Relationships between fabric, water retention, and strength of hard subsoils in the south of Western Australia

Soil Research ◽  
2010 ◽  
Vol 48 (2) ◽  
pp. 167 ◽  
Author(s):  
G. A. Kew ◽  
R. J. Gilkes ◽  
D. Evans
Keyword(s):  
Western Australia ◽  
Water Retention ◽  
Sandy Soils ◽  
Matric Potential ◽  
Clay Matrix ◽  
Plant Available Water ◽  
Western Australian ◽  
Quartz Grains ◽  
In Situ Weathering

Crop yield in the sandy soils of the Western Australian wheatbelt is influenced strongly by the plant-available water (PAW) and strength of subsoils. The fabric of hard subsoils of fluvial and aeolian origin has been compared with that of in situ saprolite materials that also occur as subsoils in Western Australia. A fabric classification was developed and relationships between, fabric, water retention, and strength were examined. The clay matrix of hard subsoils is denser and is less porous than in saprolite. Hard subsoils contain rounded quartz grains and transported, rounded aggregates of clay (spherites), while saprolite contains angular quartz grains in a more porous isotropic kaolin clay matrix developed by in situ weathering. At all matric potentials there were large differences in water retention between hard subsoils and saprolite. The dry and wet strengths of subsoils are lower than for saprolite but the strength of both materials is similarly affected by changes in water content and matric potential. A variety of factors including the size, shape, degree of sorting of quartz grains, distribution of dense clay matrix, and cementing by iron oxides or amorphous silica affect the strength of subsoils. The fabric classification is predictive of water retention and strength.

scholarly journals A Novel Frequency Domain Impedance Sensor with a Perforated Cylinder Coaxial Design for In-Situ Measuring Soil Matric Potential

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2626 ◽  
Author(s):  
Chao Chen ◽  
Xiaofei Yan ◽  
Qiang Xu ◽  
Song Yu ◽  
Yihan Ma ◽  
...  
Keyword(s):  
Water Content ◽  
Water Retention ◽  
Soil Samples ◽  
Environmental Research ◽  
Water Retention Curve ◽  
The Novel ◽  
Soil Matric Potential ◽  
Matric Potential ◽  
Retention Curve

Soil matric potential is an important parameter for agricultural and environmental research and applications. In this study, we developed a novel sensor to determine fast and in-situ the soil matric potential. The probe of the soil matric potential sensor comprises a perforated coaxial stainless steel cylinder filled with a porous material (gypsum). With a pre-determined gypsum water retention curve, the probe can determine the gypsum matric potential through measuring its water content. The matric potential of soil surrounding the probe is inferred by the reading of the sensor after the soil reaches a hydraulic equilibrium with the gypsum. The sensor was calibrated by determining the gypsum water retention curve using a pressure plate method and tested in three soil samples with different textures. The results showed that the novel sensor can determine the water retention curves of the three soil samples from saturated to dry when combined with a soil water content sensor. The novel sensor can respond fast to the changes of the soil matric potential due to its small volume. Future research could explore the application for agriculture field crop irrigation.

A mathematical model for variation in water-retention curves among sandy soils

2007 ◽  
Vol 19 (4) ◽  
pp. 427-436 ◽  
Author(s):  
H.W. Hunt ◽  
A.M. Treonis ◽  
D.H. Wall ◽  
R.A. Virginia
Keyword(s):  
Particle Size ◽  
Water Content ◽  
Bulk Density ◽  
Water Retention ◽  
Organic Matter Content ◽  
Sandy Soils ◽  
Sand Particle ◽  
Model Parameters ◽  
Calibration Data ◽  
Matric Potential

AbstractEquations were developed to predict soil matric potential as a function of soil water content, texture and bulk density in sandy soils. The equations were based on the additivity hypothesis - that water-retention of a whole soil depends on the proportions of several particle size fractions, each with fixed water-retention characteristics. The new model is an advancement over previously published models in that it embodies three basic properties of water-retention curves: a) matric potential is zero at saturation water content, b) matric potential approaches -∞ as water content approaches zero, and c) volumetric water content in dry soil is proportional to bulk density. Values of model parameters were taken from the literature, or estimated by fitting model predictions to data for sandy soils with low organic matter content. Most of the variation in water-release curves in the calibration data was explained by texture, with negligible effects of bulk density and sand particle size. The model predicted that variation in clay content among soils within the sand and loamy sand textural classes had substantial effects on water-retention curves. An understanding of how variation in texture among sandy soils contributes to matric potential is necessary for interpreting biological activity in arid environments.

