Effect Of Water Repellency Research Articles

Post-fire interactions between soil water repellency, soil fertility and plant growth in soil collected from a burned piñon-juniper woodland

Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zero-tension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soil-water content, and elevated NO3–N in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.

Hydraulic Performance of Horticultural Substrates—2. Development of an Evaluation Framework

Sustainable, environmentally friendly and resource-saving water and nutrient management in horticulture requires knowledge of the hydraulic suitability of horticultural substrates for each specific application. The aim of this study was to develop methods and a rating framework to assess the hydraulic performance of horticultural substrates. The hydraulic criteria related to high-quality horticultural substrates were defined as the amount of easily plant-available water (EAW) in the tension range between 10 and 100 hPa, the air capacity and the height of capillary rise. Limiting factors could be water repellency effects and shrinkage. The rating framework consisted of 5 classes between non-satisfactory and very good. The assessment of the hydraulic performance was split for the cultivation into 10-, 20-, and 30-cm-high containers. It was tested on 18 commercial substrates. More than 70% of the tested substrates revealed scores between very good and good. About 30% were evaluated as medium or satisfactory. The most critical aspect was the low air capacity in shallow containers. Shrinkage and water repellency sometimes strongly diminished the score. Both the measurement methods for quantifying substrate hydraulic properties and the evaluation procedure proved applicable. The impact of different ingredients and the composition of substrates of their hydraulic performance should be statistically analysed in further studies.

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

AbstractThis study explored the effect of soil water repellency (SWR) on soil hydrophysical properties with depth. Soils were sampled from two distinctly wettable and water repellent soil profiles at depth increments from 0-60 cm. The soils were selected because they appeared to either wet readily (wettable) or remain dry (water repellent) under field conditions. Basic soil properties (MWD, SOM, θv) were compared to hydrophysical properties (Ks, Sw, Se, Sww, Swh, WDPT, RIc, RImand WRCT) that characterise or are affected by water repellency. Our results showed both soil and depth affected basic and hydrophysical properties of the soils (p <0.001). Soil organic matter (SOM) was the major property responsible for water repellency at the selected depths (0-60). Water repellency changes affected moisture distribution and resulted in the upper layer (0-40 cm) of the repellent soil to be considerably drier compared to the wettable soil. The water repellent soil also had greater MWDdryand Ks over the entire 0-60 cm depth compared to the wettable soil. Various measures of sorptivity, Sw, Se, Sww, Swh, were greater through the wettable than water repellent soil profile, which was also reflected in field and dry WDPT measurements. However, the wettable soil had subcritical water repellency, so the range of data was used to compare indices of water repellency. WRCT and RImhad less variation compared to WDPT and RIc. Estimating water repellency using WRCT and RIm indicated that these indices can detect the degree of SWR and are able to better classify SWR degree of the subcritical-repellent soil from the wettable soil.

Technological properties of glulam beams made from hydrothermally treated poplar wood

ABSTRACTIn this research, technological properties of glulam beams made from hydrothermally treated poplar (Populus deltoides) wood were investigated. Poplar wood blocks with dimensions of 6 (r) × 10 (t) × 73 (l) cm3 were cut and hydrothermally treated in a stainless steel reactor at temperatures of 140 and 160°C for a holding time of 30 min. The treated wood blocks were initially air seasoned and then they were dried in a semi-pilot scale vacuum dryer to achieve moisture content (MC) of 12%. Conditioning of the treated and the untreated wood blocks was done prior to adhesive bonding. Afterwards the glulam beams (4 ply) were manufactured using polyurethane. In order to evaluate the physico-mechanical properties of the beams, density, equilibrium moisture content, water repellent effect (WRE), anti-swelling effect (ASE), mass loss (ML), wettability as well as surface roughness due to the hydrothermal treatment were determined in the treated wood and delamination, bond shear strength, tensile strength, MC and moisture-induced stresses as well as strains in cross-section of the beams were determined in the glulam beams. The results revealed that density, ML, ASE, WRE, modulus of elasticity, modulus of rupture and delamination were increasing and the others were decreased due to the hydrothermal treatment.

