The isolation and characterisation of bacteria with the potential to degrade waxes that cause water repellency in sandy soils

Soil Research ◽  
2004 ◽  
Vol 42 (4) ◽  
pp. 427 ◽  
Author(s):  
Margaret M. Roper
Keyword(s):  
Agricultural Production ◽  
Complex Mixture ◽  
Sandy Soils ◽  
Water Repellency ◽  
Water Repellent ◽  
Bacterial Isolates ◽  
Hydrophobic Compounds ◽  
Degrading Bacteria ◽  
Wide Range ◽  
Fatty Acids And Alcohols

Water repellency in soils is caused by waxy coatings on particles and can seriously limit agricultural production. Bioremediation of these soils, using wax-degrading bacteria isolated from soils and other sources rich in microorganisms, was investigated. Wool wax, a complex mixture of fatty acids and alcohols, was used to select bacteria capable of metabolising hydrophobic compounds. Of the 37 stable isolates, two-thirds were actinomycetes. These organisms are known for their ability to metabolise a wide range of organic compounds. Degradation of waxes associated with soil particles is facilitated by the production of biosurfactants that emulsify hydrophobic compounds. Measurement of biosurfactant production indicated that those isolates that grew best on hydrocarbon were also the most prolific biosurfactant producers. Inoculation of water-repellent soils, under controlled conditions, with the most efficient wax-degrading bacterial isolates resulted in significant improvements in soil wettability.

scholarly journals Management options for water-repellent soils in Australian dryland agriculture

Soil Research ◽  
2015 ◽  
Vol 53 (7) ◽  
pp. 786 ◽  
Author(s):  
M. M. Roper ◽  
S. L. Davies ◽  
P. S. Blackwell ◽  
D. J. M. Hall ◽  
D. M. Bakker ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Compounds ◽  
Agricultural Production ◽  
Particle Surface ◽  
Sandy Soils ◽  
Water Repellency ◽  
Mitigation Strategies ◽  
Water Repellent ◽  
Particle Surface Area ◽  
No Till

Water-repellent (‘non-wetting’) soils are a major constraint to agricultural production in southern and south-west Australia, affecting >10 Mha of arable sandy soils. The major symptom is dry patches of surface soil, even after substantial rainfall, directly affecting agricultural production through uneven crop and pasture germination, and reduced nutrient availability. In addition, staggered weed germination impedes effective weed control, and delayed crop and pasture germination increases the risk of wind erosion. Water repellency is caused by waxy organic compounds derived from the breakdown of organic matter mostly of plant origin. It is more prevalent in soils with a sandy surface texture; their low particle surface area : volume ratio means that a smaller amount of waxy organic compounds can effectively cover a greater proportion of the particle surface area than in a fine-textured soil. Water repellency commonly occurs in sandy duplex soils (Sodosols and Chromosols) and deep sandy soils (Tenosols) but can also occur in Calcarosols, Kurosols and Podosols that have a sandy surface texture. Severity of water repellency has intensified in some areas with the adoption of no-till farming, which leads to the accumulation of soil organic matter (and hence waxy compounds) at the soil surface. Growers have also noticed worsening repellency after ‘dry’ or early sowing when break-of-season rains have been unreliable. Management strategies for water repellency fall into three categories: (i) amelioration, the properties of surface soils are changed; (ii) mitigation, water repellency is managed to allow crop and pasture production; (iii) avoidance, severely affected or poorly producing areas are removed from annual production and sown to perennial forage. Amelioration techniques include claying, deep cultivation with tools such as rotary spaders, or one-off soil inversion with mouldboard ploughs. These techniques can be expensive, but produce substantial, long-lasting benefits. However, they carry significant environmental risks if not adopted correctly. Mitigation strategies include furrow-seeding, application of wetting agents (surfactants), no-till with stubble retention, on-row seeding, and stimulating natural microbial degradation of waxy compounds. These are much cheaper than amelioration strategies, but have smaller and sometimes inconsistent impacts on crop production. For any given farm, economic analysis suggests that small patches of water repellency might best be ameliorated, but large areas should be treated initially with mitigation strategies. Further research is required to determine the long-term impacts of cultivation treatments, seeding systems and chemical and biological amendments on the expression and management of water repellency in an agricultural context.

