IngentaConnect Wetting of agricultural soil measured by a simplified capillary r...

Authors: Matthews¹; Watts²; Powlson²; Price¹; Whalley

Source: European Journal of Soil Science, Volume 59, Number 4, August 2008 , pp. 817-823(7)

Abstract:

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.

Document Type: Research article

DOI: 10.1111/j.1365-2389.2008.01039.x

Affiliations: 1: School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK 2: Department of Soil Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK

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Wetting of agricultural soil measured by a simplified capillary rise technique