Project: Diagnostic Agronomy
Physical and chemical soil constraints of wheat crops
in southern Australia
Introductions
This is a guide to information that enables land managers to make better decisions
about physiochemical constraints for wheat grown in south-eastern Australia.
Role of Soil Constraints in agriculture (description /
contributing factors)
Soil Constraints comprise of Soil pH, Boron (B), Salinity, Sodicity and physical
constraints. They impact the growth and productivity of wheat and can reduce
wheat vigour, yield and quality. In South-eastern Australia the role of soil
constraints, particularly in sub-soils has been well documented.
Diagnosing Soil Constraints (management / how to measure)
Soil testing is the most effective means of detecting soil constraints before they
impact on grain yields. Many tests can be undertaken within the field, although
more accurate readings require laboratory analysis. Recognised tests include
Electrical conductivity (for salinity), pH (for alkalinity) and extraction from hot CaCl2
(boron).
There exists a high correlation between many of the constraints, so not all tests are
necessary. Good subsoil sampling techniques are vital for ensuring accurate values.
Tissue testing can be used, although careful consideration must be given, as this can
be problematic.
Historical records of limestone, dolomite and gypsum applications, soil tests, and the
grain yields and conditions in prior seasons can assist to estimate a paddock’s soil
constraints.
Correcting Soil Constraints (recommendations)
Applying the principles of good crop nutrition will ensure correct acidity and sodicity
within the top soil. The principles are right place, right time, right type and right
amount. Many methods for managing subsoil constraints can become financially
unviable, and can have limited effects (e.g. soil amelioration). In many cases it is
best to adapt and ‘live’ with the constraints or choose another viable crop.
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Physical and chemical soil constraints to wheat crops
in southern Australia
Scope
This review of the literature focuses on the function, importance and management
of physicochemical constraints located in the subsoil (SSC’s) for wheat production in
dryland cropping systems of south-eastern Australia. Large sections of the southern
grain belt regularly fail to meet water use efficiency benchmarks and SSC’s have
been identified as a major contributor to this problem. These constraints principally
comprise: soil pH, boron (B), salinity, sodicity and physical constraints, either
singularly or in combination. The review draws on a selection of cornerstone journal
articles and book chapters that provide foundation information about the role of and
importance of soil constraints in wheat production. Information is sourced from the
international literature and, where available, literature that provides specific
Southern Grains Region content. The selected research and extension literature
focuses at the regional level but is underpinned by the basic universal principles of
how soil constraints effect wheat production provided by the cornerstone articles
and texts. Region-specific literature may be in the form of conference papers, fact
sheets, technical reports or decision support systems (DSS).
These high quality information sources are selected to assist advisers and growers to
improve their understanding of soil constraints to provide the basis for improved
decision making for managing them.
Outcome
This literature review seeks to assist advisers and growers to make more informed
decisions about managing soil constraints. The review summarises the importance
and effects of soil constraints, how to diagnose the scale and impact of them and
potential management option in dryland cropping systems and provides a
bibliography of reliable information sources. This literature review will be combined
with reviews of other agronomic topics to provide growers and advisers with a
carefully targeted source of information that will assist them to make more informed
decisions about agronomic management.
Effects of soil constraints in broad-acre grain crops
The potential impact of some particular physico-chemical constraints in neutralalkaline soils of South eastern Australia on grain production has been known for
decades. For instance, the impact of B (B) toxicity on cereal growth in South
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Australia was identified in the 1980’s (Cartwright et al. 1984). Chemical and
physical soil constraints can significantly reduce wheat vigour, grain yields and
quality due to the direct toxic effect of some constraints on the crop or (more
commonly) indirectly via their effect on root growth and function which limit crop
access to and utilisation of nutrients and water in the soil (Adcock et al. 2007; Dang
et al. 2010, Rengasamy 2002, The Profitable Soils Group (PSG) 2009).
Root growth and function are impaired by both physical constraints such as hard
pans (using the result of tillage), naturally occurring ‘dense’ soil or a shallow rock
layer (Rengasamy 2002). Further, root growth is severely restricted to shallow soil
layers in soils that are waterlogged or have chemical constraints such as aluminium
toxicity, B toxicity, sodicity, acidity or alkalinity (Figure 3) (MacEwan et al. 2010, PSG
2009).
Figure 3: Wheat with aluminium toxicity symptoms in the roots. Sourced from
Western Australian Department of Agriculture and Food.
Soil constraints in context of south-eastern Australia
Soil constraints impacting on the growth and productivity of wheat in south-eastern
Australia are well-documented, particularly for subsoils.
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Figure 1: A model of the effects of subsoil constraints on crop growth. Sourced from
BCG (20XX), originally sourced from Rengasamy et al. (2003).
Subsoils are typically defined as below the plough layer, although some references
imply below the A1 horizon or soil profile greater than 10 cm. The nature and
impact of particular subsoil constraints in the southern region is strongly related to
soil type and soil pH, particularly Vertosols, Calcarosols, Tenosols and Sodosols with
alkaline subsoils and acidic Chromosols and Sodosols. Some soils have naturally acid
or neutral surface soils with alkaline subsoils. Many of the physico-chemical
constraints to crop (and pasture) growth, especially those located in subsoils, occur
naturally, reflecting the climate and geology of the region. However secondary
salinity, resulting from rising water tables or problems associated with acidification
of sub-soils is normally attributed to human activity (Coventry et al. 1987). In the
acid soils of southern Victoria and southern New South Wales (NSW) poor wheat
growth is often related to soil sodicity, excess acidity/high aluminium or manganese
toxicity , or the physical constraints of waterlogging and high bulk density (Conyers
et al. 2003, MacEwan et al. 2010). In the neutral and alkaline soils of northwest
Victoria and the cropping areas of South Australia, wheat production is principally
constrained by excess alkalinity, salinity, sodicity or B in subsoils (Adcock et al. 2007)
although recent studies suggest that aluminium toxicity associated with highly soil
pH may also be a major constraint to root growth (Brautigan et al. 2012). Many of
these constraints co-exist in the same soil profile (PSG 2009), making both detection
and subsequent management difficult.
Sodicity (exchangeable sodium > 6%) occurs on over 80% of cropping land in Victoria
and over 60% of cropping lands in Australia (Ford et al. 1993, Northcote and Skene
1972). Sodic soils have poor soil structure and porosity which limits available water
and reduces plant growth by up to 50% (Rengasamy 2002). Similarly, soil salinity
occurs extensively in Victoria and the cropping regions of South Australia (Figure 2)
(Hall et al. 2009). Like sodic soil, saline soils also have excessive amounts of sodium
however saline soil also contain other salts, namely calcium and magnesium as well
as chloride, sulphate and carbonates. Since both salinity and sodicity is related to a
soil’s sodium content, soil is classified along a spectrum from saline to sodic
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(Rengasamy 2010). Salinity that effects crop growth is associated with water tables
(Figure 2) and susceptibility to waterlogging (Figure 5) in southeast South Australia
whilst most cropped soils in Victoria and South Australia have the potential to
experience transient salinity associated with excess rainfall occurring in sodic soils
(Rengasamy 2002). The economic effect of salinity in agriculture is considerable
being estimated at $1.5 billion annually for the whole of Australia (Rengasamy 2010).
