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The relationships between land management practices and soil condition and the quality of ecosystem services delivered from agricultural land in Australia

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  • Kiri-ganai Research Pty Ltd

Abstract and Figures

This report shows that there is good evidence from scientific research that the land management practices adopted by farmers have a direct impact on soil condition. Improving soil condition benefits production as well as providing a range of ecosystem services to the broader community; including water purification, breakdown of wastes and toxins, regulation of atmospheric gases (including carbon and nitrogen) and water flows, regulation of weather and climate and maintenance of genetic diversity.
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STEVEN CORK (PROJECT LEADER)
LAURA EADIE
PAULINE MELE
RICHARD PRICE
DON YULE
September 2012
The relationships between land
management practices and soil
condition and the quality of ecosystem
services delivered from agricultural
land in Australia
Relationships between land management practices and soil condition
ii | P a g e
About Kiri-ganai research:
Kiri-ganai Research Pty Ltd is a Canberra based company that undertakes consultancy
and analytical studies concerned with environmental policy, industry performance, natural
resource management and sustainable agriculture. Our strength is in turning knowledge
gained from public policy, markets, business operations, science, and research into ideas,
options, strategies and response plans for industries, governments, communities and
businesses.
Kiri-ganai Research Pty Ltd
GPO Box 103 CANBERRA ACT 2601 AUSTRALIA
ph: +62 2 62956300 fax: +61 2 62327727
www.kiri-ganai.com.au
Funding

Project team
This project was managed by Kiri-ganai Research Pty Ltd. The main writing team
comprised Steven Cork (EcoInsights), Pauline Mele (Victorian Department of Primary
Industries), Laura Eadie (Centre for Policy Development), Don Yule (CTF Solutions) and
Richard Price (Kiri-ganai Research). This team was guided by four expert advisers: Anna
Roberts, Neil Byron, Geoff Gorrie and Barry White.
Acknowledgements
The project team gratefully acknowledges the contribution made to the project by members
of the Australian Government Land and Coasts Division, and in particular Science Adviser,
Dr Michele Barson.
Disclaimer
Considerable care has been taken to ensure that the information contained in this report is
reliable and that the conclusions reflect considerable professional judgment. Kiri-ganai
Research Pty Ltd, however, does not guarantee that the report is without flaw or is wholly
appropriate for all purposes and, therefore, disclaims all liability for any loss or other
consequence which may arise from reliance on any information contained herein.
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Contents
Executive summary ................................................................................................... vii
Questions addressed ............................................................................................. vii
Key conclusions ..................................................................................................... vii
Benefits and beneficiaries from better soil management ...................................... viii
1. Project rationale and approach .............................................................................. 1
1.1 Rationale .......................................................................................................... 1
1.2 Approach .......................................................................................................... 1
2. Soils: the essential asset ........................................................................................ 4
2.1 Soils, life and human interaction ....................................................................... 4
2.2 Living soils and determinants of soil condition .................................................. 4
2.3 Soils and systems ............................................................................................. 5
3. Linking management practices, soil quality and ecosystem services ..................... 7
3.1 The concept of ecosystem services .................................................................. 7
3.2 Ecosystem services and management practice ................................................ 8
4. Soil Carbon ............................................................................................................ 9
4.1 Nature of the issues .......................................................................................... 9
4.2 Impacts of agriculture and measures that could build Soil Organic Carbon .... 10
4.3 Evidence of the efficacy of practices to increase soil organic carbon ............. 16
5. Soil pH .................................................................................................................. 19
5.1 Nature of the issues ........................................................................................ 19
5.2 Impacts of agriculture and measures that could arrest soil acidification ......... 20
5.3 Evidence of the efficacy of practices to increase soil pH ................................ 26
5.4 Concluding remarks ........................................................................................ 28
6. Wind erosion ........................................................................................................ 30
6.1 Nature of the issues ........................................................................................ 30
6.2 Land management practices in relation to wind erosion ................................. 31
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6.3 Evidence of the effectiveness of management practices for reducing wind
erosion ........................................................................................................... 33
7. Water erosion ....................................................................................................... 36
