Assessment of physico-chemical changes in dryland saline soils … · 2005-10-14 · CSIRO LAND and WATER Assessment of physico-chemical changes in dryland saline soils when drained

C S I R O L A N D a nd WAT E R

Assessment of physico-chemical changes in

dryland saline soils when drained or disturbed

for developing management options

Prepared by:

RW Fitzpatrick, RH Merry, JW Cox, P Rengasamy and PJ Davies1 1 1 2 1

1

2

CSIRO Land and Water, Private Bag 2, Glen Osmond, South Australia 5064

University of Adelaide, Private Bag 1, Glen Osmond, South Australia 5064

CSIRO Land and Water

Technical Report 2/03, January 2003

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Citation Details:

Fitzpatrick, R.W., Merry R.H, Cox J.W., Rengasamy P and P.J. Davies (2003) Assessment of physico-

chemical changes in dryland saline soils when drained or disturbed for developing management options.

Technical Report 2/03. 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/

CSIRO Land and Water Technical Report 02/03, January 2003 i

EXECUTIVE SUMMARY

Background

Salinisation of land and water resources is a growing problem and concern in the rainfed agricultural regions

of Australia. While much research effort is now focussed on predicting the risks of catchment landscapes

becoming salinised in the future, community efforts are directed towards minimising the spread of dryland

salinity and reclaiming saline affected landscapes at farm, catchment and regional scales through the

adoption of better management practices.

Little of a specific nature is known about the physico-chemical changes in Australian inland saline soils that

occur when drained or disturbed, partly because saline soils have generally been considered to have little

agricultural value. Furthermore, there are various definitions of ‘saline soil’, depending on the conditions

under which they form and their morphological, physical, chemical and biological properties. It is also widely

recognised that some saline landscapes in southern Australia have already reached a state of irreversibility.

In other saline landscapes, knowledge of how the underlying aquifer responds to changed land

management and implementation of appropriate remedial action can minimise or possibly reverse the

spread of dryland salinity.

Outcomes

This technical report has assembled contemporary knowledge on the processes of soil salinisation (from a

review of published and unpublished literature and the authors’ investigations and observations at 17 paired

sites in eight different Groundwater Flow Systems across southern Australia). It has advanced new

concepts and practical information, provided to policy makers and local stakeholders at conference and

workshop presentations, and as popular articles and fact sheets, which will aid the tackling of engineering

and agronomic solutions for remediation of saline soils of southern Australia.

Particular emphasis has been directed to understanding the physico-chemical changes that operate when

dryland saline soils are drained or are otherwise disturbed, such as when annual crops and pastures are

replaced by perennial vegetation that dry the profile, engineering works are installed, pugging occurs where

animals grazing waterlogged soils and erosion develops. It also covers the risk of discharge of pollutants

from the land into regional water bodies. No attempt has been made to address salinity threats in irrigated

regions, which is also an important national issue.

Firstly, a classification scheme has been developed that identifies 22 types of dryland saline soils with

differing physico-chemical and hydrological properties, existing in dryland farming regions of southern

Australia (Figure 5; Table 1). Criteria used to distinguish soil classes were based on hydrology (presence or

absence of groundwater in the root zone), observable soil and landscape features and the dominant soil

chemistry associated with the different processes of salinisation in surface and sub-soil horizons. The

CSIRO Land and Water Technical Report 02/03, January 2003 ii

scheme covers primary saline soils where groundwater is naturally shallow, secondary saline soils where

saline groundwater has become shallow (dryland salinity), and dry saline land (transient salinity) where the

soil is not hydrologically connected to a saline groundwater table. Importantly, these different types of saline

soils will require different remediation treatments and, accordingly, preferred management options have

been associated with each class of salinised soil.

Secondly, the author’s investigations at 17 paired sites in eight different Groundwater Flow Systems across

southern Australia (Appendix 1) indicated that the progressive development of saline environments are

being caused by different physico-chemical processes when land is drained or disturbed. Indeed, detailed

investigations at toposequence scales indicate that different processes are likely to be operating at different

landscape locations within the same catchment.

In reviewing the accumulated field and laboratory evidence, three generic conceptual soil-regolith models

have been developed that summarise the complex physico-chemical processes involved in the changes that

lead to different soils (e.g. sodic, eroded, saline –halitic or gypsic, acid sulfate – sulfidic or sulfuric) and poor

water quality (mobilised salts and soil particles) when a saline landscape is drained or otherwise disturbed.

The models include:

Soils progressively affected by sodium and chloride in ground waters (halite dominant) as illustrated

in Figure 6. Catchment examples are given in Table 2;

Soils progressively affected by sulfur, sodium and chloride in ground waters (sulfidic, gypsic) as

illustrated in Figure 7. Catchment examples are given in Table 3; and

Soils progressively affected by transient salinity in the root zone (dry saline land), caused by

restricted permeability within sodic sub-soil layers as illustrated in Figure 8. Catchment examples

are given in Table 4.

Thirdly, the three generic models, together with the 22 soil types and their physical (e.g., soil texture) and

chemical indicators, were used to construct eight simplified Soil Salinisation Categories (Table 5). To

achieve this we combined primary and secondary salinity types because their processes, properties and

management are similar.

Fourthly, a set of best management practices (BMPs) for each of the eight simplified Soil Salinisation

Categories has been developed (Table 5). Those soil categories with saline soils that have dominantly

sulfidic and sulfuric materials should not be drained because they are difficult to treat, given that with

progressive drying out of the upper soil profiles acid sulfate soils develop with severe chemical and physical

problems. These soils are best left in a salinised condition supporting native wetland or salt tolerant plants.

However, if land management has resulted in lowering watertables and draining soils, lime will be needed to

be applied to the drained and acidified soils and discharge waters. In contrast, those soil categories that do

not contain high concentrations of sulfur but dominantly Na+ and Cl- ions can be drained but will require pre-

treatment depending on soil texture (e.g. application of gypsum, ripping, mulching and vegetation). The

CSIRO Land and Water Technical Report 02/03, January 2003 iii

salinity indicators should also prove to be useful tools for monitoring improvements in landscape health

when remedial treatments have been imposed to reclaim or minimise further risks of soil salinisation.

Future Research, Extension and Development of a National Network and Database

The data used to develop the new classification of saline soils, the physico-chemical models predicting what

will happen when the saline soils are drained or disturbed, and the implementation of best management

practices are based on comprehensive datasets from paired sites in 11 catchments (mostly in SA and Vic)

and 6 less complete datasets from other catchments located in southern Australia. Similar data sets are

scarce for Western Australia and New South Wales and no such data exists for Tasmania, Queensland and

Northern Territory. Little long-term monitoring has occurred at any site.

As a high priority under the National Action Plan for Salinity and Water Quality framework a coordinated

national network of dryland saline soil sites should be established (incorporating the 17 existing sites used in

this project) to provide long-term field sites for monitoring property changes in saline soils over time. These

could include:

More case studies (some involving long-term monitoring) are needed in high priority areas

especially where major regional drainage works are being constructed (e.g., in south-western

Western Australia, south-east South Australia) and New South Wales (including sites and data

collected by Semple and coworkers, e.g., Semple et al. 1996; Semple and Williams 2002) to verify

the classification, the models and the generalised best management practices.

Case studies should also be established in Tasmania, Northern Territory and Queensland.

More effort directed towards training and extension using the principles established in this report,

including revision of the current fact sheet on the NDSP website.

Further development of the proposed environmental risk assessment plan in conjunction with

stakeholders in each region where risk is high.

Experimental quantification of long-term changes in saline soils needs to be implemented. This should

include:

Field experiments involving relevant management treatments (e.g. mulching, gypsum application,

reintroducing native wetland vegetation) in different groundwater flow systems.

Replicated permanent plots, sufficiently large in area to accommodate repeated sampling over time.

Suitable archiving of all soil and water samples so that long- and medium -term temporal trends in a

comprehensive set of properties (measured using standard methods) can be tracked.

CSIRO Land and Water Technical Report 02/03, January 2003 iv

TABLE OF CONTENTS

EXECUTIVE SUMMARY...................................................................................................................i

Background.............................................................................................................................................................. i

Outcomes................................................................................................................................................................. i

Future Research, Extension and Development of a National Network and Database.....................................iii

INTRODUCTION ..............................................................................................................................1

Background.............................................................................................................................................................1

Project Objectives and Outcomes.........................................................................................................................1

Definition of Saline Soils ........................................................................................................................................2

Knowledge of Salt Affected Soils in Australia ......................................................................................................4

Soils affected by dryland salinity and saline groundwater ............................................................. 4

Sodic soils ...................................................................................................................................... 4

Dry saline land (subsoil and surface expressed) (transient salinity) .............................................. 5

Generic properties of saline soils ................................................................................................... 6

Effects of salinity on plant growth................................................................................................... 6

METHODOLOGY .............................................................................................................................7

Location of Case Study Sites ................................................................................................................................7

Classifying Saline Soils..........................................................................................................................................8

Development of Generic Soil-regolith conceptual Models ................................................................................11

PROPERTIES OF SALINE SOILS AND HOW THEY CHANGE WHEN DISTURBED OR DRAINED: THREE GENERIC CONCEPTUAL MODELS ...........................................................12

MODEL 1. Soils Influenced by Sodium And Chloride Groundwaters (Halite Dominant)................................12

MODEL 2: Soils Influenced from Sulfur plus Sodium and Chloride Groundwaters (Sulfidic, Gypsic)...........13

MODEL 3: Transient Salinity in Root Zones Caused by Restrictive and Slowly Permeable Sodic Subsoil Layers....................................................................................................................................................................16

Dry saline land with subsoil expression (transient salinity) .......................................................... 17

Dry saline land with surface expression (magnesia patches) ...................................................... 18

Common Observations on Changes in Saline Soils when Drained or Disturbed ...........................................19

GENERAL BEST MANAGEMENT PRACTICES .........................................................................21

General Best Management Practices for Saline Soils.......................................................................................21

Soil categories that should not be drained - but if drained will require additional treatment...........................21

Soil categories that can be drained but will require pre-treatment ...................................................................21

Capacity to Reverse Soil Salinisation after Drainage........................................................................................22

Risk Management Planning for Draining Saline Soils .......................................................................................22

SUMMARY AND RECOMMENDATIONS FOR FUTURE WORK...............................................26

Summary of Project..............................................................................................................................................26

Priorities for the Future.........................................................................................................................................27

CSIRO Land and Water Technical Report 02/03, January 2003 v

REFERENCES AND FURTHER READING .................................................................................28

GLOSSARY....................................................................................................................................32

APPENDIX 1: List and summaries of case studies ..................................................................36

APPENDIX 2: Steering committee, contributors and acknowledgments ..............................54

APPENDIX 3: Draining Saline Land – Risk Planning and Environmental Assessment.......55

Introduction ...........................................................................................................................................................55

Concept Planning ......................................................................................................................... 55

Drainage Planning........................................................................................................................ 55

Risk Management ................................................................................................................................................55

Risk management framework....................................................................................................... 55

Establish the context .................................................................................................................... 56

Identify risks.................................................................................................................................. 56

Analysis of risks............................................................................................................................ 57

Evaluation of risks ........................................................................................................................ 57

Treatment of risks........................................................................................................................ 57

Developing Mitigation Measures........................................................................................................................58

Operational phase mitigation measures....................................................................................... 58

Construction phase mitigation measures ..................................................................................... 58

Monitoring .............................................................................................................................................................58

Documentation .....................................................................................................................................................58

CSIRO Land and Water Technical Report 02/03, January 2003 1

INTRODUCTION

Background

Considerable research effort and on-ground action have been devoted to lowering saline watertables by

reducing recharge or disposing of discharge water (using salt tolerant plants, drains or groundwater

pumping). However, even if this can be achieved economically, there is no guarantee that the reclaimed soil

will be returned to its original productive state. Little of a specific nature is known about the physico-chemical

changes in Australian inland saline soils (only) that occur when drained or disturbed, partly because saline

soils have generally been considered to have little agricultural value. Furthermore, there are various

definitions of ‘saline soil’, depending on the conditions under which one forms and its morphological,

physical, chemical and biological properties.

This report does not deal with irrigated or coastal saline soils but is confined to inland saline soils. For more

generalised information regarding drainage, water quality and management of irrigated or coastal saline

soils the following publications are recommended:

Christen, E.W., and Ayars, J.E. (2001) Subsurface drainage system design and management in irrigated agriculture: Best Management Practices for reducing drainage volume and salt load. Technical Report 38-01. CSIRO Land and Water, Griffith, NSW, Australia. 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

Project Objectives and Outcomes

This National Dryland Program project titled “Biogeochemical and physical processes in saline soils and

potential reversibility” (CLW 27) generally aimed to:

Improve understanding of the chemical, physical and biological changes in salinised soils when they

are drained or disturbed.

List the critical datasets required to provide the information that will allow informed decisions on how

to suitably manage or reclaim saline areas and predict their response to disturbance or drainage.

Make recommendations for future work.

This was done by:

Reviewing the literature on dryland saline soils and changes that occur when these soils are drained

or disturbed.

Characterising the morphological, chemical, physical and biological changes in dryland saline soils

and the potential for reversing changes at 17 paired sites in eight different Groundwater Flow

Systems across southern Australia (Appendix 1).

Developing a user-friendly classification system for categorising inland saline soils as defined by

hydrology, landscape feature and soil chemistry.


Developing conceptual soil-regolith toposequences models from each case study, which defined

and tracked biogeochemical processes and changes that operated following either landscape

drainage or disturbance.

Developing three generic conceptual soil-regolith toposequences models that encapsulated the

various processes observed at the 17 case study sites.

Identifying critical morphological, chemical and physical indicators for classifying, monitoring and

interpreting different types of salinisation processes.

Recommending generalised principles that lead to the implementation of best management

practices for ameliorating or reclaiming identified categories of inland saline soils.

Outcomes of this project:

A literature review was published, which summarised contemporary knowledge on processes

leading to salinisation of Australian dryland landscapes (Fitzpatrick et al. 2001a; Is dryland soil

salinisation reversible? National Dryland Salinity Program (NDSP) web site, 15pp

http://www.ndsp.gov.au/10_NDSP_projects/05_project_descriptions/35_environment_protection/pr

oject_25.htm).

A range of workshops was held in southern Australian states to provide information to local

stakeholders and policy makers on the issues and outcomes of the project. Field trips were then

held to collect soil and water samples and provide further practical information.

A range of popular articles including a Fact Sheet was published (Fitzpatrick et al. 2001b; Is dryland

soil salinisation reversible? National Dryland Salinity Program (NDSP) web site. 2 pp:

http://www.ndsp.gov.au/Pdfs/can_salinisation.pdf

A database with selected results, presentations at conferences and publications of field

investigations from the 17 case studies (Appendix 1).

This technical report “Assessment of physico-chemical changes in dryland saline soils when

drained or disturbed for developing management options”, which classified different dryland saline

soils resulting from an understanding of the complex soil-landscape processes in each of the field

sites. It also indicated how each saline soil-landscape might be best managed or reclaimed and

makes recommendations for future work.

Definition of Saline Soils

For the purposes of definition, “primary” is taken to mean land condition that is essentially unaffected by

European land use changes, that is, in a natural state, while “secondary” is taken to mean land condition

changes induced as the result of European land use changes, for example, land clearance. Saline soils

have been variously categorised in the scientific literature as:

Primary or natural saline soils - where groundwater is naturally shallow (Figure 1).

Secondary saline soils (dryland salinity) - where groundwater has become shallow as the result of

European land use changes (Figure 1).