Effects of olive oil mill wastewater on chemical, microbiological, and physical properties of soil incubated under four different climatic conditions

The objective of this study was to understand the degradation of the organic matter of olive mill wastewater (OMW) and its phytotoxic and water repellent effects in dependence on four different climatic conditions. We hypothesized that warm conditions with sufficient soil moisture ensure optimal biological activity and thus minimize negative effects of the OMW treatment. Therefore, OMW-treated soil was incubated for 60 days under four climatic conditions. During incubation, we monitored pH, contents of nitrate, manganese and phenolic compounds, soil respiration, soil water repellency, and δ13C. Additionally, calorific value and thermal stability of the soil organic matter at the beginning and end of incubation were determined. Soil samples of the wet-cold and moist-warm incubation were tested for phytotoxicity using a seed germination bioassay with Lepidium sativum. As a function of climatic conditions, positive and negative effects, e.g., addition of nutrients, phytotoxicity, and soil water repellency, were observed. Under dry-hot conditions, the soil was still water repellent after 60 days of incubation whereas the wet-hot, moist-warm, and wet-cold incubation show that soil would stay wettable if soil moisture before OMW treatment would be sufficient. Thus, the impact of OMW treatment on soil quality strongly depends on the environmental conditions which should favor an enhancement of microbial activity to minimize negative effects.

Water repellent effects of manure amended soils on organic matter decomposition, C retention, and respired CO2-C

AbstractOne option that can be used to mitigate the changes in global climate caused by the elevated levels of atmospheric CO

How soil temperatures during prescribed burning affect soil water repellency, infiltration and erosion

Fire can create, strengthen or destroy soil water repellency, with potential implications for soil infiltration, surface runoff and erosion. Laboratory studies suggest fire-induced changes to water repellency relate to soil temperatures during the burn. However, relations between temperature and repellency are rarely tested in the field where spatial variations in fuel type, soil type and soil moisture may lead to more complex responses to fire. Furthermore, few studies link point-scale water repellency measurements to hydro-geomorphic effects at larger spatial scales. Therefore, the purposes of this study were to (1) measure soil temperatures during prescribed burns, (2) investigate the in-situ effects of soil heating on soil water repellency and (3) investigate the subsequent effects of soil water repellency on infiltration, runoff and erosion. Heat-sensitive liquids and thermocouples measured soil temperatures at points within three prescribed burns. Soil water repellency and infiltration were measured at the same burnt points and at adjacent unburnt points 2–6weeks post-burn. Rainfall simulations quantified plot-scale infiltration, surface runoff and erosion at one site. Peak temperatures at the surface were highly variable (averaging 238, 129 and 327°C at each burn) while sub-surface temperatures were lower (averaging 75, less than79 and 108°C at each burn). Heating durations were short with surface temperatures greater than 400°C lasting on average for 2s and temperatures greater than 200°C lasting on average for 6s. Despite pre-existing water repellency in unburnt areas, water repellency was strengthened in burnt areas at two sites. High temperatures were associated with more repellency, even when the temperatures exceeded laboratory-defined thresholds for the destruction of water repellency. Short heating durations may explain why the laboratory-defined temperature thresholds were not applicable in the field. Point-scale steady-state infiltration rates were significantly lower for burnt compared with unburnt areas, reflecting the greater water repellency. However, other factors (e.g. macropore flow, soil sealing and reduced vegetation cover) are also likely to have caused unexpectedly high or low infiltration rates for some points and higher infiltration rates at the plot-scale than expected. The relative importance of water repellency to infiltration, surface runoff and erosion appeared to vary depending on the spatial scale of measurement. These issues of scale together with the apparent spatial heterogeneity of prescribed burnt landscapes warrant the use of connectivity modelling as a way to link point and plot scale measures to impacts at larger spatial scales.

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

Abstract The biological soil crusts (BSCs) in the NW Negev cause local water redistribution by increasing surface runoff. The effects of pore clogging and swelling of organic and inorganic crust components were intensively investigated in earlier studies. However, the effect of water repellency (WR) was not addressed systematically yet. This study investigates subcritical WR of BSCs in three different study sites in the NW Negev. For this purpose, three common methods to determine soil WR were used: (i) the repellency index (RI) method (ii) the water drop penetration time (WDPT) test and (iii) the Wilhelmy plate method (WPM). Furthermore, the potential influence of WR on local water redistribution is discussed and the applied methods are compared. We found the BSC to be subcritically water repellent. The degree of WR may only affect water redistribution on a microscale and has little influence on the ecosystem as a whole. The RI method was clearly the most appropriate to use, whereas the WDPT and the WPM failed to detect subcritical WR.