7.1 Nature of the issues ........................................................................................ 36
7.2 Land management practices in relation to water erosion ................................ 38
7.3 Evidence of the effectiveness of management practices for reducing water
erosion ........................................................................................................... 40
8. Ecosystem services and resilience of soils .......................................................... 46
8.1 The concept of ecosystem services ................................................................ 46
8.2 Relating soil ecosystem processes to services and benefits .......................... 48
8.3 How better management for soil carbon, pH and erosion might affect
ecosystem services ....................................................................................... 54
8.4 Resilience of soils and associated ecosystems .............................................. 58
9. Private and public benefits of soils and soil management .................................... 65
9.1 Introduction ..................................................................................................... 65
9.2 What is the nature of benefits from improving agricultural soil condition? ...... 65
9.3 Who benefits from improving agricultural soil condition? ................................ 66
9.4 How significant might these benefits be? ........................................................ 67
9.5 How might Australia realise these benefits? Examples through case studies 73
9.6 General findings .............................................................................................. 86
10. Summary and conclusions ................................................................................. 89
10.1 Improving the organic matter status of soils ................................................. 89
10.2 Improving the pH (acid-bases balance) of soils ............................................ 91
10.3 Minimising erosion of soils by wind ............................................................... 92
10.4 Minimising erosion of soils by water ............................................................. 94
10.5 improvements in the quantity and quality of ecosystem services and benefits
delivered from agricultural lands .................................................................... 95
10.6 Summary ...................................................................................................... 98
References ............................................................................................................... 99
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Tables
4.1. List of critical functions of soil C 9
4.2 Dairy pasture management options to conserve soil carbon 15
5.1 Options for management of soil acidity and feasibility in permanent and mixed
grazing systems 25
8.1: Description of the broad groups of ecosystem services provided by soils 49
8.2: Example of the beneficiaries of soil ecosystem services 53
8.3: Conclusions from this report about the effectiveness of management practices in
Australian agricultural lands 55
8.4: Ways in which actions to address soil condition are likely to affect soil processes
and ecosystem services 56
9.1: Gross value of agricultural production 66
9.2: Existing estimates of the value of costs or benefits related to land management
practice (footnotes explained at end of table) 69
9.3: Full range of benefits and beneficiaries Reducing soil erosion in broadacre
cropping 76
9.4: Full range of benefits and beneficiaries Managing acid soils in broadacre
cropping 79
9.5: Full range of benefits and beneficiaries Increasing soil carbon in irrigated
horticulture 82
9.6: Full range of benefits and beneficiaries Reducing wind erosion in grazing
areas 86
10.1: Ecosystem services from soils and the benefits potentially derived 96
Relationships between land management practices and soil condition
vi | P a g e
Figures
4.1: Crop management practice and relationship with expected Soil Organic Carbon
levels and benefits 11
6.1: Erosion rates in relation to ground cover when four different wind speeds were
applied to lupin residues 34
7.1: Factors influencing soil erosion by water. Figure was derived from various
publications cited in the text 37
7.2: Generalised relationship between ground cover and annual average soil loss
from vertisol soils on the Darling Downs, Queensland 42
8.1: Conceptual relationship between land management, soil structures and
processes, ecosystem services, benefits to humans and human wellbeing 47
8.2: Interrelationships between living and non-living components of soils 48
8.3: Two generalised assessments of differences in ecosystem services from
 52
9.1: Who benefits, where and when? 67
9.2: Example of output from the acidity relative yield model for four plant tolerance
classes within a given Al/Mn solubility class 77
Boxes
Box S1: An example of benefits from better management of soil condition x
Box 4.1: Managing soil C through a systems approach 18
Box 5.1: Managing soil pH through a systems approach 29
Box 6.1: Managing wind erosion through a systems approach 35
Box 7.1: The Gascoyne Catchment A Case Study of Water Erosion 41
Box 7.2: Managing water erosion through a systems approach 44
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vii | P a g e
Executive summary
Questions addressed

Land and Coasts Division, a joint initiative between the Department of Sustainability,
Environment, Water, Population and Communities and the Department of
Agriculture, Fisheries and Forestry, this project addresses two key questions about
relationships between land management practices, soil condition, and the quantity
and quality of ecosystem services (i.e. the attributes of ecological systems that
contribute to benefits for humans) delivered from agricultural land:
What evidence exists about how improving land management practices will lead
to reduced soil loss (through water and wind erosion) and improved soil condition
(especially through reduced impacts of soil acidification and increased organic
matter content)?