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

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

<p>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.</p><p>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.  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.</p>

scholarly journals Eucalyptus reforestation induces soil water repellency

Soil Research ◽  
2015 ◽  
Vol 53 (2) ◽  
pp. 168 ◽  
Author(s):  
L. L. Walden ◽  
R. J. Harper ◽  
D. S. Mendham ◽  
D. J. Henry ◽  
J. B. Fontaine
Keyword(s):  
Soil Properties ◽  
Soil Water ◽  
Water Movement ◽  
Computer Modelling ◽  
Clay Content ◽  
Water Repellency ◽  
Water Repellent ◽  
Organic Carbon Content ◽  
Soil Water Repellency ◽  
Hydrophobic Compounds

There is an increasing interest in eucalypt reforestation for a range of purposes in Australia, including pulp-wood production, carbon mitigation and catchment water management. The impacts of this reforestation on soil water repellency have not been examined despite eucalypts often being associated with water repellency and water repellency having impacts on water movement across and within soils. To investigate the role of eucalypt reforestation on water repellency, and interactions with soil properties, we examined 31 sites across the south-west of Western Australia with paired plots differing only in present land use (pasture v. plantation). The incidence and severity of water repellency increased in the 5–8 years following reforestation with Eucalyptus globulus. Despite this difference in water repellency, there were no differences in soil characteristics, including soil organic carbon content or composition, between pasture and plantation soils, suggesting induction by small amounts of hydrophobic compounds from the trees. The incidence of soil water repellency was generally greater on sandy-surfaced (<10% clay content) soils; however, for these soils 72% of the pasture sites and 31% of the plantation were not water repellent, and this was independent of measured soil properties. Computer modelling revealed marked differences in the layering and packing of waxes on kaolinite and quartz surfaces, indicating the importance of interfacial interactions in the development of soil water repellency. The implications of increased water repellency for the management of eucalyptus plantations are considered.

Managing soils to enhance the potential for bioremediation of water repellency

Soil Research ◽  
2005 ◽  
Vol 43 (7) ◽  
pp. 803 ◽  
Author(s):  
Margaret M. Roper
Keyword(s):  
Management Practices ◽  
Crop Yields ◽  
Water Repellency ◽  
Water Infiltration ◽  
Most Probable Number ◽  
Water Repellent ◽  
Gradual Decline ◽  
Kaolinite Clay ◽  
Probable Number ◽  
Degrading Bacteria

Water repellency can significantly reduce crop and pasture establishment and production in sandy soils. Management practices that increase the rate of water infiltration into dry soils following the first rains at the end of the dry season were investigated. In the laboratory, addition of water to water repellent soil and maintenance of warm moist conditions produced a gradual decline in water repellency. This was supported by results in the field which showed that under daily irrigation there was a gradual decline in water repellency over time. However, under dryland conditions, other mechanisms to increase water infiltration had to be found. In the laboratory, after the addition of lime and kaolinite clay, there was an initial rapid decline in repellency, indicative of a physical mechanism, followed by a more gradual decline suggesting a biological response. In the field, under dryland conditions, the addition of lime and kaolinite clay resulted in a reduction in water repellency, and in the case of lime, this effect increased with the size of application. Estimates of the numbers of wax-degrading bacteria in the treated soils, using a most-probable-number assay, showed at least a 10-fold increase in lime-treated sands, but not in the clay-treated sands. The results suggest that lime may provide a viable alternative for increasing the wettability of soils by physical mechanisms and by promoting microbial activity by bacteria responsible for wax degradation, resulting in more consistent plant germination and establishment, and increased crop yields.

A quick fix for modeling infiltration in water-repellent soils

2021 ◽  
Author(s):  
Ryan Stewart ◽  
Majdi R. Abou Najm ◽  
Simone Di Prima ◽  
Laurent Lassabatere
Keyword(s):  
Soil Water ◽  
Wide Spectrum ◽  
Correction Term ◽  
Water Repellency ◽  
Infiltration Rate ◽  
Water Repellent ◽  
Soil Water Repellency ◽  
Simple Method ◽  
Wide Range ◽  
Infiltration Models

