Surface structure in gray clays of northwestern New South Wales in relation to micromorphology, cation suite and particle size attributes

Soil Research ◽  
1992 ◽  
Vol 30 (1) ◽  
pp. 1 ◽  
Author(s):  
IP Little ◽  
AJ Ringrose-Voase ◽  
WT Ward
Keyword(s):  
Particle Size ◽  
Surface Structure ◽  
New South ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Structural Behaviour ◽  
South Wales ◽  
Field Assessment ◽  
Structured Soils ◽  
Textural Attributes

Considerable differences in surface structure (0-100 mm) were observed in the field in two adjacent areas of grey clays near Narrabri, N.S.W. The absence of any differences in clay mineralogy and granulometry of the sand fraction supported the field assessment that both types of soil were similar in provenance. A transect of soil profiles including seven with poor structure and five with well-structured surface horizons was examined. The field observations of structure were supported by photographs of the surface, and water entry after rain. Micromorphological examination showed that closely spaced porphyric to adporphyric fabric in the poorly structured soils contributed to poor structure, highlighting the importance of textural attributes. The well-structured soils had a more widely spaced porphyric fabric. A measure of dispersibility depending on clay content and exchangeable plus soluble Na, Ca and Mg tallied very well with the field assessment of soil structure. Five groups were obtained from a euclidean distance/flexible sort strategy on the basis of cation suite, carbon content and particle size attributes. The groups identified areas of poor structure very well and the groups appear to be discriminated mainly on the basis of differences in Na, Ca and clay content. Treating the transect as a continuum of soils of very poor structure at site 1 grading to very good at site 12 showed that greater values for Ca, K, and clay were associated with good structure and greater values for Mg, C and silt were associated with poor structure. The sodium adsorption ratio and ionic strength of the soil solution were not on their own good predictors of structural behaviour possibly due to the independent contribution of Ca and Mg in this respect.

Use of products of straw decomposition by N2-fixing (C2H2-reducing) populations of bacteria in three soils from wheat-growing areas

1986 ◽  
Vol 37 (1) ◽  
pp. 1 ◽  
Author(s):  
MM Roper ◽  
DM Halsall
Keyword(s):  
Nitrogenase Activity ◽  
New South ◽  
Carbon Sources ◽  
Clay Content ◽  
Free Living ◽  
Straw Decomposition ◽  
South Wales ◽  
History Of ◽  
Straw Incorporation ◽  
The Difference

The potential for N2 fixation by free-living bacteria using straw as a source of energy was evaluated in three soils (one from Gunnedah and two from Cowra) representative of the wheat belt in New South Wales. All three soils had a history of straw incorporation. The abilities of the respective microbial populations to use a range of carbon sources, including potential products of decomposition of straw, was determined and compared with the size and composition of each population. Neutral to alkaline (pH 7.4) soil of high (51%) clay content from Gunnedah produced higher rates of nitrogenase activity with straw than more acid (pH 5.6) lower (17%) clay containing soil from Cowra (site B). Gunnedah soil also contained a larger population of N2-fixing bacteria which used a broader range of energy sources than soil from either Cowra site B or Cowra site W (pH 5.8, clay content 34%). There was little difference in the composition of the N2-fixing populations in each of the soils except that Azotobacter spp. were absent from the acid Cowra soils. It was concluded that the difference in behaviour of the respective N2-fixing populations was primarily due to the physical characteristics of the soil affecting the numbers and activities of diazotrophic microorganisms. In addition some soil environments failed to support specific organisms.

An aeolian component in Pleistocene and Holocene valley aggradation: evidence from Dicks Creek catchment, Yass, New South Wales

Soil Research ◽  
2001 ◽  
Vol 39 (1) ◽  
pp. 13 ◽  
Author(s):  
M. I. Melis ◽  
R. I. Acworth
Keyword(s):  
Late Quaternary ◽  
New South ◽  
New South Wales ◽  
Clay Mineralogy ◽  
Ice Age ◽  
Rill Erosion ◽  
Radiocarbon Dates ◽  
South Wales ◽  
Development Unit ◽  
Unit Unit

Four late Quaternary depositional units are identified overlying sub-vertically dipping Ordovician bedrock in the upper reaches of the Dicks Creek catchment, near Yass in the Southern Highlands of New South Wales. The units are spatially discontinuous and separated from each other by erosional unconformities. They are found only on the lower slopes and in the valley floors, often exposed by recent gully erosion. The oldest unit (Unit 4) is a competent consolidated well-sorted fine to medium silt that unconformably overlies bedrock. It often forms the base to erosion gullies. Unit 3 is strongly dispersible and frequently has the characteristics of a debris flow. Unit 3 is particularly prone to sheet erosion and exhibits a high risk of dryland salinity development. Unit 2 is light to dark grey, poorly sorted, and often contains irregularly dispersed charcoal. Unit 2 is unconformably overlain by a predominantly pale yellow sand (Unit 1) that shows clear evidence of very recent deposition. Physical and chemical characteristics of Units 2, 3, and 4 suggest an aeolian component. The silt size (4–8 on phi scale) fraction of Unit 4 is often >70% of the total mass, with grain sizes consistent with an origin as aeolian dust. Unit 3 is yellow brown in colour and often has the characteristics of a diamict with a major grain size component similar in size to Unit 4. Unit 2 is typically uniform in appearance and contains a predominantly kaolinite and illite clay mineralogy that contrasts strongly with a predominance of quartz in the underlying bedrock. A simple sediment budget indicates that the volume of Unit 2 could be accounted for by a combination of sheet and rill erosion within the catchment and additional aeolian deposition in the order of 4–8 t/km 2 year. Radiocarbon dates for charcoal recovered from Unit 2 indicate that some deposition was associated with cooler, drier conditions of the late Holocene ‘Little Ice Age’, approximately 200–600 years ago.