How might reducing soil loss and improving soil condition result in improvements
in the quantity and quality of ecosystem services and benefits delivered from
agricultural lands, including cleaner air, improved water quality, reduced
greenhouse gas emissions, and more productive soils?
Key conclusions
The project focuses on four aspects of soil condition identified in the Program Logic
; soil pH; wind
erosion; and water erosion. It also focuses on four broad groupings of agricultural
industries: broadacre cropping; horticulture; dairy; and grazing.
In summary, evidence in the scientific and economic literature assessed and
referenced in this report finds:
Approaches to improving the soil organic carbon (SOC) content of soils, including
minimising disturbance to soils from tillage and stock and increasing inputs of
carbon by retaining stubble, using perennial pastures, and adding manures and
other sources of carbon, have slowed the rate of loss of SOC and show potential
to increase absolute SOC over time (although predicting the outcomes of
interventions precisely is still difficult due to the many variables involved). Benefits
in terms of better production outcomes have been demonstrated.
Regular monitoring of soil pH and application of lime at appropriate rates has
been shown to reduce acidity in surface soils, although rates of adoption of these
practices are far too low to achieve widespread benefits. Net financial benefits of
controlling acidity in surface soils have been demonstrated. Build-up of acid in
Relationships between land management practices and soil condition
viii | P a g e
subsoils is of growing concern and addressing it is likely to be unaffordable for
most agricultural industries in the near future.
Maintenance of ground cover above 50-70% has been shown to be effective in
reducing wind and water erosion and to yield financial benefits to farmers across
all agricultural industries.
Addressing soil carbon, acidity and susceptibility to erosion has many public and
private benefits. These include better yields of agricultural products, which have
private and public benefits, and better outcomes for agricultural soils, which
themselves provide s
and the broader public. Better soil condition generally improves the ability of soils
to support benefits to the public (both urban and rural), such as clean water for
drinking and recreation, protection from wind and water erosion and floods, and
reduced risks from pests and diseases and reduced need to use agricultural
chemicals. They can also include a range of cultural, spiritual, and intellectual
benefits such as enhancing sense of place, mental wellbeing and acquisition of
knowledge. Modest improvements in soil condition might only produce modest
improvements in these public services and benefits, but even these modest
improvements can be significant in economic terms and often greater than the
private benefits.
One of the most substantial benefits of better management of groundcover is
reductions in dust storms, which have been shown to incur very large financial
costs in regional and metropolitan areas across Australia. These costs relate to
damage to infrastructure and health costs, as well as clean-up costs and costs of
reduced water quality. There have been substantial reductions in dust indices
since the 1940s, but large and damaging dust storms have occurred recently and
are likely to recur in coming years during prolonged dry periods.
Benefits and beneficiaries from better soil management
Ecosystem services can be described as the attributes of ecological systems that
contribute to benefits for humans. By ecological systems, we mean systems that
involve interactions among multiple species of plants, animals, and other organisms
and between those species and the non-living environment. To address the question
of how improving soil condition might result in improvements in the quantity and
quality of ecosystem services and benefits delivered from agricultural lands, a
framework was developed that relates soil properties and processes to ecosystem
services, benefits and beneficiaries. The framework, described fully in the main
report, is a synthesis and modification of several published frameworks. It was
developed because many of those available in the literature did not explicitly link
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ix | P a g e
changes in soil condition to benefits to people, and because those that addressed
this link were not entirely consistent with a set of principles distilled from the most
recent literature in this field. The key framework principles were:
Contributions that ecosystems make to meeting human needs (ecosystem
services) should be kept separate from the contributions made by humans that
are required to turn ecosystem services into benefits (for example, ecosystems
generate fertile soil but for that service to become the benefit of support for crops
requires humans to plant, manage and harvest those crops);
To avoid multiple counting of benefits, it is important to distinguis
          

and therefore can contribute indirectly to multiple benefits).
The living and non-living components of soil ecosystems interact to mediate a range
of processes that would require engineering at an unprecedented scale to replicate.
These processes transform natural resources into forms that are potentially of
benefit to humans and in so 
main report identifies 14 such services and their respective benefits from soils.
