Academic literature on the topic 'Perth sand soil'

Applying ultrasound energy to soil-water suspensions (sonication) is an established method of determining the size distributions of soil primary mineral particles and associated organic matter. The size distributions may vary, however, with sonication input energy and soil type. The objective of this study was to determine the effects of sonication input energy on the size distributions of soil mineral particles and organic matter for a range of soil textures and carbon contents typical of agricultural soils in southwestern Ontario. The soils included a Brookston clay loam, a Brookston clay, a Huron silt loam, a Perth silt loam and a Harrow sandy loam. All soils were under no-tillage management. Nine sonication energies ranging from 50 to 1500 J mL–1 were applied to soil-water suspensions (1:4 mass ratio), and the soil particle size distribution results were compared with those obtained using the standard chemical dispersion (pipette) method. The three medium- and coarse-textured soils (Huron, Perth, Harrow) required about 250 J mL–1 for complete dissociation of soil aggregates, while the two fine-textured soils (Brookston) required sonication energies of 600-750 J mL–1. Increasing sonication energy increased the amount of soil organic carbon (SOC) measured in the clay-size fraction and decreased the amounts in the sand and silt fractions. Therefore, accurate determinations of particle size distribution and SOC contents require an initial assessment of the amount of sonication energy required for the complete dispersion of the particle size fractions. For the Brookston clay loam and Brookston clay soils, 40–52% less particulate SOC was found in the sand fraction at 750 J mL–1 sonication energy than that obtained using the standard pipette method, indicating particle size reduction by sonication of particle organic matter. It should be noted that the sand-size SOC typically represents a small fraction. Furthermore, sonication had a minor effect on the SOC content of the clay fraction. It was concluded that sonication is a viable technique for determining the size distribution of soil primary mineral particles, as well as the amount of SOC associated with the silt and clay fractions. Key words: Sonication, ultrasound energy, particle size distribution, organic carbon fractionation, clay soil

On sandy soil near Esperance, W.A., prevention of burr burial compared with covering developing burrs with sand drastically reduced the seed production of three subspp. of Trifolium subterraneum (brachycalycinum, subterraneum and yanninicum) and of T. israeliticum by reducing burr production and seed weight. However, T. globosum produced similar amounts of seed from unburied and buried burrs. On sandy soil at Shenton Park, Perth, W.A., prevention of burr burial also reduced seed production of T. subterraneum subspp. brachycalycinum and subterraneum, this being due to fewer burrs, fewer seeds per burr and lighter seed. For subsp. brachycalycinum, seed yields were two to five times greater from burrs which developed within loose gravel than from those developed over sand (in which fewer burrs were able to bury) as a result of increased production of burrs, more seeds per burr and heavier seed. However, for subsp. subterraneum seed yields were similar from burrs whether developed over gravel or sand.

In general, water repellency by soil increases with the increase of total organic matter and decreases as the clay and silt contents of the soil increase. The prediction of water repellency from soil organic carbon (OC) content may be improved by examining the types of carbon associated with water repellency. This paper examines the hypothesis that measurement of aliphatic C can provide a better prediction of water repellency than measurement of total OC and also looks at the effects of soil texture on water repellency and the amount of aliphatic C in the soil. DRIFT (diffuse reflectance infrared fourier transform) spectra were measured on sandy soils from the West Midland Sandplains north of Perth in Western Australia. The areas of the aliphatic CH stretching signal (3000–2800/cm) and the OH stretching signal due to kaolin (3750–3570/cm) were used as relative measures of aliphatic carbon and kaolin contents. The relationships of aliphatic C and kaolin to water repellency have been examined and compared with the relationships of water repellency to total OC and clay contents of soil.Hydrophobic organic C as measured by DRIFT gave a better prediction of soil water repellency (r2 = 0.45) than did the total OC (r2 = 0.36). The specific hydrophobicity of organic matter (aliphatic C/OC ratio) increased as sand content increased. However, the direct influence of soil texture on water repellency was of more significance than its indirect influence on the amounts and forms of soil organic matter. A multivariate model including aliphatic C and clay + silt content was the best model for describing water repellency (r2 = 0.58). DRIFT is an effective, rapid method for screening soils for water repellent properties.For individual sand grains there was a weak positive relationship (r2 = 0.26) between the size of the aliphatic CH peak measured from surfaces of sand grains and the water repellency of the grains. A discontinuous aliphatic surface layer was present on the surface of individual sand grains.

