Dry saline land: an investigation using ground-based geophysics, soil survey and spatial

methods near Jamestown, South Australia

R.W. Fitzpatrick1,2,3, M. Thomas2,3, P.J. Davies1,2 and B.G. Williams4

1CSIRO Land & Water, PMB 2, Glen Osmond, SA 5064. 2Cooperative Research Centre for Landscape Environments and Mineral Exploration. 3University of Adelaide; PMB 2, Glen Osmond, SA 5064. 4171 Brigalow Street, Lyneham, ACT 2602. Technical Report 55/03 December 2003

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© 2003 CSIRO To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO Land and Water.

Important Disclaimer CSIRO Land and Water advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO Land and Water (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Citation Details Fitzpatrick, R.W., M. Thomas, P.J. Davies and B.G. Williams (2003). Dry saline land: an investigation using ground-based geophysics, soil survey and spatial methods near Jamestown, South Australia. Technical Report 55/03. CSIRO Land and Water, Adelaide, South Australia, Australia. Copies of this report available from Publications, CSIRO Land and Water, Private Bag 2 Glen Osmond, South Australia 5064. ISSN 1446-6163 On the web: http://www.clw.csiro.au/publications/technical2003/

Cover diagram Whole-of-landscape 3-D process model for Cootes case study area showing: (i) EM-38 map partly draped over the 3D-aerial photograph drape of study area with boundaries of landscape-soil units (LSU), (ii) photographs of representative soil profiles for each LSU, (iii) geology, (iv) cross-section of typical toposequence showing the main morphological, saline and sodic soil-regolith features/layers and (v) groundwater and fresh surface water flow paths. The EM-38 map designates high conductivity values in red (subsoil expressed dry saline land), medium values in yellow-turquoise and low values in dark blue.

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This report was produced for the South Australian Salinity Mapping and Management

Support Project (SASMMS) funded by the National Action Plan for Salinity and Water

Quality.

The National Action Plan for Salinity and Water quality is a joint initiative between the

State and Commonwealth Governments.

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TABLE OF CONTENTS Important Disclaimer.............................................................................................................................. i SUMMARY .............................................................................................................................................. 1 1. BACKGROUND AND REVIEW ..................................................................................................... 3

1.1 Objectives............................................................................................................................... 4 1.2 Work strategies ...................................................................................................................... 4 1.3 Dry saline land: a brief literature review................................................................................. 5 1.3.1 Dry saline land in root zones caused by slowly permeable subsoil layers ............................ 6 1.3.2 Dry saline land with subsoil expression ................................................................................. 7 1.3.3 Dry saline land with surface expression (magnesia patches)................................................ 7 1.3.4 Generalised best management practices for dry saline land................................................. 8

2. METHODS...................................................................................................................................... 9 2.1 Selection of representative study areas with dry saline land ........................................................ 9 2.2 Site description of Cootes case study area................................................................................... 9 2.3 Site description of Munduney case study area .......................................................................... 15 2.4 Electromagnetic induction principles.................................................................................... 17 2.4.1 EM-38 electromagnetic induction technique........................................................................ 17 2.4.2 EM-31 electromagnetic induction technique........................................................................ 18 2.5 Volume magnetic susceptibility technique ................................................................................. 18 2.6 Ground-based surveys using EM-38, EM-31 and VMS geophysical techniques........................ 20

3. RESULTS AND DISCUSSION..................................................................................................... 21 3.1 Soil and landscape data............................................................................................................. 21 3.1.1 Subsoil expressed dryland saline land: Cootes case study area ........................................... 21 3.1.2 Surface expressed dryland saline land: Munduney case study area .................................. 23 3.2 Geophysical data: EM-38, EM-31 and VMS .............................................................................. 24 3.2.1 Subsoil expressed dry saline land: Cootes case study area .................................................. 25 3.2.2 Surface expressed dryland saline land: Munduney case study area ..................................... 27 3.3 Integration of landscape-soil and geophysical data................................................................... 27 3.3.1 Whole-of-landscape 3-D process model for Cootes study area .......................................... 30 3.3.1.1 Construction of soil-landscape process model ..................................................................... 30 3.3.1.2 Application of the soil-landscape process model.................................................................. 31

4. CONCLUSIONS AND FURTHER WORK ....................................................................................... 35 5. ACKNOWLEDGMENTS .................................................................................................................. 37 6. REFERENCES................................................................................................................................. 38 APPENDIX 1: Mineralogical data ....................................................................................................... 40 APPENDIX 2: EM 38, EM-31 and Volume magnetic susceptibility data......................................... 41

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LIST OF FIGURES Figure 1. Locality of the Cootes and Munduney case study areas between Jamestown and Spalding,

South Australia. .......................................................................................................................... 3 Figure 2. Dry saline land or transient salinity (not hydrologically connected to a saline watertable);

primary salinity (caused by saline groundwater), salt bulges (below the root zone of former native vegetation) and secondary salinity (rising saline groundwater and salt accumulation due to evaporative water loss in saline seeps) (from Fitzpatrick et al., 2003). ................................. 6

Figure 3. Soil-regolith model showing salt transport and erosion processes leading to formation of subsoil and surface dry saline land (not associated with the saline groundwater tables). NOTE: A sodic duplex soil is used here as an example. These processes also do however occur in gradational soils or in soils with thin A horizons directly overlying saprolite (from Fitzpatrick et al., 2003). .............................................................................................................. 8

Figure 4a and b. Cootes study area’s regional context (a) and landscape location with toposequence A-B marked (b). Inset, photo of study area looking from A to B, which is similar to photograph of transect (A’-A”) shown Figure 5............................................................................................ 12

Figure 4c. Photograph of Cootes case study area, looking north east along selected transect from A to B, which is similar to aerial photograph showing transect (A’-A”) in Figure 5. ..................... 13

Figures 4d, e and f showing the “Freshwater Creek” deep (12m) erosion gully containing highly saline soils (edge of gully ECse 360 dS/m; bottom of gully ECse 4-140dS/m) in the Cootes study area................................................................................................................................................... 13

Figure 5. Upper: soil map boundaries with Soil Map Units (SMU A to F) overlying a hill shaded aerial photo of the Cootes study area highlighted in yellow box with toposequence/transect described in Figure 14 highlighted with a red line. Lower: Enlargement of Cootes study area showing: (i) localities of geophysical survey points at 20 m intervals along survey lines with 50 m spacing (black dots), (ii) localities of soil profile sample points with morphological descriptions (green squares) and (iii) localities of soil profile sample points with morphological descriptions, chemical and physical soil data (red circles)....................................................... 14

Figure 6. Photograph of (a) the Munduney study area north-west facing landscape with dry saline land and (b) geophysical survey lines. ..................................................................................... 15

Figure 7. Photograph of (a) surface expressed dry saline land in scalded area (i.e. magnesia patch typical of the area) and (b) exposed weathered shale coated with salt efflorescences and carbonate at the Munduney study area.................................................................................... 16

Figure 7. Photographs soil profiles with surface expressed dry saline land exposed in the drainage ditch in Munduney study area. ................................................................................................. 16

Figure 8. 3-D aerial photo drape of the Cootes study area with landscape soil unit boundaries, laboratory data and XRD sampling locations (a), (b) and (c) indicated. .................................. 22

Figure 9. Hill shaded regional context of Munduney and Cootes study areas showing (i) modelled drainage, (ii) land systems and soil landscape units (Soil and Land Information, 2002b) showing dry saline land magnesia patch mapping (red, 10-50% affected; pink, 2-10% affected; green, <2% affected), and (iii) hatched areas, showing pyritic and sulfidic geological units. .. 24

Figure 10. EM-38 (a) and EM-31 (b) and VMS (c) surveys over laid on a 3-D aerial photo drape of the study area and Landscape Soil Units (1-4). High response values are in red, medium values in yellow-turquoise, and low values in dark blue.......................................................................... 26

Figure 11. EM-38, EM-31 and VMS data for transect lines 1 (above) and 2 (below). .......................... 28 Figure 12. EM-31, EM-38 and VMS data for transect lines 3 (above) and 4 (below). ......................... 29 Figure 13. Plot of EM-38 versus VMS data for line 4 (see figure 12) of the Munduney site. ............... 30 Figure 14. Whole-of-landscape 3-D process model for Cootes case study area showing (i) 3D-aerial

photograph drape of study area with boundaries of landscape-soil units (LSU), (ii) photographs of representative soil profiles for each LSU, (iii) geology, (iv) cross-section of typical toposequence showing the main morphological, saline and sodic soil-regolith features/layers and (v) groundwater and fresh surface water flow paths. ............................... 34

Figure 15. Whole-of-landscape 3-D process model for Cootes case study area showing (i) EM-38 map partly draped over the 3D-aerial photograph drape of study area with boundaries of landscape-soil units (LSU), (ii) photographs of representative soil profiles for each LSU, (iii) geology, (iv) cross-section of typical toposequence showing the main morphological, saline and sodic soil-regolith features/layers and (v) groundwater and fresh surface water flow paths. The EM-38 map designates high conductivity values in red (subsoil expressed dry saline land), medium values in yellow-turquoise and low values in dark blue.................................... 35

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LIST OF TABLES Table 1. Categories of dry saline land soils, as defined by hydrology, landscape features and soil

chemistry (adapted from Fitzpatrick et al., 2003) ..................................................................... 10 Table 2. Generalised best management practices (BMPs) after drainage or disturbance for different

classes of dry saline land (from Fitzpatrick et al. 2003) ........................................................... 10 Table 3. The oxides, hydroxides and oxyhydroxides of iron (from Bigham et al. 2002) ...................... 19 Table 4. Particle size data and soil texture of shallow calcareous silty loam........................................ 23 Table 5. Electrical conductivity, pH, organic carbon, sulfur and carbonate carbon of shallow calcareous

silty loam................................................................................................................................... 23 Table 6. Exchangeable cations, cation exchange capacity and ESP of shallow calcareous silty loam.

.................................................................................................................................................. 23

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SUMMARY

The South Australian Salinity Mapping and Management Support Project commissioned this investigation to

evaluate ground-based geophysical techniques such as electromagnetic induction (EM-38 and EM-31) and

volume magnetic susceptibility (VMS) in the rapid detection and mapping of non-groundwater table related

forms of soil salinity called dry saline land. This form of salinity is distinct from dryland salinity, which is

induced by rising saline groundwater.

Firstly, we review the definition, landscape forming processes and best management practices of dry saline

land. We conclude the existence of the following two “end member” forms of dry saline land, which

adversely affect agricultural productivity: (i) “surface expressed”, featuring high concentrations of salts in soil

surface layers - locally termed “magnesia patches” - and (ii) “subsoil expressed” exhibiting elevated

concentrations of salts in the subsoil root zone.

Secondly, we present outcomes of field and laboratory studies to determine the value of EM-38, EM-31 and

VMS in detecting and mapping forms of dry saline land in two study areas. The study areas chosen are

located in dryland farming areas between Jamestown and Spalding in South Australia’s Northern

Agricultural District where dry saline land covers approximately 60% of the area. The area is also

characterised by a complex mosaic of soils associated with dryland salinity (saline groundwater related),

sodicity and waterlogging that is detrimental to agricultural production. Ground-based geophysical

interpretations were made in conjunction with exiting soil survey, terrain (digital elevation model - DEM) and

land use information. Several key findings emerged from the study:

• EM-38 performs well in being able to detect shallow subsoil (>1.5m) and surface expressed dry

saline land. This is because both these forms of dry saline land reside at or near the surface (i.e.

within the optimum operating depth range of the instrument). This field instrument proved cost-

effective and easy to use.

• EM-31 shows where salts are located deep (i.e. ~5m) in the landscape. As such, it is not strictly

useful in mapping shallow accumulations of salts, although it reveals soil-landscape processes

associated with deeper salt storage and mobilisation.

• VMS revealed a strong correlation (r2 = 0.77) with EM-38 in some landscape situations. This

correlation is explained largely by soil-landscape processes linked to the presence of iron oxides in

soils, which in turn is associated with redox conditions and water movement. Consequently,

interpretation of VMS data is anticipated to be highly site specific. As such, with further

investigation, VMS may prove an easy-to-use surrogate for mapping dry saline land.

• Combined EM-38, EM-31, VMS, soil survey patterns and topographic (DEM) information form the

basis for developing and constructing improved whole-of-landscape process models with three-

dimensional architecture and water flow systems (not readily apparent from previous two-

dimensional toposequence models).