&lt;p&gt;Water repellency occurs in soils under a wide spectrum of conditions. Soil water repellency can originate from the deposition of resinous materials and exudates from vegetation, vaporization and condensation of organic compounds during fires, or the presence of anthropogenic-derived chemicals like petroleum products, wastewater or other urban contaminants. Its effects on soils range from mild to severe, and it often leads to hydrophobic conditions that can significantly impact the infiltration response with effects extending to the watershed-scale. Those effects are often time-dependent, making it a challenge to simulate infiltration behaviors of water-repellent soils using standard infiltration models. Here, we introduce a single rate-constant parameter (&amp;#945;&lt;sub&gt;WR&lt;/sub&gt;) and propose a simple correction term (1-e&lt;sup&gt;-&amp;#945;WRt&lt;/sup&gt;) to modify models for infiltration rate. This term starts with a value of zero at the beginning of the infiltration experiment (t = 0) and asymptotically approaches 1 as time increases, thus simulating a decreasing effect of soil water repellency through time. The correction term can be added to any infiltration model (one- two- or three-dimensional) and will account for the water repellency effect. Results from 165 infiltration experiments from different ecosystems and wide range of water repellency effects validated the effectiveness of this simple method to characterize water repellency in infiltration models. Tested with the simple two-term infiltration equation developed by Philip, we obtained consistent and substantial error reductions, particularly for more repellent soils. Furthermore, results revealed that soils that were burned during a wildfire had smaller &amp;#945;&lt;sub&gt;WR&lt;/sub&gt;&amp;#160;values compared to unburned controls, thus indicating that the magnitude of &amp;#945;&lt;sub&gt;WR&lt;/sub&gt;&amp;#160;may have a physical basis.&lt;/p&gt;

The use of dispersible clays to reduce water repellency of sandy soils

Soil Research ◽  
1989 ◽  
Vol 27 (4) ◽  
pp. 797 ◽  
Author(s):  
M Ma'shum ◽  
JM Oades ◽  
ME Tate
Keyword(s):  
Organic Matter ◽  
Sandy Soils ◽  
Water Repellency ◽  
Cetyl Alcohol ◽  
Water Repellent ◽  
Fine Grained ◽  
Naturally Occurring ◽  
Rapid Control ◽  
Sand Particles ◽  
Coated Sand

Water-repellency in sandy soils is determined by the amount of hydrophobic organic matter coating the sand particles and the specific surface area of the sands. The hydrophobic state can be simulated by coating hydrophilic sand with cetyl alcohol. Admixture of finely particulate materials with either naturally occurring water-repellent sands or the model cetyl alcohol-coated sand markedly reduced the water-repellency. Dispersible sodic clays were more effective than calcium saturated clays in reducing water-repellency, suggesting that the addition of dispersible, fine-grained illites and kaolinites couid play an important role in the rapid control of water-repellent soils in field situations.

scholarly journals Facile Method to Prepare Superhydrophobic and Water Repellent Cellulosic Paper

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Ioannis Karapanagiotis ◽  
Diana Grosu ◽  
Dimitra Aslanidou ◽  
Katerina E. Aifantis
Keyword(s):  
Particle Concentration ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Repellent ◽  
Tissue Paper ◽  
Nanoparticle Films ◽  
High Particle ◽  
Aesthetic Appearance ◽  
Static Contact ◽  
Wide Range

Silica nanoparticles (7 nm) were dispersed in solutions of a silane/siloxane mixture. The dispersions were applied, by brush, on four types of paper: (i) modern, unprinted (blank) paper, (ii) modern paper where a text was printed using a common laser jet printer, (iii) a handmade paper sheet detached from an old book, and (iv) Japanese tissue paper. It is shown that superhydrophobicity and water repellency were achieved on the surface of the deposited films, when high particle concentrations were used (≥1% w/v), corresponding to high static (θS≈ 162°) and low tilt (θt< 3°) contact angles. To interpret these results, scanning electron microscopy (SEM) was employed to observe the surface morphologies of the siloxane-nanoparticle films. Static contact angles, measured on surfaces that were prepared from dilute dispersions (particle concentration <1% w/v), increased with particle concentration and attained a maximum value (162°) which corresponds to superhydrophobicity. Increasing further the particle concentration did not have any effect onθS. Colourimetric measurements showed that the superhydrophobic films had negligible effects on the aesthetic appearance of the treated papers. Furthermore, it is shown that the superhydrophobic character of the siloxane-nanoparticle films was stable over a wide range of pH.

scholarly journals Water vapour adsorption on water repellent sandy soils

2017 ◽  
Vol 65 (4) ◽  
pp. 395-401 ◽  
Author(s):  
Tomas Orfanus ◽  
Abdel-Monem Mohamed Amer ◽  
Grzegorz Jozefaciuk ◽  
Emil Fulajtar ◽  
Anežka Čelková
Keyword(s):  
Fractal Dimension ◽  
Surface Area ◽  
Water Vapour ◽  
Adsorption Energy ◽  
Sandy Soils ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Repellent ◽  
Vapour Adsorption ◽  
Water Vapour Adsorption