Color intensity and wash fastness properties of dyed cotton fabric after plasma treatment

In this research work, first cotton fabrics were dyed with various types of dyestuffs such as vat, reactive, and direct and then dyed fabrics were treated with low-temperature plasma (LTP) of nitrogen, air, and argon gases, and some properties of the samples were investigated. Color intensities of the dyed fabrics were measured using a UV VIS-NIR Reflective Spectrophotometer, over the range of 200–800 nm. Water drop test and wash fastness determination (ISO 105-C01) were conducted. The results show that post-plasma treatment of direct dyed cotton fabric can be a useful method for improving the fastness properties of direct dyed cotton samples. Also, by post-plasma treatment with argon gas, water repellent effect appeared for all samples.

表面テクスチャリングが材料表面の親・疎水性に与える影響

Surfaces of lotus leaf and moth eye have fine structures. The structure produces water repellent effect or reflection suppression. The purpose of this study is to reproduce these characteristic to the artificial material surface by using a precision machining method. Micro slurry-jet erosion has been proposed as the precision machining method for a glass or plastic surface. The micro slurry-jet erosion method is a wet blasting technique which used alumina particles as the abrasive medium along with compressed air and water to create the fine structures. The glass surface processed has a hydrophobic character and do not show influence of the light transmission property. These results concluded that the precision machining method was one of the promising method to create the bio-inspired surface on the artificial materials.

Atmospheric Ice Adhesion on Water-Repellent Coatings: Wetting and Surface Topology Effects.

Recent studies have shown the potential of water-repellent surfaces such as superhydrophobic surfaces in delaying ice accretion and reducing ice adhesion. However, conflicting trends in superhydrophobic ice adhesion strength were reported by previous studies. Hence, this investigation was performed to study the ice adhesion strength of hydrophobic and superhydrophobic coatings under realistic atmospheric icing conditions, i.e., supercooled spray of 20 μm mean volume diameter (MVD) droplets in a freezing (-20 °C), thermally homogeneous environment. The ice was released in a tensile direction by underside air pressure in a Mode-1 ice fracture condition. Results showed a strong effect of water repellency (increased contact and receding angles) on ice adhesion strength for hydrophobic surfaces. However, the extreme water repellency of nanocomposite superhydrophobic surfaces did not provide further adhesion strength reductions. Rather, ice adhesion strength for superhydrophobic surfaces depended primarily on the surface topology spatial parameter of autocorrelation length (Sal), whereby surface features in close proximities associated with a higher capillary pressure were better able to resist droplet penetration. Effects from other surface height parameters (e.g., arithmetic mean roughness, kurtosis, and skewness) were secondary.

Measurement and evaluation of the hydraulic properties of horticultural substrates

Sustainable, environmentally friendly and resource-saving water and nutrient management in horticulture requires knowledge of the suitability of horticultural substrates for each specific application. One specific element is their hydraulic performance. To meet this requirement, methods are needed (1) to measure the hydraulic properties and (2) to evaluate the hydraulic quality of the horticultural substrates. The aim of this study was (1) to test the extended evaporation method and the HYPROP systems for quantifying the substrate’s hydraulic properties (the water retention curve, the unsaturated hydraulic conductivity function, the shrinkage dynamics, the bulk density), and (2) to develop a rating framework for assessing the hydraulic suitability of the substrates. The hydraulic evaluation was split into cultivation under free drainage in the ground and cultivation in containers. The hydraulic criteria related to high-quality horticultural substrates were defined as the amount of easily plant-available water, the air capacity and the height of capillary rise. Limiting factors could be water repellency effects and shrinkage. The rating framework consists of five classes between non-satisfactory and very good. It was tested on 23 commercial horticultural substrates. Both the measurement methods for quantifying soil hydraulic properties and the evaluation procedure proved applicable.