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• These models provide a powerful tool for communicating salt storage and salt mobilisation

knowledge for these complex landscapes affected by dry saline land and dryland salinity, and a

framework for determining optimal patterns of regional land use and land management.

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1. BACKGROUND AND REVIEW

This investigation was commissioned by the South Australian Salt Mapping and Management Support

Project (SASMMSP) (Munday et al., 2003) as part of the National Action Plan (NAP). The work described

here was conducted in the “Jamestown” SASMMSP region. This region is located in South Australia’s

Northern Agricultural District (NAD) and surrounds the town of Jamestown. This is a rich dryland farming

area affected by a form of soil salinity called “dry saline land”. The locations of the study areas - “Cootes”

and “Munduney” - are shown in Figure 1. Dry saline land is alternatively referred to as “magnesia patches”

(Soil and Land Information, 2002a), “magnesia country” (Kennewell, 1999), or more recently, “transient

salinity” (e.g. Rengasamy, 2002). It is a form of soil salinity often associated with sodicity in subsoils that are

not influenced by current saline groundwater tables (Fitzpatrick et al., 2003). Dry saline land salinity in

various forms covers approximately 67% of South Australia’s NAD, and presents a threat to crop production

in this important agricultural area (Rengasamy 2002). The area is also characterised by a complex mosaic of

soils with the associated issues of “dryland salinity” (i.e. saline groundwater related soil salinity), sodicity and

waterlogging; individually or combined, these soil issues also hamper crop production in varying degrees.

Figure 1. Locality of the Cootes and Munduney case study areas between Jamestown and Spalding, South

Australia.

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The airborne electromagnetics (AEM) commissioned by the SASMMSP detects regolith (i.e. >5m)

conductivities linked to salt accumulation and transport systems with a nominal ground resolution of 80m.

With dry saline land salinity a problem associated with the soil surface and subsoil (i.e. <1.5m) and occurring

in discrete spatial patterns, AEM is therefore unlikely to be of much value in detecting this form of salinity. In

addition, the costs for targeted, key area AEM acquisitions are almost always likely to be prohibitive for

project-based dryland farming applications. However, ground-based electromagnetic (EM) methods such as

EM-38 and EM-31 may be useful in this respect, relatively easy to interpret, and cost-effective to contract.

Considerable research effort has been devoted into the use of ground-based EM methods to detect and

manage dryland salinity (associated with rising groundwater tables), yet little has been done to detect dry

saline land using the same techniques. Here we address this shortcoming.

The terminology and definitions surrounding the concept and various forms of dry saline land is confused.

This has important implications for research, farmer, conservation and policy communication. Consequently,

the scope of this project was to provide a brief literature review on the terminology of dry saline land. Further,

we use field information on the application of ground-based EM-38 and EM-31 techniques for rapid detection

of the various forms of dry saline land from studies conducted in dry saline land-affected landscapes. Finally,

we describe the use of a low cost, lightweight, ground-based geophysical technique called volume magnetic

susceptibility (VMS) - used simultaneously with the EM instruments - to characterise soil-landscape

attributes in the two study areas.

1.1 Objectives

The objectives of this investigation were to: (i) briefly review and define the forms of “dry saline land”, (ii)

report on the field application of ground-based geophysical techniques such as electromagnetic induction

(EM-38 and EM-31) and volume magnetic susceptibility (VMS) techniques for rapid detection and mapping

of dry saline land, and (iii) interpret EM-38, EM-31 and VMS data, together with topographic (DEM), soil

survey and geological information to construct 3-D soil-landscape process models to help explain salt

storage and salt mobilisation in complex landscapes affected by dry saline land.

1.2 Work strategies

Strategies adopted in this work were:

• Compilation of a brief review of dry saline land.

• Selection of two case study areas that illustrate the typical range of dry saline land between

Jamestown and Spalding (in consultation with Ms Mary–Anne Young, Rural Solutions SA,

Jamestown).

• Conduct EM-38, EM-31 and VMS surveys using high sampling intensities throughout the case

study areas.

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• Assessment of existing and newly sampled soil data, with emphasis on the following soil attributes

from laboratory analyses:

o pH, o particle size analysis, o electrical conductivity (EC), o exchangeable cations and cation exchange capacity (CEC), o organic carbon, and carbonate, o mineralogy (powder X-ray diffraction analysis).

• Construct 3-D soil-landscape process models by integrating topographic, soil and ground-based

geophysics data to explain salt storage and salt mobilisation in complex landscapes affected by dry

saline land.

• Provide advice on the concept of dry saline land and applicability of ground-based EM and VMS

devices for mapping dry saline land.

1.3 Dry saline land: a brief literature review

Dry saline land or transient salinity (subsurface and surface expressed) occurs in upper parts of landscapes

not influenced by saline groundwater (Fitzpatrick et al. 2003). Accumulation of salts in the soil surface range

from ECse 4-60 dS/m (surface form) and ECse 2-8 dS/m in the subsoil (i.e. 0.3-1.0 m) (subsoil form) can be

detrimental to crops, especially with increasing salt concentrations (Rengasamy 2002). This phenomenon of

salt accumulation within root zones of sodic soils is different from the "secondary” or “seepage" salinity (i.e.

dryland salinity) found typically in low parts of landscapes with shallow, rising watertables (Figure 2). Dry

saline land is not hydrologically connected to a saline watertable and is extensive in many sodic soil

landscapes in Australia, especially in low rainfall areas where evapotranspiration is high during summer, and

winter leaching of salts is minimal. While 16% of the dryland cropping area is likely to be affected by salinity

induced by shallow watertables (dryland salinity), 67% of the area has a potential for induced dry saline land

salinity, not associated with groundwater and other subsoil constraints. These forms of soil degradation cost

the Australian farming economy in the vicinity of A$1330 million per year (Rengasamy 2002). Where the

upper layers of soil are sodic, water infiltration is very slow because dispersed clay clogs soils pores. If the

subsoils are also sodic, the downward movement of water is restricted, thus causing temporary waterlogging

in the subsoil, and the development of “perched watertables”. Salts accumulate above perched watertables

during the wet winter and accumulate in the sodic subsoils following drying by water uptake by plant roots

and evaporation. Not all dry saline land is associated with the presence of perched watertables, or soils with

sodic B horizons; in some landscapes clay layers or poorly permeable, near-surface regolith with are

sufficient to impede the downward leaching of salts with the wetting front, resulting in the local accumulation

of subsoil salts in the perched watertables. The rate of salt accumulation is not large, but over time can be

detrimental to crops. This so-called ‘subsoil transient salinity’ fluctuates with depth and also changes with

season as the balance between downward and upward fluxes change.

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1.3.1 Dry saline land in root zones caused by slowly permeable subsoil layers In upper parts of agricultural landscapes, where saline groundwater tables are generally deep (i.e. greater

than 20-30 m depth), salt accumulation is usually below 5m depth and thus does not affect crops (Figures 2

and 3). Prior to agricultural development the upper soil layers (i.e. <1m) in these virgin soils were weakly

saline (Figure 3a). However, leaching and saturation within the rooting zone causes a number of chemical,

biological and physical changes, including: (i) acidity, (ii) sodicity, (iii) sodicity and salinity, and (iv) sodicity

and alkalinity.

Rate and amount of downward percolation of salts are primarily controlled by soil texture and subsoil layer

permeability. In coarse textured horizons faster rates of water flow occur since the average pore diameter is

larger than in fine textured soils. Also, less water storage is directly related to greater pore diameters. As a

result, deep percolation of water and salts is more likely to occur in coarse textured soils.

Figure 2. Dry saline land or transient salinity (not hydrologically connected to a saline watertable); primary

salinity (caused by saline groundwater), salt bulges (below the root zone of former native vegetation) and secondary salinity (rising saline groundwater and salt accumulation due to evaporative water loss in saline seeps) (from Fitzpatrick et al., 2003).

In some localities in Australia relatively coarse textured soils overlie slowly permeable sodic clay horizons

(Figure 3a). Under these circumstances, percolation leads to lateral flow of water and solutes along the

surface of the impermeable layer. If the contact between the two different layers approaches the soil surface

along a hill slope, as often happens, the laterally moving water (with solutes) will create a wet spot (i.e.

“perched watertable”), becoming saline as the accumulated water evaporates (Figures 2 and 3b).

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1.3.2 Dry saline land with subsoil expression

Subsoil expressed dry saline land has been estimated to occur on about 30% of the land in the wheat

growing regions of the mid-north of South Australia (Soil and Land Information, 2000a). Subsoil layers

between 0.3 and 0.6m deep have accumulated salt with an electrical conductivity of the soil saturation

extract (ECse) ranging between 2-16 dS/m and the surface soil layers ranging between ECse 2-8 dS/m. This

high salt concentration may cause osmotic effects, which prevents plants from absorbing water from soil. As

the soil layers dry out after winter, salt concentrations increase, plants show grey symptoms (from lack of

photosynthetic activity) and lose leaf area with some senescence. Generally, the accumulated salts in the

cropping regions of southern Australia are dominated by sodium chloride. However, significant sodium

carbonate and bicarbonate may also exist in alkaline soils with a soil pH >9.0 (i.e. alkaline-sodic saline soils).

When dry saline land with subsoil expression is drained and leached by rainfall, secondary sodic soils are

developed (Figure 3c). The development of sodic layers with low hydraulic conductivity and high bulk

density further restrict downward movement of water, leading to waterlogging, tunnel erosion and enhanced

lateral movement of water and colloids to streams. Eventually a saline scald is formed (Figure 3c).

1.3.3 Dry saline land with surface expression (magnesia patches)

The most extreme case of salt accumulation is where ECse values are very high at the surface (ECse >16 up

to 60.0 dS/m) and often has salt efflorescences. These high levels of salt prevent crops - and even

halophytes - from growing and can cause the soil to be susceptible to scalding and erosion. The cause of

this salinity is the localised mobilisation of salts above slowly permeable sodic B horizons by throughflow to

topographic depressions (Figure 3b) and salt accumulation by evaporation. This dry saline land with surface

expression (i.e. surface soil transient salinity) can occur in a variety of soil types and at all positions within

undulating landscapes, and was first reported in South Australia by Herriot (1942). Approximately 45,000 ha

of marginal cropping land in South Australia are affected by this problem (Kennewell, 1999). This form of dry

saline land salinity is commonly referred to as "magnesia patches” because of the apparent dominance of

Mg when first documented. Subsequently, however, Na has been shown to generally dominate as a natural

part of the salt evaporation sequence.

When dry saline land with surface expression (magnesia patches) is drained, soils are leached and salt

efflorescences on the soil surface are dissolved (Figure 3c). Salt crystals develop at depth in sodic soils

where salt is leached through the subsoil clay layers on edges of gullies or drains. This causes stream

banks to erode by salt weathering (Figure 3c). If these processes are expressed on the surface of the soil,

bare eroded saline scalds are evident (Figure 3c).

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1.3.4 Generalised best management practices for dry saline land

The capacity to reverse established salinisation in dry saline land will depend strongly on the specific class of

saline soil that exists (Table 1). Different management techniques are necessary for soils with different soil

textures, salt compositions and water regimes. These management techniques can include draining,

application of gypsum, ripping, mulching and efforts to revegetate (Table 2).

Figure 3. Soil-regolith model showing salt transport and erosion processes leading to formation of subsoil and surface dry saline land (not associated with the saline groundwater tables). NOTE: A sodic duplex soil is used here as an example. These processes also do however occur in gradational soils or in soils with thin A horizons directly overlying saprolite (from Fitzpatrick et al., 2003).

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2. METHODS

2.1 Selection of representative study areas with dry saline land

Based on the literature review of the definition, landscape forming processes and best management

practices of dry saline land, we concluded the existence of two “end member” forms of dry saline land that

adversely affect agricultural productivity: (i) “surface expressed”, featuring high concentrations of salts in the

soil surface layer - locally termed “magnesia patches” - and (ii) “subsoil expressed”, exhibiting elevated

concentrations of salts in the subsoil root zone.

Two representative study areas showing symptoms of each of the above forms of dry saline land were

selected from the Jamestown area. Site selection benefited considerably from local knowledge and

experience of Ms Mary-Anne Young, Rural Solutions SA senior extension officer based in Jamestown. Both

sites were located in the “Belalie Plains” area (Figures 1 and 4a), a broad valley system oriented north-to-

south and running between Jamestown (north) and Spalding (south). A “subsoil expressed” dry saline land

example study site was selected at the farming property of the Cootes and Ashby families - known as the

“Cootes study area”, and a “surface expressed” example was located at the “Munduney” property, operated

by the University of Adelaide (Figures 6 and 7). These study sites were located 25 and 20 km south of

Jamestown respectively.