Dry saline land (transient salinity) subsurface and surface expressed - not hydrologically connected

to a saline groundwater table. Subsurface expressed is where high levels of salinity occur in the


rootzone or subsoil with salinity trends increasing from the surface (ECse 2-8 dS/m) to subsoil

(ECse 4-16 dS/m). Surface expressed is where the salinity is very high at the surface (ECse >16

dS/m) (so-called “magnesia patches”) (Figure 1); Exists in both primary (naturally) and secondary

(induced) forms.

Slightly, moderately, very and highly saline soils - based on soil electrical conductivity (ECse) and

the productivity of salt tolerant plant species (glossary).

Sodic saline soils - based on pH, exchangeable sodium percentage, sodium adsorption ratio

(glossary) and EC (ECse and EC1:5).

Alkaline saline soils, based on high pH (>8), presence of sodium carbonate and high EC values.

Actual acid sulfate saline soils, based on low pH (<3.5), presence of sulfur and high EC values.

Potential acid sulfate saline soils, based on high pH (>3.5), presence of sulfur and high EC values.

Figure 1. Primary salinity (caused by saline groundwater), salt bulges (below the root zone

of former native vegetation), secondary salinity (rising saline groundwater and salt

accumulation due to evaporative water loss in saline seeps) and dry saline land

(transient salinity) (modified from Fitzpatrick et al. 2001a).

DRAINAGE AND DISTURBANCE OF SALINE SOILS

Most drainage and disturbance of saline soils results, ultimately, from human action. Some erosion and

vegetation changes can result from natural processes, and periods of low recharge (drought), may also

lower watertables. These actions can be summarised as follows:

Engineering - groundwater pumping, construction of drains (Sinclair Knight Merz 2001).

Vegetation - reducing recharge, lowering of water tables by using deep-rooted plants.

Erosion - e.g., local lowering of watertable by gully formation and deepening; removal of

surface soil layers by wind or sheet erosion exposing hardpans.


Agriculture - e.g., tillage, pugging by cattle creating densipans or introducing oxygen to sulfidic

discharge areas.

Understanding watertable hydrology, soil properties and processes is fundamental to selecting the best

options for drainage and the most appropriate management of the soils when they are drained.

Knowledge of Salt Affected Soils in Australia

Soils affected by dryland salinity and saline groundwater

Approximately 5.7 million hectares of Australia’s agricultural and pastoral zone have a high potential for

developing dryland salinity through shallow groundwater. Dryland salinity coincides with those agricultural

zones in hydrological disequilibrium caused since European settlement by extensive clearing and the

replacement of native vegetation with shallow rooted, water-inefficient annual crops and pastures. A critical

combination of hydrologic disequilibrium and a source of salt are necessary for a landscape to suffer from

dryland salinisation. The physiographic and land attribute combinations that are considered to have the

greatest potential for future dryland salinity to occur are hydrogeology; land use, climate and landform.

Predictions based on these attributes indicate that unless effective solutions are implemented, the area of

dryland salinity could increase to 17 million hectares by 2050 (Figure 2; NLWRA 2000).

Figure 2. Areas at risk of dryland salinity by 2050 (NLWA 2000)

Sodic soils

A large proportion of soils that have a high potential for developing dryland salinity through shallow

watertables are sodic and/or duplex (Figure 3; Northcote and Skene 1972). Duplex soils have a definite and

marked difference in texture between A and B horizons: a visually distinct boundary exists between these

horizons. More than 60% of the 20 million ha of cropping soils in Australia are sodic and dryland farming is

mainly practiced on these soils. More than 80% of sodic soils in Australia have dense clay subsoils with high


sodicity and alkaline pH (>8.5). Perched watertables may form within many of these subsoils in some years.

Depending on landscape position and the dominant flow pathways within these soils, salt and other

chemicals that form or accumulate within the rootzone under redoximorphic conditions, and can be

redistributed within the catchment. Where interceptor drains have been installed to lower shallow

watertables drainage waters from duplex soils can also be high in solutes.

Figure 3. Distribution of saline and sodic soils (Northcote and Skene 1972).

Dry saline land (subsoil and surface expressed) (transient salinity)

Poor water transmission properties of sodic subsoils, low rainfall in dryland areas, transpiration by vegetation

and high evaporation during summer has caused accumulation of salts in the root zone soil layers. This

transient salinity (Dry saline land - subsurface and surface expressed), which is not hydrologically connected

to a saline groundwater table (Figure 1) is extensive in many sodic soil landscapes in Australia (Figure 3).

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 transient 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.


Generic properties of saline soils

Soils with high amounts of soluble salts are called saline soils. They often exhibit a whitish surface crust

when dry. Salts found in Australian soils are of three types: (i) chlorides (Cl), (ii) sulfates (SO4) and (iii)

carbonates (CO3). Most saline soils in Australia have high amounts of chloride salts. However, in some

parts of Australia, extensive areas of saline soils are also composed of sulfate salts. Saline soils with high

amounts of carbonates of sodium (sodium bicarbonate) may also occur, and are usually associated with

coarse textured soils. The solubility of gypsum (calcium sulfate, CaSO4) is commonly used as the standard

for comparing solubilities of salts. Consequently, salts more soluble than gypsum are considered to be

soluble and cause salinity such as sodium chloride (table-salt, NaCl) and sodium sulfate (thenardite,

Na2SO4). Salts less soluble than gypsum such as calcite (lime or calcium carbonate, CaCO3), which is

commonly found in Australian soils are considered insoluble and do not cause salinity. In some soils,

sulfate-rich (e.g. saline acid sulfate soils) or boron-rich salts can be found in excessive or toxic amounts for

plant growth.

Effects of salinity on plant growth

Soil structure in sodic soils is poor and permeability is low. If a sodic clay layer occurs near the surface of

sodic soils it often acts as a barrier to roots. Hence, most roots are restricted to the topsoil above the

claypan, because movement of water, nutrients, and gases in sodic B horizons is too slow. When dry, the B

horizon can be so hard, that it physically restricts root penetration. The overall effect on plant growth is one

of stress similar to that caused by extremely dry or saline conditions.

High soil salinity (high EC) causes dehydration of plant cells, which in turn results in reduced plant growth

and often death. Dissolved salts cause dehydration of plant cells because the osmotic potential of soil water

is decreased. Water will flow from the high osmotic potential (low salts in plant cells) to low osmotic potential

(high salts in soils). Thus, plants simply cannot extract water from soils when soil solutions have lower

osmotic potentials than plant cells. The effect on plants is similar to drought stress. Yields of many crops

are reduced when the soil extract EC reaches 4 dS/m. Yields will decline proportionately as EC levels

increase above 4 dS/m. Some crops, such as sugar beets, are tolerant to EC between 4 and 8 dS/m. The

growth and yields of most crops are affected at EC values > 16 dS/m.

Further reading: Previous reviews on saline and sodic soils (e.g. Fitzpatrick et al. 2001a) have detailed their

wide range of occurrences and properties, and our aim here is not to duplicate earlier reports. Additional

information are reviewed and discussed by many workers, and readers are referred to the following

references and supplemental references provided in the list of references:

Wood (1924); U.S. Salinity Laboratory Staff (1954, 1990); Macumber (1991); McFarlane and Cox (1992);

Allan (1993), Dyson (1983, 1994); Nulsen (1993); George et al. (1995, 1997); George (1992); Tickell (1994);

Cox and McFarlane (1995); Fitzpatrick et al. (1996); Rengasamy and Sumner (1998); Shaw et al. (1998);

Maschmedt (2000); NLWRA (2000); White et al. (2000); Barnett (2000); Coram et al. (2001); Heng et al.

(2001); NLWRA (2001); Cox et al. (2002); Rengasamy (2002); Semple et al. (1996); Semple and Williams

(2002); Department of Water Land and Biodiversity Conservation (2002).


METHODOLOGY

Location of Case Study Sites

To understand salinity processes across Australia, we need to know how groundwater systems respond to

increased recharge. We also need to know how the groundwater systems respond as recharge varies over

time. Groundwater systems across Australian landscapes differ and therefore their contribution to dryland

salinity also differs. A catchment classification approach to categorise Australia's groundwater flow systems,

has been developed by Coram (1998; Coram et al. 2001). The location of the 17 paired (case study) sites

across southern Australia (Appendix 1), which were chosen in consultation with state authorities and

community groups (Appendix 2), are shown in Figure 4 in relationship to the Groundwater Flow Systems

(GWFS). Groundwater Flow Systems are based on recharge and flow behaviour and identifies groundwater

flow systems where particular management activities will lead to similar responses. Groundwater flow

systems can be classified as local, intermediate or regional.

Local groundwater flow systems respond rapidly to increased groundwater recharge and can also

respond relatively rapidly to salinity management practices.

Intermediate groundwater flow systems take longer to 'fill' following increased recharge. They

present much greater challenges for dryland salinity management than local groundwater flow

systems.

Regional groundwater flow systems take more than 100 years to 'fill' after clearing the native

vegetation. These systems require widespread community action and major land use change to

secure improvements.

The case study sites used are representative of the saline lands of southern Australia. They were located in

eight of the 17 groundwater flow systems identified by Coram et al. (2001) covering about 20% of the

continental land surface. The ‘regional and local flow systems’ indicated on Figure 4 were not represented

among the case studies.


Figure 4. Study sites with reference to Groundwater Flow Systems

Classifying Saline Soils

Current general-purpose soil classification systems (e.g. Isbell 1996, Soil Survey Staff 1998) were not

intended to distinguish between the causes of soil salinity, nor approaches to its management.

Consequently, several workers (e.g. Williams and Bullock 1989) have attempted to categorise the wide

range of dryland saline soils using hydrology (presence or absence of groundwater) and water status

(primary or natural as opposed to secondary or induced status). Based on the Williams and Bullock (1989)

system and newly acquired morphological, hydrological and chemical information about saline soil-

landscapes from 17 case studies across southern Australia, a modified classification has been developed

(Figure 5; Table 1). In the new classification, saline soils are classified using hydrological, soil landscape

features, and dominant soil chemistry (type of soluble salt or sodicity) (Figure 5; Table 1). The important soil

chemical indicators as defined by Isbell (1996) and used in the new classification are:

halitic (sodium chloride dominant),

gypsic (gypsum or calcium sulfate dominant),

sulfidic (pyrite dominant),

sulfuric (sulfuric acid dominant), and

sodic (high exchangeable sodium on clay surfaces).


Figure 5. Categories of dryland and coastal saline soils as defined by hydrology, soil water status and soil chemistry (modified from Fitzpatrick et al. 2001a)


Table 1. Categories of dryland saline soils, as defined by hydrology, landscape features and soil chemistry (adapted from Fitzpatrick et al. 2001)

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 5

Halitic Primary, salt pan, halitic A Salt pan Gypsic Primary, salt pan, gypsic B Halitic Primary, seepage scald, halitic A Seepage scald,

(unvegetated) Sulfidic Primary, seepage scald, sulfidic C Halitic Primary, salt seepage, halitic A

Primary salinity (natural dryland salinity)

Salt seepage (vegetated) Sulfidic Primary, salt seepage, sulfidic C

Halitic Secondary, salt pan, halitic A Salt pan Gypsic Secondary, salt pan, gypsic B Halitic Secondary, salt seepage, halitic A Sulfidic Secondary, salt seepage, sulfidic C

Salt seepage (vegetated)

Sulfuric Secondary, salt seepage, sulfuric D Halitic Secondary, eroded seepage scald, halitic E

Groundwater present in root zone: salinity process driven by groundwater.

Secondary salinity (induced dryland salinity)

Eroded seepage scald Sulfuric Secondary, eroded seepage scald, sulfuric F 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 E

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 E


Development of Generic Soil-regolith conceptual Models

To predict how soils and landscapes will change when saline soils are drained or are otherwise disturbed, a

basic understanding of the physico-chemical processes involved is essential. The processes are varied and

complex, and also vary between regional catchments (Appendix 1). For simplicity, it was decided to

illustrate the soil salinisation processes within a minimum set of generic conceptual models (e.g. 3 models),

which characterised all the sequences of major physico-chemical changes that occur in all types of saline

soils when they are drained or disturbed.

Detailed field morphological and laboratory investigations were used to determine diagnostic soil attributes.

Examples include the presence and amounts (or absence) of grey bleached and yellow colours in the form

of distinct mottles (iron depletions), black and red stains (iron concentrations), which are similar to the

redoximorphic features described in Soil Taxonomy (Soil Survey Staff 1999; Vepraskas (1992). These

features develop under particular conditions of water saturation, salinisation, sodification, sulfidisation in

surface and subsurface horizons.

Selected soils were analysed for a suite of chemical (including pH, electrical conductivity, sodium adsorption

ratios, exchangeable cations and exchangeable sodium percentage), physical (including bulk density,

particle size fractions and hydraulic conductivity) and mineralogical properties using a wide range of field

`and laboratory analyses (including mid infrared).

A systematic approach was used whereby predictive (i.e. 4-dimentional) soil–regolith toposequence models

for each case study were constructed from the field observations and laboratory data (Fitzpatrick and Merry

2002; Fitzpatrick and Skwarnecki 2003). These models described, explained and predicted soil and water

degradation processes at sub-catchment scale in a specific region. Each model used toposequences (soil

landscape cross-sections) to describe the basic soil–regolith features and direction of soil water and solute

movement (Fritsch and Fitzpatrick 1994). Toposequences at sub-catchment scale are most useful for

constructing such models because vertical and lateral changes can be linked to hydrological,

physicochemical and biomineralogical processes (Fritsch and Fitzpatrick 1994, Cox et al. 1996; Fitzpatrick et

al. 1996). Three generic soil–regolith toposequence models were then developed from the case study

models to describe and predict (i.e. 4-dimentional) degradation processes across the main different types of

salt-affected soils. Management approaches for overcoming the problem of irreversible changes in some

saline soils and minimisation of the risk of high chemical concentrations in drainage waters were then

described for each model using the approach developed for land managers in the Mt Lofty Ranges, South

Australia by Fitzpatrick et al. (1997) and western Victoria by Cox et al. (1998).


PROPERTIES OF SALINE SOILS AND HOW THEY CHANGE WHEN DISTURBED OR DRAINED: THREE GENERIC CONCEPTUAL MODELS

The sections below describe the three generic models (Figure 6 to Figure 8) that were produced from all

case studies (Table 2 to Table 4). They describe the physico-chemical processes that lead to the

development of saline soils and how they change when drained or disturbed.

MODEL 1. Soils Influenced by Sodium And Chloride Groundwaters (Halite Dominant)

The primary and secondary saline soils contained chloride as the dominant anion and sodium as the

dominant cation (Table 2). The accumulation of this stored salt mostly originates from the ocean via rainfall

and marine deposition in earlier geological periods. Following the clearing of upland areas, secondary saline

seepages developed through rising saline groundwater tables. When these soils dried out, halite (sodium

chloride) is the main salt efflorescence formed (Halitic saline soils). This is illustrated in Figure 6a. When

these saline soils were drained and leached by rainfall, secondary sodic soils developed (Figure 6b). The

development of sodic layers with low hydraulic conductivity and high bulk density restricted the downward

movement of water, leading to waterlogging, tunnel erosion and enhanced lateral movement of water and

colloids to steams. Eventually a saline scald is formed (Figure 6c). When saline soils were leached, salt

efflorescences on the soil surface dissolved (Figure 6b). Salt crystals developed at depth in the sodic soils

where saline groundwater discharges through the subsoil clay layer into gullies or drains. This caused

stream banks to erode by salt weathering (Figure 6b and Figure 6c).

