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Wetting of agricultural soil measured by a simplified capillary rise technique
Author(s) -
Matthews G. P.,
Watts C. W.,
Powlson D. S.,
Price J. C.,
Whalley W. R.
Publication year - 2008
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.2008.01039.x
Subject(s) - wetting , capillary action , radius , soil science , contact angle , soil water , water content , chemistry , materials science , environmental science , geotechnical engineering , composite material , geology , computer security , computer science
Summary We describe the use of a capillary rise method to measure the wettability of 10 samples of agricultural soil from Rothamsted long‐term experimental sites. The samples have very similar clay contents, but organic carbon (C) contents range from 11.5 to 31.2 g kg −1 . Their wetting rates were interpreted by an improved method of data analysis, consistent with the Washburn equation, and showed an increase in the effective contact angle between the water meniscus and the soil with increasing C content. This corresponds to a decrease in wettability with increasing C content, and accords with other results reported in the literature. By contrast with water, we found that capillary rise for n ‐hexane into soil did not depend on the soil’s bulk density or C content. A priori calculations of the expected wetting rates from fluid properties and an effective hydraulic radius estimated by other methods gave magnitudes and trends that agreed with our experimental data. The results show that estimates of effective hydraulic radius can provide a useful approximation for characterizing soil wetting, but that further modelling should be carried out.