2.2 Site description of Cootes case study area

The Cootes study area (121 ha) was selected as an example of the subsoil form of dry saline land,

demonstrating typical landscape/environmental conditions for the Jamestown area from the perspective of

geology, soils, land use, climate, and soil-water movement. To the north is Jamestown (25 km), and to the

south Spalding (20 km) and Adelaide (180 km) (Figures 1 and 4a,b). The study area is on the east-facing

slope of a broad north-south valley system, which is drained southwards by the “Freshwater Creek” (Figures

4c, d, e and f). The crest-to-valley bottom toposequence (A-B) (Figures 4 and 5) length is approximately

1,500m, and has a relief difference of 100m, i.e. 470-370m. A basement of tillites, quartzites, mudstones,

siltstones and shales underlies the area (see below, Figure 14). A prominent feature of the landscape is the

deeply incised (12m) erosional gully formed by the creek (Figures 4c, d and f). Seventy five percent of the

450 mm annual rainfall falls in the winter growing season (May to October).

A georeferenced air photo was acquired and a DEM generated photogammetrically for the supply of detailed

terrain information. The resulting DEM featured 3m spatial resolution and sub-meter vertical accuracy.

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Table 1. Categories of dry saline land soils, as defined by hydrology, landscape features and soil chemistry (adapted from Fitzpatrick et al., 2003)

Hydrology Management Options

Groundwater or Perched water

Primary/Secondary/Dry Saline Land (Transient) Salting?

Soil/Landscape Feature

Dominant Soil

Chemistry

Saline Soil Category Descriptor

See Table 2

Halitic Primary, dry saline, topsoil, halitic G Surface soil (Magnesia patch) Sodic Primary, dry saline, topsoil, sodic H

Primary dry saline land (Transient salinity) (natural) Subsoil Sodic Primary, dry saline, subsoil, sodic H

Halitic Secondary dry saline, surface soil, halitic G Surface soil (Magnesia patch) Sodic Secondary, dry saline, surface soil, sodic H

Halitic Secondary, dry saline, subsoil, halitic H Subsoil Sodic Secondary, dry saline, subsoil, sodic H

Halitic Secondary, dry saline, eroded, halitic E1

Groundwater absent from root zone: salinity process driven by seasonal perched water table in root zone

Secondary dry saline land (Transient salinity) (induced)

Eroded Sodic Secondary, dry saline, eroded, sodic E1

1 See Fitzpatrick et al. (2003) Table 2. Generalised best management practices (BMPs) after drainage or disturbance for different classes of dry saline land (from Fitzpatrick et al. 2003)

Soil Salinisation Category (Table 1) Soil Texture Indicators Management Options in Sequence1 Sands/Loams EC, pH Mulch with coarse sand or organic matter.

Drain to leach salts. Calcium application (gypsum). Vegetate with suitable species as soon as possible. May be used for agriculture.

Clays EC, pH, CaCO3, ESP or SAR, BD2

As for (G) Sands/loams but closer drain spacings will be required to leach salts

G Dry saline land with saline topsoil (EC >16 dS/m); usually alkaline (pH >8) (magnesia patch) (surface expressed transient salinity)

Sand/Clay As above, subsoil BD

As for (G) Sands/loams but closer drain spacings will be required to leach salts

H Dry saline land with saline subsoil expressed with salinity trends increasing from the surface (ECse 2-8 dS/m) to subsoil (ECse 4-16 dS/m); usually alkaline (subsoil expressed transient salinity)

All EC, pH Drain to leach salts. Calcium application (gypsum). Vegetate with suitable species as soon as possible. May be used for agriculture.

1 Most soils affected by salinity have nutrient deficiencies or imbalances. It is important, especially in eroded or scalded sites, that nutrient status is addressed when re-establishing vegetation. To minimise erosion and pugging, stock should be excluded from these areas. 2 Many clayey subsoils have high bulk densities (BD) with poor hydraulic conductivity. These conditions cause difficulty in leaching salts and exploration by plant roots. 3 Sandy textures overlying clayey textures are called duplex soils.

11

Soils: Detailed soil information (i.e. draft soil map with accompanying detailed profile descriptions

and chemical analyses) for the survey area was accessed from a previously unpublished CSIRO

soil survey (Fitzpatrick et al., 2004). Initial soil mapping (Figure 5) was based on detailed fieldwork,

soil sampling and laboratory analyses. This data was augmented by sampling additional soils

(including profile descriptions and laboratory analyses) as part of the current study at key sites not

previously sampled. As a consequence of the multi-factorial genesis of these soils, the present

landscape is described as being pedologically complex – as depicted in the following range of soil

types contained in the soil-mapping units (SMU) presented below:

• SMU A: Brown Clay (sometimes with subsoil expressed sodicity and salinity) – These soils

are a moderate to strongly structured brown clay soil with field textures dominated by silt in

the upper horizons. The soil is deep with what appears to be buried soils of generally

redder colour (than the overlying brown clay) at depths of 1m or more; sodic subsoils with

a pale A2 variant (Ab) may occur. This SMU occurs on the flat, overlying deep alluvium.

• SMU B: Sodic Brown Clay - These soils are a clay that may have a weak self-mulching

surface and a gradational texture profile that may extend beyond 2.0m, but the underlying

calcareous shales are at a mean depth of 1.6m and a range of 0.7m to 2.0m. These soils

are restricted to the very gently inclined to moderately inclined slopes emanating from the

low hills and rises overlying colluvium.

• SMU C: Red Brown Earths (sometimes with subsoil expressed sodicity and salinity) –

These soils have a hard setting A horizon of light sandy clay loam to clay loam texture and

a clear to sharp change to a dark reddish brown, strongly structured, medium to heavy

clay B horizon. The solum is usually greater than 2m deep. A shallow variant (C-s) has

been recognised for those profiles that are less than 0.5m to the C horizon. The majority of

profiles are calcareous although there is considerable variation in depth to the calcareous

layer(s), which may be soft, hard and nodular. This SMU occurs in the flat, overlying

colluvium.

• SMU D: similar profile characteristics to SMU C (Red Brown Earths) – These soils differ

from SMU C soils in that they have a sporadic bleach of varying thickness and

prominence. This SMU occurs on sloping to flat areas overlying colluvium / alluvium.

• SMU E: transitional to the Brown Clays of SMU A and SMU B (with a gradational texture) –

These soils have colours of the major horizons that are generally less red than the Red

Brown Earths. The landscape position of soils of this SMU is generally near the transition

from uniform profile forms to duplex. The gradational features in SMU E may have been

enhanced by the cultivation practices resorting surface horizons.

• SMU F: Rendzina and Terra Rossa soils with low levels of salinity and sodicity – These

soils comprise mainly shallow calcareous loams with calcrete fragments overlying mainly

calcareous weathering siltstone with some very shallow, loamy topsoils (<0.1m) overlying

massive calcrete. These shallow soils occur mainly on the crest and upper slopes, and

12

contain outcrops (40%) of mudstone, siltstone and partly carbonaceous shale (Figure 4b).

These soils have formed in situ from fine sedimentary rocks (mudstones, siltstones and

partly carbonaceous shales). The dominant vegetation is pasture. These soils are darker

and browner than SMUs C, D, E and G.

• SMU G: Red Brown Earths (mostly with subsoil expressed sodicity and salinity) - The main

morphological feature distinguishing these soils from the other Red Brown Earths is a

lighter surface texture with accompanying poorer structure; the B horizons are strongly

structured and medium to heavy clay texture; free lime is evident in the majority of profiles.

• SMU Gully Edge: The exposed soils at the gully’s edge (12m deep) are highly saline

(ECse 360 dS/m), gypsiferous and sodic soils in some layers. Some carbonate-rich gravel

bedding layers indicate the presence of alluvial fans in the profile.

• SMU Gully Flat: These soils are highly saline (ECse 4-140 dS/m) sulfidic hydrosols.

Figure 4a and b. Cootes study area’s regional context (a) and landscape location with

toposequence A-B marked (b). Inset, photo of study area looking from A to B, which is similar to photograph of transect (A’-A”) shown Figure 5.

13

Figure 4c. Photograph of Cootes case study area, looking north east along selected transect

from A to B, which is similar to aerial photograph showing transect (A’-A”) in Figure 5.

Figures 4d, e and f showing the “Freshwater Creek” deep (12m) erosion gully containing highly

saline soils (edge of gully ECse 360 dS/m; bottom of gully ECse 4-140dS/m) in the Cootes study area.

“B”

(d) (e) (f)

“A”

14

Figure 5. Upper: soil map boundaries with Soil Map Units (SMU A to F) overlying a hill shaded aerial photo of the Cootes study area highlighted in yellow box with toposequence/transect described in Figure 14 highlighted with a red line. Lower: Enlargement of Cootes study area showing: (i) localities of geophysical survey points at 20 m intervals along survey lines with 50 m spacing (black dots), (ii) localities of soil profile sample points with morphological descriptions (green squares) and (iii) localities of soil profile sample points with morphological descriptions, chemical and physical soil data (red circles).

15

2.3 Site description of Munduney case study area

The Munduney case study area was selected because it is representative of typical landscapes

with conditions (geology, climate, aspect and soil water regime) leading to the formation of surface

expressed dry saline land (magnesia patches). This study area is located 20 km south of

Jamestown at the “Munduney” property, operated by the University of Adelaide (Figures 6 and 7).

The study area is on the north-west facing flank of a broad north-south valley system, which is

drained southwards by the “Freshwater Creek” (Figure 6). The crest-to-valley bottom length is

approximately 400m and has a local relief difference of approximately 80m. Prominent features of

the landscape are two shallow interceptor drains constructed along contour lines to successfully

manage recharge from rainwater and to control earlier soil erosion problems on the mid- and -

upper slopes (Figure 6a). An erosion gully exists at the bottom of the slope as a legacy of past

erosion activity (Figure 6a).

Figure 6. Photograph of (a) the Munduney study area north-west facing landscape with dry saline

land and (b) geophysical survey lines.

Surface expressed “dryland saline land” (magnesia patch) (See figures 7a, b, c, and d)

(b)

(a)

16

Figure 7. Photograph of (a) surface expressed dry saline land in scalded area (i.e. magnesia patch

typical of the area) and (b) exposed weathered shale coated with salt efflorescences and carbonate at the Munduney study area.

Figure 7. Photographs soil profiles with surface expressed dry saline land exposed in the drainage

ditch in Munduney study area.

(a) (b)

(f)

(e)

(c)

(d)

17

A representative soil profile (Figures 7e and 7f) with surface expressed dry saline land was

described according to McDonald et al. (1990) and soil and rock (Figure 7b) samples taken for

laboratory analyses. EC1:5, pH1:5, pH (CaCl2), major and total exchangeable cations, cation

exchange capacity (CEC), and exchangeable sodium percentages (ESP) were measured on each

soil horizon using standard techniques (Rayment and Higginson 1992). ECse was estimated from

EC1:5 and soil texture to identify the salinity hazard and its affect on plants (Cass et al., 1996).

2.4 Electromagnetic induction principles

Traditional methods of measuring soil salinity involve soil sampling with an auger followed by

analysis of a water extract in the laboratory (e.g. Rayment and Higginson, 1992). This procedure is

slow, laborious and expensive. It is therefore desirable to use field methods that allow rapid, on-site

diagnosis of salinity concentrations. The EM-38 and EM-31 electromagnetic induction soil

conductivity sensors of Geonics Ltd has been developed for this purpose, as well as for rapid

salinity mapping (e.g. Slavich, 1991). Both instruments are field portable, and comprise a

transmitter and a receiver coil, a power supply, electronics and analogue display.

Briefly, both instruments operate in the same way, i.e. their transmitter coils are energised by an

alternating current. The time-varying magnetic field arising from alternating currents induce small

eddy current loops in the soil that generate secondary magnetic fields. The receiver coils measure

these secondary magnetic fields. The ratios of the secondary to primary magnetic fields are

directly proportional to the electrical conductivity (i.e. the apparent electrical conductivity [ECa], in

deciSiemens/meter [dS/m]) of the soil material. Since most soil particles are poor conductors of

electricity, it is primarily the water content/electrolyte concentration that gives rise to instrument

response. Ideally the soil should be near field capacity throughout the depth of investigation at the

time of measurement (e.g. Slavich, 1991). Despite this limitation, the technique has been shown to

be a practical field method for diagnosing and delineating soil salinity problems (e.g. McNeill, 1980;

Slavich, 1991).

