A brief overview of the causes, impacts and amelioration of soil water repellency - a review

Abstract

This article describes the phenomenon of soil water repellency, starting from the fundamental principals of water transport and storage in soil. Soil water repellency is a reduction in the rate of wetting and retention of water in soil caused by the presence of hydrophobic coatings on soil particles. For crop production and the maintenance of amenity turf, water repellency can stress plants resulting in poorer yield quality or grass 'playability' , respectively. The biological causes of water repellency, primarily the influence of fungi, will be discussed, as an understanding of the source of the problem will be beneficial in developing solutions. Exacerbation of repellency through climate change and the use of 'engineered' soils for amenity surfaces will be demonstrated using research findings from around the globe. In developing solutions to soil water repellency, its positive benefits, if maintained at very low levels, need to be considered. Water repellency is a key process in the physical stabilisation of soil and its impact on evaporation also needs to be considered. Before developing a rapid solution to repellency based only on water transport rates, a holistic understanding of the impacts on soil water relations is essential.

Soil water repellency changes with depth and relationship to physical properties within wettable and repellent soil profiles

“…Dekker et al (2001), Täumer et al (2005) and Bachmann et al (2013) also reported spatial variation of SWR using WDPT through the soil profile. Johnson et al (2005) and Madsen et al (2011) found the variability of SWR was large in both time and space, which commonly attributed to the water content Hallett, 2008). The values of actual SWR were greater than our measure of potential SWR at all depths of the repellent field-soil.…”

“…In spite of the differences in the upper part of the soil profiles (0-30 cm), there was little difference between water content of both repellent and wettable soils below the depth of 30 cm (Table 4 and 5). This result might be due to evaporation from soil caused by a water repellent surface (Hallett, 2008). Keizer et al (2007) also found that the transient wetting behavior of soil changed significantly due to the increase in soil water content from hydrophobic to hydrophilic within short time periods.…”

Biological soil crusts cause subcritical water repellency in a sand dune ecosystem located along a rainfall gradient in the NW Negev desert, Israel

“…In order to exclude time dependent reductions in WR only the time of infiltration in which a linear relationship between the cumulative infiltration and the square root of time can be observed, often the first 1-3 min. is used to calculate the RI (Hallett, 2008;Schacht et al, 2014). RI values of 1 indicate no WR and a value greater than 1 indicates a water repellent soil (Hallett and Young, 1999).…”

Improving phosphorus use efficiency for snap bean production by optimizing application rate

“…South Florida is the principal region of snap bean production in the state. Fertilization is critical for growing snap bean in this region because sandy soils are water repellent and poor at holding water and nutrients (Hallett 2008;Hall 2009). Once P fertilizers are applied to the soil, they have one of four fates: plant uptake, soil fixation, runoff, and leaching.…”