The effect of soil surfactants on soil hydrological behavior, the plant growth environment, irrigation efficiency and water conservation

The effect of soil surfactants on soil hydrological behavior, the plant growth environment, irrigation efficiency and water conservationSoil water repellency causes at least temporal changes in the hydrological properties of a soil which result in, among other things, suboptimal growing conditions and increased irrigation requirements. Water repellency in soil is more widespread than previously thought and has been identified in many soil types under a wide array of climatic conditions worldwide. Consequences of soil water repellency include loss of wettability, increased runoff and preferential flow, reduced access to water for plants, reduced irrigation efficiency, increased requirement for water and other inputs, and increased potential for non-point source pollution. Research indicates that certain soil surfactants can be used to manage soil water repellency by modifying the flow dynamics of water and restoring soil wettability. This results in improved hydrological behavior of those soils. Consequently, the plant growth environment is also improved and significant water conservation is possible through more efficient functioning of the soil.

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

Soil and Water Research ◽

10.17221/1407-swr ◽

2008 ◽

Vol 3 (Special Issue No. 1) ◽

pp. S155-S164 ◽

Cited By ~ 13

Author(s):

N.A Wahl

Keyword(s):

Soil Water ◽

Preferential Flow ◽

Water Drop ◽

Water Repellency ◽

Climatic Conditions ◽

Tree Age ◽

Critical Surface ◽

Soil Water Repellency ◽

Wide Range ◽

North Western

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.

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Spatially variable soil water repellency enhances soil respiration rates (CO2 efflux)

10.5194/bg-2017-79 ◽

2017 ◽

Author(s):

Emilia Urbanek ◽

Stefan H. Doerr

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Soil Water ◽

Water Distribution ◽

Preferential Flow ◽

Water Repellency ◽

Water Repellent ◽

Co2 Efflux ◽

Soil Co2 ◽

Soil Water Repellency

Abstract. Soil CO2 emissions are strongly dependent on water distribution in soil pores, which in turn can be affected by soil water repellency (SWR; hydrophobicity). SWR restricts infiltration and movement of water, affecting soil hydrology as well as biological and chemical processes. Effects of SWR on soil carbon dynamics and specifically on soil respiration (CO2 efflux) have been studied in a few laboratory experiments but they remain poorly understood. Existing studies suggest that soil respiration is reduced in water repellent soils, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known. Here we report on the first field-based study that tests whether soil water repellency indeed reduces soil respiration, based on in situ field measurements carried out over three consecutive years at a grassland and pine forest site under the humid temperate climate of the UK. CO2 efflux was reduced on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. However, the highest respiration rates occurred not when SWR was absent, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. This somewhat surprising phenomenon can be explained by SWR-induced preferential flow, directing water and nutrients to microorganisms decomposing organic matter concentrated in hot spots near preferential flow paths. Water repellent zones provide air-filled pathways through the soil, which facilitate soil-atmosphere O2 and CO2 exchanges. This study demonstrates that SWR have contrasting effects on CO2 fluxes and, when spatially-variable, can enhance CO2 efflux. Spatial variability in SWR and associated soil moisture distribution needs to be considered when evaluating the effects of SWR on soil carbon dynamics under current and predicted future climatic conditions.

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Induced uneven spatial distribution of agrochemicals due to preferential flow in water repellent soils and its remediation by surfactant

10.5194/egusphere-egu2020-2974 ◽

2020 ◽

Author(s):

Felix Abayomi Ogunmokun ◽

Rony Wallach

Keyword(s):

