How water moves in a water repellent sandy soil: 1. Potential and actual water repellency

Dekker, L.W.; Ritsema, C.J.

doi:10.1029/94wr00749

Cited by 544 publications

(440 citation statements)

References 33 publications

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“…For the classification of the persistence of water repellency, we used the range of the measured WDPT values (overall: 0.17 to 8.91 s) and the classification of Dekker and Ritsema (1994). The aggregate surface types B (1.16-4.43 s), C (0.75-4.84 s) and D (0.17-2.1 s) could be defined as wettable (WDPT below 5 s).…”

Section: Wettability Of Dry Aggregatesmentioning

confidence: 99%

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Fér

Leue

Kodešová

et al. 2016

Journal of Hydrology and Hydromechanics

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Abstract:The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM) composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM composition of coated and uncoated aggregate surfaces. We used 20 to 40 mm sized soil aggregates from the Bt2 horizon of a Haplic Luvisol from loess that were (i) coated, (ii) not coated (both intact), and (iii) aggregates from which coatings were removed (cut). The SOM composition of the aggregate surfaces was characterized by infrared spectroscopy in the diffuse reflection mode (DRIFT). A potential wettability index (PWI) was calculated from the ratio of hydrophobic and hydrophilic functional groups in SOM. The water drop penetration times (WDPT) and contact angles (CA) during droplet infiltration experiments were determined on dry and moist aggregate samples of the three types. The decrease in the CA with time was described using the power function (CA(t) = at -b ). For dry aggregates, the WDPT values were larger for coated as compared to uncoated regions on the aggregate surfaces, and increased with increasing PWI value (R 2 = 0.75). The a parameter was significantly related to the WDPT (R 2 = 0.84) and to the PWI (R 2 = 0.64). The relations between the b parameter and the WDPT (R 2 = 0.61) and the PWI (R 2 = 0.53) were also significant. The WDPT values of wet soil aggregates were higher than those of dry aggregates due to high water contents, which limited the droplet infiltration potential. At the wet aggregate surfaces, the WDPT values increased with the PWI of the SOM (R 2 = 0.64). In contrast to dry samples, no significant relationships were found between parameters a or b of CA(t) and WDPT or PWI for wet aggregate surfaces. The results suggest that the effect of the SOM composition of coatings on surface wettability decreases with increasing soil moisture. In addition to the dominant impact of SOM, the wettability of aggregate surfaces could be affected by different mineralogical compositions of clay in coatings and interiors of aggregates. Particularly, wettability of coatings could be decreased by illite which was the dominant clay type in coatings. However, the influence of different clay mineral fractions on surface wettability was not due to small number of measurements (2 and 1 samples from coatings and interiors, respectively) quantified.

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Section: Wettability Of Dry Aggregatesmentioning

confidence: 99%

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Fér

Leue

Kodešová

et al. 2016

Journal of Hydrology and Hydromechanics

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“…Samples were taken in September 2011, when the soil WR is expected to be at its strongest after the typical Mediterranean summer drought (DeBano, 1981;Dekker and Ritsema, 1994;Doerr et al, 2000). Soil samples were collected from the first 2.5 cm of the mineral A horizon at microsites beneath each of the four most representative species (P. halepensis, R. officinalis, Q. rotundifolia and C. albidus; n = 15 per species) and 5 samples from bare soil with no influence from any species.…”

Section: Soil Samplingmentioning

confidence: 99%

Biological and chemical factors controlling the patchy distribution of soil water repellency among plant species in a Mediterranean semiarid forest

et al. 2013

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Natural soil water repellency is a property that has already been observed in forest soils and is characterized by its patchydistribution. Ihere are many factors involved in its development. In this work, we have studied a large numberof chemical and biological factors underthe influence of differentplantspecies (Pinus halepensis, Quercus rotundifolia, Cistus albidus and Rosmarinus officinalis) to leam which has the greatest responsibility for its presence and persistence in the top-soillayer. We obselVed strong and significant correlations between ergosterol, giomalin related soil protein (GRSP), extractable lipids, soil organic matter (SOM) content and water repellency (WR). Our results suggested lipid fraction as the principal factor. Moreover, apart from Pinus, fungal biomass seems to be also related to the SOM content. Soil WR found under Pinus appears to be the most influenced by fungi. Quality of SOM, to be precise, lipid fraction could be responsible for WR and its relationship with fungal activity.

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“…[1][2][3] There are a range of distinctive environmental conditions that can give rise to water repellent soil. It is well established that fires can volatilize hydrophobic compounds in the vegetation, litter or soil and these vapors can then condense on the sandy particles producing a hydrophobic granular texture that can exhibit high levels of water repellency.…”

Section: Introductionmentioning

confidence: 99%

“…This method has been shown to be quite reproducible and diagnostic of soil water repellency, provided soil samples are reasonably dry, homogenized and atmospheric conditions are controlled. 3,[8][9][10] The relationship between surface tension and the equilibrium contact angle, a concept that assumes there is contact angle hysteresis, is often described by Young's equation. In the MED test it is assumed reducing the surface tension causes imbibition by reducing this contact angle to below 90 o at which point a parallel walled capillary would spontaneously fill.…”

Section: Introductionmentioning

confidence: 99%

Effect of Particle Size on Droplet Infiltration into Hydrophobic Porous Media As a Model of Water Repellent Soil

Hamlett

Shirtcliffe

McHale

et al. 2011

Environ. Sci. Technol.

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The wettability of soil is of great importance for plants and soil biota, and in determining the risk for preferential flow, surface runoff, flooding and soil erosion. The molarity of ethanol droplet (MED) test is widely used for quantifying the severity of water repellency in soils that show reduced wettability and is assumed to be independent of soil particle size. The minimum ethanol concentration at which droplet penetration occurs within a short time (≤ 10 s) provides an estimate of the initial advancing contact angle at which spontaneous wetting is expected. In this study, we test the assumption of particle size independence using a simple model of soil, represented by layers of small (∼0.2 to 2 mm) diameter beads that predict the effect of changing bead radius in the top layer on capillary driven imbibition. Experimental results using a three-layer bead system show broad agreement with the model and demonstrate a dependence of the MED test on particle size. The results show that the critical initial advancing contact angle for penetration can be considerably less than 90° and varies with particle size, demonstrating that a key assumption currently used in the MED testing of soil is not necessarily valid.

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How water moves in a water repellent sandy soil: 1. Potential and actual water repellency

Cited by 544 publications

References 33 publications

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Biological and chemical factors controlling the patchy distribution of soil water repellency among plant species in a Mediterranean semiarid forest

Effect of Particle Size on Droplet Infiltration into Hydrophobic Porous Media As a Model of Water Repellent Soil

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