An exception is in the higher rainfall environment of southern Victoria where salinity
is not considered a major factor effecting productivity of grain crops (Dahlhaus et al.
2000, MacEwan et al. 2010).
Boron toxicity was first detected in cereals in South Australia in 1984 and
subsequently found to be a common occurrence in south-eastern Australia
(Cartwright et al. 1984, 1986). This element is essential for plant growth at trace
levels and B is used as a fertiliser in south-eastern Australia on leguminous pastures
and horticultural crops such as potatoes and poppies in acid coarse textured soils in
high rainfall areas where B can be leached from the root zone (Shorrocks 1997, Dear
and Weir 2004). Soil pH outside the range considered suitable to wheat production
(soil pH 5.5-7 (Hazelton and Murphy 2007) occurs in the Mallee, Wimmera, much of
the cropping areas of South Australia (alkaline) and in southern Victoria and
southern NSW (acidic) (de Caritat et al. 2011, Slattery and Hollier 2002, Upjohn et al.
2005). Overcoming soil constraints in the subsoil by use of fertilisers or other soil
amelioration strategies (e.g. deep ripping and deep liming) can be prohibited by cost
even if it is technically possible (Gill et al. 2008, PSG 2009).
Despite the prevalence of subsoil constraints in wheat cropping regions there are
questions about their relative impact on yield potential. An analysis of 233 field
trials conducted over 12 years on the alkaline to neutral soils of southern Australia
shows that subsoil constraints only reduce grain yield of wheat about 40% of the
time (McDonald et al. 2012). Similarly, Nuttall et al. (2003) suggested that up to
40% of the variance in the grain yield of Yipti wheat in the southern Mallee region of
Victoria could be explained by the impact of subsoil constraints. Thus although
subsoil constraints are an important issue in crop production the actual impact on
grain yield depends on several other factors including crop and cultivar tolerance
and the nature of season (especially soil water (Nuttall and Armstrong 2010).
Local tools available to help diagnose and manage
chemical and physical constraints
There is a comprehensive diagnostic guide to identify and manage subsoil
constraints in neutral and alkaline soils of south-eastern Australia (PSG 2009) as well
as practical local guides to diagnosing and managing constraints like sodicity (Central
West Catchment Management Authority (CW CMA) 2008, Dear et al. 2005). A key
consideration in managing subsoil constraints is the assessment of the financial
viability of different management options, including ‘living with the problem’ (PSG
2009). A video animation is also available that helps explain the behaviour of sodic
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soils; one of the major constraints discussed in local management guides. The guide
for alkaline and neutral soils (PSG 2009) also contains information for managing
physical constraints (waterlogging, high bulk density and hard pan layers) and
technical information about installing raised beds to alleviate water logging is found
elsewhere (Wightman et al. 2005).
There are also tools to help diagnose acidic topsoils in south-eastern Australia
(Upjohn et al. 2005) that explain the effects of soil pH and benefits of liming to
reduce soil acidification (e.g. this factsheet). This video animation helps explain how
soils become acidic, how liming acts to reverse the process, how soils can re-acidify
and need to be limed again at a later date. On-line calculators are available to help
compare the cost of different sources of lime and the anticipated benefits of
applying lime. However, no ready-reckoner type calculator is promoted in extension
literature to support decisions about how much lime needs to be applied to effect a
targeted change in soil pH.
Management strategies for subsoil constraints
The basic approach to managing subsoil constraints in cropping systems involve the
following steps:

Diagnosis of the subsoil constraint

Identification of the subsoil constraint (location and magnitude)

Potential management options (amelioration, genetic solutions)
Diagnosing whether subsoil constraints are limiting crop
production
The key manifestation of subsoil constraints impacting on crop growth is the
presence of ‘unused’ water within the potential rooting zone of a crop during a dry
finish (Armstrong et al. 2009). Poor growth of wheat directly due to chemical or
physical subsoil constraints is compounded by root growth being insufficient for
plants to physically access available nutrients and soil water (Adcock et al. 2007)
(Nuttall and Armstrong 2010). Temporal and spatial variation in the manifestation of
subsoil constraints makes it challenging to diagnose their presence and impact.
However, difficulties in diagnosing subsoil constraints that arise from variation
within a paddock can be at least partially addressed by dividing the paddock into
sections based on soil properties, crop growth and historic grain yields. Monitoring
tools such as electromagnetic spectrum (EM38), remote sensing including
normalised difference vegetation index (NDVI), and grain yield monitoring during
harvest can be used to determine where boundaries, and therefore sampling areas,
should be set within a paddock. This not only applies to the properties directly
monitored but also for other soil properties that are well correlated to
measurements (e.g. EC and soil water or clay content) (Armstrong et al. 2009,
Whelan and Taylor 2013).
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Physical constraints
Physical constraints to wheat growth commonly occur throughout south-eastern
Australia in acid and neutral to alkaline soils (Adcock 2007; Hall et al. 2009, PSG
2009, MacEwan et al. 2010). The types of physical constraints differ between soil
types and may be a natural phenomenon or due to soil management practices such
as trafficking by vehicles and livestock causing soil compaction.
Wheat growth in the acid soils of southern Victoria and southeastern South Australia
(Figure 2) is constrained by the compounding effects of rainfall being excess to crop
requirements and naturally occurring high bulk densities related to high (> 50%) clay
content in the subsoil (Hall et al. 2009, MacEwan et al. 2010). The effect of excess
water with high bulk density is physical impediment of root growth into the subsoil
and waterlogging (Figure 5); either visible on the soil surface or below the soil
surface as a perched water table (Shaw et al. 2013). Waterlogging is also a physical
constraint in some neutral to alkaline soils and is related to soil sodicity which tends
to occur in soils that also have dense clay subsoils and high bulk density that is either
naturally occurring or due to soil compaction that causes hard-pans (Rengasamy
2002, PSG 2009).
Effects of constraints on wheat
Salinity, B toxicity and aluminium toxicity all produce similar visual symptoms in
older wheat leaves; lack of vigour and yellowing (Figures 1 and 2) (Wurst et al.