Spatial Distribution ◽

Soil Water ◽

Soil Profile ◽

Preferential Flow ◽

Sandy Soils ◽

Water Repellency ◽

Treated Wastewater ◽

Water Repellent ◽

Soil Water Repellency ◽

Mediterranean Countries

Soil water repellency is a common feature of dry soils under permanent vegetation and drought conditions. Soil-water hydrology is markedly affected by soil-water repellency as it hinders infiltration, leading to enhanced surface runoff and soil erosion. Although this phenomenon was primarily ascribed to sandy soils, it has been observed in loam, clay, and peat soils in dry and humid regions. One detrimental effect of soil water repellency on plants is the reduction of soil water availability that stems from the non-uniform water retention and flow in preferential pathways (gravity-induced fingers) with relatively dry soil volume among these paths. It was recently discovered that prolonged irrigation with treated wastewater, a widely used alternative in Israel and other Mediterranean countries due to the limited freshwater, triggers soil water repellency which invariably resulted in preferential flow development in the field. Due to climate change events, the use of treated wastewater for irrigation as a means of freshwater conservation is expected to widen, including in countries that are not considered dry.While a vast amount of research has been devoted to characterizing the preferential flow in water repellent soils, the effect of this flow regime on the spatial distribution of salt and fertilizers in the root zone was barely investigated. Results from a commercial citrus orchard irrigated with treated wastewater that includes the spatial and temporal distribution of preferential flow in the soil profile measured by ERT will be demonstrated. The associated spatial distribution of salinity, nitrate, phosphate, and SAR in the soil profile will be shown as well.&#160; We investigated the efficacy of two nonionic surfactants application to remediate hydrophobic sandy soils both in the laboratory and field. The effect of the surfactant application to the water repellent soils in the orchards on the spatial distribution of soil moisture and the associated agrochemicals will be presented and discussed.

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Characterization of disaggregated nonwettable surface soils found at old crude oil spill sites

Canadian Journal of Soil Science ◽

10.4141/s97-039 ◽

1998 ◽

Vol 78 (2) ◽

pp. 331-344 ◽

Cited By ~ 40

Author(s):

Julie L. Roy ◽

William B. McGill

Keyword(s):

Plant Growth ◽

Crude Oil ◽

Soil Water ◽

Oil Spill ◽

Thermal Analyses ◽

Water Repellency ◽

Water Repellent ◽

Soil Water Repellency ◽

Water Desorption ◽

Crude Oil Spill

We characterized some of the physical, chemical, and microbiological properties of soils that have become severely water-repellent and disaggregated several years or decades following oil contamination. A growing number of patches (usually <2 ha) of disaggregated water-repellent soils have recently been discovered throughout the province of Alberta at 20 to 50-yr-old crude oil spill sites. The disaggregated water-repellent soil is usually confined to a dry and powdery surface layer 10 to 15 cm deep, which no longer smells, feels, or looks like it contains any oil. These soils appear to have permanently lost the ability to support plant growth and recover through natural processes. We analyzed samples of disaggregated water-repellent and adjacent normal soils from three old crude oil spill sites to provide a background set of information about these poorly known soils and assist in the development of hypotheses concerning the development and persistence of soil water repellency and structural degradation. Compared with normal adjacent soils, disaggregated nonwettable soils are characterized by: (1) a strong resistance to wetting, as determined by the molarity of ethanol droplet (MED) test; (2) a smaller population of viable and culturable microorganisms, which contains at least some representatives from nonspore-forming bacterial genera; (3) a high content of mineral N and total C, a comparable pH and ratio of exchangeable cations, but a lower cation exchange capacity; (4) a slightly lower clay content, as determined by the Bouyoucos hydrometer method; (5) a comparable water desorption behaviour following forced saturation with water; (6) dry aggregates of a smaller mean weight diameter (MWD), as determined by dry sieving and scanning electron miscroscopic (SEM) analyses; (7) slightly less pronounced thermal reactions when heated up to 525 °C, as determined by differential thermal analyses (DTA); and (8) a reduced ability to support plant growth. From these observations, we infer that disaggregated water-repellent soils found at old crude oil spill sites do not differ appreciably from normal adjacent soils in terms of their inorganic chemistry. Nonwettable and adjacent wettable soils differ mostly in terms of some physical and biological characteristics, which probably stem from differences in the quality of the organic matter they contain. Key words: Crude oil spills, petroleum hydrocarbons, soil water repellency, soil disaggregation, soil hydrophobicity