Figure 6. Soil-landscape model showing the progressive transformation of saline soil (a), via a

sodic soil (b), to a saline soil in salt scald (c) (modified from Fitzpatrick et al. 2001a)


Table 2. Occurrence of Model 1: Soils influenced by sodium and chloride groundwaters (halite dominant) in each state with key references

State Distribution and key references to case studies SA Model has widespread occurrence when Na+ and Cl– dominant groundwater discharge

occurs in broad flat areas and is underlain by sedimentary aquifers with sediment lenses of low hydraulic conductivity. For example, from: (i) Quaternary and Murray Group limestones in the South-western Murray Basin: Type examples: Upper South East, near Marcollat (Fitzpatrick et al. 2002) (ii) perched or unconfined Tertiary aquifers at the base of sandhills (i.e. dune fields of the Mallee, where young aeolian sands overlie the less hydraulically conductive Parilla Sands): Type example: Lower South East, Cooke Plains (Hollingsworth et al. 1996). (iii) both sedimentary and fractured rocks in areas where steep ranges sharply change gradient to broad alluvial flats: Type example: Mount Lofty Ranges, Herrmanns catchment (Fitzpatrick et al. 1995; Nathan 2002; Fitzpatrick and Merry 2002; Fritsch and Fitzpatrick 1994).

Vic As above but also where groundwater discharge occurs in Western Basalt Plains in conjunction with the change from the regional unconfined basalt aquifer to much lower hydraulic conductivity lacustrine sediments. Type examples: Woorndoo catchment in lake systems (Cox et al. 2001) and Lake Tyrrell. Sedimentary and fractured rocks in areas where steep ranges sharply change gradient to broad alluvial flats: Type examples: Saline seeps on the Dundas Tableland: • Gatum catchment (Brouwer and Fitzpatrick 2002a, b). • Vasey catchment (Cox et al. 2001).

WA Model is also widely applicable throughout the SW of Western Australia for small playas and other lakes, swamps and depressions, which typically overly materials of low hydraulic conductivity (saprolite and sediments) containing saline groundwaters. Also occurs in areas where sands or lateritic gravels overlie saprolite and/or clay-rich regolith as the aquifer thins. Type examples: Dumbleyung and Rundles (case studies)

NSW As above. Type example: Rouse Hill near Sydney (Cox et al. 2002)

MODEL 2: Soils Influenced from Sulfur plus Sodium and Chloride Groundwaters (Sulfidic, Gypsic)

In their pristine state, the inland potential acid sulfate soils (PASS) with sulfidic materials were found at the

surface in saline wetlands or seeps (Figure 7a) or were buried beneath alluvium (Table 3). These soils:

were black, waterlogged, anaerobic and exist under reducing conditions at near-neutral pH (6-8),

had high organic content (up to 2.71 % organic C), and

contained pyrite (typically framboidal).

Saline groundwater enriched in sulfate (SO42-) can seep up through soil, along with other ions in solution

such as Na+, Ca2+, Mg2+, AsO42-, I- and Cl-, and concentrate by evaporation to form various mineral

precipitates within and on top of the soil (Figure 7a). Pyrite framboids form in sulfidic materials in saline

seeps from reduction of infiltrating sulfate-rich groundwaters.

Actual acid sulfate soils result when soils become pugged from animal traffic, drainage works or other

disruptions, which exposes the pyrite in previously saturated soils to oxygen in the air. As the pyrite is


oxidized, sulfuric acid and various iron sulfate-rich minerals form, and ASS develop (Figure 7b). When

sulfuric acid forms, soil pH can drop from neutral (pH 7) to below 4 and locally may attain values as low as

2.5 to form a "sulfuric horizon" (Figure 7b). The sulfuric acid dissolves clay particles in soil, causing basic

cations and associated anions (e.g., Na+, Mg2+, Ca2+, Ba2+, Cl-, SO42-, SiO4

4-), trace elements, and metal ions

such as Fe, Mn and Al to be released onto soil surfaces and into stream waters (Figure 7b).

As the regolith structure degrades due to the accompanying sodicity, soils become clogged with clay and

mineral precipitates and they lose their permeability and groundcover. This prevents the groundwater below

from discharging and forces it to move sideways or upslope (Figure 7b). Soil around the clogged area

eventually erodes, sending acid, metal ions and salts into waterways and dams. A new area of PASS

develops upslope or adjacent to the original ASS zone. Where cattle graze or other activities continue to

disturb the soil around the newly created or secondary PASS, the affected area progressively expands

(Figure 7b). If these processes are expressed on the surface of the soil, bare eroded saline scalds

surrounding a core of slowly permeable, highly saline, eroded ASS results (Figure 7c). These saline

landscapes are characterised by slimy red or white ooze and scalds with impermeable iron-rich crusts.

Sulfuric horizons generally had bright yellow or straw-coloured mottles of mainly natrojarosite with lesser

occurrences of jarosite where pH was 3.5–4.5 and was in contact with Na-rich groundwaters. In rare

instances, mottles also contained plumbojarosite if they overlaid mineralised zones in bedrock, where soil

pH was between 3.5 and 4.5 and was in contact with saline groundwaters, enriched in Pb sourced from the

mineralised zone seeping up through soils. Yellow-green mottles and salt efflorescences containing

sideronatrite occur in acidic (pH 2.0 – 3.5), saline (Na-rich) and sandy layers. The formation of these

hydroxysulfate minerals was indicative of rapidly changing local environments, variations in pH and rates of

availability of Fe, S and other elements such as Na and Pb (Skwarnecki et al. 2002).


Figure 7. Soil-regolith model showing the geochemical dispersion and erosion processes in saline landscapes and formation of secondary sulfides in potential acid sulfate soils in a

perched wetland and actual acid sulfate soil when eroded or drained (modified from Fitzpatrick et al., 2000a).


Table 3. Occurrence of Model 2: Soils influenced from sulfur plus sodium and chloride groundwaters (sulfidic, gypsic) in each state with key references

State Distribution and key references to case studies SA Model has widespread occurrence in groundwater discharge from fractured rock

aquifers in valleys, but can also occur on hillslopes above bedrock highs and also in some sedimentary areas where steep ranges sharply change gradient to broad alluvial flats. Type examples: Saline seeps in the Mt Lofty Ranges with: • sulfidic materials, Herrmanns catchment (Fitzpatrick et al. 1996; 2001a) • sulfuric horizons, Dairy Ck. and Guthries catchments (Fitzpatrick et al. 1996;

2000b; 2001a; Skwarnecki et al. 2002). • sulfidic materials, Keyneton catchment (Fitzpatrick et al. in prep). Other examples: Kangaroo Island, Waitpinga on Fleurieu Peninsula, Cleve Uplands on Eastern Eyre Peninsula, Lincoln Uplands and Tumby Bay, Lower Eyre Peninsula

Vic As above Type examples: saline seeps on the Dundas Tableland with: • sulfidic materials, Gatum catchment (Brouwer and Fitzpatrick 2001; 2002a, b). • sulfidic materials, Vasey catchment (Cox et al. 2001). • sulfidic & sulfuric horizons, Merriefields catchment (Fitzpatrick et al. 2003, in prep). Woorndoo catchment with sulfidic materials (Cox et al. 2001). Corangamite catchment with sulfidic & sulfuric horizons (Fitzpatrick et al. 2003, in prep).

NSW As above but groundwater discharge occurs from fractured Devonian granites and Ordovician/Silurian fractured metasediments overlain by Tertiary basalts. Discharge areas occur as surface scalds where bedrock highs occur (for example, as the result of differential depths of weathering). Type examples: saline seeps in Dick's Creek catchments, near Yass (Acworth and Jankowski 1993; Corpuz 1990; this case study).

WA As above. The model has widespread occurrence but is poorly defined for some drainage systems in WA. Groundwater discharges from sedimentary aquifers with changes in the shape of palaeo-drainage channels, and may be localised or extensive depending on the local seepage mechanism. Type examples: acid saline seeps in Yalanbee and Crocodile creek catchments, Merredin area and Narembeen palaeodrainage system (Lee Soo Young 2002). Blackwood catchment near Darkan (this study). Stirling lakes, Swan Plain (Fitzpatrick and Appleyard 2003, in prep).

MODEL 3: Transient Salinity in Root Zones Caused by Restrictive and Slowly Permeable Sodic 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 5 m depth and thus does not affect crops. Prior to

cultivation the upper soil layers (i.e. < 1 m) in these virgin soils were weakly saline (Figure 8a). 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 (Table 4).

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. In some localities

in Australia relatively coarse textured soils overlay impermeable sodic clay horizons (Figure 8a). 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 that eventually

becomes saline as the accumulated water evaporates (Figure 8b).

Dry saline land with subsoil expression (transient salinity)

Slow accumulation of salts in subsoil layers in small amounts that can be detrimental to crops have been

identified in a recent survey of sodic soils in South Australian wheat growing regions (Figure 8b). This

phenomenon, termed dry saline land with subsoil expression (subsoil transient salinity) within root zones of

sodic soils is different from the "secondary or seepage" salinity found in landscapes with rising ground

watertables. Dry saline land is not hydrologically connected to a saline groundwater table and is extensive in

many sodic soil landscapes in Australia. 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 a ‘perched

watertable’. Salts accumulate above the perched watertable during the wet season and accumulate in the

sodic subsoils following drying by water uptake by plant roots and evaporation. 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.

Subsoil transient salinity has been estimated to occur on about 30% of the land in the wheat growing regions

of the mid-north of South Australia (Maschmedt 2000; Department of Water Land and Biodiversity

Conservation, 2002). Subsoil layers between 0.3 and 0.6 m deep have accumulated salt with an electrical

conductivity of the soil saturation extract (ECse) ranging between 2.0 to 16.0 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 sodium

chloride. However, 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 8c). The development of sodic layers with low hydraulic conductivity and high bulk

density further restricted the downward movement of water, leading to waterlogging, tunnel erosion and

enhanced lateral movement of water and colloids to steams. Eventually a saline scald is formed (Figure 8c).


Figure 8. Soil-regolith model showing salt transport and erosion processes leading to formation of subsoil and surface soil transient salinity (not associated with the saline

groundwater tables). NOTE: Sodic duplex soil is used here as an example but these processes also do occur in gradational soils or in soils with thin A horizons directly overlying saprolite

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 have 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 8b). 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 45000 ha of marginal cropping land in South

Australia are affected by this problem (Kennewell 1999;). It is commonly referred to as "magnesia" patches

because of the “supposed” presence of high Mg, as well as Na, since Mg is a natural part of the evaporation

sequence.

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

efflorescences on the soil surface dissolved (Figure 8c). Salt crystals developed at depth in the sodic soils

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

banks to erode by salt weathering (Figure 8c). If these processes are expressed on the surface of the soil,

bare eroded saline scalds are evident (Figure 8c).


Table 4. Occurrence of Model 3: Transient salinity in root zones caused by restrictive and slowly permeable sodic subsoil layers in each state with key references

State Distribution and key references to case studies SA Model has widespread occurrence within the rootzones of soils occurring in up-land

terrains overlaying sedimentary and fractured rocks; mostly in areas where steep ranges sharply change gradient to broad alluvial flats. Type examples are restricted to soils occurring in upslope and midslope positions: north-south valley systems in Mid-North (Spalding catchment): • Subsoil transient salinity (Rengasamy 2000; 2002; Fitzpatrick et al. 2001a) • Surface soil transient salinity (magnesia patch) (Herriot 1942; Kennewell 1999). Mt Lofty Ranges (Dairy Ck and Herrmanns catchments) • Subsoil transient salinity (Fitzpatrick et al.1996).

Vic As above (but not well defined and characterised): Type examples are restricted to soils occurring in upslope and midslope positions: • Dundas Tableland, Gatum catchment (Brouwer and Fitzpatrick 2002a, b). • Dundas Tableland, Vasey catchment (Cox et al. 2001). • Dundas Tableland, Merrifields catchment (Fitzpatrick et al. 2002). • Woorndoo catchment (Cox et al. 2001).

NSW As above (but not well defined and characterised) Type examples are restricted to soils occurring in upslope and midslope positions. • Dick’s creek catchments within the Yass River Valley (Herwantoko 1991)

WA As above (but not well defined and characterised) Type example: restricted to soils occurring in upslope and midslope positions: • Rundles catchment, south western wheatbelt • Darkan catchment, south western wheatbelt.

Common Observations on Changes in Saline Soils when Drained or Disturbed

An important aspect of managing of drained saline soils is the need to provide land managers with clearly

presented information about relevant soil and hydrological processes and landscape features (see also

Sinclair Knight Merz, 2001, who made similar recommendations). This information should include aids for

recognising key soil and landscape features and then relate these to appropriate management options (see

Table 5) and possible off-site effects. For example, such information is found in manuals for land managers

in the Mount Lofty Ranges, South Australia (Fitzpatrick et al. 1997) and south western Victoria (Cox et al.

1999).

Based on information obtained from the 17 case studies (Appendix 1), the following common features were

observed where saline soils were drained or disturbed:

effects from water erosion:

o loss of topsoil, carbon and fertility,

o drainage of perched wetlands,

o erosion and gully formation with deepening and increasing local drainage,

o movement of dispersed clay,

o deposition of soil/sediment on soil surfaces.


effects from accession of low EC water:

o formation and movement of dispersed clay forming throttles in B horizons,

o tunnelling and gullying within sodic layers,

o transport of salt and nutrients to drainage lines, formation of sulfidic layers in drains.

residual effects from (salt) chemistry with drainage:

o formation of sodic layers,

o formation of sulfidic material under reducing conditions in drains (if SO4= is present),

o high sodium carbonate concentrations leading to high soil pH (> 8.5), altered solubility of

soil minerals, low availability of some nutrient elements (e.g. Mn, Fe, Zn) and possibly re-

precipitation of silica forming pans in E horizons,

o deterioration of soil structure,

o salt fretting.

formation of layers with low hydraulic conductivity:

o formation of “pavements” or surface hardpans– usually highly sodic, which shed water,

increase sheet erosion are barriers to capillary rise and infiltration. These are sometimes

overlain by sandy materials,

o sodic B horizons may retard vertical leaching of salts or upward movement of

groundwaters,

o iron cemented pans at the surface in some discharge areas may form a barrier to capillary

water flow.

effects from loss of vegetation:

o increased erosion,

o introduction of exotic tolerant plants altering biodiversity,

o loss of organic carbon inputs and root channels.

alteration from redox condition:

o drainage increases oxygenation with potential positive effect on depth of root penetration,

o formation of iron cemented pans that may be a barrier to water movement and root

penetration.

changes from increases in bulk density:

o pugging, an undesirable effect of grazing,

o increases in sodicity,

o increases lower air and water filled porosity,

o associated with siliceous pans in E horizons of sand over clay soils with illuviated clay,

o high bulk density prevents root penetration.

effects of time:

o Although the passage of time may result in decreased salinity levels in a drained soil

profile, detrimental effects (such as erosion or sodicity) may intensify unless remedial

actions are taken.


GENERAL BEST MANAGEMENT PRACTICES

We have concentrated here on proposing what might be best management practices for saline soils in

particular toposequence or landscape settings. But drained soils also need to be managed from a risk

management perspective, which should account for both on- and off-site consequences. To this end an

individual farmer/land manager must have access to relevant information on the processes that support any

actions and investments that might be taken within any paddock and includes cost effective guidelines.

General Best Management Practices for Saline Soils

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

soil that exists (Table 1). Consequently, the three process models, together with the 22 soil types and their

physical (e.g., soil texture) and chemical indicators, were used to construct eight simplified Soil Salinisation

Categories (Table 5). To achieve this we combined primary and secondary salinity types because their

biogeochemical properties and management are similar. Finally, a generalised set of best management

practices (BMPs) for each of the eight Soil Salinisation Categories was developed (Table 5). Salinity

indicators are also provided in Table 5 (see column 3) because they are useful tools for monitoring

improvements in landscape health when remedial treatments have been imposed to reclaim or minimise

further risks of soil salinisation.