2010). Wheat growing under excessively saline conditions or in soils with high
aluminium have the additional symptom of appearing drought effected or wilted
(Figure 1). Wheat leaves subjected to excessive B also appear yellowed starting at
the leaf tips (Figure 2). Visual symptoms of micronutrient deficiencies that occur due
to soils being too acidic or alkaline for wheat production vary with climatic and
edaphic conditions (Grundon et al. 1997).
Figure 1: Wheat with B toxicity. Sourced from: Western Australian Department of
Agriculture and Food.
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Figure 2: Wheat with salinity symptoms. Sourced from: Western Australian
Department of Agriculture and Food.
The effect that underlying subsoil constraints have on the uptake of other nutrients
and water can make diagnosis complex. Management is challenged by the need to
differentiate between deficiencies or toxicities that can be actively managed and
constraints that need to be accepted as limiting production (Grundon et al. 1997,
PSG 2009).
In highly acidic or alkaline soils, some nutrients are chemically unavailable due to
being in an inaccessible form (Hazelton and Murphy 2007). In acid soils, minor
elements such as molybdenum and magnesium can appear deficient (Upjohn et al.
2005) and in higher rainfall environments with highly acidic soil (pH <5) aluminium
and manganese toxicity can appear in wheat (Hazelton and Murphy 2007, MacEwan
et al. 2010). Conversely in alkaline soils, plants exhibit deficiencies in the nutrients
iron, manganese, copper, zinc and phosphorus whilst sodium and B are common
toxicity issues (Nuttall et al. 2003, Naidu and Rengasamy 1993).
Identifying subsoil constraints by soil and tissue analysis
Soil testing
Soil testing in a pre-emptive indicator of a chemical constraint to crop production.
Testing for subsoil constraints requires sampling the potential root zone. Many
subsoil constraints, especially B, salinity and sodicity, tend to increases with clay
content which in turn tends to increase with depth in south-eastern Australia
(MacEwan et al. 2008, Table 1.). Much of the soil testing required to identify
alkalinity, acidity, salinity and sodicity can be undertaken in the field or in an
informal laboratory (Baxter and Williamson 2001, Emerson 1967, Rengasamy and
Bourne 1997).
Formal laboratory testing is required to accurately measure soil constraints.
However, there is a high correlation between many constraints so not all tests may
need to be performed to conclude that several constraints are likely to be present in
a particular neutral to alkaline soil (Nuttall et al. 2003). Electrical conductivity (EC) is
measured in a 1:5 soil : water suspension to quantify salinity (method 3A1) (Rayment
and Higginson 1992). The raw value of EC is modified to take account of soil texture
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using factors specific to each textural classification and the modified value (ECe) is
used to assess soil salinity. Wheat is considered to be a tolerant crop and is not
effected by ECe values up to 6 dS/m (Hazelton and Murphy 2007). In neutral to
alkaline soils, ECe is correlated with exchangeable sodium (r = 0.96) and
exchangeable sodium percentage (ESP) (r = 0.71); the measurement for soil sodicity
(Nuttall et al. 2003). Independently, soil sodicity is assessed using method 15A1 to
measure exchangeable sodium percentage (ESP). Soils are technically classified as
sodic if ESP is > 6% of the exchangeable cations calcium, magnesium, sodium,
potassium (Rayment and Higginson 1992).
Soil pH is measured in a 1:5 soil : water or CaCl2 suspension to quantify alkalinity and
acidity (methods 4A1 and 4B1 or 4B2) and is correlated with B (r = 0.7) in neutral to
alkaline soil (Nuttall et al. 2003). The independent method commonly used to
predict if the level of B in soil is toxic for wheat is to extract B from soil in hot CaCl2
(methods 12C1 (manual) or 12C2 (automated) as given in Rayment and Higginson
(1992). Extraction in hot CaCl2 is suitable for alkaline soils, sodic soils and acid soils
that dominate south-eastern Australia (Bell 1999). The local information needed to
establish critical values for extracted B is rare and international literature is used to
define critical values for B on wheat as ranging from 0.15 to 0.5 mg B/kg (Bell 1999).
Tissue analysis
The use of tissue testing to detect soil physical constraints and acidity or alkalinity is
problematic as often the impact on the soil constraint on the crop is expressed
indirectly. Technically, wheat leaves can be tested for minor nutrients which may be
present in the plant in toxic or deficient concentrations. However, critical levels
have not be established for many minor nutrients in wheat leaves and samples are
easily contaminated by soil or metals from cutting tools (Reuter et al. 1997a,
1997b). An alternative means of assessing whether B toxicity is impacting on wheat
yield is to measure B in wheat grain. Concentrations greater than 3 mg B/kg are
considered to indicate B is at toxic levels in the soil (Bell 1999). Boron
concentrations higher than 3 mg B/kg occur in grain samples taken from National
Variety Trials in 2009 in the Wimmera and Victorian Mallee (Norton 2012).Symptoms
of B toxicity can also occur on leaves of cereals (often during warm, dry periods) but
there is considerable debate as to whether these visual symptoms will necessarily
translate to reductions in grain yield.
Managing subsoil constraints
Increasing profitability rather than yields should be the key consideration in
managing subsoil constraints. It is highly recommended that a financial analysis is
undertaken before embarking on any major strategy as soon options e.g. deep
ripping/gypsum addition can involve costs approach half of the land value (See
financial analysis chapter (PSG 2009)). Management options for subsoil constraints
generally fall into three broad categories:
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Amelioration
Soil amelioration with fertilisers has limited application for alleviating subsoil
constraints, specifically acidity and sodicity. Lime (for acidity) and gypsum (for
sodicity) can be applied at depth either during cultivation (Scott et al. 1997) or
during deep ripping (Coventry et al. 1987, Gill et al. 2008). Field experiments show
that combining liming with deep ripping to change subsoil pH increases grain yields
in northern Victoria (Coventry et al. 1987). The use of lime accounts for the majority
of the increase in grain yield in the year of application whilst deep ripping causes an
increase in root growth and mitigates the adverse effects of hard pans on root
placement. However, the benefit of applying lime at only 20 cm is the same as
applying lime at 40 cm. Deep placement of gypsum does not have any benefit to
grain yield when applied at 30-40cm depth to overcome sodicity in southern Victoria
(Gill et al. 2008). Placement of lime and gypsum at depth not only has limited
benefits but is also considered to be economically unviable in more situations (Scott
et al. 1997, PSG 2009).
More commonly, lime and gypsum are broadcast or incorporated to alleviate acidity
and sodicity when these are constraints in the top soil. Application of lime and
gypsum to the top soil has no impact of subsoil constraints due to both having
limited movement down the soil profile (Conyers and Scott 1989, Scott et al. 1999,
PSG 2009).
