird, Nigel R. A.;Young, Iain M.
土壤水分释放特性受土壤孔隙的控制，孔隙系统的改变会对土壤水分释放特性产生影响。我们试图研究各种孔隙变形的影响，在一系列的耕地和草地土壤从英国。筛选表土材料被压缩到50或200千帕，或重塑，以模拟剪切变形的塑性极限。然后使用常规的张力和压力板装置使它们经受从0到-1500 kPa的基质势。监测体积变化以评估收缩。进一步的样品在压缩状态下进行X射线计算机断层扫描，以非破坏性地表征土壤孔隙系统。从50到200 kPa的压缩增加主要影响>30 μ m的孔隙，改变了一个双孔系统的内部和intraaggregate孔隙的主要占主导地位的intraaggregate孔隙，证实了重量水分释放特性数据和扫描。剪切变形土壤保留更多的水比压缩土壤和收缩更多，使他们保持张力饱和在低（负）基质势。我们开发了一个函数来预测土壤饱和状态作为基质势和孔隙度的函数。这解释了28%至63%的方差，与初始结构状态无关，但是当允许拟合参数之一针对不同的初始状态变化时，高达94%的方差。这是足够系统的建议，土壤变形和收缩对水分释放特性的影响的一般模型是可能的。
The soil water release characteristic is controlled by the soil pores and so alteration of the pore system will have an effect. We sought to examine the effects of various pore deformations in a range of arable and grassland soils from the UK. Sieved topsoil materials were compressed to 50 or 200 kPa, or remolded to simulate shear deformation at the plastic limit. They were then subjected to matric potentials from 0 to -1500 kPa using conventional tension and pressure plate apparatus. Volume changes were monitored to assess shrinkage. Further samples in the compressed state were subjected to x-ray computed tomography scanning to nondestructively characterize the soil pore system. Increasing the compression from 50 to 200 kPa mainly affected the >30-mu m pores, changing a dual porous system of inter- and intraaggregate pores to one mainly dominated by intraaggregate pores, as confirmed by gravimetric water release characteristic data and the scans. Shear-deformed soils retained more water than the compressed soil and shrank more, such that they remained tension saturated at low (negative) matric potentials. We developed a function to predict the soil saturation state as a function of matric potential and porosity. This explained 28 to 63% of the variance, irrespective of the initial structural state, but up to 94% of the variation when one of the fitted parameters was allowed to vary for the different initial states. This was sufficiently systematic to suggest that a general model of the effects of soil deformation and shrinkage on the water release characteristic may be possible.