The Wiluna Meteorite fall, Western Australia—2 September 1967

1970 ◽  
Vol 37 (292) ◽  
pp. 880-887 ◽  
Author(s):  
G. J. H. McCall ◽  
P. M. Jeffery
Keyword(s):  
Western Australia ◽  
British Museum ◽  
Field Investigation ◽  
Reasonable Estimate ◽  
Total Recovery ◽  
Nickel Iron ◽  
Australian Museum ◽  
Meteorite Fall ◽  
Western Australian

SummaryThe fall of a shower of meteorites numbering several hundred fragments at Wiluna, Western Australia, on the night of 2 September 1967, has been investigated. Although the dispersion ellipse had been largely obscured by removal of fragments before a party of scientists were able to make a field investigation, it has, nevertheless, been possible to make a reasonable estimate of the shower distribution pattern. In spite of this removal of fragments, a number of pieces of meteorite were still found in situ. The bulk of the total recovery is in the collections of the Western Australian Museum, and the physical characteristics of these masses and their petrography is described. In all, some 490 individual fusion-crust coated stones and a large number of broken stony fragments are known to have been recovered. The meteorite is an olivine bronzite chondrite remarkably rich in discrete nodules of nickel iron, up to an inch across, commonly aggregated with troilite. A full chemical analysis of this fresh meteoritic material has been supplied by the British Museum (Natural History).

Detailed characterization of quartz grains in two sandy soils, Western Australia

Geoderma ◽  
1987 ◽  
Vol 41 (1-2) ◽  
pp. 29-47 ◽  
Author(s):  
K. Asumadu ◽  
R.J. Gilkes ◽  
H.M. Churchward ◽  
T.M. Armitage
Keyword(s):  
Western Australia ◽  
Sandy Soils ◽  
Detailed Characterization ◽  
Quartz Grains

Refugia within refugia: in situ speciation and conservation of threatened Bertmainius (Araneae : Migidae), a new genus of relictual trapdoor spiders endemic to the mesic zone of south-western Australia

2015 ◽  
Vol 29 (6) ◽  
pp. 511 ◽  
Author(s):  
Mark S. Harvey ◽  
Barbara York Main ◽  
Michael G. Rix ◽  
Steven J. B. Cooper
Keyword(s):  
Western Australia ◽  
New Genus ◽  
South Australia ◽  
Fire Regimes ◽  
Morphological Criteria ◽  
The Subject ◽  
Refugia Within Refugia ◽  
Western Australian

The trapdoor spider family Migidae has a classical Gondwanan distribution and is found on all southern continents except the Indian region. The Australian fauna consists of three genera including Moggridgea O. P. Cambridge from south-western Australia and Kangaroo Island, South Australia; Moggridgea is otherwise widespread throughout Africa. The sole named species of Moggridgea from Western Australia, M. tingle Main, and its unnamed relatives are the subject of the present paper, which was stimulated by concern for the long-term persistence of populations, and the discovery of deep genetic divergences between populations. A phylogeny of the Western Australian species relative to African and South Australian Moggridgea was generated using molecular COI and ITS rDNA data, and based on both molecular and morphological criteria we conclude that the Western Australian taxa should be removed from Moggridgea and transferred to a new genus, Bertmainius. The seven species are delimited using both morphological and molecular criteria: B. tingle (Main) (the type species), and six new species, B. colonus, B. monachus, B. mysticus, B. opimus, B. pandus and B. tumidus. All seven species are considered to be threatened using IUCN criteria, with the major threatening processes being inappropriate fire regimes and climate change.