The nature, distribution and management of sodic soils in New-South-Wales

Soil Research ◽  
1993 ◽  
Vol 31 (6) ◽  
pp. 839 ◽  
Author(s):  
DC Mckenzie ◽  
TS Abbott ◽  
KY Chan ◽  
PG Slavich ◽  
DJM Hall
Keyword(s):  
New South ◽  
New South Wales ◽  
Clay Mineralogy ◽  
Carbonate Content ◽  
Chemical Compositions ◽  
Sodic Soils ◽  
Sodic Soil ◽  
Related Factors ◽  
South Wales ◽  
Murray Darling Basin

Accurate data on the distribution of the various types of sodic soils in New South Wales are not available. However, general observations suggest that large areas are affected by structural instability as a result of sodicity, particularly on grey clays and red-brown earths of the Murray-Darling Basin. There is a strong need for new sodicity surveys because the production of crops and pasture often is well below potential on these lands. Exchangeable sodium data on their own do not adequately describe sodic soil behaviour, so information is also required about related factors such as electrical conductivity, exchangeable magnesium, clay mineralogy, pH, calcium carbonate content, degree of remoulding, and the frequency of continuous stable macropores. Critical limits for sodicity that are used by soil management advisory services need to be redefined. Considerable research into the reclamation and management of sodic soils has occurred in the irrigation areas and rainfed cropping districts of the Murray-Darling Basin in New South Wales. Mined and by-product gypsum, and to a lesser extent lime, have been shown to greatly improve the physical condition and profitability of production from soils with a dispersive surface. However, the responses to these treatments are less likely to be economical when sodicity is confined to the subsoil. Adequate supplies of gypsum and lime are available in New South Wales, but further research is required to determine economically optimal and environmentally acceptable rates and frequencies of application, particle sizes and chemical compositions for different farming systems that utilize the various types of sodic soil.

Body lengths and maximum gut food-particle sizes of the dominant cladocerans and calanoid copepods in Wallerawang Reservoir, New South Wales

1991 ◽  
Vol 42 (4) ◽  
pp. 399 ◽  
Author(s):  
T Kobayashi
Keyword(s):  
Particle Size ◽  
Competitive Ability ◽  
New South ◽  
Particle Sizes ◽  
Calanoid Copepods ◽  
Food Particle ◽  
South Wales ◽  
Cladoceran Species ◽  
Body Sizes ◽  
Food Particles

Body length influences the maximum gut food-particle size of the dominant cladocerans and calanoid copepods in Wallerawang Reservoir. For the Wallerawang cladocerans, a linear regression equation, similar to the Northern Hemisphere equivalent, relates food-particle and body sizes. The larger cladoceran species ingest larger food particles than do the smaller species they displace, thus seemingly supporting the size-efficiency hypothesis. On the other hand, the competitive ability of the Wallerawang calanoid copepods cannot be explained simply by the observed differences in the upper food-particle size limit of these species.

The pedogenesis of desert loam soils in the Barrier Range, western New South Wales. I. Soil parent materials

Soil Research ◽  
1982 ◽  
Vol 20 (4) ◽  
pp. 269 ◽  
Author(s):  
C.J. Chartres
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Saline Lake ◽  
New South ◽  
Morphological Properties ◽  
Parent Materials ◽  
Rock Types ◽  
Aeolian Deposits ◽  
South Wales ◽  
Mineral Assemblages

The particle-size distribution, silt (63-20 �m) mineralogy and micro-morphological properties of three desert loam soils developed over contrasting rock types are examined. The silt mineral assemblages in the soils contain more weatherable minerals and are more varied than those of the underlying rocks. Round to subround clayey pellets constitute the majority of the soil materials. Such pellets are probably aeolian in origin and are similar to clayey pellets originating in dried-out, saline lake beds elsewhere in southern Australia. The combination of aeolian silts and clays in the desert loam soils indicate that the soil parent materials are primarily transported aeolian deposits.