2.4.1 EM-38 electromagnetic induction technique

Designed to be particularly useful for agricultural surveys measuring soil salinity, the EM-38

can cover large areas quickly because it is very lightweight and is only one meter long. The

EM-38 provides rapid surveys with excellent lateral resolution. Measurements are obtained

with the instrument placed on the soil surface. The EM-38 provides depths of exploration of

approximately 0.75 to 1.5m in the horizontal and vertical dipole modes respectively. The

current EM-38 electromagnetic induction survey was conducted using the vertical dipole (i.e.

to 1.5m in depth).

18

2.4.2 EM-31 electromagnetic induction technique

The EM-31 instrument was designed to measure apparent electrical conductivity (ECa) in the

regolith profile to an approximate depth of 5m when used at hip height. Like the EM-38 instrument,

the EM-31 is portable and can cover large areas quickly on foot.

2.5 Volume magnetic susceptibility technique

Mineral magnetic techniques are a relatively recent development (post 1971) and have now

become a very powerful and widely used research tool to characterise natural materials in

landscapes (Thompson and Oldfield, 1986). Palaeomagnetic and mineral magnetic

measurements have been most effectively applied to soils, soil parent materials, bedrock, river

sediments and estuarine cores in studies of whole catchments. For example, mineral magnetic

techniques have been used in a wide range of environmental studies such as sourcing sediments

in reservoir catchments; establishing stream arm sediment contributions at river confluences;

sourcing estuarine sediments; characterisation of soils; tracing overland soil movement; and

identification of fire-induced magnetic oxides in soils and lake sediments. Soil magnetic properties

can be used in conjunction with other pedological and mineralogical methods to trace sources of

alluvium to measure the extent of erosion and deposition in eroding landscapes. These magnetic

techniques can also be used for relative soil age dating and for the determination of soil and parent

material discontinuities (e.g. evidence for buried soil layers).

Magnetic susceptibility measurements can detect the presence of iron oxides in soils at lower

concentrations than other methods such as X-ray diffraction analyses. In soils, their magnetic

properties reflect the varied magnetic behaviour of the bulk of soil minerals present. In many soil

samples, the magnetic susceptibility is largely determined by the ferrimagnetic mineral present

such as magnetite and maghemite (Table 3). Other major soil constituents may also affect

magnetic susceptibility values. Quartz, calcium carbonate, orthoclase, organic matter and water

are diamagnetic and, in most soils, these dilute the magnetic properties. In extreme cases, such as

pure silica sands and pure limestone, the diamagnetic component will have a significant effect on

the magnetic susceptibility of the sample. Paramagnetic soil minerals are those rich in iron but low

in ferrimagnetic properties. They may make a significant contribution to bulk magnetic

susceptibility. Antiferrimagnetic minerals will also increase magnetic susceptibility values. Of

these, goethite and hematite are the most abundant (Table 3) and therefore can make an important

contribution to the magnetic properties of soils.

Magnetic susceptibility is essentially a measure of how "magnetisable" a mineral is

(Thompson and Oldfield, 1986). Volume susceptibility, κ, is defined by the relation, κ = M/H,

where M is the volume magnetisation induced in a material with susceptibility, κ, by an

applied field, H. Mass specific magnetic susceptibility, χ, is the volume susceptibility divided

by the sample density, χ = κ/ρ, and has units of m3kg-1. The ferrimagnetic Fe oxides, such as

19

magnetite, maghemite, titanomagnetite and titanomaghemite, commonly dominate the

magnetic signature of a soil, rock or sediment. These minerals have strong, positive mass

specific magnetic susceptibilities of the order of 20,000 to 50,000 x 10-8 m3kg-1. They are

attracted to the weak magnetic field of a hand magnet, which provides a useful field test for

their presence in a sample. In contrast, the other Fe oxides have magnetic susceptibilities in

the order of 20 to 100 x 10-8 m3kg-1. These values are comparable to or slightly greater than

those of other common soil minerals and are not particularly diagnostic. Fifteen oxides,

hydroxides, and oxyhydroxides of Fe have been recognised (Table 3). Of these, twelve occur

naturally, but only eight are common in soils or other surface environments. The magnetic

susceptibility of a mixed-mineral sample is influenced by the composition, size and shape of

the ferrimagnetic crystals, but it is primarily determined by their concentration. Thus,

magnetic susceptibility measurements from a set of related samples commonly show a

positive, linear relationship to magnetite or maghemite content (e.g. da Costa, et al., 1999).

Table 3. The oxides, hydroxides and oxyhydroxides of iron (from Bigham et al. 2002)

Oxides Hydroxides Oxyhydroxides Mineral Formula Mineral Formula Mineral Formula

Hematite† α - Fe2O3‡

Bernalite Fe(OH)3 Goethite α - FeOOH

Maghemite γ - Fe2O3 Ferrihydrite Fe5HO8.4H2O Lepidocrocite γ - FeOOH Magnetite Fe3O4 Green rust § see below Akaganéite β - FeOOH.Cl Wüstite FeO Fe(OH)2 Feroxyhyte δ' - FeOOH β -Fe2O3¶ Schwertmanni

te Fe808(OH)6SO4

ε - Fe2O3 δ - FeOOH † Minerals that have been reported as naturally occurring in soils are in bold. Minerals in normal type

occur under more restricted conditions. ‡ Greek letters (α, β, γ etc.) are used to distinguish minerals or compounds that have the same

chemical composition but different structures. § Refers to a group of compounds with the basic Fe(OH)2 structure. Charge arising from partial

oxidation of Fe(II) is balanced by various interlayer anions, typically Cl- , SO42-, and CO3

2- as per: Fe(II)1-xFe(III)x(OH)2(Cl-, SO4

2-, CO3-)x.

¶ Formulas given without corresponding mineral names indicate compounds that have been synthesised in the laboratory but have not been found as naturally-occurring, inorganic phases.

Many studies have documented that the magnetic susceptibility of surface soil is commonly

higher than that of underlying materials (e.g. Thompson and Oldfield 1986). This “magnetic

enhancement” can result from: (i) simple accumulation of primary ferrimagnetic minerals (e.g.

maghemite) that are resistant to weathering or transport; (ii) burning of the soil and the

conversion of goethite, hematite or lepidocrocite to maghemite; (iii) neoformation of

maghemite or magnetite from the soil solution; (iv) accumulation of ferrimagnetic minerals

through atmospheric deposition; and (v) cultivation of abrasive soils (Fitzpatrick and Riley,

1990).

20

Volume magnetic susceptibility determinations were conducted in the field using a Bartington

magnetic susceptibility instrument model MS2 (Bartington Instruments Ltd., Oxford, England)

equipped with a MS2D probe, which determines concentrations of magnetic materials in the

top 60 mm.

2.6 Ground-based surveys using EM-38, EM-31 and VMS geophysical techniques EM-38, EM-31 and VMS surveys were conducted simultaneously at the Cootes’ property in a key

area of 121ha (Figure 5). The survey was carried out over a grid comprising 975 GPS-located

sample points along 16 x ~1,000m crest-to-valley (west-east) transects, 50 m apart (north-south).

An along-transect sampling interval for 20 m was used (Figure 5).

EM-38, EM-31 and VMS surveys were conducted at the Munduney property in a key area

comprising 2 ha (Figures 6 and 7). The surveys were conducted along four contour transects that

were approximately 20m apart, with along-transect sampling conducted at 10m intervals, with 82

sample points being GPS-located (Figure 6).

Using a GIS the three geophysical surveys were co-registered to the GPS locations and individually

interpolated by Ordinary Kriging to generate GIS surfaces for each survey.

The Munduney survey lines were plotted graphically for visual assessment and interpretation, and

are discussed in the following section.

21

3. RESULTS AND DISCUSSION 3.1 Soil and landscape data

3.1.1 Subsoil expressed dryland saline land: Cootes case study area

Using SMU mapping as a basis, the study area was divided into a number of “landscape soil units”

(LSUs) based on similarities in: topography, soil-regolith morphology (soil texture, structure); zones

of salt accumulation; and hydrology (i.e. groundwater and freshwater flows). These, with the

laboratory analysis data (clay %, ECse and ESP), are shown in Figure 8, overlaid on a 3-D aerial

photo drape of the study area. Also shown are the locations of soils (“a” and “b” from < 0.3m, and

“c” at 1.0 m) and taken for mineralogical (powder X-ray diffraction) analysis.

The LSUs that have been identified are described as follows:

• LSU 1: Crests, upper north-south oriented ridges and topographic highs along west-east

oriented spurs; shallow calcareous loams with very low salinity and sodicity (Rendzina and

Terra Rossa soils) interspersed with outcropping (i.e. 5-50% surface cover) shales and

siltstones.

• LSU 2: High slopes intruding up drainage and gully lines to the west-east oriented spurs

and upper north-south oriented ridges: saline/sodic clay soils with gradational texture

profile and weak self mulching surface.

• LSU 3: Lower slopes intruding up drainage or gully lines; Red Brown Earths with subsoil

expressed sodicity and salinity; strong texture contrasts between leached upper layer

loams above sodic clay layers (see profile data, Figure 8). B horizons are strongly

structured and medium to heavy clay texture; free lime is evident in the majority of profiles.

• LSU 4: Flat alluvial plain; deep moderate to strongly structured sodic clays (sometimes

with subsoil expressed sodicity and salinity) with thin leached A horizons; field textures

dominated by silt.

• LSU 5: Gully Edge: Highly saline (ECse 360 dS/m), gypsiferous and sodic soils on steeply

inclined slopes with some carbonate-rich gravel bedding indicting alluvial fans

• LSU 6: Gully Flat: Highly saline (ECse 4-140 dS/m) sulfidic hydrosols.

22

Figure 8. 3-D aerial photo drape of the Cootes study area with landscape soil unit boundaries, laboratory data and XRD sampling locations (a), (b) and (c) indicated.

23

3.1.2 Surface expressed dryland saline land: Munduney case study area

Dry saline land with surface expression (magnesia patches) is associated with upper slopes of

undulating to rolling rises and low hills in the Munduney study area (Figures 6a,b; 7a and 9). The

regional distribution of dry saline land magnesia patch soils are shown in the hill shaded map

(Figure 9; red, 10-50% affected; pink, 2-10% affected; green, <2% affected), together with areas

showing the modelled drainage and pyritic/sulfidic geological units. These landscapes are

associated with shallow, saline, greyish brown, powdery calcareous silty loams that, within one

metre, become more silty with depth and grade to weathering calcareous siltstone bedrock

containing pyritic/sulfidic minerals (Figures 7b, c, d). The near-surface, slowly permeable,

weathering calcareous siltstone tends to restrict drainage of saline soil water. Evaporation

subsequently strongly concentrates salts in the topsoil.

Tables 4-6 present physical and chemical (pH, electrical conductivity, ESP and carbonate content)

from soil horizon data for representative soil profiles in the study area. Mineralogical data is

presented in Appendix 1. The soil photographed in Figure 7f, was classified according to Isbell

(1996) as a Hypervescent, Paralithic, Hypercalcic Calcarosol; medium,slightly gravely, loamy/silty,

moderate.

Table 4. Particle size data and soil texture of shallow calcareous silty loam.

Depth (cm) Fine Coarse Texture Clay Silt Sand Sand % % % % 0-5 11 40 37 1 Fine silty loam5-20 12 40 37 1 Find silty loam20-35 7 33 37 3 Find silty loam

Table 5. Electrical conductivity, pH, organic carbon, sulfur and carbonate carbon of shallow calcareous silty loam.

Depth (cm) ECse EC pH pH Organic Total CO3 as (1:5 soil:water) (0.01M C S CaCO3 dS/m dS/m CaCl2) % % % 0-5 2.9 0.3 8.4 7.8 2.0 0.03 6.2 5-20 16.9 1.6 8.2 8.0 1.1 0.02 8.5 20-35 15.7 1.3 9.2 8.5 0.5 0.02 19.0

Table 6. Exchangeable cations, cation exchange capacity and ESP of shallow calcareous silty loam.