AbstractSoil sorptivity is considered a key parameter describing early stages of water (rain) infiltration into a relatively dry soil and it is related to build-up complexity of the capillary system and soil wettability (contact angles of soil pore walls). During the last decade an increasing water repellency of sandy soils under pine forest and grassland vegetation has been frequently observed at Mlaky II location in SW Slovakia. The dry seasons result in uneven wetting of soil and up to hundredfold decrease in soil sorptivity in these vegetated soil as compared to reference sandy material, which was out of the reach of ambient vegetation and therefore readily wettable. As far as water binding to low moisture soils is governed by adsorption processes, we hypothesized that soil water repellency detected by water drop penetration test and by index of water repellency should also influence the water vapour adsorption parameters (monolayer water content, Wm, specific surface area, A, maximum adsorption water, Wa, maximum hygroscopic water MH, fractal dimension, DS and adsorption energies, Ea) derived from BET model of adsorption isotherms. We found however, that the connection of these parameters to water repellency level is difficult to interpret; nevertheless the centres with higher adsorption energy prevailed evidently in wettable materials. The water repellent forest and grassland soils reached less than 80% of the adsorption energy measured on wettable reference material. To get more conclusive results, which would not be influenced by small but still present variability of field materials, commercially available homogeneous siliceous sand was artificially hydrophobized and studied in the same way, as were the field materials. This extremely water repellent material had two-times lower surface area, very low fractal dimension (close to 2) and substantially lower adsorption energy as compared to the same siliceous sand when not hydrophobized.

scholarly journals Water-entry pressure in water repellent soils: a review

2020 ◽  
Vol 195 ◽  
pp. 02030
Author(s):  
Xin Xing ◽  
Sérgio D.N. Lourenço
Keyword(s):  
Soil Water ◽  
Water Repellency ◽  
Water Entry ◽  
Water Infiltration ◽  
Water Repellent ◽  
Key Factors ◽  
Soil Water Repellency ◽  
Factors Affecting ◽  
Hydrophobic Compounds ◽  
Entry Pressure

Water repellent soils can be naturally promoted (e.g. after wildfires) or synthetically induced by mixing with hydrophobic compounds (e.g. polydimethylsiloxane). The study of soil water repellency has lasted for over one century which implied the significant effect of soil water repellency on water infiltration, evaporation, soil strength, and soil stability. Water repellent soils can also be exploited by geotechnical engineers to offer novel and economical solutions for ground infrastructure. This paper synthesizes different methods for assessing soil water repellency based on varied indexes (e.g. contact angle, time for a drop to infiltrate) and with a focus on water entry pressure. Measurements of these parameters in synthetic water- repellent sands were taken, some results of which are summarized with discussion of key factors affecting water repellency. A comparison of these methods shows that water entry pressure can be more representative for assessing the water repellency of bulk samples.

Potential for remediation of water repellent soils by inoculation with wax-degrading bacteria in south-western Australia

Biologia ◽  
2006 ◽  
Vol 61 (19) ◽  
Author(s):  
Margaret Roper
Keyword(s):  
Water Repellency ◽  
Water Infiltration ◽  
Small Scale ◽  
Water Repellent ◽  
Degrading Bacteria ◽  
Soil Conditioners ◽  
Scale Experiment ◽  
Increased Activity ◽  
Reduced Water ◽  
Rhodococcus Sp

AbstractWater repellency resulting from waxy coatings around soil particles causes significant crop and pasture losses. Bioremediation of these soils using inoculation of wax-degrading bacteria was investigated under field conditions. In a small scale experiment without any additional nutrients or soil conditioners, 2 inoculants (Rhodococcus sp. and Roseomonas sp.) out of 7 resulted in significant improvements in water infiltration. A larger scale experiment had compost and fertiliser applied to support inoculants in nutrient-poor sands and lime was added to half the treatments. There were 6 different inoculants and their mixtures. One inoculant (Mycobacterium sp.) significantly reduced water repellency on its own. However, the addition of lime produced a significant “inoculant by lime” interaction, and limed treatments with each of the 5 individual cultures of Rhodococcus spp. and a mixture containing the 5 cultures of Rhodococcus spp. and 1 culture of Mycobacterium sp. all resulted in significant reductions in water repellency when compared with their non-limed counterparts and controls. Lime alone (1 t/ha, 70% neutralising value) produced a small but significant benefit compared with the non-limed control. The results indicate that there is potential to increase soil wettability through increased activity by wax-degrading bacteria.

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