The absence of leaching of molybdenum in acidic soils from Western Australia

Soil Research ◽  
1987 ◽  
Vol 25 (2) ◽  
pp. 179 ◽  
Author(s):  
MM Riley ◽  
AD Robson ◽  
JW Gartrell ◽  
RC Jeffery
Keyword(s):  
Western Australia ◽  
Sodium Molybdate ◽  
Sandy Soils ◽  
Acidic Soils ◽  
Glasshouse Experiment ◽  
Western Australian

A glasshouse experiment was conducted to estimate the extent of leaching of molybdenum on acidic sandy soils from Western Australia. Sodium molybdate, at a rate equivalent to 40 g of molybdenum per hectare, was added to pots of soil either before or after leaching a column of the soil with the equivalent of 500 mm water. Molybdenum concentrations were determined in the leachate and in the wheat plants grown on the soils in pots after leaching. Approximately 10% of added molybdenum was removed with leaching from two grey sands, while negligible quantities were removed from three more acidic sandy soils. Leaching does not appear to be an important factor in the occurrence and recurrence of molybdenum deficiency on the yellow-brown acidic sandplain soils of the Western Australian wheatbelt.

IN SITU SOIL FLUSHING - STUDIES ON REMEDIATION EFFICIENCY OF POLLUTED SANDY SOILS WITH ORGANIC ACIDS

2012 ◽  
Vol 11 (12) ◽  
pp. 2163-2168
Author(s):  
Alexandra-Dana Chitimus ◽  
Valentin Nedeff ◽  
Emilian Florin Mosnegutu ◽  
Mirela Panainte
Keyword(s):  
Organic Acids ◽  
Sandy Soils ◽  
Soil Flushing ◽  
Remediation Efficiency

Factors that contribute to urban–rural gradients in risk of schizophrenia: Comparing Danish and Western Australian registers

2021 ◽  
pp. 000486742110096
Author(s):  
Oleguer Plana-Ripoll ◽  
Patsy Di Prinzio ◽  
John J McGrath ◽  
Preben B Mortensen ◽  
Vera A Morgan
Keyword(s):  
Confidence Interval ◽  
Western Australia ◽  
Urban Areas ◽  
Proportional Hazards ◽  
Cox Proportional Hazards ◽  
Hazard Ratio ◽  
Indigenous Status ◽  
Increased Risk ◽  
The Relationship ◽  
Western Australian

Introduction: An association between schizophrenia and urbanicity has long been observed, with studies in many countries, including several from Denmark, reporting that individuals born/raised in densely populated urban settings have an increased risk of developing schizophrenia compared to those born/raised in rural settings. However, these findings have not been replicated in all studies. In particular, a Western Australian study showed a gradient in the opposite direction which disappeared after adjustment for covariates. Given the different findings for Denmark and Western Australia, our aim was to investigate the relationship between schizophrenia and urbanicity in these two regions to determine which factors may be influencing the relationship. Methods: We used population-based cohorts of children born alive between 1980 and 2001 in Western Australia ( N = 428,784) and Denmark ( N = 1,357,874). Children were categorised according to the level of urbanicity of their mother’s residence at time of birth and followed-up through to 30 June 2015. Linkage to State-based registers provided information on schizophrenia diagnosis and a range of covariates. Rates of being diagnosed with schizophrenia for each category of urbanicity were estimated using Cox proportional hazards models adjusted for covariates. Results: During follow-up, 1618 (0.4%) children in Western Australia and 11,875 (0.9%) children in Denmark were diagnosed with schizophrenia. In Western Australia, those born in the most remote areas did not experience lower rates of schizophrenia than those born in the most urban areas (hazard ratio = 1.02 [95% confidence interval: 0.81, 1.29]), unlike their Danish counterparts (hazard ratio = 0.62 [95% confidence interval: 0.58, 0.66]). However, when the Western Australian cohort was restricted to children of non-Aboriginal Indigenous status, results were consistent with Danish findings (hazard ratio = 0.46 [95% confidence interval: 0.29, 0.72]). Discussion: Our study highlights the potential for disadvantaged subgroups to mask the contribution of urban-related risk factors to risk of schizophrenia and the importance of stratified analysis in such cases.

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