The detrimental effects of waterlogging on crop production on soils with naturally
high bulk densities is reduced by installing raised beds to improve soil structure
through increasing air porosity and drainage (Holland et al. 2008). Impediment to
root growth caused by high bulk density in sodic clay soil is reduced by applying
organic amendments (dynamic lifter or lucerne) at 30 – 40 cm depth (Gill et al.
2009). These amendments reduce bulk density, increase macroporosity and increase
root length density at the depth of amendment. These effects are not achieved by
simply deep ripping to the same depth (Gill et al. 2009).
Similarly, reduced root growth due to hard pans are alleviated by deep ripping
through the dense layer (Coventry et al. 1987). In soils that also are also
constrained by acidity or sodicity, an amendment (gypsum, lime or clay) can also be
applied as appropriate to compliment the deep ripping action. A table is present in
the manual produced by PSG (2009) to assist in the decision making process.
Genetic solutions
Choice of different crop type and cultivar offers probably the best strategy for grain
growers to overcome subsoil constraints. There is considerable genetic variation for
acid, salinity and B tolerance within crop types (McDonald et al. 2012). The genetic
variation in wheat has been exploited by breeders (Jefferies et al. 2000), an example
being the incorporation of B tolerance into recent wheat cultivars (e.g. Yipti).
Successful breeding for the trait of excluding sodium ions from wheat may explain
why salinity is not considered a major factor affecting crop production yet is a
prevalence soil characteristic (Dahlhaus 2000, McDonald et al. 2012). Overall, the
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result of selective breeding is that growers and agronomist can mitigate the
detrimental effects of high levels of B, salinity and acidity through thoughtful
selection of cultivars with a preference for choosing tolerant cultivars (Coventry et
al. 1989). Given crops growing on the alkaline soils of south-eastern Australia
experience multiple constraints, greater improvement in crop performance is
obtained where crops and varieties have tolerances to multiple constraints so that
overall yield improvements are considerably more than the sum of responses to
individual constraints (Nuttall et al. 2010).
This strategy of careful cultivar and crop selection can be used in conjunction with
surface soil amelioration where topsoil constraints are evident and is an alternative
to costly subsoil amelioration (PSG 2009). The tolerance of wheat cultivars to acid
soils and B is rated in crop sowing guides that are produced annually for regions
within south-eastern Australia (Department of Primary Industries 2014, NSW
Department of Primary Industries 2013, SARDI 2013).
Acceptance
In many cases, there is no financially or technically viable option to overcome subsoil
constraints. In such cases the best option is to ‘live with the problem’ and adjust
input costs e.g. N fertiliser application rates or alter crop choice, accordingly to meet
the actual yield expectations after accounting the severity of the subsoil constraint.
Management strategies for topsoils constraints
Diagnosing topsoil constraints to crop production
Constraints in the topsoil for wheat production (other than inadequate plant
nutrition) are principally acidity, sodicity and salinity. A visual assessment of the
landscape can aid in initial diagnosis of salinity or sodicity (Baxter and Williamson
2001, CW CMA 2008).Excessive soil acidity is difficult to directly diagnose from plant
growth as it causes toxicities and deficiencies to be expressed for other nutrients
(Hazelton and Murphy 2007).
Identifying acidity, sodicity and salinity in topsoils
As stated in the earlier section ‘Identifying subsoil constraints by soil and tissue
analysis’, salinity and sodicity in soil are quantified in the laboratory with electrical
conductivity (EC) used to measure salinity (method 3A1) and exchangeable sodium
percentage (ESP) (method 15A1) used to measure sodicity. Alternatively, sodicity
can be estimated from ECe in neutral to alkaline soils using the equation given by
Nuttall et al. (2003). In the field, simple soil testing using a pH meter identifies
acidity and alkalinity (method 4A1) (Rayment and Higginson 1992) whilst sodicity can
be estimated using the field method established by Emerson (1967).
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Historical records are a valuable source of information when assessing whether
acidity or sodicity in the topsoil is likely to be constraining crop growth. The effects
of adding limestone, dolomite and / or gypsum on soil chemistry are long-term thus
historical records of their application is relevant when deciding whether to re-apply
these fertilisers. In southern NSW, the application of dolomite and limestone effects
soil pH, exchangeable calcium and exchangeable magnesium where it was applied at
least five years after application. Further, small quantities of limestone and dolomite
are still present in their native form five years after application. Assessment of the
impact of applying lime to acid soils in northern Victoria and southern New South
Wales on grain yield shows that liming can be effective for up to 12 years (Conyers et
al. 2003, Coventry et al. 1987, Scott et al. 1999). Recent observations in the field
(e.g. waterlogging, surface crusting, restricted root growth) are indicators that soil
constraints are not currently mitigated. Visual symptoms of restrictions in crop
production vary across the paddock and the areas where constraints apply vary from
season to season as soil water varies. Historic yield map and biomass measurement
by NDVI can be used to identify where constraints are located and management of
the crop can be customised for the constrained and non-constrained areas
accordingly (Armstrong et al. 2009).
Managing acidity, sodicity and salinity as a topsoil constraint
For the constraints of acidity and sodicity in the top soil, the principles for effective
fertiliser use are applicable, that is selecting the right source of nutrients, right
placement, right timing and right amount (Norton and Roberts 2012). The principles
are to select the right source of nutrients, applied as the right rate, and in the right
place and at the right time.
Right source
There are few chemical fertiliser options to alleviate soil acidity and sodicity.
Soil pH is altered from acidic to alkaline (or at least less acidic) using limestone
(CaCO3) or dolomite (CaMgCO3) which can be purchased in various grades in term of
particle size and purity. Together, the particle size and purity are termed the
neutralising value and this value is used to rate to efficacy of limestone products in
NSW (Upjohn et al. 2005). Reducing sodicity as a constraint in topsoil is achieved
using gypsum (CaSO4.2H2O) which comes in various purities depending on source or
organic matter (Armstrong et al. 2007a, 2007b, CW CMA 2008).
An alternative to chemical fertilisers is organic amendment which is shown to
improve wheat growth and grain yields when applied to topsoil. Organic
amendments such (pig litter) spread on the soil surface at 20 - 40 kg/ha reduces the
detrimental effects of sodicity on crop growth and grain yields in the Wimmera
(Armstrong et al. 2007a). The beneficial effects of pig litter are principally through
improved soil structure but also due to increasing soil pH, lowering ESP and
increasing soil N for several season, (Armstrong et al. 2007b). In the Wimmera, the
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effect of applying pig litter is shown to be greater than applying gypsum and urea at
commercial rates and the benefits remain for at least 3 years.
An experimental option for reducing sodicity is applying a combination of gypsum
and polyacrylamides to sodic soils. Polyacrylamides enhance the effects of gypsum,
improve grain yield and reduce water turbidity under laboratory conditions however,
polyacrylamides have not be commercialised at this stage for use in broad acre crop
production (Sivapalan 2005).