Management of land for agriculture dramatically changes the balance among
ecosystem services, increasing some provisioning services, decreasing some
regulating services and changing the nature of many cultural services. One aim of
improved agricultural management is to adjust this balance to meet a wider range of
private and public needs.
Research reviewed in this report shows that best-practice approaches to managing
soil carbon, acidity and wind and water erosion are generally effective at addressing
those issues and improving soil condition. Practices like minimal tillage, maintaining
ground cover above 50%, adding organic matter to soil (within limits), and managing
the impacts of stock and machinery on soil disturbance and compaction, have
beneficial outcomes for all aspects of soil condition. These practices, therefore,
potentially enhance most ecosystem services and their benefits (Box S1).
The beneficiaries include farmers, agricultural industries, communities, families and
individuals in regional areas and in cities. It is possible to estimate the magnitude of
these benefits under different conditions in the future, but it is not meaningful to
make a single estimate of future value because of the many combinations of
management practices, soil types, climatic variations, products, market opportunities,
demographic changes, and demands of consumers over the coming decades.
Relationships between land management practices and soil condition
x | P a g e
Some general conclusions can, however, be made:
There are achievable opportunities to address declining soil carbon and
increasing acidity and reduce wind and water erosion and at the same time
improve profitability of agriculture and deliver a range of public benefits (which in
some cases will be worth more than the private benefits in terms of health and
wellbeing outcomes);
To do this it will be important to consider the ability of soil ecosystems to cope
with ongoing and potential future shocks (i.e., their adaptive capacity and
resilience), which cannot be considered in isolation from the adaptive capacity
and resilience of the humans who manage agricultural landscapes;
The resilience of soils in many parts of Australia depends strongly on building and
maintaining soil carbon stocks, which affect a wide range of functions, including
nutrient cycling and water infiltration and storage, and the ability of landscapes to
retain topsoil;
Another key aspect of the resilience of Australian soils is their ability to avoid
passing through thresholds of change, some of which could be irreversible;
Such thresholds include critical proportions of ground cover (50-70% depending
on factors like rainfall and slope), below which erosion accelerates dramatically,
carbon-content thresholds, and thresholds of acidification, especially of subsoil,
which currently cannot be addressed economically by most agricultural industries.
Box S1: An example of benefits from better management of soil condition
Maintenance of 50-70% groundcover a management practice shown to be
effective at reducing wind and water erosion and contributing to increasing soil
carbon content and, indirectly, to addressing soil acidity will affect the texture of
soil by retaining the small particles that would otherwise be lost due to water and
wind erosion. Organic matter content and biodiversity of soil will be enhanced
because of reduced losses of carbon by erosion, increased inputs of carbon as
groundcover plants die and degrade, and enhanced habitat for soil species. This will
affect soil structure, soil biological activity and cycling of organic matter, nutrients,
gases and water within soil and between soils and the atmosphere. These processes
combine in different ways to support the full range of ecosystem services and their
potential benefits. The extent of the benefits and the beneficiaries from maintaining
ground cover will depend on the demand for different ecosystem services and
benefits, who needs these and at what scales of space and time. The benefits are
likely to be increased production of food and other commodities as well as a range of
public benefits to people from local to regional, national and international scales.
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1. Project rationale and approach
1.1 Rationale
Soils are a national asset, the condition of which is integrally tied to the health of
Australian industries, ecosystems and, ultimately, communities. However, for a
country for which the vagaries of climate variability have been manifested in dust
storms and land degradation on the one hand, and rich production and economic
wealth on the other, soils remain very much taken for granted.
Fund
Land and Coasts Division, a joint initiative between the Department of Sustainability,
Environment, Water, Population and Communities and the Department of
Agriculture, Fisheries and Forestry, this project addresses two key questions about
the relationships between land management practices, soil condition, and the
quantity and quality of ecosystem services delivered from agricultural land:
What evidence exists about how improving land management practices will lead to
reduced soil loss (through water and wind erosion) and improved soil condition
(especially through reduced impacts of soil acidification and increased organic
matter content)?
How might reducing soil loss and improving soil condition result in improvements in
the quantity and quality of ecosystem services and benefits delivered from
agricultural lands, including cleaner air, improved water quality, reduced greenhouse
gas emissions, and more productive soils?
The project focuses on four aspects of soil condition identified in the Program Logic
 
erosion; and water erosion. It also focuses on four broad groupings of agricultural
industries: broadacre cropping; horticulture; dairy; and grazing.