Depth (cm) Exchangeable Cations cmol/kg CEC ESP Ca Mg Na K Total (NH4) 0-5 9.7 1.1 0.2 0.7 11.7 9.1 1.8 5-20 7.1 1.6 0.5 0.4 9.6 7.6 6.8 20-35 3.5 1.2 1.8 0.2 6.7 3.7 49.1

24

Figure 9. Hill shaded regional context of Munduney and Cootes study areas showing (i) modelled

drainage, (ii) land systems and soil landscape units (Soil and Land Information, 2002b) showing dry saline land magnesia patch mapping (red, 10-50% affected; pink, 2-10% affected; green, <2% affected), and (iii) hatched areas, showing pyritic and sulfidic geological units.

3.2 Geophysical data: EM-38, EM-31 and VMS The EM surveys were conducted for the Cootes case study area using an EM-38 for the vertical

dipole mode (Figure 10a), EM-31 (Figure 10b) and VMS (Figure 9c). The EM-38 determines

subsoil conductivity at approximately 1.5m deep, and the EM-31, the regolith conductivity to

25

approximately 5m deep. VMS is measured at the soil surface. Figure 10 shows high response

values in red, medium values in yellow-turquoise, and low values in dark blue. Conductivity values

are generally strongly related to salt content (ECa).

3.2.1 Subsoil expressed dry saline land: Cootes case study area Figure 10a (EM-38) displays three zones of relatively high subsoil conductivity. Feature “m” in LSU

2 is likely to represent an area of near-surface mineralisation. LSU 3 displays regions of

conductivity associated with sloping areas that are not in near-surface (i.e. <1.5m) drainage zones.

These regions are likely to represent subsoil salts, and are indicative of the subsoil form of dry

saline land discussed earlier. This variable pattern shows the importance of micro relief and the

structure of near surface geology on near surface drainage patterns, and hence subsoil dry saline

land expression.

The EM-38 (Figure 10a) high conductivity zones are strongly correlated with VMS (Figure 10c)

showing magnetic minerals near the soil surface, which can also contribute to the high conductivity.

Moderate conductivities are displayed throughout LSU 4 areas, and are likely to be associated with

low salt concentrations in the subsoil (see Figure 9 profile data) (Thomas et al., 2003).

By contrast, the EM-31 plot (Figure 10b) shows deeper regolith (approximately 5m) conductivity in

all LSUs, especially in the drainage zones on sloping areas, and throughout LSU 4. Values ranged

from ‘very low’ (<20 mS/m) in the more resistant knolls to ‘very high’ (>150 mS/m) at the NE

discharge zone into the deep gully (Figure 10b). Conductivity values increased with distance

downslope from the major knolls – as would be expected due to deeper, and perhaps, moister

soils. Looking from the western ridge there appears to be a crescent of higher conductivity (100-

150 mS/m) zones following the ‘break of slope’ areas. However high values are also found in the

upper sections of the gullies leading up to the ridge. A large proportion of high conductivity

response on the sloping areas is probably associated with conductive basement rock or the

deposition of magnetic colluvial material. In the sloping area drainage zones, the highly conductive

regolith pattern is likely to reflect magnetic colluvial material and/or salt accumulation. These salts

are likely to have been washed down from upper-slope areas, or from below in saline groundwater.

The LSU 3/4 boundary forms a prominent contrasting conductivity feature. The high conductivity

throughout most of LSU 4 is likely to reflect the hydraulic barrier - caused by the low sodic clay

permeability - which traps and concentrates up-slope regolith salts. Perhaps after a considerable

time in storage the salts seep out of the gully face, evidenced by high EM-31 conductivity zones

and laboratory data. The high values along the edges of the main eastern creek bank or edge of

the erosion gully (LSU 5) is indicative of salt discharge via throughflow and evaporative

concentration within the soil profile (see Figure 14).

26

Figure 10. EM-38 (a) and EM-31 (b) and VMS (c) surveys over laid on a 3-D aerial photo drape of the study area and Landscape Soil Units (1-4). High response

values are in red, medium values in yellow-turquoise, and low values in dark blue

27

3.2.2 Surface expressed dryland saline land: Munduney case study area

The Munduney EM-38, EM-31 and VMS field data for each survey transect were plotted together

so that the datasets can be easily compared (Figures 11 and 12). High EM-38 responses were

associated with the strongly saline (ECse >3 dS/m) reddish and yellowish soils that have silty loam

top and subsoils overlying shallow weathered siltstone in topographic highs. In contrast, low EM-38

responses were recorded in less saline grey and eroded soils in topographic lows that overlie near-

surface and outcropping bedrock. The VMS responses strongly matched the EM-38 patterns (i.e.

high correlation: r2 = >0.77) for line 4, which correspond to the saline red and yellow silty loam soils

overlying shallow bedrock in topographic highs (Figure 13). The lower VMS for the less saline grey

soils in the low lying area associated with waterlogging and reducing (i.e. de-magnetising) soil conditions, and where the salts from these soils have been leached from the profile via through

flow. However, for lines 1, 2 and 3 r2 values were 0.21, 0.36 and 0.46 respectively and

corresponded with survey lines corresponding with shallower, near-surface weathered rock, unlike

line 4 (i.e. r2 = >0.77), which corresponded with deeper soil profiles.

The EM-31 detected salt stores at depth in the low-lying areas only. Because the EM-38 and VMS

detects near surface features (< 1.5m) and the EM-31 detects depth at approximately 5m, it was

not surprising that the EM-31 patterns did not match those of the EM-38 (Figures 11 and 12). The

main features shown in these figures are a series of high and low ECa values. The ‘highs’ of the

EM-38 plots correspond with areas of salt storage or accumulation; whilst the large ‘lows’ appear to

be associated with very localised topographic lows (or depressions) where the soils are more

leached by rainwater flushing through the subsoil. These trends, although exploratory in nature,

are reasonably cohesive, given the minimal sampling carried out.

3.3 Integration of landscape-soil and geophysical data

Soil-regolith process models are a simplification or abstraction of the mechanisms that occur in a

particular geological-pedological cross-section or toposequence under study so that it can be more

easily handled either physically or mentally for a specific purpose (e.g. Dijkerman 1974). Several

kinds of simplification or abstraction may be used; for example, in creating conceptual models that

describe, explain or predict particular aspects of soil–regolith processes. Here, we use topographic,

soil and ground-based geophysics data to construct a 3-D soil-landscape process models to

explain salt storage and salt mobilisation in these complex landscapes affected by dry saline land

salinity.

28

Munduney survey - Line 1

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 17 12 19 16 19 8 11 18 16 19 11 12 9 12 10 9 9 9 8 10

EM38 36 27 30 44 35 22 49 31 29 23 30 30 25 20 8 37 22 30 50 50

VMS 210 151 130 170 179 146 122 148 186 186 145 149 169 119 95 81 135 227 220 251

NE SW

Munduney survey - Line 2

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 14 13 17 15 19 17 16 15 20 24 17 18 14 19 12 9 9 9 13 15

EM38 20 18 48 32 32 46 35 46 44 19 40 54 35 38 29 40 46 46 55 53

VMS 193 115 165 153 107 161 118 168 157 148 154 194 177 193 70 148 184 228 358 255

NE SW

Figure 11. EM-38, EM-31 and VMS data for transect lines 1 (above) and 2 (below).

29

Munduney survey - Line 3

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM 31 13 12 12 11 9 6 21 14 12 17 18 18 15 12 15 17 15 14 11 13 14

EM 38 50 36 34 35 26 12 16 38 63 36 40 43 33 58 50 56 27 28 35 33 10

VM S 218 184 195 190 91 93 110 154 191 184 171 162 168 200 155 168 155 151 173 170 146

NE SW

Munduney survey - Line 4

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 13 12 13 11 11 24 9 11 14 15 16 18 19 16 20 17 13 12 11 12 14

EM38 44 54 42 24 18 4 11 19 45 38 42 30 40 47 28 45 28 40 17 54 35

VMS 243 234 250 173 115 47 78 105 178 179 200 188 187 184 158 188 142 190 111 195 199

NE SW

Figure 12. EM-31, EM-38 and VMS data for transect lines 3 (above) and 4 (below).

30

Figure 13. Plot of EM-38 versus VMS data for line 4 (see figure 12) of the Munduney site. 3.3.1 Whole-of-landscape 3-D process model for Cootes study area

3.3.1.1 Construction of soil-landscape process model

Colour photographs of typical soil profiles from each LSU occurring in different parts down the

landscape slope or toposequence are shown in Figure 14. To understand the lateral linkages and

relationships between soil-regolith, geology and hydrology down landscape slopes, we used the

systematic structural approach (Fritsch and Fitzpatrick 1994) to identify and describe, by depth

interval, all similar soil-regolith features (i.e. soil components with similar consistency, colour,

textural and structural patterns, and physico-chemical and mineralogical properties). Similar soil-

regolith features were grouped into fewer soil-regolith layers using nested or concordant

relationships to group soil-regolith features, and discordant relationships to separate them and draw

boundaries around similar features to link them down the toposequence, and map them at

toposequence scale in cross section (Figure 14).

Each soil-regolith layer displayed in the cross section or toposequence were linked to soil-regolith

and hydrological processes (e.g. water flow paths, salinity and sodicity). In Figure 14, we used

mostly soil-regolith colour (together with other morphological, chemical and mineralogical indicators) and geology in the toposequence to construct the 3D linkages that describe water flow

paths and development of salinity (descriptive soil-regolith models). Some visual indicators are

obvious (e.g. occurrences of thick black accumulations of organic matter on soil surfaces) but some

are more subtle (e.g. subsoil mottling patterns). Subsoil expressed salinity and sodicity can occur

without any evidence on the surface. In Figure 14 cross hatching and shading represents soil

VMS versus EM38 - Munduney Line 4

y = 3.3074x + 57.727R2 = 0.7765

0

50

100

150

200

250

300

0 10 20 30 40 50 60EM38

VMS

31

sodicity and salinity with the thick dark blue arrows indicating salt groundwater flow and broken blue

arrows freshwater flow.

Interpretations of the ground-based geophysical data, together with soil survey patterns and

topographic (DEM) information were also used as a basis for developing and constructing

improved whole-of-landscape process model with three-dimensional architecture displaying

groundwater and fresh surface water flow systems. The process model incorporates a 3D-aerial

photograph drape of the study area with boundaries of landscape-soil units (LSU) including

photographs of representative soil profiles for each LSU, geology and cross-section of a typical

toposequence showing the main morphological, saline and sodic soil-regolith features/layers

(Figure 14).

3.3.1.2 Application of the soil-landscape process model

The EM-38 and EM-31 surveys of the Cootes study area have revealed a highly variable pattern of

electrical conductivity especially when draped over topography (i.e. in 3D, Figures 10a and b).

Similarly, the VMS survey has shown a variable pattern for soil magnetic properties (Figure 10c).

Briefly, LSU 1-type soils are shallow loams on the crest or ridge, interspersed with outcropping (i.e.

5-50% surface cover) shales and siltstones. LSU 2-type soils are saline/sodic clays on steep upper

slopes. LSU 3-type soils are on lower colluvial/alluvial slopes, and demonstrate strong texture

contrasts between the leached upper layer loams above sodic clay layers (ref. Fig. 2 profile data).

LSU 4-type soils are deep alluvial sodic clays with thin leached A horizons.

In SLU 1, the upper north-south ridge has low ECa values (EM-38 and EM-31), as do the west-east

spurs leading down from the ridge (Figures 10 a and b). The intervening areas (gullies with various

degrees of definition as drainage lines) have slightly higher ECa values but these are interrupted in

a north-south direction with lower conductivity ‘troughs’. The troughs could be due to coarse-

textured colluvium or could represent remnants of vertically dipping shales, now covered with

colluvium (Figure 15). Regardless of which is the true answer, the troughs would have

considerable hydrological significance. The 3-D perspective emphasises the crescent of higher

conductivity around the lower slopes of the main north-south ridge and the intrusion to higher

elevations up the main gullies.

The ECa patterns displayed from both the EM-38 and EM-31 surveys generally indicate higher

conductivity areas across the lower slopes of the landscape. However, where the EM-31 shows

higher conductivities in the drainage zones of LSUs 2 and 3, the EM-38 and VMS shows lower

relative values in the drainage zones (Figures 10a, b and c). The high ECa values (>150 mS/m)

observed high in the landscape (Line 11 – Appendix 2) from the EM-31 survey may suggest that

the source of electrical conductivity is related to magnetic minerals at depth rather than just an

accumulation of soluble salts. In general, electrical conductivity values tend to increase downslope

in most landscapes, even though they may show peaks and troughs along the way. However this is

32

not always the case in this area (e.g. compare Lines 10 and 11 with Lines 6 to 9 in Appendix 2).

