A stochastic study on the heterogeneity of soil moisture and bulk density based on a pore structure model
2000
Haraguchi, N. (National Research Inst. of Agricultural Engineering, Tsukuba, Ibaraki (Japan))
To evaluate the heterogeneity of soil physical properties in the field, the knowledge about the effect of sample size (ex. sample area, sample volume) on theoretical distributions of soil physical properties is very important. To study this, a pore structure model was proposed. In the model, pores were divided into two categories, that is, cylindrical macropores and pores in soil matrix. In each category, random variables were defined. Using these variables, the effects of sample area and suction on the theoretical distributions of five soil pysical properties (bulk density, etc.) were examined with probability theory. Combining the information about saturated hydraulic conductivity obtained in the previous study, the results were summarized as follows: 1) Theoretical distributions of saturated hydraulic conductivity, volume water percentage drained from saturation to a certain suction and volume water percentage drained between two suctions skewed to the right when both of the sample area and the suction were relatively small. And they fitted to normal distribution when either the ample area or the suction was relatively large. 2) Theoretical distributions of bulk density, water content by volume at a certain suction and water content by weight at a certain suction fitted to normal distribution regardless of the magnitude of the sample area and the suction
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