Abstract Stable fly (Stomoxys calcitrans L.) remain a significant pest affecting livestock and rural communities on the Swan Coastal Plain around Perth, Western Australia. Vegetable crop residues remaining after harvest enable stable fly development. Left untreated they can produce from several hundred to >1,000 stable fly/m2 of post-harvest residues. We studied the effect of burial and compaction of sandy soils on adult emergence of stable fly and house fly (Musca domestica L.) (Diptera: Muscidae). Adults of both fly species can move up through 50 cm of loose, dry sand, however at depths greater than 60 cm, emergence rapidly declines with <5% of adults surviving under 100 cm of soil. Burial of stable fly larvae and pupae under 15 cm of soil followed by compaction using a static weight dramatically reduced adult emergence. Moist soil compacted at ≥3 t/m2 completely prevented stable fly emergence whereas house fly emergence was not affected. One t/m2 of compaction resulted in <5% emergence of stable fly buried as pupae. Soil that was easily compactible (i.e., high silt, fine sand and clay content) reduced stable fly emergence more than soil with more coarse sand and low clay content. This study demonstrates the potential for a novel and chemical-free option for controlling stable fly development from vegetable crop post-harvest residue. Field trials are needed to confirm that burial and compaction of vegetable post-harvest residues using agricultural machinery can dramatically reduce the subsequent emergence of adult stable fly on a large scale.

The natural hybrid Drosera × sidjamesii Lowrie & Conran from Lake Gnangarra north of Perth, Western Australia is described and defined as a cross between D. nitidula Planch. subsp. omissa Marchant & Lowrie auct. non Diels and D. pulchella Lehm., between which it shows a high degree of intermediacy for almost all characters. Cytological examination of the hybrid and its parents confirms that the former at 2n = 46 is a combination of the 2n = 28 in D. nitidula subsp. omissa and 2n = 18 in D. pulchella. The hybrid grows along a narrow ecotone between the parental species, largely on sandy peat and along a presumed soil moisture/elevation gradient caused by the nearby lake. Nevertheless, within this ecotone the hybrid is significantly more frequent than either parental species, with D. pulchella mainly growing in peat soils closer to the lake and D. nitidula subsp. omissa on white sand further from the water. Field observations of morphotypes also suggest that the hybrid has arisen several times at the site, and that a limited number of plants at the site are becoming fertile and setting seed.

The natural hybrid Drosera � sidjamesii Lowrie & Conran from Lake Gnangarra north of Perth, Western Australia is described and defined as a cross between D. nitidula Planch. subsp. omissa Marchant & Lowrie auct. non Diels and D. pulchella Lehm., between which it shows a high degree of intermediacy for almost all characters. Cytological examination of the hybrid and its parents confirms that the former at 2n = 46 is a combination of the 2n = 28 in D. nitidula subsp. omissa and 2n = 18 in D. pulchella. The hybrid grows along a narrow ecotone between the parental species, largely on sandy peat and along a presumed soil moisture/elevation gradient caused by the nearby lake. Nevertheless, within this ecotone the hybrid is significantly more frequent than either parental species, with D. pulchella mainly growing in peat soils closer to the lake and D. nitidula subsp. omissa on white sand further from the water. Field observations of morphotypes also suggest that the hybrid has arisen several times at the site, and that a limited number of plants at the site are becoming fertile and setting seed.