1.2 Approach
Literature review

soil, agricultural systems and ecosystem service researchers.
The Program Logic         
identified four key aspects of soil condition in Australia, including carbon and pH
(which are soil conditions) and water and wind erosion (which are threatening
processes). Declining soil carbon and increasing acidity (which affect both the
Relationships between land management practices and soil condition
2 | P a g e
physical properties of soils and a number of the processes occurring in it), and
continuing susceptibility to wind and water erosion (which affect both the loss of soil
from some sights and its build up in others) have been identified as key concerns in
recent comprehensive analyses of agricultural and other landscape processes in
Australia (NLWRA 2001). This project focuses on how land management practices
affect these aspects of soil, and in particular:
the extent to which land management practices are available that can reduce
erosion, increase soil carbon and slow rates of acidification; and
the degree of change likely to be possible from plausible changes in land
management over a range of land and farming systems and a range of future time
periods.
A second component of the project addresses the extent to which soil condition
affects the quality of the market and non-market benefits received by people (so-
d.
Valuation of benefits from better soil management
The valuation of the benefits from changed land management practices is complex
and requires a wide array of data on what changes might be made, who might make
them and where, how those changes might affect ecological processes, and how
those processes might affect ecosystem services and the benefits that flow from
them. Because of this, the valuation component of the project makes assumptions
and estimates upon which the valuations are contingent. The aim is to provide
indications of the size of costs and benefits that might arise from improved soil
management and the types of uncertainties that still remain in those estimates.
Based in the latest thinking about valuing ecosystem goods and services, the project
develops a framework that makes explicit the links between:
soil and other landscape processes
landscape processes and ecosystem services
benefits that potentially flow to a range of beneficiaries
who the beneficiaries are likely to be
how the value to those beneficiaries can be best assessed.
Valuations are based on realistic scenarios for marginal changes in land
management practices in different regions and farming systems rather than any
attempt to estimate the total value of all existing soil ecosystem services across
Australia. Scenarios for changes in land management practices are developed from
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         -use systems over
many years, and selected contacts with key experts on different land-use systems.
The three scenarios used, as far as possible, reflect business as usual, modest
improvements to farm management and optimistic improvements.
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4 | P a g e
2. Soils: the essential asset
2.1 Soils, life and human interaction
Soils underpin, literally and figuratively all of the processes that support human
societies and economies and, indeed, all other terrestrial life on earth. The
overwhelming focus of both ecology and agricultural sciences has been on what
happens above ground, which can be seen and experienced directly by humans.
Soils play physical roles in supporting plants and structures, including those created
by humans. They contain a vast diversity of living organisms and non-living elements
that interact to mediate processes as diverse as provision of raw materials, water
filtration, breakdown of wastes, pest control, regulation of atmospheric composition,
regulation of water and wind flows across landscapes, and maintenance of
hydrological cycles (Bardgett et al. 2001; Nelson and Mele 2006; Barrios 2007; Mele
and Crowley 2008; McAlpine and Wotton 2009; Colloff et al. 2010; Dominati et al.
2010; Robinson et al. 2012). Soils also contribute in important ways to cultural,
spiritual, intellectual and other intangible aspects of landscapes that are important to
humans in many different ways (Dominati et al. 2010).
We are entering an age that has been termed the Anthropocene: an age when the
impacts of humans represent the most significant drivers of change in Earth systems
(Steffen et al. 2011). Thus, it is timely to consider how the tools available to humans
have been and might be used to improve the functioning of soils, including reversing
the degradation caused by past human activities.
2.2 Living soils and determinants of soil condition
Soil condition can be defined as the capacity of a soil to function, within land use and
ecosystem boundaries, to sustain biological productivity, maintain environmental
health, and promote plant, animal, and human health (Doran and Zeiss 2000). The
condition of a soil can be inferred by measuring specific soil properties (e.g., organic
matter content) and by observing soil status (e.g., fertility).