The influence of water-repellent admixtures on the behaviour and the effectiveness of Portland limestone cement mortars

Water-repellent mortars were prepared using different hydrophobic compounds as admixtures. Calcium and zinc stearates, silane/siloxane products (as liquid solution and powder) were mixed into limestone cement mortars for obtaining in-bulk water-repellent mortars suitable for building protection and resistant to the degrading action of water. The influences of the admixtures on the hydration and structure of the designed mortars were investigated by SEM, TG–DSC, FT-IR, XRD, and isothermal calorimetry. The effectiveness of these agents against water action was evaluated by using techniques and methods such as mercury intrusion porosimetry, water absorption tests and contact angle measurements. Siloxane products conveyed good water-repellent effectiveness, without strongly influencing the setting and hydration of the binder, while the zinc stearates slowed down the hydration reactions.

Sequential estimation of hydraulic parameters in layered soil using limited data

Field-scale estimation of soil hydraulic parameters is important for describing water movement in vadose zones. The importance of soil water measurements has been acknowledged with increasing soil water measurements becoming available; thus, the estimation of hydraulic parameters from observed soil water would be quite useful for hydrological modeling. This study estimated the hydraulic parameters of Brooks–Corey and Mualem model using the monitored soil water changes at two depths together with the rainfall intensity at two soil plots in a tropical rain forest in Indonesia. A one-dimensional multi-scale parameterization method was used for the analysis, beginning with homogeneous parameterization and identifying the depth of discontinuity using refinement indicators, thus increasing the number of zones. A method for sequential parameterization was developed in each step of zoning. The measured and simulated volumetric water contents with the optimized parameters showed good agreement for one plot (standard error is 0.0419) with 2-zone parameterization, and the effects of the initial parameters derived from different pedo-transfer functions on the optimized hydraulic functions were small, confirming the robustness of this method. However, at another field site, agreement between measured and simulated water contents was not very good (standard error is 0.0854), because the effect of the soil water repellency might have influenced the results, and the effects of the initial parameters were large. The algorithm proposed in this study systematically determines the hydraulic parameter set that describes field-scale water flow.

A Study on Water Repellent Effectiveness of Natural Oil-Applied Soil as a Building Material

This study was performed to investigate the water repellent effectiveness of natural oil-applied soil when it is used as a building material. Natural oil types such as olive oil, bean oil, perilla oil and linseed oil, which are being used for producing water repellent timber, are selected for the experiments. It is expected that perilla oil and in seed oil, which are drying oil types will have better water repellent effectiveness than the other types. For the evaluation of water repellence of natural oil-applied soil, a contact angle test was performed. A contact angle of water drop on various surface conditions were tested, and large differences were seen between the natural oil-applied soil and untreated soil. As a result, it is showed that all natural oil types have water repellent effectiveness. However, linseed oil, which is a drying oil type, shows an outstanding water repellent effectiveness value, while perila oil, which is also a drying oil type, shows the lowest value. Additionally, results show that there is no link between water repellent effectiveness and the number of applications of natural oil. Nevertheless, existing commercial water repellents show better performance than natural oil, and it is anticipated that the results of this study will provide essential information for further research to enhance the water repellent effectiveness of soil as a building material.

2303 鉱物資源を処理する機械装置の設計支援のためのバイオミミクリー手法の考察(GS1-1 一般セッション(1),GS1 一般セッション)

New product designs are sometimes inspired by nature. An example includes umbrella superior in a water repellency effect in imitation of the leaf of the lotus. In this study, the authors attempt to develop new design methods based on knowledge obtained from the natural world. In particular, the authors paid attention to shock relaxation and abrasion resistant improvement about Rotary drum type dryer. With the method that has been already shown, it can suggest new design plan effectively. Discovering analogy of the tooth of the living body and then hypothesizing and be able to show one of the improvement plan. Probably be able to change depending on the structure change from a "material" and "device" in contact with "material" and "material". As the result, the situation will be optimized. It is revealed that this paper can show some design guidance by using an existing method. The result must be inspected the validity of the design guidance doing experiment and analysis, and it is necessary to become the establishment of the method.