Abstract. The groundwater resource contained within the sandy aquifers of the Swan Coastal Plain, south-west Western Australia, provides approximately 60 percent of the drinking water for the metropolitan population of Perth. Rainfall decline over the past three decades coupled with increasing water demand from a growing population has resulted in falling dam storage and groundwater levels. Projected future changes in climate across south-west Western Australia consistently show a decline in annual rainfall of between 5 and 15 percent. There is expected to be a reduction of diffuse recharge across the Swan Coastal Plain. This study aims to quantify the change in groundwater recharge in response to a range of future climate and land cover patterns across south-west Western Australia. Modelling the impact on the groundwater resource of potential climate change was achieved with a dynamically linked unsaturated/saturated groundwater model. A vertical flux manager was used in the unsaturated zone to estimate groundwater recharge using a variety of simple and complex models based on climate, land cover type (e.g. native trees, plantation, cropping, urban, wetland), soil type, and taking into account the groundwater depth. In the area centred on the city of Perth, Western Australia, the patterns of recharge change and groundwater level change are not consistent spatially, or consistently downward. In areas with land-use change, recharge rates have increased. Where rainfall has declined sufficiently, recharge rates are decreasing, and where compensating factors combine, there is little change to recharge. In the southwestern part of the study area, the patterns of groundwater recharge are dictated primarily by soil, geology and land cover. In the sand-dominated areas, there is little response to future climate change, because groundwater levels are shallow and much rainfall is rejected recharge. Where the combination of native vegetation and clayey surface soils restricts possible infiltration, recharge rates are very sensitive to reductions in rainfall. In the northern part of the study area, both climate and land cover strongly influence recharge rates. Recharge under native vegetation is minimal and is relatively higher where grazing and pasture systems have been introduced after clearing of native vegetation. In some areas, the recharge values can be reduced to almost zero, even under dryland agriculture, if the future climate becomes very dry.

The Gnangara Mound is an area of elevated sandy soil on the Swan Coastal Plain to the north of Perth. It constitutes a major groundwater resource for metropolitan Perth. Sixteen wetlands on the Mound had total phosphorus concentrations of 12-462�g L-1, the high values being attributed to agricultural and urban activity. Sediment concentrations of total phosphorus and total nitrogen were 61-954 and 1212-16739 �g g-1, respectively. Conductivities were 505-10270 �S cm-1, and pH values were 3.3-9.3. Only one wetland was highly coloured (79.9 8440 m-1), with an E4/E6 ratio of 4.6. Chlorophyll a concentrations were 0.01-130.8�g L-1; in wetlands with low gilvin concentrations, Myxophyceae dominated, whereas wetlands with higher gilvin concentrations had large numbers of diatoms and Chlorophyceae. The highly coloured wetland had the lowest chlorophyll a concentration despite high nutrient concentrations, supporting the hypothesis that the consequent reduction in light or other associated factors are important in maintaining low phytoplankton biomass in dystrophic wetlands of the region, particularly those on Bassendean sands.

The objective of this work was to study the degradation kinetics of a nitrification inhibitor (NI), dicyandiamide (DCD), and evaluate its effectiveness in reducing nitrous oxide (N2O) emissions in different types of soils. Three soils contrasting in texture, mineralogy, and organic carbon (C) content were incubated alone (control) or with urine at 600 mg N/kg soil with 3 levels of DCD (0, 10, and 20 mg/kg). Emissions of N2O and carbon dioxide (CO2) were measured during the 58-day incubation. Simultaneously, subsamples were collected periodically from the incubating soils (40-day incubation) and the amounts of DCD, NH4+, and NO3− were determined. Our results showed that the half-life of DCD in these laboratory incubating soils at 25°C was 6–15 days and was longer at the higher rate of DCD application. Of the 3 soils studied, DCD degradation was fastest in the brown loam allophanic soil (Typic orthic allophanic) and slowest in the silt loam non-allophanic soil (Argillic-fragic Perch-gley Pallic). The differences in DCD degradation among these soils can be attributed to the differences in the adsorption of DCD and in the microbial activities of the soils. Among the 3 soils the highest reduction in N2O emissions with DCD from the urine application was measured in the non-allophanic silt loam soil followed by non-allophanic sandy loam soil and allophanic brown loam soil. There was no adverse impact of DCD application on soil respiratory activity or microbial biomass.