Soil categories that should not be drained - but if drained will require additional treatment

Soil categories C and D (Table 5) should not be drained. For example, sulfidic (C) and sulfuric (D) dominant

saline soils are difficult to treat, given that with progressive drying out of the upper soil profiles acid sulfate

soils develop with severe chemical and physical problems. Landscape systems with such variable and

complex soils cannot be managed by simplistically-designed revegetation or drainage strategies. These

soils are best left in a salinised condition supporting native wetland or salt tolerant plants. These strategies

include wetland protection to maintain the sulfidic condition by stock exclusion and planting salt tolerant,

wetland vegetation that is evergreen and perennial. However, management of regional recharge may

eventually lower watertables and result in the drying of wetlands and discharge areas. Lime will be needed

to be applied to the drained and acidified soils and discharge waters. Eroded areas should be stabilised with

salt tolerant trees, shrubs or grasses (e.g. tall wheat grass) or by the construction of control weirs or gully

head structures.

Soil categories that can be drained but will require pre-treatment

Soil categories other than C and D (Table 5) can be drained because they do not contain high

concentrations of sulfur but dominantly Na+ and Cl- ions. Management strategies for these saline soils must

be designed with processes of salt accumulation and mobilisation in mind as outlined in Table 5. 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

vegetation (see Table 5).

Capacity to Reverse Soil Salinisation after Drainage

Preliminary assessment of the capacity to reverse established salinisation after drainage depends on the

type of saline soil present. The range of likely treatment options are discussed in Table 5 for each saline soil

category.

Risk Management Planning for Draining Saline Soils

Similarly, several general principles, including the need for risk management planning (see section below

and Appendix 3), should be taken into consideration before rehabilitation of salt-affected land is attempted.

Often the adoption of several approaches provide synergies:

management of soil EC to prevent dispersion or controlled accession of freshwater; use of gypsum

to ameliorate sodicity

prevention/management of cemented pans by ripping, mulching and applying gypsum

interruption to capillary flow by ripping

minimisation of evaporation losses by mulches or lowering the groundwater table

flexibility of approaches to cope with sequences expected over longer periods (e.g. decades)

construction of stable drains to control off-site effects from increased salt or colloid mobilisation.

management of soil fertility for establishing desirable plant species

It is clear that revegetation alone will generally not be sufficient to lower the groundwater in either primary or

secondary saline areas (Hatton and Nulsen 1999; NLWRA 2001). Engineering structures will have to be

strategically placed within catchments to reduce recharge and enhance discharge. For example, in dry

saline land (transient salinity), shallow drainage that diverts water into drainage lines rather than allowing

infiltration, will be needed to lower the freshwater perched watertables. However, the effectiveness of these

drains is very dependent on soil physical parameters (properties) such as hydraulic conductivity (Table 5).

There is still much to be learned before proven and innovative systems are developed to return salinised

soils to productive states, whilst minimising potential off-site impacts. Even with the best rehabilitation, there

will be some situations where changes in soil chemistry will remain irreversible, and these affected soils will

permanently limit agricultural production. In some situations there will also be detrimental off-site effects.

Risk management is essential for managing drained saline land. Many factors should be addressed by

planners for managing the on- and off-site consequences before saline soils are drained. Appropriate

drainage risk management plans should be developed for individual catchments or drainage areas and be a

part of the overall catchment plan. An approach, based on the generic framework of Standards Australia (to

ISO standards), is presented in Appendix 3.

In addition, risk management plans should address the following issues:


Is it economically/socially/politically acceptable and feasible?

Is it possible to provide appropriate drainage?

Is leaching water available?

Is the soil and water chemistry right?

Are appropriate vegetation, other biota and land management systems available for adoption?

Should appropriate biota be introduced or re-introduced?

Will there be unacceptable off-site effects?

In outline, the key areas that should be considered (and presented in more detail in Appendix 3) for risk

planning are:

Preliminary

Concept planning

Drainage planning

Risk management

Risk management framework

Establish context

Identification of potential risks

Analyse and evaluate risks

Evaluate risks

Treat risks by identifying (i) barriers to amelioration/reclamation and (ii) best strategy for preventing risks

Development of mitigation measures

Operational phase mitigation measures.

Construction phase mitigation measures.

Monitoring effects of reclamation and during construction phase.

Documentation of processes undertaken, risk assessment procedures and responsibilities.


Table 5. Generalised best management practices (BMPs) after drainage or disturbance for different categories of dryland, saline soil profiles.

Soil Salinisation Category (based on Table 1)

Soil Texture Indicators Management Options in Sequence1

Sands/Loams EC, pH, CaCO3, ESP or SAR, BD2

Drain to leach salts. Calcium application (lime if acidic, or gypsum if not acidic). Vegetate with perennial or salt tolerant species May be used for agricultural production.

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

Drain subsoil (e.g. slotting). Drain to leach salts. Calcium application (lime if acidic, or gypsum if not acidic). Vegetate with perennial or salt tolerant species May be used for agricultural production.

A Primary or secondary salinity; saltpan, with mainly sodium and chloride salts

Sand/Clay3 As above, subsoil BD

Drain topsoil to leach salts Drain subsoil (e.g. slotting) Calcium application (lime if acidic, or gypsum if not acidic). Vegetate with perennial or salt tolerant species May be used for agricultural production.

Sands/Loams EC, pH As for (A) Sands/Loams, but apply lime (not gypsum). Prevent significant periods of fluctuating water logging (anoxic) conditions by draining soil or alternatively create wetlands.

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

As for (A) Clays but improve soil structure with organic matter, and lime (not gypsum) as leaching proceeds or alternatively create wetlands

B Primary or secondary salinity; saltpan, with significant gypsum

Sand/Clay As above, subsoil BD

As for (B) Clays

C Primary or secondary salinity; with significant sulfidic materials present

All pH, Sulfide S, CaCO3, acid production potential and neutralising capacity

Do not drain – by engineering, trees, pugging (grazing) Maintain or create permanent wetlands Vegetate with native wetland salt tolerant species. If drained, follow appropriate management in (B) i.e. do not add gypsum but use lime Protect area (should not be used for agricultural production)

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.


Table 5 cont. Generalised best management practices (BMPs) after drainage or disturbance for different classes of dryland, saline soil profiles.

Soil Salinisation Category (based on Table 1)

Soil Texture Indicators Management Options in Sequence1

D Secondary salinity; with sulfuric horizons, and significant sulfates present

All EC, pH, CaCO3

Add lime to soil and leaching products i.e. do not add gypsum. Do not drain – by engineering, trees, pugging (grazing) Maintain or create permanent wetlands. Vegetate with native wetland salt tolerant species Protect area (should not be used for agricultural production).

E Secondary salinity; eroded, with sodium and chloride salts

All EC, pH, ESP or SAR

Ripping and mulching – to manage crusts which are usually sodic and have high BD

Drain to leach salts. Calcium application (lime if acidic, or gypsum if not acidic). Vegetate with perennial or salt tolerant species May be used for agricultural production.

F Secondary salinity; eroded, with significant sulfates present

All EC, pH, ESP or SAR

As for (E), but only apply lime if acidified, but do not apply gypsum.

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.


SUMMARY AND RECOMMENDATIONS FOR FUTURE WORK

Summary of Project

Particular emphasis has been directed to understanding the physico-chemical changes that operate when

dryland, saline soils are drained or are otherwise disturbed, such as when annual crops and pastures are

replaced by perennial vegetation that dry the profile, engineering works are installed, pugging occurs where

animals graze waterlogged soils and erosion develops. Investigations were conducted at 17 paired sites in

eight different Groundwater Flow Systems across southern Australia. At each site soil physical, chemical

and mineralogical properties measured by comparing salinised sites with those no longer salinised as a

result of intervention. From this data a user-friendly classification scheme for identifying 22 different types of

saline soil was developed.

Prior to this project, uncertainties existed on the specific nature of the processes involved, partly because

saline soils have generally been considered to have little agricultural value. At this stage (after an 18 month

project), a classification scheme has been developed to identify 22 types of saline soils, with differing

physico-chemical properties, existing in 17 dryland farming regions of southern Australia. Three conceptual

soil-regolith models have been developed that summarise the complex physico-chemical processes

involved in the changes that lead to different soils (e.g. sodic, eroded, saline –halitic or gypsic, acid sulfate –

sulfidic or sulfuric) and poor water quality (mobilised salts and soil particles) when a saline landscape is

drained or otherwise disturbed.

Finally, a set of best management practices (BMPs) for eight simplified Soil Salinisation Categories has been

developed. As well, key indicators for assessing and monitoring physico-chemical changes should prove to

be useful for monitoring improvements in landscape health when remedial treatments have been imposed to

reclaim or minimise further risks of soil salinisation.

A preliminary approach to environmental risk assessment planning (to assess risks, prepare environmental

assessments and identify responsibilities during the planning, implementation and monitoring phases) has

been prepared to assist investigators and community groups dealing with reclamation of disturbed or drained

dryland saline soils.

Our work has advanced new concepts and practical information, provided to policy makers and local

stakeholders at conference and workshop presentations and as popular articles and fact sheets, which will

aid the tackling of engineering and agronomic solutions for remediation of saline soils of southern Australia.


Priorities for the Future

The data used to develop the new classification of saline soils, the physico-chemical models predicting what

will happen when the saline soils are drained or disturbed, and the implementation of best management

practices are based on comprehensive datasets from 11 catchments (mostly in SA and Vic) and 6 less

complete datasets from other catchments located in southern Australia. Similar data sets are scarce for

Western Australia and New South Wales and no such data exists for Tasmania, Queensland and Northern

Territory. Little long-term monitoring has occurred at any site.

As a high priority under the National Action Plan for Salinity and Water Quality framework a coordinated

national network of paired dryland saline soil sites should be established (incorporating the 17 existing paired

sites used in this project) to provide long-term field sites for monitoring property changes in saline soils over

time. These could include:

More case studies (some involving long-term monitoring) are needed in Western Australia and New

South Wales (including sites and data collected by Semple and coworkers, e.g., Semple et al. 1996;

Semple and Williams 2002) to verify the classification, the models and the generalised best

management practices.

Case studies should also be established in Tasmania, Northern Territory and Queensland.

More effort directed towards training and extension using the principles established in this report,

including revision of the current fact sheet on the NDSP website.

Further development of the proposed environmental risk assessment plan in conjunction with

stakeholders in each region where risk is high.

Experimental quantification of long-term changes in saline soils needs to be implemented. This should

include:

Field experiments involving relevant management treatments (e.g. mulching, gypsum application,

reintroducing native wetland vegetation) in different groundwater flow systems.

Replicated permanent plots, sufficiently large in area to accommodate repeated sampling over time.

Suitable archiving of all soil and water samples so that long- and medium -term temporal trends in a

comprehensive set of properties (measured using standard methods) can be tracked.


REFERENCES AND FURTHER READING

Acworth, R.I., and Jankowski, J. 1993. Dryland salinity processes in the Yass Water Supply

Catchment and other locations in NSW: Final report to The Land and Water Resources Research and Development Corporation, Research Contract UNS10.

Acworth, R.I., and Jankowski, J. 2001. Salt source for dryland salinity—evidence from an upland catchment on the Southern Tablelands of New South Wales. Australian J Soil Res. 39: 39-59.

Allan, M.J., 1993. Victorian dryland salinity database. Centre for Land Protection Research, Department of Conservation and Natural Resources, Victoria.

Allan, M.J., 1994. An assessment of secondary dryland salinity in Victoria. Land Protection Branch, Department of Conservation and Natural Resources, Victoria.

Barnett, S., 2000. Extent and Impacts of Dryland salinity in South Australia. PIRSA Report Book 2000/00045. LWRRDC Project DAS 19. Department for Water Resources, South Australia. pp31.

Brouwer J. and R.W. Fitzpatrick 2002a. Interpretation of morphological features in a salt-affected duplex soil toposequence with an altered soil water regime in western Victoria. Aust. J. Soil Research. 40: 903-926.

Brouwer J. and R.W. Fitzpatrick 2002b Restricting layers, flow paths and correlation between duration of soil saturation and soil morphological features along a hillslope with an altered soil water regime in western Victoria. Aust. J. Soil Research. 40: 927-946.

Christen, E.W., and Ayars, J.E. 2001 Subsurface drainage system design and management in irrigated agriculture: Best Management Practices for reducing drainage volume and salt load. Technical Report 38-01. CSIRO Land and Water, Griffith, NSW, Australia..

Coram, J., ed. 1998 National Classification of Catchments for land and river salinity control. A catalogue of groundwater systems responsible for dryland salinity in Australia. Report for the Rural Industries Research and Development Corporation, compiled by the Australian Geological Survey Organisation.

Coram, J.E., Dyson, P.R., Houlder, P.A. and Evans, W.R. 2001. Australian Groundwater Flow Systems contributing to Dryland Salinity. A Bureau of Rural Sciences Project for the National Land and Water Resources Audit’s Dryland Salinity Theme. pp 77.

Corpuz, A.C., 1990. Groundwater flow in fractured rock and dryland salinity at Williams Creek and Dick's Creek: UNSW. unpublished M.Sc. Thesis.

Cox J.W., Fitzpatrick R.W, Davies, P.G. and Forrester, S. 2002. Salinity Investigation at Second Ponds Creek. CSIRO Land & Water, CSIRO Land and Water Consultancy Report to Rouse Hill Infrastructure Pty LTD: pp 56.

Cox, J.W. and McFarlane, D.J. 1995. The causes of waterlogging in shallow soils and their drainage in south-western Australia. Journal of Hydrology 167, 175-194.

Cox, J.W. and Pitman, A. 2001. Chemical concentrations in drainage from perennials grown on sloping duplex soils. Australian Journal of Agriculture Research 52, 211-220.

Cox, J.W., Chittleborough, D.J., Brown, H.J., Pitman, A. and Varcoe, J. 2002. Seasonal changes in hydrochemistry along a toposequence of texture-contrast soils. Australian Journal of Soil Research 40, 1-24.

Cox, J.W., Fitzpatrick, R.W., Mintern, L., Bourne, J. and Whipp, G. 1998. ‘Managing waterlogged and saline catchments in south-west Victoria.’ CRC Soil and Land Management Catchment Management Series No 2 CSIRO Land and Water pp48.

Cox, J.W., Fritsch, E. and Fitzpatrick, R.W. 1996. Interpretation of soil features produced by modern and ancient processes in degraded landscapes: VII. Water duration. Australian Journal of Soil Research 34: 803-24.

Department of Water Land and Biodiversity Conservation (2002). Atlas of key soil and landscape attributes of the agricultural districts of South Australia, Soil and Land Information Group, Department of Water, Land and Biodiversity Conservation, South Australia. 2002.

Dyson, P.R., 1983. Dryland salting and groundwater discharge in the Victorian Uplands. Proc. R. Soc. Vic., 95: 113-116.

Dyson, P.R., 1990. The development, dynamics and management of groundwater systems and dryland salinity in the Uplands of south eastern Australia. In: Management of soil salinity in southeastern Australia, pp 253-267. Aust. Soc. Soil Sci., Riverina Branch.


Fitzpatrick, R.W., Cox, J.W., Munday, B., B Bourne, J.C., and Hu, Chunsheng 2002. Transferring scientific knowledge to farmers. p. 173-186. 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 No. 84. CSIRO Publishing, Melbourne, Australia.