The high values in elevated positions indicate the presence of electrically conductive material i.e.

most likely salts or magnetic minerals in these soil types. East-west cross sections (Appendix 2) of

the landscape reveal considerably more variability in EM-31 electrical conductivity than is shown in

the contoured data of Figure 10. Practically all transects exhibit a series of ‘peaks’ and ‘troughs’ –

some more so than others (e.g. Lines 11 to 14) but also further north at Lines 4 & 5 (Appendix 2).

Such troughs may be interpreted as indicating the presence of ‘preferred’ pathways for the

downward movement of water i.e. a surrogate measure of recharge. It is possible that this

explanation might also be true in this area but that interpretation is confounded by the possible

presence of magnetic minerals in the slope colluvium (Figure 10c). A third explanation, given the

near vertical bedding of the underlying shales, is that the troughs may reflect a zone of increased

weathering (and leaching) between different layers of the shale material (Figure 15). The apparent

continuity of troughs from transect to transect (Appendix 2) would lend support to this hypothesis,

particularly if the shale is within a few meters of the land surface.

Other, electrically non-conductive, rock material is also present in the landscape (“m” in Figure

10a). This is shown quite clearly as a large trough on the eastern sector of Line 1 and it carries

through at least to Line 4 (Appendix 2). The trough corresponds with a topographic high on Line 1

that diminishes in magnitude until it has disappeared before reaching Line 4. A further, similar

example occurs on Lines 15 and 16 where transects passed over a long east-west spur (Appendix

2). A north-south transect, relatively high in the landscape at Easting 278755, demonstrates the

higher electrical conductivities in the re-entrant valleys and also a ‘high’ well up the slope of the

southernmost spur encountered along Lines 15 and 16.

The conductivity patterns from Figure 10, combined with soil profile data (ESP, salinity and clay %)

in A and B horizons in Figure 8, suggest that soil-landscape patterns with LSU 3-type soils up-slope

of LSU 4-type soil are likely to be indicative of landscapes prone to dry saline land formation and

salt entrapment. Dry saline land soils are typically associated with upland soils that exhibit vertical

(i.e. down profile) and lateral (i.e. down slope) impediments to drainage (mainly in LSU 3). Subsoil

expressed dry saline land is associated with soils that have a sodic clay B-horizon (Btn). The sodic

clay condition acts to hamper vertical drainage of soil water, forcing it to move laterally down slope

(Figure 14 – see arrows in LSU 3). As the water moves over the Btn horizon it accumulates and

transports salts from the up-slope topsoil where they become concentrated in the upper clay

horizon and / or in seasonally wet patches, e.g. at break of slope and in topographic lows. Here

salts become seasonally concentrated in subsoils as water evaporates or is used by plants. The

concentration of salts may vary from time to time at depth in response to changes in seasonal

rainfall / soil hydraulic conditions, explaining the “transient” nature of salinity that has been observed

on poor plant growth in affected areas.

33

Figures 10a and b show a clear divide between a high electrical conductivity zone associated with

LSU 3 to the west and low conductivity with LSU 4 to the east of the main road (Figure 14). The

area to the west (LSU 3) is largely influenced by colluvium and that to the east largely influenced by

alluvium (i.e. approaching the main creek line with variability that is reminiscent of a typical alluvial

plain) as illustrated in Figure 14. The low conductivity divide may represent a north-south bed of

siliceous material, with a surface expression best seen on Line 1 (Appendix 2) as a distinct knoll or

it may simply represent the divide between colluvial outwash from the western ridge and alluvium

from the (now deeply incised) creek system (Figure 14).

The high ECa values (EM-38 and EM-31) in the easternmost sector (LSUs 5 and 6) are consistent

with saline groundwater and soluble salt discharge into the deeply incised creek line (Figures 10a, b

and c; 14).

In summary, the descriptive 3-D whole-of-landscape process model characterizes the catchment-

scale variability of relict (past geomorphological processes in development of rock weathering and

erosion) and current (saline, sodic and sulfidic soils) soil forming processes and helps develop a

better understanding of the salt storage and flow paths. The model also explains the contemporary

geochemical dispersion and erosion mechanisms present in the lower parts (erosion gully) of the

toposequence (Figure 14). The model illustrates some of the pedological, geological, mineralogical

and hydrological processes involved in catchments between Jamestown and Spalding. In

particular, the model explains salt storage and salt mobilisation in this complex landscape that is

affected by both dry saline land and dryland salinity (i.e. groundwater induced, occurring in the

lowest part of the landscape/ in the erosion gully with stream salinity).

The model identifies a complex palaeovalley system (SLU 4 and 5 derived from alluvium), which

provides new insights (see below) into the soil-regolith, geological and hydrological features

associated with salt stores in both upland soil surface features and in low-lying valley-fill sediments.

The combined EM-31/EM-38 and topographic pattern (Figures 10a and b) describe the true

underlying physical and magneto/chemical variation that exists in this landscape. Therefore, types

of soil-landscape pattern expressed in areas with similar environmental conditions (e.g. climate,

geology, land use) is likely to be a useful predictor of where dry saline land issues are likely to occur

in the landscape. If so, the ability to predict these patterns will be important in managing these

areas more effectively.

The higher conductivities in LSU 3 may be due to soluble salts, transported magnetic material, or a

combination of both. Only more targeted sampling and detailed laboratory analyses will determine

that factor and no final conclusion should be drawn until that process is carried out.

34

Figure 14. Whole-of-landscape 3-D process model for Cootes case study area showing (i) 3D-aerial photograph drape of study area with boundaries of landscape-soil units (LSU), (ii) photographs of representative soil profiles for each LSU, (iii) geology, (iv) cross-section of typical toposequence showing the main morphological, saline and sodic soil-regolith features/layers and (v) groundwater and fresh surface water flow paths.

35

4. CONCLUSIONS AND FURTHER WORK For the two research sites each dominated by either subsoil expressed or surface expressed

(magnesia patch) dry saline land, EM-38, EM-31 and VMS used in combination shows strong

promise for obtaining high intensity, non intrusive, spatially continuous soil information.

These three geophysical techniques - together with topography and soil survey data - have

been used to: (i) produce maps showing the aerial extent of dry saline land and (ii), construct

a colour cross-sectional diagram or model to show the various saline and sodic soil

horizons/layers and water flow pathways (Figure 15).

Figure 15. Whole-of-landscape 3-D process model for Cootes case study area showing

(i) EM-38 map partly draped over the 3D-aerial photograph drape of study area with boundaries of landscape-soil units (LSU), (ii) photographs of representative soil profiles for each LSU, (iii) geology, (iv) cross-section of typical toposequence showing the main morphological, saline and sodic soil-regolith features/layers and (v) groundwater and fresh surface water flow paths. The EM-38 map designates high conductivity values in red (subsoil expressed dry saline land), medium values in yellow-turquoise and low values in dark blue.

36

Presently, the EM-38 method appears to be the method of choice for quick characterisation of

dry saline land in the Jamestown region. This technique has proven very successful for

detection of shallow lateral changes in the apparent electrical conductivity (ECa) of soils

(Figure 15). The EM-38 map and cross-section shows that subsoil expressed dry saline land

is confined mainly to Landscape Soil Unit 3, where salts have preferentially accumulated.

The accumulation of these salts in this part of the landscape can be explained by the barrier

to onward (down-slope) drainage formed by the sodic clays at the surface of Landscape Soil

Unit 4, blocking the flushing of sloping area salts out of the catchment. However, within

Landscape Soil Unit 3, it is evident that subsoil salt concentrations are lower in areas within

near-surface subsoil drainage areas due to the higher rates of freshwater flushing

experienced (Figure 15). This topographic flushing pattern is repeated at a finer scale in

surface expressed dry saline land at the Munduney study area where marked reduction in

ECa was measured in drainage lines. These studies highlight the usefulness of EM-38 as a

broad precursory investigative tool that can be used to direct and focus the more costly and

time-consuming detailed soil surveys.

These geophysical techniques (EM-38, EM-31 and VMS) - in conjunction with terrain

information and soil analyses - have been used to successfully help interpret discreet soil-

landscape patterns that have been attributed to dry saline land forming conditions. However,

to confirm these interpretations more quantitative work is required (e.g. geomorphologic

mineralogical and geochemical characterization).

Further work should also involve exploiting the regional perspective offered by linking ground-

based data to airborne geophysics and other regional scale data sets (soil mapping, terrain

and geology) to extrapolate the established patterns of dry saline land for focus study areas.

Thomas et al. (2003) describes some preliminary work using this approach by featuring

airborne K% gamma radiometrics in mapping soil-landscape patterns in the Jamestown study

area.

Finally, the conceptual toposequence model that we have “constructed” for the Cootes case study

area provides a powerful tool for communicating salt storage and salt mobilisation knowledge for

this complex landscape affected by dry saline land and dryland salinity, and a framework for

determining optimal patterns of regional land use and land management. We anticipate that the

model developed here could be applied to landscapes in the region with similar environmental

conditions (e.g. geology, rainfall, land use, topography, soils, etc.) to highlight whole-of-landscape

salt storage and mobilsation mechanisms.

37

5. ACKNOWLEDGMENTS We acknowledge the following people/organisations for their important contributions:

• the Cootes and Ashby families for access to their land.

• Mark Raven (CSIRO Land and Water) for X-ray diffraction analyses.

• Greg Rinder (CSIRO Land and Water) for drafting the 3-D process model.

• Mary-Anne Young, Rural Solutions SA (Jamestown) for help in site selection.

• James Hall (DWLBC), Richard Merry (CSIRO Land and Water) and Richard Cresswell

(BRS) for valuable editorial comments.

• In-part funding from the National Action Plan for Salinity and Water Quality.

Mark Thomas strongly acknowledges CSIRO Land and Water, DWLBC and CRC-LEME for their continued support.

38

6. REFERENCES Bigham J.M. R.W. Fitzpatrick and D.G. Schulze (2002) Iron Oxides. p 323 – 366. In J.B.

Dixon and D. G. Schulze (ed.). Soil Mineralogy with Environmental Applications. Soil Science Society America Book Series No 7. SSSA, Madison, Wisconsin.

Cass A, Walker RR, Fitzpatrick, RW 1996. Vineyard soil degradation by salt accumulation and the effect on the performance of the vine. p. 153-160. In: C.S. Stockley, R.S. Johnstone and T.H. Lee (eds.). Proceedings of the 9th Australian wine industry technical conference; July, 1995; Adelaide, South Australia.

da Costa, A.C.S., Bigham, J.M., Rhoton, F.E. and Traina, S.J. 1999. Quantification and characterization of maghemite in soils derived from volcanic rocks in southern Brazil. Clays Clay Min. 47:466-473.

Dijkerman, J.C. 1974. Pedology as a science: The role of data, models and theories in the study of natural soil systems. Geoderma 11 73-93.

Fitzpatrick, R.W., Fritsch, E. and Self, P.G. 1996. Interpretation of soil features produced by ancient and modern processes in degraded landscapes: V Development of saline sulfidic features in non-tidal seepage areas. Geoderma 69, 1-29.

Fitzpatrick R.W. and Merry, R.H. 2002. Soil-regolith models of soil-water landscape degradation: development and application. p. 130-138. In McVicar, T.R., Rui, L., Walker, J., Fitzpatrick, R.W. and Liu Changming (ed.), Regional Water and Soil Assessment for Managing Sustainable Agriculture in China and Australia. ACIAR Monograph 84. CSIRO Publishing, Melbourne, Australia.

Fitzpatrick R. W., Merry R. H., Cox J., Rengasamy P. & Davies P. J., 2003 Assessment of physico-chemical changes in dryland saline soils when drained or disturbed for developing management options. CSIRO Land and Water, Technical Report 02/03. CSIRO, 56pp. http://www.clw.csiro.au/publications/technical2003/tr2-03.pdf.

Fitzpatrick, R. W. and Riley, T.W. (1990) Abrasive soils in Australia: Mineralogical properties and classification. p. 404-405. In: Trans. 14th Int. Soil Sci. Soc. Conf., Kyoto, Japan. VII.