Right place
Lime and gypsum are applied on the soil surface or incorporated shallow as a means
of changing soil pH and sodicity in the topsoil, respectively. Surface application of
lime (CaCO3 or CaMgCO3) causes soil to become less acidic where the lime is applied
in south-eastern Australia (Conyers et al. 2003).
Right time
Applying lime or gypsum to change soil chemistry is a long-term strategy.
Recommendations from NSW state that limestone needs to be applied 12 months
prior to when the change is soil chemistry is needed especially if reduced tillage is
being practiced (Upjohn et al. 2005). Increased grain yields and changes in soil
chemistry are achieved in sodosols in NSW 12 months after application of gypsum to
surface soil (Valzano et al. 2001). The efficacy of gypsum is also related to seasonal
conditions as gypsum improves water infiltration through improving soil structure.
Thus the application of gypsum leads to an increase in wheat grain yields but only in
years with excess rainfall (Dear et al. 2005).
Right amount
The amount of limestone applied to soil in southern Australia tends be about 2 – 2.5
t/ha (Conyers and Scott 1989, Conyers et al. 2003). This practice is supported by
field research in north-eastern Victoria that shows the maximum grain yield
response to lime occurs with an application of 2.5 t/ha and grain yield is decreased
with applications of 5 t/ha (Coventry et al. 1987). A tabulated guide for NSW
recommends applying limestone at rates between 0.2 t/ha and 12.5 t/ha based on
soil ECEC tests and an aim of raising soil pH by 0.5 to 1.5 units (Upjohn et al. 2005).
The amount of lime required can also be calculated using one of several equations
based on exchangeable aluminium and soil pH buffering capacity rather than
targeting a change in soil pH per se (Rayment and Higginson 1992).
An alternative way of deciding how much lime to apply is to consider the amount of
lime required to counteract acidification that occurs as a result of each farm practice
(Hazelton and Murphy 2007). In southern NSW, the amount of lime required ranges
from 75 kg /ha/yr for crops grown in lower rainfall locations (< 500 mm/yr) to 300
kg/ha/yr for continuous cropping practised on the slopes with rainfall > 500 mm/yr.
The amount of gypsum recommended in a fact sheet developed for NSW is 2.5 t/ha
(Abbott and McKenzie 1996). This fact sheet is commonly referred to in more recent
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Australian publications focused on improving management of sodic soils (e.g. Brown
and Green 2001). However, it is acknowledged that this rate may be lower than
required to improve grain yields in soils with very high sodicity (PSG 2009) or higher
than required when gypsum and lime are applied together to sodic soils that are also
acidic. This second situation is the case at a long-term field site in NSW where the
maximum response to combinations of gypsum and lime occur with 1 t gypsum/ha
and 2.5 t lime/ha (Valzano et al. 2001).
Conclusions
The diagnosis and management of soil constraints differs between topsoils and
subsoils. Soil constraints in topsoils including B, salinity, sodicity, excessive acidity
and physical constraints can be readily diagnosed and managed. Management in
topsoils includes physical alteration of the soil (e.g. raised beds or deep cultivation)
and the use of ameliorants. Diagnosis and management of constraints in the subsoil
and more complex.
Complexity arises due to the direct effects of subsoil constraints being confounded
by nutritional toxicities or deficiencies that are induced by their presence. Correct
diagnosis of subsoil constraints is aided by using the various decision support tools
discussed in this review that are available and specific to local areas of southern
Australia. Management of subsoil constraints by soil amelioration is only viable in
limited circumstances. This limitation particularly applies to the use of fertilisers to
management subsoil constraints; an action that is likely to be ineffective or
economically unviable. More commonly, genetic solutions with careful selection of
crops and cultivars is an effectives means of managing subsoil constraints. However,
in many circumstances management means accepting the limitations to crop
production that result from the constraint and targeting lower grain yields.
14
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Figure 1: Map of B toxicity in southern South Australia . Sourced from Nature Maps (March 2014).
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Figure 2: Map of salinity induced by water tables in southern South Australia . Sourced from Nature Maps (March 2014).
16
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Figure 3: Map of surface soil and subsoil acidity in southern South Australia . Sourced from Nature Maps (March 2014).
17
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Figure 4: Map of surface soil and subsoil alkalinity in southern South Australia . Sourced from Nature Maps (March 2014).
18
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Figure 5: Map of soils’ susceptibility to waterlogging in southern South Australia . Sourced from Nature Maps (March 2014).
19
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Figure 6: Map of landscapes in Victoria.
A similar map can be sourced from Victorian Resources Online.
20
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Resources
Abbott TS, McKenzie DC. (1996). Improving soil structure with gypsum and lime.
NSW Agriculture AgFact No. 10.
Adcock D, McNeill AM, McDonald GK, Armstrong RD. (2007). Subsoil constraints to
crop production on neutral and alkaline soils in south-eastern Australia: a review
of current knowledge and management strategies. Australian Journal of
Experimental Agriculture, 47, 1245-1261.
Armstrong RD, Eagle C, Matassa V, Jarwal SD. (2007a). Application of composted pig
bedding litter on a Vertosol and Sodosol soil. I. Effect on crop growth and soil
water. Australian Journal of Experimental Agriculture, 47, 689-699.
Armstrong RD, Eagle C, Matassa V, Jarwal SD. (2007b). Application of composted pig
bedding litter on a Vertosol and Sodosol soil. II. Effect on soil chemical and
physical fertility. Australian Journal of Experimental Agriculture, 47, 1341-50
Armstrong RD, Fitzpatrick J, Rab MA, Abuzar M, Fisher PD, O’Leary G. (2009).
Advances in Precision Agriculture in south-eastern Australia. III. Interactions
between soil properties and water use help explain spatial variability of crop
production in the Victorian Mallee. Crop and Pasture Science, 60, 870_884
Baxter N, Williamson J. (2001). Know you soils : Assessing your soils. Part II. (Ed L
Macartney). Department of Natural Resources and Environment. pp 25.
Accessed from Victorian Resources Online in March 2014.
Bell (1999). Boron. In: Soil analysis an interpretation manual. (Eds KI Peverill, LA
Sparrow, DJ Reuter). CSIRO Publishing, Collingwood, Australia. pp 309-317.
Brautigan DJ, Rengasamy P, Chittleborough DJ. (2012) Aluminium speciation and
phytotoxicity in alkaline soils. Plant & Soil, 360, 187-196.
Brown N, Green T. (2001). SOILPak for Southern Dryland Farmers. NSW
Department of Agriculture. Accessed from www.dpi.nsw.gov.au in March 2014.
de Caritat P, Cooper M, Wilford J. (2011). The pH of Australian soils: field results
from a national survey. Soil Research, 49, 173-182.