Fitzpatrick, R.W., Cox, J.W., and Bourne, J. 1997. Managing waterlogged and saline catchments in the Mt. Lofty Ranges, South Australia: A soil-landscape and vegetation key with on-farm management options. Catchment Management Series. CRC for Soil and Land Management. CSIRO Publishing, Melbourne, Australia, 36 pp. ISBN 1 876162 30 9.

http://www.publish.csiro.au/books/bookpage.cfm?PID=1449 Fitzpatrick R.W., Boucher, S.C., Naidu, R. and Fritsch, E. 1995. Environmental consequences of soil

sodicity. . p. 163-176. In: R. Naidu, M.E. Sumner and P. Rengasamy (eds.). Distribution properties and management of Australian sodic soils. CSIRO Publishing, Melbourne, Australia.

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, and Cox J.W., 2000a. What are saline soils? What happens when they are drained? Natural Resource Management, Special Issue, June: 26-30.

Fitzpatrick R.W., McKenzie, N.J. and Maschmedt, D. 1999. Soil morphological indicators and their importance to soil fertility. p 55-69. In K. Peverell, L.A. Sparrow and D.J. Reuter (ed.) In Soil Analysis: an Interpretation Manual. CSIRO Publishing, Melbourne, Australia.

Fitzpatrick R.W., Raven, M., Self, P.G., McClure, S., Merry, R.H. and Skwarnecki, M. 2000b. Sideronatrite in acid sulfate soils in the Mt. Lofty Ranges: First occurrence, genesis and environmental significance. In New Horizons for a New Century. Australian and New Zealand Second Joint Soils Conference Volume 2: Oral Papers. (Eds. J.A. Adams and A.K Metherell). 3-8 December 2000, Lincoln University, New Zealand Society of Soil Science. pp. 109-110.

Fitzpatrick, R.W., Rengasamy, P., Merry, R.H, and Cox, J.W. 2001a. Is dryland soil salinisation reversible? National Dryland Salinity Program (NDSP) web site. 15pp http://www.ndsp.gov.au/10_NDSP_projects/05_project_descriptions/35_environment_protection/project_25.htm.

Fitzpatrick, R.W., Rengasamy, P., Merry, R.H, and Cox J.W. 2001b. Fact Sheet: Is dryland soil salinisation reversible? National Dryland Salinity Program (NDSP) web site. 2 pages: http://www.ndsp.gov.au/Pdfs/can_salinisation.pdf

Fitzpatrick R.W., Merry, R.H., Cox, J.W. and McFarlane, J 2002. Effects of drainage on processes in saline soil profiles in the South East of South Australia. Proceedings for the 8th National Conference and workshop on: “Productive use and rehabilitation of saline lands (PUR$L)”. Perth, Western Australia, September, 16th to 20th, 2002. p. 299. EDITED http://www.promaco.com.au/conference/2002/pursl/index.htm

Fitzpatrick, R.W and M.S. Skwarnecki 2003. Soil-regolith toposequence models to assist land use planning and mineral exploration. Geoderma (In Press).

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.

George, R. J., McFarlane, D.J. and Speed, R.J., 1995. The consequences of a changing hydrological environment for native vegetation in south-western Australia. In Saunders, D.A., Craig, J.L. and Mattiske (eds): Nature Conservation 4 - The Role of Networks pp9-21. Surrey-Beatty, Sydney.

George, R.J., 1992. Hydraulic properties of groundwater systems in the saprolite and sediments of the wheatbelt, Western Australia. Journal of Hydrology, v.130:50-278.

George, R.J., McFarlane, D.J. and Nulsen, R.A., 1997. Salinity threatens the viability of agriculture and ecosystems in Western Australia. Groundwater 5(1):6-21.

George, R.J., Speed, R. and Commander, P., 1997. Hydrogeological models used for dryland salinity research and management: Western Australia. Unpublished paper prepared for the Conceptual Models Workshop held at the Australian Geological Survey Organisation in Canberra, October 7th, 1997.


Ghassemi, F., Jakeman A.K. and Nix H.A. 1995. Salinisation of land and water resources: Human causes, extent, management and case studies. Chapter 2: Australia (p. 143-212. University of New South Wales Press LTD, Australia and CAB International, UK.

Gordon, I. 1991. A survey of dryland and irrigation salinity in Queensland. Department of Primary Industries Information Series, Queensland.

Hatton, T.J. and Nulsen, R.A. 1999 Towards achieving functional ecosystem mimicry with respect to water cycling in southern Australian agriculture. Agroforestry Systems 45:203-214.

Heng, L.K., White, R.E., Helyar, K.R., Fisher, R. and Chen, D. 2001. Seasonal differences in the soil water balance under perennial and annual pastures on a acid Sodosol in southeastern Australia. European Journal of Soil Science 52: 227 – 236.

Hollingsworth I.D., Fitzpatrick, R.W. and Hudnall, W.H. 1996. Distribution and properties of soils in an experimental sub-catchment with altered soil water regimes near Cooke Plains, South Australia. CSIRO Division of Soils Divisional Report No. 126; 42 pp. (ISBN 0 643 05863X).

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.

Herwantoko, K.D., 1991. Hydrogeochemical study of upland salinity at Dick's Creek Catchment, Yass Valley, NSW. Unpublished University of New South Wales M. App. Sc. Thesis.

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. Lee Soo Young 2002 Groundwater geochemistry and associated hardpans in southwestern

Australia, Unpublished Master of Science thesis. University of WA, Nedlands, WA. 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). Macumber, P.G. 1991. Interactions between Groundwater and Surface Systems in Northern Victoria.

Dept Conservation and Environment, Victoria. Maschmedt, D. 2000. Assessing agricultural land: agricultural land classification standards used in

South Australia's land resource mapping program. Adelaide, Primary Industries and Resources South Australia.

McFarlane, D.J. and Cox, J.W. 1992. Management of excess water in duplex soils. Australian Journal of Experimental Agriculture 32, 857-864.

McFarlane, D.J., George, R.J. and Farrington, P., 1993. Changes in the Hydrologic Cycle. In: Hobbs, R.J. and Saunders, D.A. (eds) Reinventing Fragmented Landscapes. Springer-Verlag, New York, pp107-145.

Melis, M. I. Acworth, R. I. 2002. An aeolian component in Pleistocene and Holocene valley aggradation: evidence from Dicks Creek catchment, Yass, New South Wales. Australian J Soil Res. 39: 13-38.

Merry R.H., Fitzpatrick R.W., Bonifacio E, Spouncer L.R. and Davies P.J. (2002). Redox changes in a small wetland with potential acid sulfate, saline and sodic soils. In Soil Science: Confronting new realities in the 21st century. Transactions of International Union of Soil Science 17th World Congress of Soil Science. Bangkok, Thailand. 14-21 August, 2002. Symposium No. 63; 13pp. CD-ROM.

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. 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

Nathan Muhammad (2001) Clay movement in a saline-sodic soil toposequence. Unpublished Master of Agricultural Science Thesis. The University of Adelaide, South Australia.

Nicoll, C. and Scown, J., 1993. Dryland salinity in the Yass Valley - processes and management. Final technical report for The Natural Resources Management Strategy June, 1993.

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

Nulsen, R.A. 1993. Changes in soil properties. In: Reintegrating Fragmented Landscapes. Springer-Verlag, New York, pp 107-145.

Peck, A.J. and Hurle, D.H. 1976. Chloride balance of some farmed and forested catchments in south-western Australia. Water Resources Research, (9) v.3: 648-657.


Please, P.M., Knight, M.J. and Corpuz, A. 1989. Role of large scale geological structures in groundwater driven dryland salinity. In: Management of soil salinity in South East Australia. Proc. of Symp. Albury, NSW Australia, Sept. 1989. Australian Society of Soil Science, Inc. 1990.

Rengasamy, P. 2000. Transient salinity in the root zones of sodic soils. Crop Science Society of South Australia, Newsletter No.187.

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.

Salama R.B., CJ. Otto and R.W. Fitzpatrick 1999. Contributions of groundwater conditions to soil and water salinisation. Hyrogeology Journal. 7: 46 - 64.

Scott, D.I., 1990. Hydrogeological, geophysical and water balance study of dryland salinity at Dick's Creek, Yass Valley, NSW. Unpublished Master Applied Science Thesis, Project Report, Department of Applied Geological University of NSW.

SCAV, 1982. Salting of non-irrigated land in Australia. Soil Conservation Authority of Victoria. Government Printer, Melbourne, Victoria.

Semple, W.S., Koen, T.B., Williams, B.G., Murphy, B.W. and Nicholson, A.T. (1996) Saline seepage scalds in the Central West of NSW. Technical Report No 29, Department of Land and Water Conservation. Sydney 77 pp.

Semple, W.S. and Williams, B.G. 2002. Saline seepage scalds. Can they be usefully classified? Natural Resource Management, 5(1): March, 13-21.

Shaw, R.J., Coughlan, K.J. and Bell, L.C. 1998. Root zone sodicity. p. 95-106. In: M.E. Sumner and R. Naidu (eds.). Sodic Soils: Distribution, Properties, Management and Environmental Consequences. Oxford University Press.

Soil Survey Staff 1999. Soil Taxonomy - a basic system of soil classification for making and interpreting soil surveys, Second Edition. United States Department of Agriculture, Natural Resources Conservation Service, USA Agriculture Handbook No. 436 pp 869.

Soil Survey Staff. 1987. Sodic, sodic-saline, and saline soils of North Dakota. Misc. Publ., Soil Conservation Service, USDA, Bismarck, ND.

Sinclair Knight Merz. 2001. Assessment of Efficacy of Engineering Options for the Management of Dryland Salinity. Research Report Final – December 2001. National Dryland Salinity Program. ftp://ftp.ndsp.gov.au/pub/general/10_NDSP_projects/05_discussion_paper/Finaldec2001.pdf

Skwarnecki, M., Fitzpatrick, R.W., and Davies, P.J. 2002. Geochemical dispersion at the Mount Torrens lead-zinc prospect, South Australia, with emphasis on acid sulfate soils. Cooperative Research Centre for Landscape Environments and Mineral Exploration. CRC LEME Restricted Report No 174. pp. 68 (volume 1) (plus 13 appendices: volumes 2 and 3).

Tickell, S.J. 1994. Dryland salinity hazard map of the Northern Territory. Report 54/94D, Power and Water Authority, Northern Territory of Australia.

Vepraskas, M. J. 1992. Redoximorphic features for identifying aquic conditions. North Carolina State University Technical Bulletin 301 (NCSU: Raleigh, North Carolina, USA).

White, R.E., Helyar, K.R., Ridley A.M., Chen, D., Heng L.K., Evans, J., Fisher, R., Hirth, J.R., Mele, P.M., Morrison, G.R., Cresswell, H.P., Paydar, Z., Dunin, F.X., Dove, H. and Simpson, R.J. 2000. Soil factors affecting the sustainability and productivity of perennial and annual pastures in the high rainfall zone of south-eastern Australia. Australian Journal of Experimental Agriculture 40: 267– 283.

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.

Williams, B.G. and Semple W.S. 2001. Implications of the chemical composition of saline seepage scalds. In: C. Grose, L. Bond and T. Pinkard (eds). Wanted Sustainable Futures for Saline Lands, Seventh National PURSL (Productive Use and Rehabilitation of Saline Land) Conference. Launceston, Tasmania 20-23 March 2001. pp 1-6.

Wood, W.E., 1924. Increase of salt in soil and streams following the destruction of the native vegetation. Journal of the Royal Society, Western Australia, 10: 35-47.


GLOSSARY

acid sulfate soils saline soils or sediments containing pyrites, which once drained (as part of remedial land management measures, or as part of coastal development), become acidic releasing large amounts of acidity into the ecosystem with consequent adverse effects on plant growth, animal life, etc. These soils are widespread around coastal Australia (especially when associated with mangrove swamps) and occur to an unknown extent in inland areas.

potential acid sulfate soils (PASS) – in their pristine state, acid sulfate soils (also termed potential acid sulfate soils (PASS)), occur in saline wetland seeps or are buried beneath alluvium and:

(i) contain black sulfidic material (see below), are waterlogged and anaerobic; (ii) contain pyrite (typically framboidal); (iii) have high organic matter content; (iv) have pH 6-8.

actual acid sulfate soils (AASS) - when PASS are disturbed: (i) contain a sulfuric horizon (see below) because pyrite is oxidised to sulfuric

acid (pH <3.5-4); (ii) iron sulfate-rich minerals form, commonly as bright yellow or straw-

coloured mottles containing jarosite, natrojarosite or sideronatrite. alluvial deposited by a river aquifer water bearing rock unit bedrock unweathered, consolidated rock beneath the regolith zone biophysical relating to biological and physical processes break of slope the point on a slope at which topographic gradient is reduced classification soil - the systematic arrangement of soils into groups or categories on the basis of their

characteristics. Broad groupings are made on the basis of general characteristics and subdivisions on the basis of more detailed differences in specific properties. For complete definitions of taxa (Soil Survey Staff 1999).

colluvial transported by gravity confined flow groundwater flow that is restricted by overlying rocks and is consequently

under pressure conceptual schematic model model based on simplified and condensed geomorphological,

geological, hydrological, soil, regolith, geochemical information. discharge flow of groundwater from the saturated zone to the earth surface dryland cleared or naturally treeless, non-irrigation, non-urban land electrical conductivity (EC) - conductivity of electricity through water or an extract of soil. Commonly

used to estimate the soluble salt content in solution. ECse the electrical conductance of an extract from a soil saturated with distilled

water, normally expressed in units of siemens (S) or decisiemens (dS) per meter at 25°C. A variety of other units, shown in the following table with conversion factors, have been used to describe salinity. Most scientists, planners and regulatory agencies endorse a strong plea for abandonment of these units in favour of standardisation on dS/m Factors for conversion of salinity units to dS/m:

Salinity Unit Multiply to get dS/m µS/cm 0.001 mS/cm 1 mS/m 0.01 S/m 10 µmho/cm 0.001 mmho/cm 1 ppm 0.0016(1) to 0.0019(2) mg/L 0.0016(1) to 0.0019(2) grains/gal 0.023(1) to 0.027(2)

(1) Approximate conversion for natural surface and well waters. (2)Approximate conversion for pure salt solutions of sodium and calcium chlorides


EC 1:5 - the electrical conductance of a 1:5 soil:water extract (i.e. soil is extracted with distilled water), normally expressed in units of siemens (S) or decisiemens (dS) per meter at 25°C. While the EC1:5 method is quick and simple it does not take into account the effects of soil texture. It is therefore inappropriate to compare the EC1:5 readings from two soil types with different textures. It is possible to approximately relate the conductivity of a 1:5 soil-water extract (EC1:5) to that of the saturation extract (ECse) and predict likely effects on plant growth. The following criteria are used for assessing soil salinity hazard and yield reductions for plants of varying salt tolerance, ECse is saturated paste electrical conductivity (after Richards, 1954) and EC1:5 is the corresponding calculated electrical conductivity of a 1:5 soil:water extract for various soil textures.

Salinity hazard ECse

dS/m Effects on plant yield 1:5 Soil/Water Extract (dS/m)

Loamy

sand Loam Sandy

clay loam

Light clay

Heavy clay

Non-saline <2 Negligible effect <0.15 <0.17 <0.25 <0.30 <0.4 Slightly saline 2-4 Very sensitive plants

effected 0.16-0.30 0.18-

0.35 0.26-0.45

0.31-0.60

0.41-0.80

Moderately saline

4-8 Many plants effected 0.31-0.60 0.36-0.75

0.46-0.90

0.61-1.15

0.81-1.60

Very saline 8-16 Salt tolerant plants uneffected

0.61-1.20 0.76-1.45

0.91-1.75

1.16-2.30

1.60-3.20

Highly saline >16 Salt tolerant plants effected

>1.20 >1.45 >1.75 >2.30 >3.20

faulting a rock fracture along which observable displacement has occurred geomorphology the study of land forms gleyed a soil condition resulting from prolonged soil saturation, which is manifested

by the presence of bluish or greenish pigmentation through the soil mass or in mottles (spots or streaks). Gleying occurs under reducing conditions under which iron is reduced predominantly to the ferrous state.

groundwater: subsurface water in the zone of saturation, including water below the watertable and water occupying cavities, pores and openings in underlying soil and rock.