Many sandy soils of the Swan Coastal Plain, Western Australia, are poor in Fe and P retention. A novel concept proposes to relocate Fe from groundwater to surface soils via watering, which should consequently improve P retention. To test the viability of this concept we examined several soils in Perth suburbs that had been watered for 3–27 years with groundwater containing high Fe. Energy dispersive X-ray microanalysis indicated that ‘Fe-watered’ soils had significantly higher Fe materials on the surface of soil particles. Oxalate-extractable Fe (Feo) increased by 52 times and citrate/dithionite-extractable Fe (Fed) increased by 6.6 times. Unusually high Feo/d ratios (average Feo/d = 0.71) in ‘Fe-watered’ soils strongly suggest that the accumulated Fe materials are predominantly amorphous and secondary Fe oxides, probably ferrihydrite. There was a substantial increase in P retention in top-soils, to a magnitude of 45–128 times, demonstrating that increasing Fe oxides in severely leached soils, caused by groundwater irrigation, increases P retention. This approach could be applied to other areas with similar physical characteristics and the present study demonstrates that watering with Fe rich groundwater might have strategic significance not only in the control of water pollution, but also in the rational use of water resources and the amelioration of soil salinisation associated with rising watertables.

Fibres are mixed with soils to enhance their strength and hydraulic characteristics. Fibre-mixed soils are often known as the fibre-reinforced soils. In the past, both systematically and randomly reinforced soils have been used widely in civil and geotechnical structures. Randomly reinforced-soils using fibres exhibit advantages over systematically reinforced-soils because systematic reinforcements may result in weak planes within the soil mass. Randomly distributed reinforcements are also easier to apply and maintain for some applications. Previous researchers have studied the strength, compaction and compressibility behaviour of fibre-reinforced soil. Study on characteristics of fibre-reinforced soils when saturated, however, is limited to piping resistance improvement. One of the main reasons for collapse of some of the hydraulic structures is soil piping that takes place on the downstream side as a result of upward seepage. Fibre-reinforced soils can be a solution in sustainable watershed management as they can be used in irrigation and drainage projects, such as river levees, contour bunds, temporary canal diversion works, temporary check dams, soil structures, stream restoration, etc., for seepage and permeability control. This study focuses on permeability characteristics of fibre-reinforced soil. Permeability characteristics can vary depending on soil, fibre and methods used. Materials used in this study are Perth sandy soil, and locally available jute and waste tyre fibres. These materials were chosen because they are abundantly available in Perth area and surroundings. As for the waste tyre fibre, it was also chosen as a green approach to use waste materials in structures and solve their disposal problems. Fibre content varied from 0 to 10% with 1% intervals for tyre fibres and from 0 to 1.5% with 0.25% intervals for jute fibres. Fibre length varied from 5 to 25 mm with 5 mm intervals for jute fibres. Fibre length was constant in all experiments for tyre fibres as they come in a mixture of different lengths and studying the effect of length of permeability characteristics was not possible. Experimental tests were conducted on fibre-reinforced specimens in a constant-head permeameter. Experimental results suggest that the coefficient of permeability increases with an increase in fibre content for both fibre types (up to 100% for jute fibres and up to about 40% for tyre fibres). Also, it is observed that the coefficient of permeability increases with an increase in fibre length for jute fibres, as a general trend. As expected, water content increases and dry and saturated unit weights decrease with inclusion of higher fibre contents and longer fibres as a general trend. Fibre-reinforced soil specimens and the water discharge were modelled numerically using the commercial software SEEP/W in order to study the effects of fibre inclusion on permeability characteristics. The findings from the developed numerical model agree well with the experimental observations.