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Pines influence hydrophysical parameters and water flow in a sandy soil

Biologia ◽

10.2478/s11756-013-0254-7 ◽

2013 ◽

Vol 68 (6) ◽

Cited By ~ 12

Author(s):

Ľubomír Lichner ◽

Jozef Capuliak ◽

Natalia Zhukova ◽

Ladislav Holko ◽

Henryk Czachor ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Forest Soil ◽

Soil Water ◽

Water Flow ◽

Sandy Soil ◽

Preferential Flow ◽

Water Repellency ◽

Water Repellent ◽

Wetting Front ◽

Soil Water Repellency

AbstractPines, used for sand dune stabilization, can influence the hydrophysical parameters and water flow in an aeolian sandy soil considerably, mainly due to soil water repellency. Two sites, separated by distance of about 20 m, formed the basis of our study. A control soil (“Pure sand“) with limited impact of vegetation or organic matter was formed at 50 cm depth beneath a forest glade area. This was compared to a “Forest soil” in a 30-year old Scots pine (Pinus sylvestris) forest. Most of the hydrophysical parameters were substantially different between the two soil surfaces. The forest soil was substantially more water repellent and had two-times the degree of preferential flow compared to pure sand. Water and ethanol sorptivities, hydraulic conductivity, and saturated hydraulic conductivity were 1%, 84%, 2% and 26% those of the pure sand, respectively. The change in soil hydrophysical parameters due to soil water repellency resulted in preferential flow in the forest soil, emerging during a simulated heavy rain following a long hot, dry period. The wetting front established in pure sand exhibited a form typical of that for stable flow. Such a shape of the wetting front can be expected in the forest soil in spring, when soil water repellency is alleviated substantially.

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Exponential increase of publications related to soil water repellency

Soil Research ◽

10.1071/sr05007 ◽

2005 ◽

Vol 43 (3) ◽

pp. 403 ◽

Cited By ~ 96

Author(s):

Louis W. Dekker ◽

Klaas Oostindie ◽

Coen J. Ritsema

Keyword(s):

Soil Water ◽

Preferential Flow ◽

Flow Behavior ◽

Water Repellency ◽

Water Repellent ◽

Soil Water Repellency ◽

Exponential Increase ◽

Preferential Flow Paths ◽

The Usa ◽

Number Of Publications

Soil water repellency is much more wide-spread than formerly thought. During the last decades, it has been a topic of study for soil scientists and hydrologists in at least 21 States of the USA, in Canada, Australia, New Zealand, Mexico, Colombia, Chile, Congo, Nepal, India, Hong Kong, Taiwan, China, Ecuador, Venezuela, Brazil, Mali, Japan, Israel, Turkey, Egypt, South Africa, Germany, The Netherlands, Spain, Portugal, United Kingdom, Denmark, Sweden, Finland, Poland, Slovakia, Russia, France, Italy, and Greece. Although, water repellent soils already have been indicated at the end of the nineteenth century, they have been discovered and studied in most countries in the last decades. Water repellency is most common in sandy soils with grass cover and in nature reserves, but has also been observed in loam, heavy clay, peat, and volcanic ash soils. From 1940 to 1970 research was focussed on identifying vegetation types responsible for inducing water repellency and on developing techniques to quantify the degree of water repellency. Of special interest has been the effects of wildfire on the development of soil water repellency and its consequences for soil erosion. Due to increasing concern over the threat to surface and groundwater posed by the use of agrichemicals and organic fertilisers, studies on water repellent soils have also been focused on its typical flow behavior with runoff and the existence of preferential flow paths. Since the end of the 1950s, wetting agents and clay amendments have been studied to ameliorate water repellent soils. Since 1883, more than 1200 articles related to soil water repellency have been published in journals, reports, and theses. An exponential increase in number of publications started in 1960, resulting in an average of 200 publications per 5 years.

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