Cartwright B, Zarinas BA, Mayfield AH. (1984). Toxic concentrations of boron in the
red-brown earth at Gladstone, South Australia. Australian Journal of Soil
Research, 22, 261-272.
Cartwright B , Zarinas BA, Spoucer LR. (1986). Boron toxicity in South Australian
barley crops. Australian Journal of Agricultural Research, 37, 351-359.
Central West Catchment Management Authority (2008). Sodic surface soil
management. A best management practice guide for the Central West
Catchment. (Ed D. McKenzie). Central West Catchment Management Authority,
Wellington NSW. pp 24. Accessed from cw.cma.nsw.gov.au in March 2014.
Conyers MK, Mullen CL, Scott BJ, Poile GJ, Braysher BD. (2003). Long-term benefits
of limestone applications to soil properties and to cereal crop yields in southern
and central New South Wales. Australian Journal of Experimental Agriculture, 43,
71-78.
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Conyers MK, Scott BJ. (1989). The influence of surface incorporated lime on
subsurface soil acidity. Australian Journal of Experimental Agriculture, 29, 201207.
Coventry DR, Reeves TG, Brooke HD, Ellington A, Slattery WJ. (1987). Increasing
wheat yields in north-eastern Victoria by liming and deep ripping. Australian
Journal of Experimental Agriculture, 27, 679-685.
Coventry DR, Walker BR, Morrison GR, Hyland MT, Avery JC, Maden JJL, Bartram DC.
(1989). Yield responses to lime of wheat and barley on acid soils in north-eastern
Victoria. Australian Journal of Experimental Agriculture, 29, 209-214.
Dahlhaus PG, MacEwan RJ, Nathan EL, Morand VJ. (2000). Salinity on the
southeastern Dundas Tablelands, Victoria. Australia Journal of Earth Sciences,
47, 3-11.
Dang YP, Dalal RC, Buck SR, Harms B, Kelly R, Hochman Z, Schwenke GD, Biggs AJW,
Ferguson NJ, Norrish S, Routley R, McDonald M, Hall C, Singh DK, Daniells IG,
Farquharson R, Manning W, Speirs S, Grewal HS, Cornish P, Bodapati N, Orange
D. 2010. Diagnosis, extent, impacts and management of subsoil constraints in
the northern grains cropping region of Australia. Australian Journal of Soil
Research, 48, 105–119.
Dear BS, Peoples MB, Chan KY, Swan AD, Hayes RC, Oates A, Gault RR, Sandral GA.
(2005). Managing heavy clay soils of the Bland-outcomes and management
guidelines. Report on GRDC Project CSP 291. NSW Department of Primary
Industries, Wagga Wagga NSW. Accessed from www.dpi.nsw.gov.au in March
2014.
Dear BS, Weir RG. (2004). Boron deficiency in pastures and field crops. AgFacts P1
AC1 AFDEX 103/531 (2nd edition). pp 8. Accessed from www.dpi.nsw.gov.au in
March 2014.
Department of Primary Industries (2014). Victorian Winter Crop Summary. (Eds G
Stratford, A Wait). Department of Primary Industries, Melbourne Victoria. pp
78. Accessed from www.grdc.com.au in March 2014.
Emerson WW. (1967). A classification of soil aggregates based on their coherence in
water. Australian Journal of Soil Research, 5, 47-57.
Ford GW, Martin JJ, Rengasamy P, Boucher SC, Ellington A. (1993). Sodic soils in
Victoria. Australian Journal of Soil Research, 31, 869-909.
Gill JS, Sale PWG, Peries RR, Tang C. (2009). Changes in soil properties and crop root
growth in dense sodic subsoil following incorporation of organic amendments.
Field Crops Research, 114, 137-146.
Gill JS, Sale PWG, Tang C. (2008). Amelioration of dense sodic subsoil using organic
amendments increases wheat yield more than using gypsum in a high rainfall
zone of southern Australia. Field Crops Research, 107, 265-275.
Grundon NJ, Robson AD, Lambert MJ, Snowball K. (1997). Nutrient deficiencies and
toxicity symptoms. In: Plant Analysis: an interpretation manual. 2nd Edition (Eds
DJ Reuter, JB Robinson). CSIRO Publishing, Collingwood. pp 37-51.
Hall J, Maschmedt D, Billing B. (2009). The soils of southern South Australia. The
South Australian Land and Soil Book Series, Volume 1; Geological Survey of South
22
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Australia, Bulletin 56, Volume 1. Department of Water, Land and Biodiversity
Conservation, Government of South Australia. pp 430.
Hazelton P, Murphy . (2007). Interpreting soil test results: what do all the numbers
mean. CSIRO Publishing, Collingwood. pp 152.
Holland JE, White RE, Edis R. (2008). Improved drainage and greater air-filled
porosity of raised beds in south-western Victoria. Australian Journal of Soil
Research, 46, 397-402.
Jefferies SP, Pallotta MA, Paull JG, Karakousis A, Kretschmer JM, Manning S, Islam
AKMR, Langridge P, Chalmers KJ. (2000). Mapping and validation of
chromosome regions conferring boron toxicity tolerance in wheat (Triticum
aestivum). Theoretical and Applied Genetics, 101, 767-777.
MacEwan R, Robinson N, Imhof M, Rees D, Sposito V, Elsley M. 2008. Primary
Production Landscapes of Victoria. Proceedings of 14th Agronomy Conference
2008. 21-25 September 2008, Adelaide, South Australia. ' Ed. MJ Unkovich.
Accessed from www.regional.org.au in March 2014.
MacEwan RJ, Crawford DM, Newton PJ, Clune TS. (2010). High clay contents,
dense soils, and spatial variability are the principal subsoil constraints to
cropping the higher rainfall land in south-eastern Australia. Australian Journal
of Soil Research, 48, 150-166.
McDonald GK, Taylor JD, Verbyla A, Kuchel H. (2012). Assessing the importance of
subsoil constraints in yield of wheat and its implications for yield improvement.
Crop and Pasture Science, 63, 1043 – 1065.
Naidu R, Rengasamy P. (1993). Ion interactions and constraints to plant nutrition in
Australia. Australian Journal of Soil Research, 31, 801-819.
Northcote KH, Skene JKM. (1972). Australian soils with saline and sodic properties.
CSIRO, 27, Melbourne.
Norton R. (2012). Wheat grain nutrient concentrations for south-eastern Australia.
Proceedings of 16th Australian Agronomy Conference 2012, 14-18 October 2012,
Armidale, NSW. Accessed from www.regional.org.au in March 2014.
Norton RM, Roberts T. (2012). Nutrient management to nutrient stewardship.
Proceedings of 16th Australian Agronomy Conference 2012, 14-18 October 2012,
Armidale, NSW. Accessed from www.regional.org.au in March 2014.
