Characterizing Water Dependent Soil Repellency with Minimal Parameter Requirement

Abstract

Soil water repellency varies nonlinearly with soil moisture, describing a repellency versus water content curve. Despite this water dependence, soil repellency is usually characterized by repellency indexes measured at fixed soil water content. We provide a statistically robust yet simple method to determine water repellency at a range of soil water contents, by proposing alternative water‐dependent soil repellency parameters derived from the molarity of an ethanol droplet (MED) test. Useful correlations are found between some of these proposed repellency parameters, such is the case of the integrated area below the repellency curve, which is found to be strongly correlated with the soil water content at minimum repellency. Consequently, an efficient strategy for describing the repellency versus water content curve is designed based on a combination of parameter interdependence and a minimum number of determinations necessary. Following this strategy, only 27 samples are sufficient (p < 0.05) to characterize the water‐dependent repellency of the studied soil. The integrated area below the repellency curve is proposed as the key index for repellency characterization. Furthermore, a new combined parameter IRDI (Integrative Repellency Dynamic Index) is defined as a measure of the average water dependent repellency. This allows simple comparisons of the whole water repellency behavior among different soils by coalescing the repellency curve into a single characteristic value.

Characterization of water repellency for hydrophobized grains with different geometries and sizes

“…Several past studies have characterized WR curves for naturally water repellent soils (de Jonge et al 1999;Regalado and Ritter 2005;Kawamoto et al 2007). They introduced several indices that characterize WR curves (WR as a function of either soil-water content or soilwater potential) such as area below the WR curve and the soil-water content which gives WR peak, and so on.…”

Water repellency of air-dried and sieved samples from limestone soils in central Portugal collected before and after prescribed fire

“…Prior to the assessment of SWR measurements, the sub-samples were kept under controlled conditions of temperature (20-22°C) and relative humidity (~50 % relative humidity) for 2 days, in order to eliminate potential effects of any variations in preceding atmospheric humidity on soil (Doerr et al 2002). In general SWR varies nonlinearly with soil moisture content (Regalado and Ritter 2005;Kawamoto et al 2007). Despite its water dependency, soil repellency is usually characterized by repellency indexes measured at fixed soil moisture content.…”

Effect of land use change on the dynamic behaviour of structural properties of an Andisol in southern Chile under saturated and unsaturated hydraulic conditions

“…The latter, however, should be not completely realistic, since volcanic ash soils are partially hydrophobic (e.g. Iwata et al, 1995;Miyamoto et al, 2003;Regalado and Ritter, 2005;Hamamoto et al, 2008). According to the capillary theory, the pore size distribution of a soil can be derived from the water retention curve as has been done by many authors in scientific literature (e.g.…”