Subplasticity in Australian soils. IV. Plasticity and structure related to clay cementation

Soil Research ◽  
1976 ◽  
Vol 14 (3) ◽  
pp. 261 ◽  
Author(s):  
AV Blackmore
Keyword(s):  
New South ◽  
Pore Space ◽  
Clay Content ◽  
Clay Particles ◽  
Highly Active ◽  
South Wales ◽  
Degree Of Orientation ◽  
The Individual ◽  
High Degree ◽  
Stability Of Structure

Subplastic behaviour apparently arises from some form of cementation between clay particles and between groups of particles. Five red-brown earth subsoils from the Riverina area of New South Wales, with subplasticity ratings from SP0 to SPIII+, have been examined here in order to relate plasticity, and other physical properties which reflect structure and stability of structure, to an appropriate laboratory measure, or index, of cementation. The soils were so chosen as to minimize the number of other properties that vary among them. The properties and indexing of the soils in the laboratory show broad consistence with their range of subplasticity as described in the field. When it has been released from cementation, the clay in the more subplastic soils is highly active, having properties similar to those of a montmorillonite with calcium and sodium on the exchange surface. The structure and the high total clay content of the subplastics require a high degree of orientation of individual clay particles into packets or domains. These packets are stabilized by cementation, largely at their edges, and at the same time attached to neighbouring non-parallel packets. Water readily reaches most of the pore space and the material, although very stable, continues to display some properties which are consistent only with a large content of clay particles. Consequently it seems likely that much of the planar surface of the individual clay particle is not contaminated with a cement.

The calibration, interpretation, and evaluation of tests for the phosphorus fertilizer requirements of wheat in Northern New South Wales

Soil Research ◽  
1968 ◽  
Vol 6 (1) ◽  
pp. 105 ◽  
Author(s):  
JD Colwell ◽  
RJ Esdaile
Keyword(s):  
Field Experiments ◽  
New South ◽  
General Procedure ◽  
New South Wales ◽  
Clay Content ◽  
Calibration Procedure ◽  
Yield Response ◽  
Phosphorus Fertilizer ◽  
South Wales ◽  
Soluble Phosphorus

A general procedure is described for the estimation of fertilizer requirements from measurements on all factors that affect plant response to fertilizer. Tests for fertilizer requirement are defined as all measurements of factors that affect the fertilizer requirements of a crop, and the calibration procedure is based on the prediction of yield response functions for particular sites from test measurements representing the sites. Several tests can be used simultaneously for the prediction of fertilizer requirements, and this is demonstrated by the calibration of the soil tests, NaHCO3-soluble phosphorus, NaHC03-soluble potassium, and pH, against yield response of wheat to phosphorus fertilizer using data from 49 field experiments in northern New South Wales. The value of rainfall and clay content as tests was also investigated but their contributions to the calibration equations were non-significant. The application of economic principles for the estimation of optimal phosphorus fertilizer requirements is demonstrated. Fertilizer requirements decrease with increase in the value of NaHCO3-soluble phosphorus, with increase in pH, and with decrease in NaHCO3-soluble potassium. A statistical and economic evaluation of the tests is made on the basis of the regression surfaces established under the calibration procedure, and it is concluded that the value of testing for phosphorus fertilizer requirements is considerable.

Irrigation increases groundwater recharge in the Macquarie Valley

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 837 ◽  
Author(s):  
TM Willis ◽  
AS Black
Keyword(s):  
New South ◽  
New South Wales ◽  
Clay Content ◽  
Soil Surface ◽  
Irrigated Agriculture ◽  
Deep Percolation ◽  
South Wales ◽  
Chloride Profiles ◽  
Groundwater Rise

Rising groundwater, and the potential for development of shallow watertables, were recognised in the Lower Macquarie Valley of New South Wales in the late 1980s. Irrigated agriculture was proposed as a possible source of the recharge causing the problem. This paper reports the increase in deep percolation rates resulting from cotton irrigation on 4 soils in the Lower Macquarie Valley, New South Wales. Changes in deep percolation rates were measured on these soils over the long-term, using temporally separated chloride profiles and mass balance modelling. These changes in long-term deep percolation rates were integrated over all years since irrigation commenced. Irrigation affected deep percolation on all soils, with an increase in long-term mean rates ranging from 17 to 202 mm/year. This equated to increased leaching rates ranging from 3 to 25%. Deep percolation appeared to be related to the clay content of the B horizon. The potential groundwater rise varied from 37 to 524 mm/year. The largest increases in deep percolation rates corresponded to sites where the watertable was closest to the soil surface. This suggests that the development of shallow watertables is related to recharge resulting from irrigated agriculture. Detailed studies of deep percolation under irrigated agriculture are required in the Macquarie Valley.

Photographic Utilisation Standards for Three Perennial Grasses.

1994 ◽  
Vol 16 (1) ◽  
pp. 135 ◽  
Author(s):  
VJ Anderson ◽  
RB Hacker ◽  
KC Hodgkinson
Keyword(s):  
New South ◽  
New South Wales ◽  
Perennial Grasses ◽  
South Wales ◽  
Field Assessment ◽  
North Western ◽  
Semi Arid

Height-weight profiles were established for Monachather paradoxa, Thyridolepis rnitchelliana and Eragrostis eriopoda based on field populations from semi-arid mulga woodlands in north-western New South Wales. These profiles were subsequently used to develop photographic standards of percentage canopy remaining by weight as a guide to field assessment of the severity of grazing. Examples of the standards are presented.

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