Maintaining soil condition is not only important to sustaining life and ecosystems
beyond the immediate physical presence of soils, but also within. Soils are the home
to over a quarter of all living species on earth (Turbé et al. 2010). Indeed, there is a
strong relationship between soil condition and the biodiversity soils support. The
many organisms and micro-organisms living within soils can interact to perform three
major functions required of healthy soils: chemical engineering, biological regulation
and ecosystem engineering. In the case of chemical engineering, bacteria, fungi and
protozoans help in the decomposition of plant organic matter into nutrients readily
Relationships between land management practices and soil condition
5 | P a g e
available for plants. In the case of biological regulation, small invertebrates, such as
nematodes, pot worms, springtails, and mites, act as predators of plants and other
invertebrates or microorganisms to regulate their dynamics in space and time.
Finally, in the case of ecosystem engineering, earthworms, ants, termites and some
small mammals help modify or create habitats for smaller soil organisms by building
resistant soil aggregates and pores, thus regulating the availability of resources for
other soil organisms and supporting plant systems.
Soil biodiversity is not the only determinant of soil condition. Soil can be defined as
the weathered and fragmented outer layer of the earth’s terrestrial surface (Hillel
1980), and the physical properties of soil such as particle size and mineral
composition are important in its differentiation and condition. Moreover, the
chemistry and nutrient status of soils are also important. However, it is the interaction
of soil physics and chemistry with soil biodiversity that influences the overall
condition of soils. For example, soil pH is one of the abiotic factors susceptible to
influence biology and activity of biological regulators (Turbé et al. 2010). In every
sense, the term living soils is a reminder that soils too have a lifespan that can either
be cut short through inappropriate interaction or sustained by appropriate nurturing
or remedial attention.
2.3 Soils and systems
This report considers the relationship between soil condition and agricultural
practices in four distinct sections (i.e. sections on soil carbon, acidification, wind
erosion and water erosion). These aspects of soil condition do not exist in isolation,
however. For example, soil carbon content also influences susceptibility to erosion
as soil carbon affects soil physical and chemical properties. Similarly many soil
management practices, such as ground cover maintenance, address multiple
aspects of soil condition (e.g., ground cover management can increase soil carbon
and decrease soil erosion).
Across Australia many farmers and graziers face more than one form of resource
degradation and most will have multiple objectives they seek to achieve. Some of
these objectives will be economic, but certainly environmental and social objectives
also play an important part in determining agricultural practice. Because of this,
taking a systems approach to agricultural practice is not only theoretically important,
but it also plays an important part in the day-to-day operations of Australian farms.
The extent to which systems approaches are well practised is an altogether different
question. One of the aims of any system approach is to become efficient in achieving
multiple objectives, and so in the context of this report the question arises: can good
Relationships between land management practices and soil condition
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practices be combined so they are additive and multiplicative, without negative
impact. An example of a systems approach in managing soil follows. The traditional
response to managing soil erosion on a grain farm may be to put in contour banks to
reduce the length of water flow, hence its velocity and power this prevents rills
becoming gullies. Systems thinking would suggest that erosion is caused by runoff,
adding soil sediment to the runoff and then the flow moving this across the
landscape. Systems practice would be to reduce runoff by increasing infiltration,
hence reducing sediment concentration, and managing the flow to maintain spread
across the landscape and prevent runoff concentration (where rills and gullies form).
This is usually achieved by management of ground cover.
At the conclusion of each of the soil condition Sections (4-8), a box has been
included to provide an example of a systems approach to managing soil C, soil pH,
water erosion and wind erosion.
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7 | P a g e
3. Linking management practices, soil quality and
ecosystem services
3.1 The concept of ecosystem services
One key purpose of this report is to consider the links between soil condition and the
benefits that soils in good condition provide for humans. There is increasing demand
              
(Soils Research Development and Extension Working
Group 2011). Rarely, however, have these needs been fully and clearly articulated in
the past, especially with respect to soils. Soils are often seen as simply the substrate
in which plants grow. This narrow view has been changing over the past decade as
there has been increasing focus on the roles of soils in ecosystems and their

The dependence of humans on ecosystems has been the focus for a body of
research over the past decade and more, under the banner 
Ecosystem services can be described as the attributes of ecological systems that
contribute to benefits for humans (Fisher et al. 2009). In Section 8 we discuss in
more detail how ecosystems services are defined and categorised, and how the
concept can be put into practice with respect to soils. The essence of the concept is
that the multitude of interactions among living organisms in ecological systems, and
between those organisms and the non-living components of the environment,
produce outcomes that not only have great value to humans but can potentially be
more efficient and less costly than alternatives that involve humans and their
technologies (Daily 1997).