Holocene a period of time from about 10 000 years ago to the present, an epoch of the Quaternary period.

hydraulic conductivity the rate at which water is transmitted hydraulic gradient the change in ground water level elevation over the distance at which the

change occurs hydrochemical relating to the chemistry of water hydrogeological relating to groundwater hydrological relating to surface water impermeable relatively impervious to the passage of water infiltration the unsaturated movement of water through the soil and regolith lacustrine derived from a lake leachate the soil constituent that is washed out from a mixture of soil solids mobilise situation where the naturally occurring metals in soil or sediment are changed

from an insoluble to a soluble state numerical model computer model based on mathematics oxidised process of chemical change involving the addition of oxygen following

exposure to air. palaeodrainage drainage lines that existed in the geological past pH a measure of the acidity of alkalinity of a soil of water body on a logarithmic

scale of 0 to 14; a pH <7 is acid, pH 7 is neutral, and pH >7 is alkaline. Note that one unit change in pH is a tenfold change in acidity

Palaeozoic a period of time from about 545 - 230 million years ago


perched aquifer a hydraulically conductive rock with saturated groundwater flow that is underlain by an unsaturated zone

perennial pastures pastures that grow all the year round permeable able to transport water primary salinity saline groundwater discharge that existed prior to European land use

changes natric horizon a mineral soil horizon that satisfied the requirements of an argillic horizon, but

that also has prismatic, columnar, or blocky structure and a subhorizon having >15% saturation with exchangeable Na+.

recharge area the portion of the landscape in which rainwater enters the soil body moving down the profile to the groundwater.

regolith is the surficial blanket of material including weathered rock, sediments, soils and biota that forms by the natural processes of weathering, erosion, transport and deposition. It has complex architecture, and may vary in thickness from a few centimetres to hundreds of metres

scalded areas areas which are bare of vegetation due to extremely adverse growing conditions, such as being too saline or acidic.

saline seep intermittent or continuous saline water discharge at or near the soil surface under dryland conditions which reduces or eliminates crop growth. It is differentiated from other saline soil conditions by recent and local origin, shallow water table, saturated root zone, and sensitivity to cropping systems and precipitation.

saline soil a nonsodic soil containing sufficient soluble salt to adversely affect the growth of most crop plants. The lower limit of saturation extract electrical conductivity of such soils is conventionally set at 4 dS m-1(at 25° C). Sensitive plants are affected at half this salinity and highly tolerant ones at about twice this salinity.

salinity soil - the amount of soluble salts in a soil. The conventional measure of soil salinity is the electrical conductivity of a saturation extract.

salt mobilisation transport of salt stored in the unsaturated zone by rising groundwaters salinisation the process by which saline groundwater is discharged into streams and at

the earth's surface saprolite weathered material with the same volume as the original rock material secondary salinity discharge of saline groundwater that has occurred as the result of European

land use changes sediments derived from erosion of pre-existing rocks seeps areas where there is continuous discharge of groundwater semi-confined transient between confined (under pressure) and unconfined (under

atmospheric pressure only) skeletal soil thin, poorly developed soil sodic soil a nonsaline soil containing sufficient exchangeable sodium to adversely affect

crop production and soil structure under most conditions of soil and plant type. The exchangeable sodium percentage (ESP) is at least 15 or the sodium adsorption ratio (SAR) of the saturation extract is at least 13. exchangeable sodium percentage (ESP) - exchangeable sodium fraction expressed as a percentage.

sodium adsorption ratio (SAR) a relation between soluble Na and soluble divalent cations, which can be used to predict the exchangeable Na fraction of soil equilibrated with a given solution. It is defined as follows, where concentrations in brackets, are expressed in mmoles per litre:

soil horizon a layer of soil or soil material approximately parallel to the land surface and

differing from adjacent genetically related layers in physical, chemical, and biological properties or characteristics such as colour, structure, texture, consistency, kinds and number of organisms present, degree of acidity or alkalinity, etc.

soil permeability a measure of the ease with which water can enter or move through a soil body soil profile an accurate representation of spatial proportions of the different vertical layers

in a soil body; each layer has individual chemical and physical properties that govern its behaviour


soil texture reflects the proportion of sand (2 – 0.02 mm), silt (0.02 – 0.002 mm) and clay (< 0.002 mm) in soil

soil texture (field method) is determined in the field by the following procedure: Take a sample of soil sufficient to fit comfortably into the palm of the hand (separate out gravel and stones). Moisten soil with water, a little at a time, and work until it just sticks to your fingers and is not mushy. This is when its water content is approximately at "field capacity". Continue moistening and working until there is no apparent change in the ball (bolus) of soil. This usually takes 1-2 minutes. Attempt to make a ribbon by progressively shearing the ball between thumb and forefinger. The behaviour of the worked soil and the length of the ribbon produced by pressing out between thumb and forefinger characterises ten selected soil texture grades as shown in McDonald et. al. (1990).

soil texture groups according to Northcote, 1979): 1. The Sands = sand (S), loamy sand (LS), clayey sand (CS).

2. The Sandy Loams = sandy loam (SL). 3. The Loams = Loam (L); sandy clay loam (SCL); Silty loam (ZL). 4. The Clay loams = Clay loam (CL). 5. The Light Clays = light clay (LC). 6. The Medium-Heavy Clays = Medium clay (MC), Heavy clay (HC).

subsoil commonly understood as that portion of the soil formed below the A horizon; the depth at which it commences varies enormously (e.g. from 5 cm to 5 metres); it has particular characteristics

sulfidic material waterlogged material or organic material that has a pH >3.5 and contains sulfide-sulfur. If incubated as a layer 1 cm thick under moist conditions (field capacity) while maintaining contact with the air at room temperature shows a drop in pH of more than 0.5 or more units to a pH value of 4 or less (i.e. 1:1 by weight in water, or in a minimum of water to permit measurement) within 8 weeks (Soil survey Staff 1999).

sulfuric horizon a horizon composed either of mineral or organic soil material that has both pH <3.5 (1:1 by weight in water, or in a minimum of water to permit measurement) and bright yellow jarosite mottles. A sulfuric horizon is defined as (Soil Survey Staff ,1999), 15 cm or more thick

recharge infiltration of water from the earth surface to the saturated zone topographic gradient steepness of the ground surface transmissivity ability to transmit water, reflecting both the hydraulic conductivity and the area

of the rock unconfined flow groundwater flow that is not restricted by overlying rocks and which is

consequently at atmospheric pressure unconformity a plane that separates older rocks below from younger rocks above, and

represents a break in deposition unconsolidated loosely compacted; uncemented unsaturated zone the zone above the water table that is not saturated in water watertable portion of the ground saturated with water; often used specifically to refer to

the upper limit of the saturated ground weathering the process by which rocks are decomposed The above information has been extracted and/or updated from: Coram, J., ed. (1998). Eggleton, R.A. (editor) 2002. The regolith glossary: surficial geology, soils and landscapes. CRC

LEME, 144pp. McDonald et al. (1990). Northcote, K.H. 1979. A Factual Key for the Recognition of Australian Soils. 4th Ed. (Rellim:

Adelaide). Richards, L. A. 1954.Diagnosis and improvement of saline and sodic soils.

agriculture Handbook No. 60, United States Department of Agriculture, Washington, USA;

Soil Science Society of America. 1997. Internet Glossary of Soil Science Terms [Online]. Available at http://www.soils.org/sssagloss/ (verified 3 May 2001).

Soil Survey Staff (1999).


APPENDIX 1: List and summaries of case studies

This Appendix, firstly, lists the 17 paired case study sites and their geographic location in eight different

Groundwater Flow Systems across southern Australia (Figure 4).

Secondly, individual summary data sheets for each site is given outlining salinity occurrences according to

topographic position and the most applicable generic conceptual model, soil salinisation category, soil

management options, comments and key references.

Site No. Site Name State Easting Northing Datum 1 Merriefields Dundas Tableland, Vic 141.9359 37.3347 (DD; GDA94) 2 Vasey Dundas Tableland, Vic 141.9159 37.3939 (DD; GDA94) 3 Gatum Dundas Tableland, Vic 142.0257 37.3915 (DD; GDA94) 4 Woorndoo South-Western Vic 142.7658 37.8105 (DD; GDA94) 5 Corangamite South-Western Vic 143.5387 38.5052 (DD; GDA94) 6 Spalding Mid North, SA 138.6253 33.4002 (DD; GDA94) 7 Keyneton Mt Lofty Ra, SA 139.1559 34.5087 (DD; GDA94) 8 Dairy Ck Mt Lofty Ra, SA 139.0223 34.8767 (DD; GDA94) 9 Herrmanns Mt Lofty Ra, SA 139.0125 34.8928 (DD; GDA94) 10 Marcollat Upper South-East, SA 140.2773 36.6317 (DD; GDA94) 11 Dick’s Ck Yass Valley, NSW 149.1754 34.9588 (DD; GDA94) 12 Ive Yass Valley, NSW 149.1690 35.9568 (DD; GDA94) 13 Rouse Hill Western Sydney, NSW 150.9088 33.7069 (DD; GDA94) 14 Stirling Swan Plain, WA 115.8104 31.8784 (DD; GDA94) 15 Rundles South-Western WA 117.4547 33.7565 (DD; GDA94) 16 Dumbleyung South-Western WA 117.8607 33.2454 (DD; GDA94) 17 Darkan South-Western WA 116.6192 33.3522 (DD; GDA94)


Site No: 1 Site Name: Merriefields

Location: Dundas Tableland, Vic Groundwater Flow System: Local

Latitude: 37.3347o Longitude: 141.9359o (GDA94)

Slope Position in Landscape Conceptual Model No 1

a) Upper a) 3

b) Mid b) 3 > 1

c) Lower c) 2 > 1

d) Flat d) 2 1Soil Salinisation Category (Table1) 1Management Option Category (Table 5)

a) Secondary, dry saline, subsoil sodic a) H

b) Secondary, dry saline, subsoil sodic Secondary, salt seepage, sulfidic

b) H C

c) Secondary, salt seepage, sulfidic Secondary, eroded seepage scald, sulfuric Secondary, eroded seepage scald, halitic

c) C F E

d) Secondary salt seepage, halitic Secondary, eroded seepage scald, halitic

d) A E

Comments: 2Soil-regolith toposequence model indicates: Lower slopes contain saline, sulfidic seepages with eroded scalds that have crusts and iron slicks overlying sulfidic materials. Thematic cross sections have been constructed to show salinity levels, sodicity, pH and water flow patterns..

References: Rob Fitzpatrick, Jon Fawcett, Melanie Trethowen, Rob Norton, Bill Gardner, Richard Merry and

Peter Dahlhaus Soil morphology and chemistry of a toposequence through saline seepages at the Merrifields experimental site, eastern Dundas Tableland, western Victoria CSIRO Land & Water Technical Report (in prep)

Fawcett, J. PhD thesis (in prep) 1Conceptual models, Tables 1 and 5 as in CSIRO Land and Water Technical Report No 02/03, January 2003. RW Fitzpatrick et al. “Assessment of physico-chemical changes in dryland saline soils when drained or disturbed for developing management options.” 2Selected photos, figures, soil-regolith models and tables, where available, are included in Appendix 3 of the report “Database of Case Studies” that accompanies the final report to NDSP titled “Biogeochemical and physical processes in saline soils and potential reversibility (CLW27)”

n/a - not applicable


Site No: 2 Site Name: Vasey



Slope Position in Landscape 1Conceptual Model No

a) Upper a) 3

b) Mid b) Not saline in upper 2 m.

c) Lower c) 1 and 2


a) Dry, saline, induced, subsoil sodic a) H

b) n/a b) n/a

c) Secondary, eroded seepage scald, halitic Secondary, salt seepage, sulfidic

c) E C

d) Secondary, salt seepage, halitic Secondary, salt seepage, sulfidic

d) A C

Comments: 2 Soil-regolith data down a toposequence indicate some dry saline land (sodic) on upper slopes but only mild sodic subsoils (no salinity) on midslopes. Lower slopes and flats have high salinity and some caused by saline groundwater.

References: Cox, J.W., Fitzpatrick, R.W., Merry, R.H., McCaskill, M. and Mao, R. 1998. Characterisation of

six soil profiles at the MLA SGSKP site at Vasey, Victoria. CSIRO Land and Water Technical Report 38/98 October 1998.

McCaskill, M., Melland, A., Cox, J.W. and Smith, A. 2000. Recharge to groundwater: a snapshot in time from SW Victoria. New Zealand Soil Science Society (NZSSS) and Australian Soil Science Society (ASSS) Conference. 3-8 December 2000. Lincoln University, Canterbury, Christchurch, New Zealand.

1Conceptual models, Tables 1 and 5 as in CSIRO Land and Water Technical Report No 02/03, January 2003. RW Fitzpatrick et al. “Assessment of physico-chemical changes in saline soils when drained or disturbed to develop management options.” 2Selected photos, figures, soil-regolith models and tables, where available, are included in Appendix 3 (Database of Case Studies) that accompanies the final report to NDSP titled “Biogeochemical and physical processes in saline soils and potential reversibility (CLW27)”



Site No: 3 Site Name: Gatum




a) Upper a) n/a*

b) Mid b) 3 (where slope wanes)

c) Lower c) n/a*

d) Flat d) 1 and 2 1Soil Salinisation Category (Table1) 1Management Option Category (Table 5)

a) n/a a) n/a

b) Secondary, dry saline subsoil sodic b) H

c) n/a c) n/a

d) Secondary, salt seepage halitic Secondary, eroded seepage scald halitic Secondary, salt seepage sulfidic

d) A E C

Comments: 2Soil-regolith toposequence model indicates: Past and present hydrological processes. Upper slope: waterlogging in surface horizons caused by perching of soil water within the B-horizon (as opposed to on top of the B-horizon) and the changes in soil structure and the colour of cutans and mottles is an indicator of this first restricting layer. Also, interpedal cracks and old tree root holes act as preferred paths for water to flow through this first restricting layer. Midslope (where slope wanes) a second fresh perched watertable, occurs on top of the pallid zone. Where pallid zone reaches the near surface the two perched watertables merge and cause a local increase in hillside saline seeps that result from seasonal waterlogging. Flats have permanent saline watertable that occur on top of the bedrock and cause salting problems where it comes too close to the soil surface. Salting problems at the bottom of the slope are more severe where fresh perched watertables increase waterlogging.

References: Brouwer J. and R.W. Fitzpatrick (2002). Interpretation of morphological features in a salt-

affected duplex soil toposequence with an altered soil water regime in western Victoria. Aust. J. Soil Research. 40: 903-926.

Brouwer J. and R.W. Fitzpatrick (2002) Restricting layers, flow paths and correlation between duration of soil saturation and soil morphological features along a hillslope with an altered soil water regime in western Victoria. Aust. J. Soil Research. 40: 927-946.