Effects of Soil Water Repellency on Moisture Patterns in a Degraded Sapric Histosol

AbstractAn understanding of soil moisture content variability is fundamental in hydrological studies of peat soils, whose preservation depend on water‐related processes. Dehydration of fens and adapting them for agricultural production have contributed to the degradation of peat soils. The goal of this study was to determine how the critical soil moisture content (CSMC) and soil water repellency (SWR) affect soil moisture patterns in a degraded peat‐muck soil profile. SWR was measured under laboratory conditions using the water drop penetration time test, and then the CSMC was assessed. An investigation of moisture patterns was based on soil moisture data collected over short distances in a grass‐covered peat‐muck soil profile on seven dates. Observed differences in moisture patterns demonstrate that the CSMC can be used for the prediction of preferential flow occurrences in peat‐muck soils. Lower values of the CSMC and lower levels of SWR persistence in muck layers than in peat layers indicate that degradation of peat soils improves their wettability. The relatively low values of CSMC and the low shrinkage potential in the muck layer suggest that preferential water flow in the degraded organic soils can occur when heavy rains are preceded by long periods of summer drought. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of Soil Water Repellency on Energy Partitioning Between Soil and Atmosphere: A Conceptual Approach

Water repellency (WR) is a phenomenon known from many soils around the world and can occur in arid as well as in humid climates; few studies, however, have examined the effect of soil WR on the soil-plant-atmosphere energy balance. The aim of our study was to estimate the effects of soil WR on the calculated soil-atmosphere energy balance, using a solely model-based approach. We made out evapotranspiration to have the largest influence on the energy balance; therefore the effect of WR on actual evapotranspiration was assessed. To achieve this we used climate data and measured soil hydraulic properties of a potentially water-repellent sandy soil from a site near Berlin, Germany. A numerical 1D soil water balance model in which WR was incorporated in a straightforward way was applied, using the effective cross section concept. Simulations were carried out with vegetated soil and bare soil. The simulation results showed a reduction in evapotranspiration of 30–300 mm year−1 (9%–76%) at different degrees of WR compared to completely wettable soil, depending on the severity degree of soil WR. The energy that is not being transported away by water vapor (i.e., due to reduced evapotranspiration) had to be transformed into other parts of the energy balance and thus would influence the local climate.

Water stable aggregates of Japanese Andisol as affected by hydrophobicity and drying temperature

Abstract Hydrophobicity is a property of soils that reduces their affinity for water, which may help impeding the pressure build-up within aggregates, and reducing aggregate disruption. The purpose of this study was to examine the relation of soil hydrophobicity and drying temperature to water stability of aggregates while preventing the floating of dry aggregates using unhydrophobized and hydrophobized surface Andisol. Soil was hydrophobized using stearic acid into different hydrophobicities. Hydrophobicity was determined using sessile drop contact angle and water drop penetration time (WDPT). Water stability of aggregates (%WSA) was determined using artificially prepared model aggregates. The %WSA increased as the contact angle and WDPT increased. Contact angle and WDPT, which provided maximum %WSA showing less than 1 s of floating, was around 100° and 5 s, respectively. Although the %WSA gradually increased with increasing contact angle and WDPT above this level, high levels of hydrophobicity initiated aggregate floating, which would cause undesirable effects of water repellency. Heating at 50°C for 5 h d-1 significantly affected %WSA and hydrophobicity in hydrophobized samples, but did not in unhydrophobized samples. The results indicate that the contact angle and wetting rate (WDPT) are closely related with the water stability of aggregates. The results further confirm that high levels of hydrophobicities induce aggregate floating, and the drying temperature has differential effects on hydrophobicity and aggregate stability depending on the hydrophobic materials present in the soil.

Water Retention and Repellency of a Sandy Soil Amended with Municipal Compost

ABSTRACTThe aim of this study was to investigate the influence of a drying process on sandy soil amended with different rates of compost on physical properties and with a special focus on soil water retention characteristics. The mixtures of compost and sandy soil with different compost rates were prepared, namely, 100% compost, 20% compost, 10% compost, and soil without compost. The samples were dried in the following temperatures: 20, 40, and 80°C. The compost addition to the sandy soil led to an increase in soil porosity. Three pore fractions, bonding space, residual, and storage pores reached their highest values in the samples with higher compost rates. A reduction of residual and storage pores volume resulted in a decrease in available and productive water content. Lower compost content reduced the amount of stored water. The drying of the sandy soil amended with compost at rates of 100 and 20% triggered the water repellency effect.