Perth’s Swan Coastal Sand Plain soils are typically nutrient impoverished, and the native trees of the region are therefore adapted to maximise nutrient uptake. Although the dune systems here are generally not known to be particularly saline or alkaline, there are areas that susceptible to salinity, flooded and elevated pH, especially those that have been modified by human activities. This study investigated the seedlings growth of three Eucalyptus species (Corymbia calophylla, Eucalyptus gomphocephala and E. marginata) to three environmental stress; salinity waterlogging and alkalinity in a greenhouse at Curtin University to assess their relative tolerance to these stressors, and hence understand more about their potential use in landscape restoration and rehabilitation. Knowing the seedling growth and physiological responses of three prominent Perth eucalypts to soil-induced stresses provides us with invaluable knowledge for rehabilitating and restoring Perth’s urban bushland.For the salt tolerance experiment, seedlings of the three species were subjected to 81 days growing in potting mix watered weekly with either 0, 50, 100, 150, 250 mM NaCl solutions. Measurements of relative plant growth, biomass allocation and leaf water loss and seedling survival suggested that E. gomphocephala was the most tolerant. Survival data suggests that E. gomphocephala seedlings have shown ability to cope with a weekly dosage of NaCl solution much greater than 0.25 M, and at least survived for more than 11 weeks under moderately saline conditions. Corymbia calophylla, and E. marginata were the least tolerance with more than half the seedlings succumbing to salt solutions > 250 mM NaCl.A flooding experiment, caused by prolonged inundation of water, lasting for 70 days, all three species grew most vigorously in well watered condition but when waterlogged condition E. gomphocephala and E. marginata seedlings grew slowly and became more water stressed compared to C. calophylla seedlings. These finding suggest that although E. gomphocephala and E. marginata can occurs in wetter areas of Perth’s Swan Coastal Plain they are not flood tolerant. C. calophylla is a common tree species in the moderately wet lower south-west of Western Australia; it is less common north of Perth where it is restricted to river valleys (Powell 2009). This may explain Marri’s ability to physiologically tolerate seasonal flooding (i.e. no significant reduction in stomatal conductance or transpiration rate), despite a reduction in seedling growth.A liming experiment, was conducted with 20% w/w crushed and sifted Tomala limestone add to potting mix to increase soil pH. The pot trial was conducted over 82 days. E. gomphocephala is restricted soils overlying limestone on Perth’s Swan Coastal Plain, and according to total seedling dry weight data and calculated relative growth rates coped best in a limestone-enriched soil. However, when examining all the growth and physiological data collected C. calophylla appears to be the most tolerant, with no significant difference in leaf allocation or leaf water loss between the well-watered controls and the limestone-enriched treatments. E. marginata was the least tolerant with a 14% reduction in stomatal conductance.As seedlings, E. marginata was the least tolerant to the three soil-induced stresses (i.e. flooding, salinity, alkalinity) imposed. The next most tolerant species, E. gomphocephala wasn’t the most tolerant to an increase is soil alkalinity, although it displayed the least change in seedling dry weight and relative growth rate. C. calophylla was the most tolerant of the three eucalypts to the three stressors. However soil-induced stresses will last for longer than the 70-80 days when plants are growing in more natural environments than the seedlings were exposed to in these experiments. By itself, these results will assist Perth’s urban land managers in understanding how these tree species respond at the seedling stage to three important soil-induced stressors, more work is required to understand how the observed responses after seedling physiology and how long the seedlings can tolerate these extreme changes in their growing environment.