Brouwer J. and R.W. Fitzpatrick (2001). Characterisation of nine soils down a salt-affected toposequence near Gatum on the Dundas Tablelands in south-west Victoria: Application of the structural approach for constructing soil-water-landscape models. CSIRO Land & Water Technical Report. 21/00. pp.48. http://www.clw.csiro.au/publications/technical2000/tr21-00.pdf

1 Conceptual models, Tables 1 and 5 as in CSIRO Land and Water Technical Report No 02/03, January 2003. RW Fitzpatrick et al. “Assessment of physico-chemical changes in saline soils when drained or disturbed to develop management options.” 2Selected photos, figures, soil-regolith models and tables, where available, are included in Appendix 3 of the report “Database of Case Studies” that accompanies the final report to NDSP titled “Biogeochemical and physical processes in saline soils and potential reversibility (CLW27)”



Site No: 4 Site Name: Woorndoo

Location: Dundas Tableland, Vic Groundwater Flow System: Intermediate & Local



a) Upper a) n/a*

b) Mid b) n/a

c) Lower c) 1

d) Flat d) 1 and 2

Soil Salinisation Category 1 (Table1) 1Management Option Category (Table 5)

a) n/a a) n/a

b) n/a b) n/a

c) Secondary, dry saline, subsoil sodic c) H

d) Primary, seepage scald, sulfidic d) C

Comments: 2Soil-regolith toposequence model indicates: Saline profiles on the flat are mostly primary seepage scalds, but expanded by European agriculture.

References: Cox, J.W., Fitzpatrick, R.W., Mintern, L., Bourne, J. and Whipp, G. 1998. ‘Managing

waterlogged and saline catchments in south-west Victoria.’ CRC Soil and Land Management Catchment Management Series No 2 CSIRO Land and Water pp48.

Fitzpatrick RW, Cox JW, Munday B, Bourne J 2000 Development of soil- landscape and vegetation indicators for managing waterlogged and saline catchments. In: Special Issue featuring papers on “Application of Sustainability Indicators” Australian Journal of Experimental Agriculture: (In Press).

1 Conceptual models, Tables 1 and 5 as in CSIRO Land and Water Technical Report No 02/03, January 2003. RW Fitzpatrick et al. “Assessment of physico-chemical changes in saline soils when drained or disturbed to develop management options.” 2Selected photos, figures, soil-regolith models and tables, where available, are included in Appendix 3 (Database of Case Studies) that accompanies the final report to NDSP titled “Biogeochemical and physical processes in saline soils and potential reversibility (CLW27)”

n/a =not applicable


Site No: 5 Site Name: Corangamite




a) Upper a) n/a (very deep sand)

b) Mid b) 2 (underlies deep sand)

c) Lower c) 2 (underlies deep sand)

d) Flat d) 2 1Soil Salinisation Category (Table1) 1Management Option Category(Table 5)

a) n/a a) n/a

b) Secondary, salt seepage, sulfuric b) D

c) Secondary, salt seepage, sulfuric c) D

d) Secondary, salt seepage, sulfuric Primary, salt seepage, sulfidic

d) D C

Comments:

This site is a single observation site where drainage of sulfidic saline sediments have been exposed in a road cut. It illustrates the development of saline acid sulfate soil materials due to drainage.

References:

CSIRO Land & Water Technical Report (in development).

1Conceptual models, Tables 1 and 5 as in CSIRO Land and Water Technical Report No XX/03, January 2003. RW Fitzpatrick et al. “Assessment of physico-chemical changes in saline soils when drained or disturbed to develop management options.” 2Selected photos, figures, soil-regolith models and tables, where available, are included in Appendix 3 (Database of Case Studies) that accompanies the final report to NDSP titled “Biogeochemical and physical processes in saline soils and potential reversibility (CLW27)”



Site No: 6 Site Name: Spalding

Location: Mid North, SA Groundwater Flow System: Local



a) Upper a) 3

b) Mid b) 3

c) Lower c) 3


a) Dry saline, induced, subsoil sodic a) H

b) Dry saline, induced, subsoil sodic b) H

c) Dry saline, induced, subsoil sodic Dry saline, induced, surface soil halitic

c) H G

d) Dry saline, induced, subsoil sodic Secondary, salt seepage, halitic

d) H A

Comments: As shown in the toposequence and cross section diagrams, dry saline land (transient salinity) subsurface and surface expressed is not hydrologically connected to a saline groundwater table. Subsurface expressed is where high levels of salinity occur in the rootzone or subsoil with salinity trends increasing from the surface (ECse 2-8 dS/m) to subsoil (ECse 4-16 dS/m). Surface expressed is where the salinity is very high at the surface (ECse >16 dS/m) (so-called “magnesia patches”); Exists in both primary (naturally) and secondary (induced) forms.

References: Fitzpatrick, RW, Cannon, MG, Thompson, JM, and Cootes, TR. (undated) Soils and Land Use

of a Sub-Catchment of Freshwater Creek near Spalding, South Australia. Unpublished report, CSIRO Land and Water.

Maschmedt, D. 2000. Assessing agricultural land: agricultural land classification standards used in South Australia's land resource mapping program. Adelaide, Primary Industries and Resources South Australia.

Rengasamy, P. 2000. Transient salinity in the root zones of sodic soils. Crop Science Society of South Australia, Newsletter No.187.

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.




Site No: 7 Site Name: Keyneton

Location: Mt Lofty Ranges, SA Groundwater Flow System: Local



a) Upper a) 3

b) Mid b) 3

c) Lower c) 1 and 2?



b) Secondary, dry saline, subsoil sodic b) H

c) Secondary, dry saline, subsoil sodic Secondary, salt seepage, halitic Secondary, salt seepage, sulfidic

c) H A C

d) Secondary, dry saline, subsoil sodic Secondary, salt seepage, halitic Secondary, salt seepage, sulfidic

d) H A C

Comments: Several soil-regolith toposequence models from this catchment indicate: Lower slopes contain saline, sulfidic seepages with eroded scalds that have crusts and iron slicks overlying sulfidic materials. Several thematic cross sections have been constructed to show salinity levels, sodicity, pH and water flow patterns. Selected soil data are included in tables and numerous publications.

References: Brown Ben (1997) Transportation of the salts required in the formation of acid sulphate soils

through a saline rocky microcatchment. Unpublished Bachelor of Environmental Management (Honours) thesis; University of Adelaide

Cox, J.W. and Pitman, A. 2002. Chapter 5 The water balance of pastures in a South Australian catchment with sloping texture-contrast soils. In McVicar et al. (eds) ‘Regional Water and Soil Assessment for Managing Sustainable Agriculture’ p82-94 (ACIAR Canberra, Australia).

Cox, J.W. and Davies, P.J. 2002. Chapter 17 The duration of soil saturation: point measurements versus a catchment scale method. In T. McVicar et al. (eds) ‘Regional Water and Soil Assessment for Managing Sustainable Agriculture’ p224-230 (ACIAR Canberra, Australia).

Fitzpatrick, R.W., Cox, J.W. and Bourne, J. 1997. ‘Managing waterlogged and saline catchments in the Mt Lofty Ranges, South Australia.’ CRC Soil and Land Management Catchment Management Series CSIRO Land and Water pp38

Cox, J.W., Chittleborough, D.J., Brown, H.J., Pitman, A. and Varcoe, J. 2002. Seasonal changes in hydrochemistry along a toposequence of texture-contrast soils. Australian Journal of Soil Research 40: 1-24.


* not applicable


Site No: 8 Site Name: Dairy Ck

Location: Mt Lofty Ra, SA Groundwater Flow System: Local



a) Upper a) n/a*

b) Mid b) n/a

c) Lower c) 1 and 2


a) n/a a) n/a

b) n/a b) n/a

c) Secondary, dry saline, subsoil sodic Secondary, salt seepage, sulfidic Secondary, salt seepage, sulfuric

c) H C D

d) Secondary, dry saline, subsoil sodic > Secondary, salt seepage, sulfidic > Secondary, salt seepage, sulfuric

d) H C D

Comments:

Only the lower parts of the catchment, the lower slopes and alluvial plain with wetlands, have been examined in detail. The remainder of the catchment will likely be as for Site 9 (Herrmanns), that is, the upper parts of the catchment are not saline or similar to Conceptual Model 3.

References: Skwarnecki, M., Fitzpatrick, R.W., and Davies, P.J. 2002. Geochemical dispersion at the Mount

Torrens lead-zinc prospect, South Australia, with emphasis on acid sulfate soils. Cooperative Research Centre for Landscape Environments and Mineral Exploration. CRC LEME Restricted Report No 174. pp. 68 (volume 1) (plus 13 appendices: volumes 2 and 3).

Fitzpatrick R.W., Raven, M., Self, P.G., McClure, S., Merry, R.H. and Skwarnecki, M. 2000. Sideronatrite in acid sulfate soils in the Mt. Lofty Ranges: First occurrence, genesis and environmental significance. In New Horizons for a New Century. Australian and New Zealand Second Joint Soils Conference Volume 2: Oral Papers. (Eds. J.A. Adams and A.K Metherell). 3-8 December 2000, Lincoln University, New Zealand Society of Soil Science. pp. 109-110.




Site No: 9 Site Name: Herrmanns

Location: Mt Lofty Ranges, SA Groundwater Flow System: Local



a) Upper a) 3

b) Mid b) 3 and 2 (minor)

c) Lower c) 1 and 2

d) Flat d) n/a 1Soil Salinisation Category 1 (Table1) 1Management Option Category (Table 5)


b) Secondary, dry saline, subsoil sodic Secondary, salt seepage, sulfidic Secondary, eroded seepage scald, halitic

b) H C E

c) Secondary, dry saline, subsoil sodic Secondary, salt seepage, sulfidic

c) H C

d) n/a d) n/a

Comment: Note that this catchment drains into Dairy Ck (Site 8).

References: Fitzpatrick, R.W., Cox, J.W., and Bourne, J. 1997. Managing waterlogged and saline

catchments in the Mt. Lofty Ranges, South Australia: A soil-landscape and vegetation key with on-farm management options. Catchment Management Series. CRC for Soil and Land Management. CSIRO Publishing, Melbourne, Australia, 36 pp. ISBN 1 876162 30 9.

Fitzpatrick R.W., Boucher, S.C., Naidu, R. and Fritsch, E. 1995. Environmental consequences of soil sodicity. . p. 163-176. In: R. Naidu, M.E. Sumner and P. Rengasamy (eds.). Distribution properties and management of Australian sodic soils. CSIRO Publishing, Melbourne, Australia.

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.

Merry R.H., Fitzpatrick R.W., Bonifacio E, Spouncer L.R. and Davies P.J. (2002). Redox changes in a small wetland with potential acid sulfate, saline and sodic soils. In Soil Science: Confronting new realities in the 21st century. Transactions of International Union of Soil Science 17th World Congress of Soil Science. Bangkok, Thailand. 14-21 August, 2002. Symposium No. 63; 13pp. CD-ROM.




Site No: 10 Site Name: Marcollat

Location: Upper South-East, SA Groundwater Flow System: Regional



a) Upper a) n/a

b) Mid b) n/a

c) Lower c) 1


a) n/a a) n/a

b) n/a b) n/a

c) Secondary, salt seepage, halitic c) A

d) Secondary, salt seepage, halitic Secondary, salt seepage, sulfidic

d) A C

Comments:

Salt accumulation currently strongest in the bleached, lower E (A2) and upper B2t horizons in the undrained soils. Soil profiles reduced (anoxic) below about 130cm. Soil profiles (A and E) become sodic when drained and become highly saline (>6 times sea water) with salt fretting and erosion on edge of drain below 2m with monosulfidic black ooze (MBO) accumulating in drains.

Note: the two pictures presented on the cover of these reports are from this site.

References: Rob Fitzpatrick, Richard Merry, Jim Cox and Jock McFarlane (2002). Effects of drainage on

processes in saline soil profiles in the South East of South Australia. Proceedings of the 8th National Conference and workshop on: “Productive use and rehabilitation of saline lands (PUR$L)”. Perth, Western Australia, September, 16-20, 2002. p.299. http://www.promaco.com.au/conference/2002/pursl/index.htm

A PowerPoint presentation accompanies this paper outlining soil properties and a conceptual model for management.




Site No: 11 Site Name: Dick’s Ck

Location: Yass Valley, NSW Groundwater Flow System: Intermediate and Local



a) Upper a) None

b) Mid b) 1 and some 2 (in saline seeps only)

c) Lower c) 1 and some 2 (in saline seeps)

d) Flat d) 1 and some 2 1Soil Salinisation Category (Table1) 1Management Option Category (Table 5)

a) n/a* a) n/a

b) Secondary, dry saline, subsoil sodic Secondary, eroded seepage scald, halitic

b) H E

c) Secondary, dry saline, subsoil sodic Secondary, eroded seepage scald, halitic

c) H E

d) Secondary, salt seepage, sulfidic Secondary, eroded seepage scald, halitic Secondary, salt seepage, halitic

d) C E A

Comments:

Soil-regolith toposequence models and data indicate: Lower slopes contain saline, sulfidic seepages with eroded scalds that have crusts and iron slicks overlying sulfidic materials. Data show salinity levels, sodicity, acidity, and water flow patterns. Selected soil data are included in tables.

References: Acworth, R.I., and Jankowski, J. 2001. Salt source for dryland salinity—evidence from an

upland catchment on the Southern Tablelands of New South Wales. Australian J Soil Res. 39: 39-59.

Melis, M. I. Acworth, R. I. 2002. An aeolian component in Pleistocene and Holocene valley aggradation: evidence from Dicks Creek catchment, Yass, New South Wales. Australian J Soil Res. 39: 13-38.

Ghassemi, F., Jakeman A.K. and Nix H.A. 1995. Salinisation of land and water resources: Human causes, extent, management and case studies. Chapter 2: Australia (p. 143-212. University of New South Wales Press LTD, Australia and CAB International, UK.

Herwantoko, K.D., 1991. Hydrogeochemical study of upland salinity at Dick's Creek Catchment, Yass Valley, NSW. Unpublished University of New South Wales M. App. Sc. Thesis.




Site No: 12 Site Name: Ive

Location: Yass Valley, NSW Groundwater Flow System: Intermediate and Local



a) Upper a) Not saline or 3?

b) Mid b) 2 and 3 (restricted area of seeps)

c) Lower c) 1

d) Flat d) 1 1 Soil Salinisation Category (Table1) 1Management Option Category (Table 5)

a) n/a* a) n/a

b) Secondary, salt seepage, sulfidic b) C


d) Secondary, eroded seepage scald, halitic d) E

Comments:

Limited quantitative data.

References:

None.




Site No: 13 Site Name: Rouse Hill

Location: Western Sydney, NSW Groundwater Flow System: Intermediate and Local



a) Upper a) 3

b) Mid b) 3

c) Lower c) 1

d) Flat d) 1 1Soil Salinisation Category (Table1) 1 Management Option Category (Table 5)




d) Secondary, eroded seepage scald, halitic d) E

Comments:

Soil-regolith toposequence model indicates that sodic soils are the dominant soils in the area (approximately 80%). The highest values of exchangeable sodium were present in subsoils in the creekline. These soils are highly dispersive when in contact with low salinity water (e.g. rainwater) and some of these soils also have pronounced shrink-swell characteristics. Some very acid layers were present in the subsoils and weathered shale.

Topsoils are generally only saline in the immediate vicinity of Second Ponds Creek. Subsoils in the creek and immediately adjacent (approx. 20 m) are highly saline and due to saline groundwater . All subsoils within 150 m of the creek are moderately saline due to leaching of salts in rainfall and natural weathering processes and salt accumulation around the rootzone of past vegetation.