Fitzpatrick R. W., Thomas M., Cannon M. G., McThompson J. & Cootes T. R., 2004 Soils and land use of a sub-catchment of Freshwater Creek near Spalding, South Australia, CSIRO Land and Water (in preparation).

Fritsch, E. and Fitzpatrick, R.W. 1994. Interpretation of soil features produced by ancient and modern processes in degraded landscapes: I. A new method for constructing conceptual soil-water-landscape models. Australian Journal of Soil Research 32: 880-887, 889-907.

Herriot, R.I. 1942. The reclamation of highland "Magnesia" patches, a preliminary note on work being conducted at Mt Bryan East. South Australian Journal of Agriculture, pp 94-95.

Isbell, R.F. 1996. The Australian soil classification system. CSIRO, Publishing, Melbourne, Australia.

Isbell, R.F., Reeve, R. and Hutton, J.T. 1983. Salt and sodicity: in Soils: An Australian viewpoint, Division of Soils, CSIRO, pp.107-111. (CSIRO: Melbourne/ Academic Press: London).

Kennewell, B.K. 1999. Investigations into the management of dry saline land. PIRSA Technical Report No 272, June 1999, 81 pp.

Macumber, P.G. 1991. Interactions between Groundwater and Surface Systems in Northern Victoria. Dept Conservation and Environment, Victoria.

McDonald, R.C., Isbell, R.F., Speight, J.G., Walker, J. & Hopkins, M.S. (1990). Australian soil and land survey field handbook. 2nd Edition, (Inkata Press, Melbourne).

McNeill, J.D. 1980 Electromagnetic terrain conductivity measurements at low induction numbers. Technical Note TN-6, Geonics Ltd., Ontario, Canada.

Munday T., Walker G., Cresswell R., Wilford J. R., Barnett S. & Cook P., 2003 South Australian Salt Mapping and Management Support Project - An example of the considered application of airborne geophysics in natural resource management, in ASEG 16th Geophysical Conference and Exhibition, Adelaide.

National Land and Water Resources Audit (NLWRA) 2001. Australian Dryland Salinity Assessment 2000. National Land and Water Resources Audit, Canberra.

National Land and Water Resources Audit 2001. Australian Agricultural assessment 2001. Volume 2.

39

National Working Party on Acid Sulfate Soils. 2000. National Strategy for the Management of Coastal Acid Sulfate Soils. Published by NSW Agriculture, Wollongbar Agricultural Institute, Wollongbar NSW 2477. http://www.dpie.gov.au/dpie/armcanz/pubsinfo/ass/ass.html

Northcote, K.H. and Skene, J.K.M. 1972. Australian soils with saline and sodic properties. CSIRO (Aust.) Soil Publication No. 27.

Rayment, G. E. and Higginson, F.R. (1992) Australian Laboratory Handbook of Soil and Water Chemical Methods. Inkata Press. Melbourne.

Rengasamy, P. 2002. Transient salinity and subsoil constraints to dryland farming in Australian sodic soils: an overview. Australian Journal of Experimental Agriculture 42, 351-361.

Rengasamy, P. and Sumner, M.E. 1998. Processes involved in sodic behaviour. p. 35-50. In: M.E. Sumner and R. Naidu (eds.). Sodic Soils: Distribution, Properties, Management and Environmental Consequences. Oxford University Press.

Soil and Land Information (2002a) Atlas of key soil and landscape attributes of the Agricultural Districts of South Australia [CD ROM]. SaLI Group Department of Water Land and Biodiversity Conservation.

Soil and Land Information (2002b) Land Resource Information – Northern Agricultural Districts of South Australia [CD ROM]. SaLI Group Department of Water Land and Biodiversity Conservation.

Slavich, P.G. (1991) Measuring soil salinity in field screening trials for salt tolerance. In: Eds. N. Davidson and R. Galloway. Productive use of saline land. Proceedings of workshop held in Perth, Western Australia, 10-14 May, 1991. ACIAR Proceedings No. 42, 124p.

Thomas M., R.W. Fitzpatrick and G.S. Heinson 2003. Mapping complex soil-landscape patterns using radiometric K%: a dry saline land farming area case study near Jamestown, SA, In: Roach I. C. ed. 2003. Advances in Regolith, pp. 411-416. CRC-LEME.

Thompson, R. and Oldfield, F. (1986) Environmental magnetism. Ch.2. Allen and Unwin Ltd, London.

U.S. Salinity Laboratory Staff, 1954. Diagnosis and improvement of saline and alkali soils. USDA US Govt. Printing Office, Washington DC.

Williams, B.G., and Bullock P.R. 1989. The classification of salt-affected land in Australia. CSIRO Division of Water Resources, Technical Memorandum 89/8. pp11.

40

APPENDIX 1: Mineralogical data

Sample No. Locality / Soil Map Unit XRD trace

Number Layer silicate minerals LSU

SPMT 1.1 Munduney 'magnesia patch' 1 Chlorite Mica (CD) rutile

(T) Munduney

SPMT 1.2 Munduney 'magnesia patch' 2 Chlorite Mica (CD) rutile

(T) Munduney

SPMT 1.3 Munduney 'magnesia patch' 3 Chlorite Mica (CD) rutile

(T) Munduney

SPMT 1.4 Munduney 'magnesia patch' (rock)

Recent Chlorite, Mica (CD), pyrite (M), felspar (M), rutile (T)

Munduney

SPMT 2.1 Cootes, "F block" (upper) 4 Chlorite (T) Mica (D) 1 SPMT 2.2 Cootes, "F block" (upper) 5 Chlorite Mica (CD) 1 SPMT 2.3 Cootes, "F block" (upper) 6 Chlorite Mica (C(D) 1

SPMT 3.1 Cootes, "F block" (lower) 7 Chlorite (T) Vermiculite

(T), Mica (D) Kaolin (M) 3

SPMT 3.2 Cootes, "F block" (lower) 8 Chlorite (M) Vermiculite

(T), Mica (M) Kaolin (M) 3

SPMT 3.3 Cootes, "F block" (lower) 10 Chlorite (M) Vermiculite

(T), Mica (M) Kaolin (M) 3

SPMT 4.1 Cootes, SPM2 (crest site)

11 Chlorite (T) Mica (D) Smectite (T) and Kaolin (M)

1

SPMT 4.2 Cootes, SPM2 (crest site) 12 Chlorite (D) Vermiculite

(T), Mica (M) Kaolin (M) 1

SPMT 4.3 Cootes, SPM2 (crest site) 13 Chlorite (D) Vermiculite

(T), Mica (M) Kaolin (M) 1

SPMT 5.1 Cootes, F/water Creek gully face

14 Mica (D) Smectite (M) and Kaolin (M)

5

SPMT 5.2 Cootes, F/water Creek gully face

15 Mica (D) Smectite (M) and Kaolin (M)

5

SPMT 5.3 Cootes, F/water Creek gully face

16 Mica (D) Smectite (M) and Kaolin (M)

5

SPMT 6.1 Cootes, F/water Creek, wetland

17 Mica (CD) Smectite (CD) and Kaolin (M)

6

SPMT 6.2 Cootes, F/water Creek, wetland

18 Mica (CD) Smectite (CD) and Kaolin (M)

6

SPMT 6.3 Cootes, F/water Creek, wetland

19 Mica (CD) Smectite (CD) and Kaolin (M)

6

D = Dominant; CD – co-dominant; M = Minor; T = Trace

41

APPENDIX 2: EM 38, EM-31 and Volume magnetic susceptibility data

42

Cootes survey - Line 1

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 20 16 23 16 21 24 27 56 53 81 124 111 42 44 50 90 64 29 48 39 38 32 17 7.5 14 17 8.2 11 12 14 18 7.8 10 6.2 3.6 11 8.2 5 4 2.6 2.6 2 7.5 8.5 9.5 12 79 89 83 90 110 136

EM38 50 65 50 14 21 26 22 28 50 78 72 60 36 58 66 62 74 140 170 180 155 140 160 110 135 72 53 28 30 24 32 32 24 22 20 28 66 22 2 21 11 4 110 140 80 110 115 110 130 84 100 82 90

VMS 198 210 239 250 168 215 234 198 246 292 222 218 178 240 217 232 386 486 448 522 511 415 452 390 339 288 248 227 223 194 209 154 197 238 197 132 195 204 120 15 223 256 123 180 298 288 322 292 299 412 359 331 297 169

W E

43

Cootes survey - Line 2

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 72 58 30 30 28 23 34 52 67 86 120 110 93 92 78 112 102 71 45 62 50 36 21 36 46 49 39 17 14 9 18 17 19 16 8.4 6.3 4.8 8.2 5.7 4.4 4.4 4.8 3 11 6.2 3.8 7.2 22 75 83 69 69 65 73 53 85 95 125

EM38 40 36 40 50 44 39 52 56 68 74 100 88 82 62 69 84 52 70 52 92 115 150 155 185 215 160 130 160 180 140 42 54 42 57 120 30 24 24 40 25 12 14 14 22 21 17 11 120 115 105 100 92 84 100 79 78 105 120

VMS 156 155 197 185 252 215 227 252 252 193 213 220 213 214 196 198 183 225 216 323 524 540 442 500 779 450 535 594 482 507 258 235 267 283 298 267 155 191 246 200 245 250 283 235 272 234 290 250 304 259 284 290 274 299 272 284 302 394

W E

44

Cootes survey - Line 3

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 47 21 21 15 13 14 16 23 27 15 15 20 17 16 16 28 57 54 71 72 42 96 93 93 88 136128135136138133 87 72 83 58 97 65 89 66 68 71 54 77 130125140121130120 72 71 60 64 67 52 62 66 86 84 178

EM38 90 68 84 30 21 74 140140 49 52 46 140180170170150165160150130170200120 95 66 74 70 72 46 58 62 56 54 44 44 54 40 42 46 32 32 48 40 30 36 46 36 40 50 96 115 90 87 95 84 89 98 74 94 100

VMS 334314290312348384407424295261306429589520529535483529582473585538378511367289249243220224228242253278227238233242226220205198209179205182210170168307271281238303264261263340312341

W E

45

Cootes survey - Line 4

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 66 11 11 13 14 11 11 12 10 10 76 64 55 59 57 53 71 53 61 80 78 86 85 58 80 10 12 11 75 86 69 33 34 55 58 52 47 39 62 61 32 30 19 17 18 25 17 24 27 40 50 61 94 64 61 66 63 69 74 79 74 10 11 14

EM38 15 20 42 44 44 44 40 48 59 30 36 40 64 62 56 48 52 66 84 62 44 56 50 50 70 73 68 88 84 96 12 16 13 19 16 16 15 16 11 11 13 14 17 12 14 12 14 10 96 90 80 86 92 94 11 10 88 90 10 11 86 95 88 11 82

VMS 35 27 18 21 15 19 20 17 21 15 18 18 29 25 27 20 20 20 25 21 24 25 23 22 23 28 31 27 29 45 51 63 50 58 64 65 59 54 62 57 56 44 48 48 47 38 37 39 42 36 36 34 41 29 35 28 24 25 25 23 22 28 30 36

W E

46

Cootes survey - Line 5

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 46 36 83 132 96 96 81 84 83 92 91 68 40 90 80 61 63 61 65 66 58 70 77 82 87 88 61 92 96 88 62 65 59 67 62 70 40 40 34 57 55 52 48 30 36 40 60 77 88 93 77 61 90

EM38 81 72 68 52 65 38 40 74 68 75 27 15 21 13 18 48 48 52 50 60 53 44 56 47 43 62 34 46 56 46 72 75 92 100 110 130 123 138 105 110 132 150 32 96 80 79 70 78 73 83 86 84 105

VMS 402 396 396 339 273 314 296 288 299 215 215 237 260 211 222 285 319 272 328 296 295 270 292 321 227 325 285 233 345 303 399 396 421 549 602 530 515 661 554 576 534 551 444 447 374 375 334 339 369 336 364 333 357

W E

47

Cootes survey - Line 6

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 25 42 28 24 37 39 43 51 52 38 58 61 48 55 93 84 84 90 64 69 86 72 68 75 81 80 83 66 58 44 41 38 41 46 54 54 60 59 51 45 39 38 63 84 92 98 10 83 87 94 87 81 84 65 69 64 55 60 64 60 83 82 96 10 12

EM38 76 57 76 67 88 56 48 13 10 26 12 94 90 67 43 51 52 58 66 64 70 61 63 53 62 70 67 72 76 66 62 70 65 87 90 11 12 12 11 11 10 12 10 90 11 11 10 12 10 12 11 11 68 75 77 84 83 91 91 77 91 10 84 94 85