NSW Department of Primary Industries 2013. Winter crop variety sowing guide
2013. NSW Department of Primary Industries, a part of the Department of Trade
and Investment, Regional Infrastructure and Services. pp 124. Accessed from
www.dpi.nsw.gov.au in March 2014.
Nuttall JG, Armstrong RD, Connor DJ, Matassa VJ. 2003. Interrelationships between
edaphic factors potentially limiting cereal growth on alkaline soils in north-west
Victoria. Australian Journal of Soil Research, 41, 277-292.
Nuttall, JG, Hobson KB, Materne M, Moody DB, Munns R, Armstrong RD. (2010).
Use of genetic tolerance in grain crops to overcome subsoil constraints in alkaline
cropping soils. Australian Journal of Soil Research, 48, 188-189.
Nuttall, JG and Armstrong RD. (2010). Impact of subsoil physicochemical constraints
on crops grown in the Wimmera and Mallee is reduced during dry seasonal
conditions. Australian Journal of Soil Research, 48, 125-139.
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Rayment GE, Higginson FR. (1992). Australian laboratory handbook of soil and
water chemical methods. (Ed. R. Leydon). Inkata Press, Melbourne. pp 330.
Rengasamy P, Bourne J. (1997). Managing sodic, acid and saline soils. Cooperative
Research Centre for Soil and Land Management. pp 14.
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. (2010). Soil processes affecting crop production in salt-affected soils.
Functional Plant Biology, 37, 613-620.
Reuter DJ, Edwards DG, Wilhelm NS. (1997b). Temperature and tropical crops. In:
Plant analysis: an interpretation manual. 2nd Edition. (Eds. DJ Reuter, JB
Robinson). p 81-284.
Reuter DJ, Robinson JB, Peverill KI, Price GH, Lambert MJ. (1997a). Guidelines for
collecting, handling and analysing plant material. In Plant analysis: an
interpretation manual 2nd Edition. (Eds. DJ Reuter, JB Robinson). p 53-80.
SARDI. (2013). Sowing guide 2013. Published by SARDI. pp 55. Accessed from
www.viterra.com.au in March 2014.
Scott VJ, Conyers MK, Poile GJ, Cullis BR. (1997). Subsurface acidity and liming affect
yield of cereals. Australian Journal of Agricultural Research, 48, 843-854.
Scott VJ, Conyers MK, Poile GJ, Cullis BR. (1999). Reacidification and reliming effects
on soil properties and wheat yield. Australian Journal of Experimental
Agriculture, 39, 849-856.
Shaw RE, Meyers WS, McNeill A, Tyerman SD. (2013). Waterlogging in Australian
agricultural landscapes: a review of plant response and crop models. Crop and
Pasture Science, 64, 549-562.
Shorrocks VM. (1997). The occurrence and correction of boron deficiency. Plant
and Soil, 193, 121-148.
Sivapalan S. (2005). Effect of gypsum and polyacrylamides on water turbidity and
infiltration in a sodic soil. Australian Journal of Soil Research, 43, 723-733.
Slattery B, Hollier C. (2002). The impact of acid soils in Victoria. Department of
Natural Resources and Environment. pp 52. Accessed from Victorian Resources
Online in March 2014.
The Profitable Soils Group. (2009). Identifying, understanding and managing hostile
subsoils for cropping. The Profitable Soils Group. pp 92. Accessed from
Victorian Resources Online in March 2014.
Upjohn B, Fenton G, Conyers M. (2005). Soil acidity and liming. Agfact AC 19 3rd
edition. NSW Department of Primary Industries. pp 24. Accessed from
www.dpi.nsw.gov.au in March 2014.
Valzano FP, Murphy BW, Greene RSB. (2001). The long-term effects of lime (CaCO3),
gypsum (CaSO4.2H2O) and tillage on the physical and chemical properties of
asodic red-brown earth. Australian Journal of Soil Research, 39, 1307-1331.
Whelan B, Taylor J. (2013). Precision agriculture for grain production systems. (Ed.
A de Kretser). CSIRO Publishing, Collingwood, Australia. pp 199.
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Wightman B, Peries R, Bluett C, Johnston T. (2005). Permanent raised bed cropping
in southern Australia: practical guidelines for implementation. In: Evaluation and
performance of permanent raised bed cropping systems in Asia, Australia and
Mexico. Proceedings of a workshop held in Griffith, NSW, Australia, 1-3 March
2005. (Eds CH Roth, RA Fischer, CA Meisner). Australian Centre for International
Agricultural Research Proceedings No. 121, Canberra. Accessed from
aciar.gov.au in March 2014.
Wurst M, Wilhelm N, Brennan R. (2010). Winter cereal nutrition: The ute guide.
Primary Industries and Resources South Australia. iOS or Android app.
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Table 1: Major soil types in each Primary Production Landscape showing principal management constraints (severity represented by colours;
green=no problem; amber=for consideration in management; red=major limitation). (MacEwan et al. 2008)
Mallee
Rudosols and Tenosols
Vertosols
Vertosols
Northwest
Southern Mallee /
Northern Wimmera
Southern Wimmera
Potential chemical excess
Sodicity subsoil
Waterlogging
Sodicity surface
Wind erosion
Water erosion
Surface structure
Alkalinity subsoil
Potential chemical
deficiency
Calcarosols
Acidity subsoil
Dominant soil order (ASC)
Alkalinity surface
Primary Production Landscapes of
Victoria
Acidity surface
Management Issues
P
B, Soluble salts
P
P, Fe, Zn, Cu,
Mn
P, Fe, Zn, Cu,
Mn
Al
Soluble salts
Soluble salts
Calcarosols
P
B, Soluble salts
Tenosols, Rudosols
P
Al
Sodosols (yellow/brown)
P
ESP, Soluble salts, B
Sodosols (Red)
P
ESP, Soluble salts, B
Sodosols
P
ESP, Soluble salts
Vertosols
P, Fe, Zn
ESP, Soluble salts
Tenosols
P
Al
Sodosols, Calcarosols
P
ESP, Soluble salts, B
Vertosols
P, Fe, Zn
ESP, Soluble salts
Sodosols
P
ESP, Soluble salts
Chromosols
P
Sodosols
P
Chromosols
P
Sodosols
P
ESP, Soluble salts
Vertosols
P, Fe, Zn
ESP, Soluble salts
Riverine Plains
Northern
Plains
Northeast Plains and
Slopes
ESP, Soluble salts
Other Management and related Issues
Surface: water repellence.
Subsoil: high clay content.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: water repellence
Subsoil: high clay content.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention, deep drainage.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, dense and coarse structure, high clay content and shrink-swell properties.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, dense and coarse structure, high clay content and shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel (buckshot).