The source of salinity in and near the creek is saline groundwater discharge. The volume and quantity of groundwater discharge into the creeklines will vary depending on seasonal groundwater fluctuations (seasonal groundwater recharge). When groundwater levels are high the areal extent of the salinity problem will be greatest. Salts are being concentrated due to evaporation of surface water and groundwaters. Some minor sulfidic materials are present in the vicinity of the creek.

References: Cox, J., Fitzpatrick, R. Williams B., Davies, P. and Forrester, S. 2002. Salinity investigations at

Second Ponds Creek. CSIRO Land and Water Consultancy Report for Rouse Hill Infrastructure Pty Ltd July 2002 pp 54.




Site No: 14 Site Name: Stirling

Location: Swan Plain, WA Groundwater Flow System: Regional



a) Upper a) n/a

b) Mid b) n/a

c) Lower c) n/a


a) n/a a) n/a

b) n/a b) n/a

c) n/a c) n/a

d) Secondary, salt seepage, sulfuric d) D

Comments:

Drained sulfidic peat layer exposing sulfidic material in the drain and stockpiling the sulfidic spoil has formed saline acid sulfate soils (pH <3.5) with Fe-rich gels containing high levels of As at Stirling on the Perth Plain. It is preferable that such sulfidic materials are not drained and an anoxic environment is maintained. Awareness of the potential problems and an adequate risk analysis plan would have prevented environmental problems that have occurred in this area. The groundwater also contains high levels of As.

References: Unpublished reports by Steve Appleyard and Stephen Wong (Department of Environment,

Water and Catchment Protection DEWCP; Environmental Regulation Division.




Site No: 15 Site Name: Rundles

Location: South-Western WA Groundwater Flow System: Local



a) Upper a) 3

b) Mid b) 3

c) Lower c) 1

d) Flat d) 1 and 2 1 Soil Salinisation Category (Table1) 1 Management Option Category (Table 5)



c) Secondary, salt seepage, halitic c) E

d) Secondary, eroded seepage scald, halitic Secondary, eroded seepage, sulfidic

d) E C

Comments: Several preliminary toposequence process models have been constructed and analytical data is available but was not in a form that was able to be included in this report.

References:

Unpublished material CSIRO Land & Water.




Site No: 16 Site Name: Dumbleyung

Location: South-Western WA Groundwater Flow System: Intermediate



a) Upper a) n/a

b) Mid b) n/a

c) Lower c) n/a

d) Flat d) 1

Soil Salinisation Category 1 (Table1) 1Management Option Category (Table 5)

a) a) n/a

b) b) n/a

c) c) n/a

d) Secondary, salt seepage halitic d) A

Comments:

The processes at this site closely resembles the drained Marcollat site (Site no. 10). Original saline soil surface layers become sodic after drainage with subsoil layers exposed in the drain showing salt fretting and dispersion and some evidence of formation of monosulfidic black ooze in the drain sediments. Analytical data is available but was not in a form that was able to be included in this report. Soil morphological variability at this site made paired profile (drained and non-drained) comparisons difficult. However, we expect that rehabilitation of these soils should be successful.

References:

None


*n/a not applicable


Site No: 17 Site Name: Darkan

Location: South-Western WA Groundwater Flow System: Local



a) Upper a) not inspected

b) Mid b) not inspected

c) Lower c) not inspected

d) Flat d) 2, 1 Soil Salinisation Category (Table1) 1 Management Option Category (Table 5)

a) n/a a) n/a

b) n/a b) n/a

c) n/a c) n/a

d) Secondary, salt seepage, sulfidic d) C

Comments:

The processes at this site closely resembles the sites on Dundas Tableland (Sites 1, 2 and 3) and Mount Lofty Ranges (Sites 7 and 9).

References:

None

1 Conceptual models, Tables 1 and 5 as in CSIRO Land and Water Technical Report No XX/03, January 2003. RW Fitzpatrick et al. “Assessment of physico-chemical changes in saline soils when drained or disturbed to develop management options.” 2Selected photos, figures, soil-regolith models and tables, where available, are included in Appendix 3 (Database of Case Studies) that accompanies the final report to NDSP titled “Biogeochemical and physical processes in saline soils and potential reversibility (CLW27)”



APPENDIX 2: Steering committee, contributors and acknowledgments

The steering committee was the South Australian State Dryland Salinity Committee. A series of workshops

was held with key groups including:

Woorndoo Land Protection Group,

Corangamite Catchment Management Authority.

Glenelg-Hopkins Catchment Management Authority.

Funding support from the National Dryland Salinity Program and Land and Water Australia is gratefully

acknowledged. Investment by the Australian Centre for International Agricultural Research (ACIAR) and

CRC LEME was also important in enabling this research.

Many scientists and workers in the field of dryland salinity contributed to method development, data,

comments and suggestions, helpful discussion and testing of the user friendly classification of saline soils,

conceptual models and best management practices, all of which were important to the development of the

outcomes of the project. However, it is not possible to acknowledge all of these contributions individually,

but this study would not have been possible without the past and present efforts of many workers, including

the following:

South Australia

Bruce Munday (NDSP Communicator), Jock McFarlane (PIRSA), Nathan Mohammad (Masters student),

Chris Henschke (Rural Solutions SA), Marian (Swanny) Skwarnecki (CRC LEME)

Western Australia

Steve Appleyard and Stephen Wong (Department of Environment, Water and Catchment Protection

DEWCP; Environmental Regulation Division); Neil Coles (Agriculture Western Australia), Noel Schoknecht

(Agriculture Western Australia), Russell Speed (Agriculture Western Australia).

Victoria

Lee Anne Mintern (DNRE), Peter Dahlhaus (Ballarat University), Richard MacEwan (CLPR), Jon Fawcett

(PhD student).

New South Wales

Greg Bowman (DLWC), Gavin Wood (Rouse Hill Infrastructure Pty Ltd), John Ives (CSIRO), Dr Baden

Williams.

Others

The drafting assistance of Greg Rinder (CSIRO Land and Water) is gratefully acknowledged. Sean Forrester

(CSIRO Land and Water) helped with laboratory and field work. Doug Reuter edited a draft of the

manuscript. Evan Christen supplied information on drainage in irrigated regions.


APPENDIX 3: Draining Saline Land – Risk Planning and Environmental Assessment

Introduction

Risk management must be an essential part for managing drained saline land. Many factors that need to be addressed by planners in managing the on- and off-site consequences before drainage of saline soils is attempted. Individual farmer/land manager must have access to relevant information to support any actions that might be taken in paddocks, has understanding of the processes and includes clear guidelines on, for example, the cost-effectiveness of soil remediation. This attachment is provided as an example for environmental risk management and is largely based on a project planning and environmental assessment process used by Transport South Australia. Their permission to use parts of their process is gratefully acknowledged. This process follows the generic framework in AS/NZS 4360:1999 Risk Management. Concept Planning

The potential impact of drainage should be considered when evaluating and scoping options, and the cost of mitigation measures should be included in budget estimates. Drainage Planning

An evaluation of the impact of drainage on soil properties, drain maintenance, the quality of drainage water and aquatic environments (including flora and fauna) should be undertaken as part of the environmental impact assessment for the project. This should be included when evaluating alternatives and selecting preferred options. The following steps should be undertaken and reported:

Assess and document the nature of the receiving environment affected by the project. Assess and document the potential impacts of works both during construction and operation on the

receiving environment. Obtain appropriate soil data and devise optimum and achievable soil management strategies. Identify potential risk mitigation measures. Undertake a risk assessment to evaluate risks and identify most appropriate risk alternatives and

mitigation measures. All documentation will demonstrate a 'duty of care' and provide opportunities for reviewing the appropriateness and effectiveness of the measures taken. Risk Management

Risk management framework

Risk management is applied to all spheres of organisational planning and management, including environmental management to ensure that key risks are being recognised and addressed. Risk assessment addresses the causes and effects for potential environmental harm and the economic viability of the proposed activity. It evaluates risk linked to treatments so that the most appropriate measures are identified and expenditure can be prioritised. Risk assessment should be undertaken to determine the potential nature, scale and likelihood of any impacts during both the construction phase and the operation of the drains. Consideration should be given to the potential impacts of staged earthworks; altered surface or groundwater hydrology and drainage pathway; and to the transport of pollutants (salts, acidity, alkalinity, heavy metals) in runoff. The main steps in the risk management process are:


Establish the context Identify risks Analyse risks Evaluate risks Treat risks.

There is some iteration in the process (or feedback loops that are required) to ensure that the overall drainage project proceeds with an acceptable level of risk. The effectiveness of the risk treatment plan, strategies and the management system set up to control implementation must also be monitored through this iterative process. Ongoing review is essential to ensure that the management plans remain relevant. Each main step is discussed in the following sections. Establish the context

The nature of drainage plans vary widely. Each project should define scope of the risk, which include: The purpose and nature of the project. The productivity or environmental benefit to be expected. Input from local community, catchment groups and land boards, and recognise catchment

management plans. Legislative compliance requirements under relevant acts - for example, some activities are

prescribed in legislation and are subject to approvals and licence conditions. Criteria for accepting of risk should be understood or determined. These will involve considerations

of cost, as well as opportunities. How much effort and expenditure do the works warrant? What are community expectations?

Identify risks

This step is applied to all drainage projects, large or small and may need to be an iterative process as more information becomes available or adjustments to the project are made. It can be undertaken as a brainstorming exercise. Every conceivable environmental risk arising from the project should be identified and recorded, as prompted by answers given to the key questions:

What can happen? How and why can it happen?

To carry out this step, a thorough understanding of the local environment is essential. Risk identification may require input from many areas and other agencies or stakeholders and from consultation to risk management workshops. Knowledge of the methods to be used in the project's construction and of the ongoing operational characteristics will also be needed. All information gathered should be documented to a level of detail appropriate to the scale of environmental impact. Relevant expertise and advice should be sought and used where necessary. All risks should be documented where a risk is not identified at the planning stage. Appropriate tools for risk identification and management during the remainder of the process should be selected. The 'owners' of risks identified during this process should be documented together with the names of those considered to be accountable and responsible for the management of risk. Thus, a risk might be identified during drain design, a treatment developed during project management, and responsibility for ongoing operation and review transferred to a maintenance contractor on completion of the project. The aspects listed below should be considered in identifying risks. A proforma to assist in risk identification should consider: Environmental characteristics

The topography of the site. Climate and rainfall patterns. Soil properties (Table 1) and scope for remediation (Table 5) for productive or environmentally

advantageous use. The drainage pattern and size of catchments. The quality and nature of areas receiving waters. The quality and depth to groundwater and any pollution transport mechanisms.


The vegetation and ecology of the site and surrounding area, including the downstream aquatic environment (e.g. important wetlands, aquatic habitat, rare or endangered flora or fauna, or other significant area).

The land use of the adjacent and downstream areas. Any sensitive land and water uses that may be affected by soil erosion or water quality impacts from the draining (including downstream water users) should be identified.

The nature and capabilities of any water quality treatment measures already in place downstream of the project area.

Project characteristics

The timing and scale of the project. Any proposed staging of the project (extent of area under construction at any one time), particularly

the area exposed to ingress of saline water or to erosion during high rainfall or potential storm events.

The extent of cut and fill. Effective drain maintenance programs. Concentration or dispersion of waters, changing the nature, timing, location and quality of flows or

altering flood patterns. The extent to which risks can be avoided by management justified (proven) measures. The effect of the project on any water quality treatment measures already in place downstream of

the project area. Impediments to achieving water quality objectives for the catchment.

Analysis of risks

Risk Analysis is accomplished through examination of all the previously identified risks in relation to two questions:

How likely is it to happen? What could be the consequences if it does happen?

The information about the site and the project re-examined to answer these questions. In making these judgements (about likelihood), it is useful to recognise that some factors are not influencing absolute probability but are relative. As an example: erosion is more likely to occur if the accession of low salinity precipitation water disperses sodic soil materials. The likelihood of risk will relate to aspects such as exposure of sodic soils in drains or erosion gullies, likelihood of heavy rainfall, capacity to apply gypsum or the cost–effectiveness of stabilising drain walls. The off-site consequences or impacts of a particular drain depend largely on the nature of the receiving environment. For example, increased saline runoff that drains into an established wetland may affect the ecology of the wetland. Evaluation of risks

Once the likelihood and potential consequences have been assigned levels, a qualitative risk analysis matrix (eg, adapted from AS/NZS 4360:1999) provides a simple way to evaluate the level of risk. There maybe difficulties in achieving consistency in the application of qualitative scales. When allocating risk categories, it is advisable to involve a range of people with suitable expertise. Treatment of risks

The risk assessment process indicates, which risks require priority attention, during both the drain construction and operational phases. For drained soils, risk should include the possibility that productivity goals are not met, or that soil remediation is ineffective. A general indication is needed of the efforts in treatment and mitigation that would typically be warranted for the risk levels indicated. Detailed consideration of specific treatment measures to address risks requires answers to the following questions:

How effective are any existing mitigation measures? Are the criteria set in the first step-'establish the context' satisfied by the mitigation measures? If not, what additional treatments are available and how effective would they be in reducing the risk

to an acceptable level?


Are the additional measures reasonable and practicable? Are the criteria set in the first step -'establish the context' satisfied by the additional measures?

The logical sequence of the risk management process explained above can be adapted to suit the nature of each project and its risks. With an understanding of, and confidence in the use of the process, it is possible to combine the documentation of many of the steps in one table. Developing Mitigation Measures

Operational phase mitigation measures

Documentation of the nature and source of risks from drainage as well as site constraints, opportunities, or any existing treatment measures downstream of the site will enable appropriate treatment measures to be identified. Addressing potential problems such as water quality may require partnerships with other stakeholders, Catchment Water Management Boards and Councils. The approach must consider selection of reasonable and practicable measures. As different treatment measures treat different risks, a series of treatment measures may need to be put in place to achieve effective control by possibly achieving synergies (Table 5). Where practical, treatment measures should be sited as close as possible to the source of risk rather than understating larger, downstream measures. However, the practicality and cost of maintaining a relatively large number of small-scale treatment measures, compared with a single or a few larger-scale treatment measures needs to be considered. Construction phase mitigation measures

During the planning phase, consideration should be given to the potential impacts from construction phase activities on soil erosion, vegetation management, water quality, aquatic ecology, downstream users and so on. The objective is to avoid, where possible, or minimise impacts during construction. Appropriate management measures should be identified in the planning phase and documented. Approvals or licences required for the project (under the Environment Protection Act or Water Resources Act) must be acquired. Monitoring

Both soil (Table 5) and water quality monitoring should be undertaken to detect changes in soil quality and nature of effluent discharges, and to assess the potential impact of the discharge on the downstream environment. During the construction phase, monitoring must be undertaken to determine whether site management practices and mitigation measures are successful in preventing sediment, waters or pollution from accessing drainage lines, groundwater and waterways being transported or disposed. The level of monitoring required is determined by evaluation of the nature of a threat from a discharge and the level of protection required for the environment. Generally, the greater the potential environmental risk posed by a project, the more rigorous and complex the monitoring requirements become. The environmental monitoring program should identify the level of monitoring required (e.g. long term monitoring). Documentation

Where measures are required to manage drained soils or protect aquatic environments, the measures should be documented and lodged with an appropriate body. For example, unless approvals and compliance with licensing or legislation is documented, it may be difficult to manage future changes in imposed conditions. Similarly, unless groundwater levels and drain water quality are monitored and recorded, the efficacy of soil and water management cannot be gauged and changes in salt loads understood. An effective documentation mechanism is essential and should be appropriate to manage the various potential risks and the assumptions made. In accordance with the relevant environmental approval process for the project, the environmental assessment of the project, incorporating the information on the risk management, should be forwarded to the relevant approving authority.

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