VMS 29 36 27 34 28 23 27 19 25 30 27 29 26 27 21 21 26 34 24 25 26 22 23 25 26 23 27 22 28 25 22 22 21 28 26 37 40 42 50 40 39 34 27 35 34 31 27 29 28 28 27 24 32 32 33 31 30 33 31 30 31 38 37 39 38

W E

48

Cootes survey - Line 7

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 15 19 15 14 10 14 11 11 10 7.2 5.6 7.2 8 12 14 27 55 52 67 78 102 110 96 105 65 57 70 54 45 53 52 53 50 54 56 49 44 50 62 64 65 47 45 81 88 100 102 95 99 98 95

EM38 58 77 45 28 38 38 28 24 28 42 68 57 24 51 27 82 110 81 117 85 88 97 76 73 46 51 41 36 50 50 48 53 60 60 60 74 69 68 76 70 76 84 85 96 100 100 110 89 100 120 80

VMS 467 347 439 357 343 368 227 307 378 408 335 305 344 352 368 339 428 375 405 354 335 370 333 309 273 236 347 255 223 269 253 239 270 324 268 682 284 324 336 265 275 322 291 333 311 272 292 262 246 298 255

W E

49

Cootes survey - Line 7

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 15 19 15 14 10 14 11 11 10 7.2 5.6 7.2 8 12 14 27 55 52 67 78 102 110 96 105 65 57 70 54 45 53 52 53 50 54 56 49 44 50 62 64 65 47 45 81 88 100 102 95 99 98 95

EM38 58 77 45 28 38 38 28 24 28 42 68 57 24 51 27 82 110 81 117 85 88 97 76 73 46 51 41 36 50 50 48 53 60 60 60 74 69 68 76 70 76 84 85 96 100 100 110 89 100 120 80

VMS 467 347 439 357 343 368 227 307 378 408 335 305 344 352 368 339 428 375 405 354 335 370 333 309 273 236 347 255 223 269 253 239 270 324 268 682 284 324 336 265 275 322 291 333 311 272 292 262 246 298 255

W E

50

Cootes survey - Line 9

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 18 15 11 14 9 11 11 11 10 11 8 11 12 12 18 16 14 21 48 66 50 56 51 50 87 108 118 130 121 112 88 69 53 50 45 42 66 79 88 75 50 50 61 79 81 89 84 92 99 87 67

EM38 20 23 23 30 32 56 30 44 12 42 68 61 76 40 73 84 82 120 125 120 115 105 130 120 105 110 110 100 88 86 68 66 69 76 72 87 64 86 68 68 94 105 100 110 92 100 100 90 94 92

VMS 287 360 300 339 387 354 277 254 241 354 363 324 321 299 336 292 333 324 355 322 362 364 375 408 381 374 418 302 313 374 266 260 245 325 281 258 253 321 312 278 271 329 268 246 261 263 290 253 235 275 250

W E

51

Cootes survey - Line 10

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 14 12 13 36 38 42 16 15 26 14 16 16 12 13 13 18 17 17 44 30 26 20 26 53 58 73 62 67 65 82 92 73 42 55 60 48 42 37 38 49 48 45 45 60 84 84 82 88 90 89 62 94 71 78 56 50 50 56 57 60 62 60 54 49 44 58 75 72 80 64

EM38 54 74 82 70 66 64 94 89 90 98 89 12 11 58 66 81 88 75 14 11 11 13 13 13 19 17 14 13 12 96 13 90 86 76 85 66 82 82 69 64 84 94 82 11 10 10 11 96 89 77 88 11 81 64 69 70 78 83 84 85 90 96 97 91 10 95 10 50 70 50

VMS 20 23 35 25 28 41 32 34 26 32 31 35 35 33 36 40 40 38 42 43 35 38 48 42 57 66 62 45 43 35 29 49 33 29 33 29 24 24 29 34 31 28 28 34 29 29 28 25 24 25 26 25 38 27 28 27 32 31 30 30 28 33 31 29 29 29 34 38 37 30

W E

52

Cootes survey - Line 11

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 150 192 122 78 80 108 103 82 87 56 94 70 32 33 37 20 21 19 25 34 55 67 70 60 47 54 78 41 34 103 87 108 72 58 42 38 34 34 32 32 46 46 48 42 41 52 50 70 61 64 64 68 76 73

EM38 52 50 36 52 48 80 67 48 48 54 44 24 43 75 76 82 70 60 110 118 112 140 120 130 110 115 105 68 52 68 69 87 75 72 60 39 47 50 49 30 47 46 50 83 71 71 79 85 72 91 74 78 73 58

VMS 156 108 145 256 251 296 261 213 257 270 264 219 364 309 373 374 357 375 426 410 493 560 552 573 520 450 440 381 444 316 469 448 372 279 325 311 326 293 312 302 321 312 291 341 364 352 298 299 524 280 279 265 269 312

W E

53

Cootes survey - Line 12

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 18 29 70 77 88 77 54 56 80 56 62 59 52 43 40 66 41 51 58 52 63 11 12 91 60 54 64 77 70 67 59 56 54 65 69 11 11 81 40 36 52 46 42 48 42 41 50 76 10 86 66 41 44 57 54 50 49 65 60 62 58 40 51 50 51 56 50 50

EM38 27 27 25 60 48 20 36 52 53 50 69 33 50 27 46 32 34 50 50 42 44 52 66 59 22 18 30 32 22 39 22 26 34 28 48 44 46 45 34 36 34 34 32 38 80 70 76 71 79 82 74 74 66 82 68 70 60 84 70 60 74 73 65 84 82 90 78 96

VMS 28 28 26 24 30 17 22 20 21 26 23 21 22 11 22 18 23 26 23 19 20 24 28 40 18 19 22 20 25 32 24 24 20 20 27 25 24 20 22 26 34 22 20 23 21 23 24 27 27 24 22 22 22 21 27 33 28 32 32 29 30 32 27 35 32 31 30 42

W E

54

Cootes survey - Line 13

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 7.5 8 23 28 44 85 49 24 58 93 130 66 56 43 57 71 97 133 87 57 50 65 62 63 108 95 100 110 100 82 86 78 78 58 44 42 67 68 55 61 47 78 36 32 48 44 38 39 68 84 110 62 63 61

EM38 42 38 72 115 54 90 96 86 73 52 64 41 42 44 60 66 90 65 46 60 85 59 51 56 82 70 72 74 77 89 82 83 82 66 57 83 69 70 80 74 69 66 52 63 84 82 82 115 93 75 74 71 69 88

VMS 420 443 317 320 286 307 376 440 357 338 257 234 332 212 269 262 404 219 238 282 326 267 267 228 330 257 272 274 265 250 251 313 250 206 322 271 302 278 362 292 318 236 213 267 287 316 336 357 302 327 319 283 285 323

W E

55

Cootes survey - Line 14

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 34 36 29 40 68 10 14 11 11 77 49 78 78 82 40 71 64 70 68 80 82 56 59 85 64 49 40 50 58 52 54 58 40 51 30 39 32 34 34 38 50 48 38 44 39 38 34 46 69 84 76 78 78 61 60 63 61 57 62 61 56 55 67 75 54 64 94 11

EM38 72 74 82 70 91 96 86 72 74 68 78 82 75 30 65 10 54 50 72 74 80 64 70 91 11 11 13 12 12 12 11 14 90 12 80 91 73 88 74 47 63 60 56 71 67 68 67 88 80 10 69 88 94 83 82 94 96 81 77 82 93 11 96 10 81 11 71 28

VMS 41 32 28 38 36 30 25 27 33 37 39 29 29 21 33 15 26 31 30 28 22 25 30 39 28 50 50 53 53 38 46 53 39 41 43 37 35 30 36 51 31 23 25 29 32 29 35 31 29 29 29 28 26 28 28 32 30 36 36 30 32 31 40 42 34 42 48 25

W E

56

Cootes survey - Line 15

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 4.8 4.8 4.2 6.8 17 7.5 6.5 8 8 60 47 27 72 90 12 11 12 11 44 67 70 60 40 40 12 9 10 10 13 13 15 44 21 16 16 26 14 12 20 15 16 20 34 13 13 16 29 56 28 40 42 50 46 37 27 30 39 34 40 42 86 82 75

EM38 45 44 20 64 28 70 55 68 36 78 64 66 95 78 45 73 55 38 70 68 25 40 11 79 50 76 11 12 91 10 11 16 12 13 13 13 16 15 18 19 20 20 19 14 16 13 12 91 70 70 60 66 84 68 50 73 67 69 82 84 75 62

VMS 30 16 31 21 45 28 30 35 31 23 45 35 42 29 23 25 26 27 25 30 31 26 26 34 40 27 27 40 41 41 34 43 38 44 48 50 60 61 55 77 73 69 88 81 73 65 50 59 44 36 27 24 29 33 31 33 30 33 24 32 30 31 44

W E

57

Cootes survey - Line 16

0

50

100

150

200

250

300

ECa

(mS

m-1

)

0

150

300

450

600

750

900

VMS

(x10

-8 m

3 kg)

EM31 5 5 6 7 7 6 7 6 9 18 23 56 14 11 82 86 35 36 34 30 45 15 10 15 5 8 5 8 7 10 10 10 19 11 13 9 8 4 6 5 10 12 15 16 13 13 16 17 28 29 41 29 30 36 35 11 28 28 30 33 46 45 48 38 45 37 44 58 68 56 76 74 66 70 72 70 50 89

EM38 14 22 28 80 74 34 76 33 94 90 10 78 83 90 66 76 77 74 23 80 90 12 50 44 77 65 46 61 74 44 52 36 13 68 12 85 92 13 20 19 12 15 17 16 14 97 19 21 19 12 11 11 89 11 13 12 10 96 11 11 12 11 13 98 92 93 88 93 98 10 10 96 90 87 92 89 93 80

VMS 30 10 26 35 42 37 45 42 41 41 35 27 36 24 21 24 23 29 15 27 31 36 38 39 27 25 25 35 36 33 30 25 35 45 40 54 57 70 63 66 62 60 63 53 73 53 51 56 58 40 46 30 33 26 29 30 25 29 32 32 34 35 36 40 34 40 33 37 32 34 39 33 32 35 39 37 37 49

W E

58

Munduney survey - Line 1

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 17 12 19 16 19 8 11 18 16 19 11 12 9 12 10 9 9 9 8 10

EM38 36 27 30 44 35 22 49 31 29 23 30 30 25 20 8 37 22 30 50 50

VMS 210 151 130 170 179 146 122 148 186 186 145 149 169 119 95 81 135 227 220 251

NE SW

59

Munduney survey - Line 2

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 14 13 17 15 19 17 16 15 20 24 17 18 14 19 12 9 9 9 13 15

EM38 20 18 48 32 32 46 35 46 44 19 40 54 35 38 29 40 46 46 55 53

VMS 193 115 165 153 107 161 118 168 157 148 154 194 177 193 70 148 184 228 358 255

NE SW

60

Munduney survey - Line 3

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 13 12 12 11 9 6 21 14 12 17 18 18 15 12 15 17 15 14 11 13 14

EM38 50 36 34 35 26 12 16 38 63 36 40 43 33 58 50 56 27 28 35 33 10

VMS 218 184 195 190 91 93 110 154 191 184 171 162 168 200 155 168 155 151 173 170 146

NE SW

61

Munduney survey - Line 4

0

10

20

30

40

50

60

70

80

Eca

(mS

m-1

)

0

50

100

150

200

250

300

350

400

VMS

(x10

-8 m

3 kg)

EM31 13 12 13 11 11 24 9 11 14 15 16 18 19 16 20 17 13 12 11 12 14

EM38 44 54 42 24 18 4 11 19 45 38 42 30 40 47 28 45 28 40 17 54 35

VMS 243 234 250 173 115 47 78 105 178 179 200 188 187 184 158 188 142 190 111 195 199

NE SW

62

VMS versus EM38

y = 2.415x + 81.85R2 = 0.4169

0

50

100

150

200

250

300

350

400

0 10 20 30 40 50 60 70

EM38

VMS

63

VMS versus EM38 - Munduney Line 4

y = 3.3074x + 57.727R2 = 0.7765

0

50

100

150

200

250

300

0 10 20 30 40 50 60EM38

VMS

CSIRO Division of Soils 64 Technical Report xx/1996