Variability of water repellency in sandy forest soils under broadleaves and conifers in north-western Jutland/Denmark

Abstract

Soil water repellency has important consequences for ecological and hydrological properties of soils and usually retards infiltration capacity and induces preferential flow. This phenomenon has been known to occur on a wide range of sites under a variety of climatic conditions. The objective of this study was to investigate and characterize soil water repellency on forest sites with identical substrate and climatic conditions, differing in tree age and species. In the Vester Torup Klitplantage, an area comprising a conifer dominated forest plantation stocking on sandy deposits in a coastal setting near the Jammer Bay in north-western Jutland/Denmark, four different forest plots were investigated for water repellency effects four times in 2005. To measure soil water repellency, the water drop penetration time test and the critical surface tension test were carried out. Both tests revealed a seasonal variability in water repellency, exhibiting the highest water repellency for the upper 10 cm of the soil during the summer months, whereas the variability between the different plots seems to be less significant. There was no coherence between humus forms, thickness of litter layer and water repellency.

Hydro-physical processes and soil properties correlated with origin of soil hydrophobicity

“…The fi rst studies that sought to relate the occurrence of hydrophobicity with the granulometric composition reported that the phenomenon were mainly present in sandy soils (MEEUWIG, 1971). Recent studies too indicated that extreme cases of water repellency were found in sandy soils (DOERR et al, 2006;WAHL, 2008). These authors explained that the high hydrophobicity in sandy soils is related to the ease of coating of coarse particles by hydrophobic substances, due to smaller specifi c surface area.…”

“…The degree of hydrophobicity depends on the proportion of soil particles with a hydrophobic surface layer, which is infl uenced by the specifi c surface area and varies considerably with soil texture (WAHL, 2008). Sandy soils have a lower specifi c surface area, so a hydrophobic surface will push a greater proportion of particles than in the case of a silt clay soil or where the specifi c surface area is larger (TÄUMER et al, 2005;WOCHE et al, 2005).…”

“…In addition to moisture, particle size and soil organic matter, compounds also related to hydrophobicity are substances such as extracellular polymers produced by bacteria or fungi (MATAIX-SOLERA et al, 2007;RODRIGUEZ-ALLERES et al, 2007;WAHL, 2008). Biofi lms exudates can induce or remove the repellency soil materials depending on the strain bacteria .…”

“…The local vegetation, depending on their chemical composition, may contribute to hydrophobic organic compounds, by deposition or decomposition (MATAIX-SOLERA et al, 2007). It may also be associated with other factors such as soil moisture conditioned by rain and drought (ROBINSON et al, 2010), the granulometric composition (WOCHE et al, 2005;KAWAMOTO et al, 2007;VOGELMANN et al, 2010), soil pH (BAYER & SCHAUMANN, 2007) and presence of some species of fungi WAHL et al, 2008) and burnings (MADSEN et al, 2011.…”

“…Occurrence and variability of hydrophobicity in the soil Hydrophobicity has been documented in various locations and soil and climatic conditions, found in humid tropical climates (VOGELMANN et al, 2010;CAMBRONERO et al, 2011), in humid and cold climates of northern Europe (DLAPA et al, 2008, WAHL, 2008, or even in regions of warm and dry climate of central Australia (THWAITES et al, 2006) or in Mediterranean climate of southwest Europe (MATAIX-SOLERA et al, 2007;RODRÍGUEZ-ALLERES et al, 2007;KEIZER et al, 2007). In the literature, there are vast records of this phenomenon in a wide variety of soils, from sandy to clay soils, the highly to low weathered, very acidic to alkaline and fertile to less fertile (MÜLLER & DEURER, 2011).…”