Weak and unsuitable soil conditions have always caused problems for civil engineers during the construction of structures. To avoid problems in a cost-effective manner, proper and reliable solutions need to be developed. Fibre reinforcement and cement stabilisation are the most efficient and common methods in geotechnical engineering applications when engineers have problematic soil conditions. These methods can be used in different applications, such as pavement layers, retaining walls and slopes. Over the past three decades, many studies have been done to investigate the effects of adding synthetic and natural fibres to soil as the reinforcing material alone or with cement. The present work focuses on investigating the characteristics of local Perth sandy soil after inclusion of waste tyre fibres and cement. These wastes can be utilised in ground improvement projects in large quantities and could provide a cost-effective and environmentally friendly strategy that avoids tyre disposal problems. Fibres for reinforcement applications in soils are available in different types in terms of materials and their geometrical configurations. Using waste materials, which are present nowadays in large quantities and in different forms, such as used tyres and carpets, as reinforcing materials can be environmentally and economically beneficial. In the past, waste tyres have been used in some geotechnical applications, such as highway construction, retaining wall backfill and drainage layers for roads, but the efforts seem to be insufficient. Although much research has been conducted on cement stabilisation, but on fibre reinforcement, and their combination, no comprehensive research has been done to investigate the UCS and CBR behaviour of sandy soils mixed with cement and tyre fibres, especially on the sandy soils available in Perth and its surrounding areas. A series of laboratory tests including compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were conducted to investigate the effects of adding tyre fibre and cement on the engineering behaviour of Perth sandy soil. The contents were varied from 0 to 5% of dried soil by weight for cement and 1% of dried soil by weight for tyre fibres. The cemented specimens were cured in for 3, 7, 14, and 28 days. This study aims at investigating the effect of different parameters, including cement content, tyre fibre content, curing time and confining pressure on the CBR behaviour of Perth sandy soils. Feasible, ecologically friendly, and economically reasonable solutions, both theoretically and practically, are studied in this research so that geotechnical/civil engineers can effectively use them in the construction projects. The compaction test results indicate that the maximum dry unit weight generally increases by adding cement and decreases by tyre fibres inclusion, while adding cement and tyre fibre results in a lower optimum water content. For the fibre-reinforced and unreinforced materials, the compressive strength increases with an increase in the cement content. Adding 1% of tyre fibres to mixtures increases the UCS of the soil approximately by 10-70%. The results also show that as the curing time increases, the UCS increases, and the effect of curing is more pronounced for higher stabiliser contents.

Abstract OTC-28901-MS proposed the novel dynamically installed "fish" anchor in 2018, adopting a geometry taken from nature, for potential economic and safer tethering of floating facilities in deep water. Every cross section of the fish anchor shaft is elliptical, leading to very low drag resistance during free fall through the water column, and also low resistance in penetrating the seabed sediments. The padeye is fitted on the widest part of the shaft to mobilise the maximum resistance area under operational loading. The fish anchor embedment depth during dynamic installation, and capacity under both monotonic and cyclic operational loading in calcareous silt were assessed through centrifuge model tests and large deformation finite element analyses. During dynamic installation, the normalised tip embedment depth of the fish anchor was typically three times that for the torpedo anchors and 50% greater than that for the OMNI-Max anchors. Under operational loading, the fish anchor dove deeper, reaching penetrations 20 to 60% greater than achieved during installation. By contrast the torpedo anchors (for all mooring mudline inclinations) and the OMNI-Max anchors (apart from a single test with mooring mudline inclination of 0°) pulled out directly without diving, reflecting insufficient free-fall penetration in calcareous soil. This paper provides a follow up reporting the performance of the fish anchor through field tests in the Swan River, Perth. A 1/15th scale model fish anchor was fabricated with dry weight being 0.304 kN. The anchor was tested at five different locations. At two shallow water locations (water depths 1.1 and 1.9 m, respectively), the tests were performed from the Burswood and Maylands jetty. At relatively deeper water depths of 2.91∼4.73 m, the tests were performed from a barge. The riverbed soils consisted of clay, silty clay, silt and sandy silt. The impact velocities were 5.9∼11.7 m/s. The normalised tip embedment depths were even greater compared to those achieved from centrifuge tests in calcareous silt. Under operational monotonic loadings, the fish anchor dove, as opposed to pull out of the riverbed, for mooring angles ≤ 37∼47°. Interestingly, in contrast to non-diving torpedo and suction caisson anchors, the diving fish anchor resulted non-elliptical failure envelopes, which have been expressed mathematically. The ultimate capacity was 3.5∼15 times the weight of the anchor submerged in water for taught and catenary moorings.