Evaluating fractal dimension of the soil particle size distributions and soil water retention curve obtained from soil texture components

ABSTRACT

It is much easier to measure solid phase data or particle size distribution (PSD) than pore size distribution, therefore it is useful to determine relationship between fractal dimension of the soil particle size distributions (D_PSD) and soil water retention curve ($D_{SWRC}$). The present research aims to firstly measure fractal dimension of the soil PSD using three radii 1 (clay), 25 (silt) and 1000 (sand) µm (D_PSD3) and subsequently compare it with fractal dimension obtained from D_PSD, and secondly develop a relationship between $D_{PSD3}$ and $D_{SWRC}$. The results showed that the maximum and minimum values for $D_{PSD}$ were 2.93 and 2.65 and for $D_{PSD3}$ were 2.91 and 2.63 and there was no significant difference between $D_{PSD3}$ and ${\mathrm{D}}_{\mathrm{P}\mathrm{S}\mathrm{D}}$. A linear relationship between $D_{PSD3}$ and $D_{SWRC}$ was developed for some of soils UNSODA databases. The relationship developed here was compared with three present methods to calculate $D_{SWRC}$ from soil texture including (1) non-linear relationship with clay, (2) logarithmic relationship with clay, and (3) percent of sand, silt and clay for some of the northern soil of Iran. The results indicated that the proposed method in this study, especially in fine-grained soils, can efficiently predict $D_{SWRC}$ with appropriate precision.

KEYWORDS:

• Clay
• soil particle radius
• retention curve
• fractal

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the University of Zabol [UOZ-GR-9618-122].