Subsoil: compaction, dense and coarse structure, high clay content and some shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
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Table 1 continued
Potential chemical excess
P
ESP, Soluble salts
Vertosols
P, Fe
ESP, Soluble salts
Tenosols
P
Al
Sodosols
P
ESP, Soluble salts
Chromosols
P
na
Dermosols
P
Al
Kurosols
P
Al
Ferrosols
P
Al
P
Al
P
Al
Sodosols, Chromosols
P
ESP, Soluble salts
Kurosols
P
Al
Sodicity subsoil
Sodosols
Waterlogging
Al
Sodicity surface
P
Wind erosion
Kurosols
Water erosion
P
Surface structure
Chromosols
Alkalinity subsoil
ESP, Soluble salts
Acidity subsoil
P
Alkalinity surface
Sodosols
Dominant soil order (ASC)
Acidity surface
Primary Production Landscapes of
Victoria
Potential chemical
deficiency
Management Issues
Northern Slopes
Central
Victoria
Southern Slopes
Tenosols, Rudosols and
Kandosols
Tenosols, Rudosols, Podosols
and Kandosols
Grampians
Other Management and related Issues
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content and some shrink-swell properties.
Surface: stoniness and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: stoniness and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
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Table 1 continued
Potential chemical excess
Potential chemical
deficiency
Sodicity subsoil
Waterlogging
Sodicity surface
Wind erosion
Water erosion
Surface structure
Alkalinity subsoil
Acidity subsoil
Dominant soil order (ASC)
Alkalinity surface
Primary Production Landscapes of
Victoria
Acidity surface
Management Issues
Chromosols
P
Sodosols
P
ESP, Soluble salts
Sodosols
P
ESP, Soluble salts
Hydrosols
P
Soluble salts (subsoil)
Vertosols
P, Fe, Zn
ESP, Soluble salts
Dermosols
P
Al
Ferrosols
P
Al
Dundas Tablelands
Victorian Volcanic Plain
Southern
Plains
Sedimentary Plain
Chromosols
P
Vertosols
P, Fe, Zn
ESP, Soluble salts
Dermosols, minor Kurosols
P
Al
Podosols
P
Al
Sodosols
P
ESP, Soluble salts
Kurosols
P
Al
Podosols
P
Al
Ferrosols, Chromosols
P
Al
Rudosols
P
Al
Millicent Coast
Other Management and related Issues
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: Nutrient retention, shrink-swell properties, compaction.
Subsoil: high clay content, dense and coarse structure, compaction.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: stoniness and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: water repellence, nutrient retention, compaction, pans and gravel.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: nutrient retention, water repellence.
Subsoil: pans or dense soil at depth.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: nutrient retention, water repellence.
Subsoil: pans or dense soil at depth.
Surface: stoniness and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: nutrient retention, surface water repellence, stoniness and shallow depth.
Subsoil: shallow, stony.
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Project: Diagnostic Agronomy
Table 1 continued
Southwest Valleys and
Plains
Eastern
Uplands
Southeast Valleys and
Plains
P
Dermosols/Kandosols
P
Al
Ferrosols, Dermosols
P
Al
Sodosols
P
ESP, Soluble salts
ESP, Soluble salts
Sodicity subsoil
Chromosols
Waterlogging
P
Sodicity surface
Chromosols
Wind erosion
Al
Water erosion
P
Surface structure
Dermosols
Alkalinity subsoil
Al
Acidity subsoil
P
Alkalinity surface
Potential chemical excess
Northern Valleys and
Plains
Kandosols, Kurosols
Dominant soil order (ASC)
Acidity surface
Primary Production Landscapes of
Victoria
Potential chemical
deficiency
Management Issues
Vertosols, Dermosols
P, Fe
Chromosols. Sodosols
P
Chromosols
P
Kandosols, Dermosols
P
Al
Dermosols
P
Al
Kandosols
P
Al
Kurosols
P
Al
Rudosols
P
Al
Dermosols, Kandosols
P
Al
Chromosols
P
Kurosols
P
Highlands
Eastern Hills and
Valleys
Al
Other Management and related Issues
Surface: water repellence, nutrient retention.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: stoniness and variable depth, nutrient retention, compaction.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: stoniness and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: nutrient retention, water repellence.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention.
Subsoil: compaction, high clay content, shrink-swell properties.
Surface: nutrient retention, stoniness and shallow depth.
Subsoil: shallow, occasional high fine earth (clayey) subsoil.
Surface: variable soil depth, stoniness.
Subsoil: high clay content, stoniness.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
29
Project: Diagnostic Agronomy
Table 1 continued (final page)
P
Al
Podosols
P
Al
Vertosols, Hydrosols
P, Fe
ESP, Soluble salts
Dermosols
P
Al
Kurosols, Chromosols
P
Al
Dermosol
P
Al
Ferrosols
P
Al
Tenosols, Kandosols, Rudosols
P
Al
Sodicity subsoil
Kurosols
Waterlogging
Soluble salts (subsoil)
Sodicity surface
P
Wind erosion
Dermosols, Hydrosols
Water erosion
P
Surface structure
Chromosols
Alkalinity subsoil
ESP, Soluble salts
Acidity subsoil
P
Alkalinity surface
Potential chemical excess
Eastern Plains
Sodosols
Dominant soil order (ASC)
Acidity surface
Primary Production Landscapes of
Victoria
Potential chemical
deficiency
Management Issues
Eastern Plains
Otways
Strzelecki
Soutthern
Uplands
Mornington Peninsula
Wilson's Promontory
Chromosols
P
Podosols, Tenosols &
Rudosols
P
Al
Vertosols, Sodosols
P, Fe
ESP, Soluble salts
Dermosols, Ferrosols
P
Al
Dermosols
P
Al
Kurosols, Podosols
P
Al
Tenosols, Rudosols, Podosols
P
Al
Other Management and related Issues
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: Nutrient retention, occassional shrink-swell properties, compaction.
Subsoil: high clay content,dense and coarse structure, compaction.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: nutrient retention, water repellence.
Subsoil: pans or dense soil at depth.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention, potential surface sealing.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: stoniness and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: water repellence, nutrient retention, potential surface sealing, pans and gravel.
Subsoil: compaction, dense and coarse structure, high clay content, shrink-swell properties.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
Surface: compaction, high clay content and shrink-swell properties.
Subsoil: compaction, coarse structure, high clay content and shrink-swell properties.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: stoniness, nutrient retention and variable soil depth.
Subsoil: stoniness, compaction, variable soil depth, high clay content.
Surface: nutrient retention, surface water repellence.
Subsoil: compaction, high clay content, occassional pans.
Surface: water repellence, nutrient retention.
Subsoil: nutrient rentention.
30