The types of benefits that come from ecosystems broadly (i.e., including above and
below ground ecosystems) include: support for production of food, fibre, fodder and
other products of crops; provision of chemicals and genetic material that can have
value in human health and/or industrial processes; clean air and water; natural pest
control; disposal of wastes; and a range of cultural, intellectual, spiritual and other
intangible benefits. Obtaining these benefits usually requires some final input from
humans, which is why several recent approaches have explicitly separated the
services from the benefits (see Section 8).
Soils are at the heart of virtually all processes leading to ecosystem services and
subsequent benefits (Daily et al. 1997; Sparling 1997; Wall and Virginia 2000;
Barrios 2007; Soils Research Development and Extension Working Group 2011).
Hence, any changes in soil condition potentially affect a range of processes, services
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8 | P a g e
and benefits to humans. The changes in benefits are not, however, always readily
attributable to soils as many involve inputs from other parts of ecosystems, such as
plants, animals and atmospheric processes. As such, soils often provide
         
therefore support benefits to humans indirectly rather than directly) (Fisher et al.
2008). In Sections 8 and 9, we explore how changes in soil quality relate to soil
ecosystem services and how the value of those services can be estimated.
3.2 Ecosystem services and management practice
A focus of this study is the relationship between ecosystem services (their quality,
quantity and diversity) and agricultural practice. We know from the history of
agriculture that inappropriate practices may lead to land and water degradation and
potentially to the loss of the productive resources upon which agriculture depends.
Examples of this are provided in Sections 4 to 8.
It is important to note that the relationships between management practices and
ecosystem services provided by soils are neither linear nor homogenous; what is a
sustainable practice on one soil type within one climatic zone may not be sustainable
elsewhere. Moreover, some practices may result in trade-offs between different
ecosystem services. For example, tree planting to manage local erosion might
enhance local productive capacity but the reduction in run-off may lead to less water
being made available elsewhere. From a natural resource management perspective,
this example may translate into the trade-off between managing dryland salinity and
environmental river flows (van Buren and Price 2004).
The heterogeneity of Australian landscapes, Australian soils and Australian
production systems demands heterogeneity in agricultural practices and policy
approaches across our landscapes, our soils and our production systems. This
makes determining an aggregated valuation of ecosystem services resulting from
changes in practice very difficult, if not impossible, as discussed in Sections 8 and 9.
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9 | P a g e
4. Soil Carbon
4.1 Nature of the issues
The global soil organic carbon (SOC) pool is estimated to be ~1,395 × 1015 g (Post
et al. 1982) which is three times more than that found in the atmosphere or in
terrestrial vegetation (Schmidt et al. 2011). SOC refers to the diverse range of
organic material that enters (e.g. plants/ manures/ herbicides) or resides (e.g. soil
animals and microbes) in soil. Soil therefore contains C in diverse structural forms
and with diverse residence times, encompassing living (labile), recently dead and
long-dead (non-labile and recalcitrant) forms. A comprehensive list of critical
functions of soil C has been developed (Lal 2004) (Table 4.1).
Table 4.1. List of critical functions of soil C (after Lal 2004)
These functions of SOC can be associated with provisioning, regulating and cultural
ecosystem services as well as the soil processes that support these services (MA
2005). They relate to water, air and food quality, nutrient cycling and disease control
(Kibblewhite et al. 2008)        
nationally and internationally. It is also a key component of greenhouse accounting
programs used by the Australian Greenhouse Office (AGO) through the National
Carbon Accounting System (NCAS) to track changes in carbon loss and storage
under alternative land-use scenarios (Wilson et al. 2007). Further development of
NCAS is supported by the Soil Carbon and Research Program (SCaRP) which
examines variations in soil organic carbon (SOC) and composition under different
agricultural management practices in regional Australia using a nationally consistent
methodology (Sanderman et al. 2011).
Function
Source and sink of principal plant nutrients (e.g., N, P, S, Zn, Mo)
Source of charge density and responsible for ion exchange
Absorbent of water at low moisture potentials leading to increase in plant available water capacity
Promoter of soil aggregation that improves soil tilth
Cause of high water infiltration capacity and low losses due to surface runoff
Substrate for energy for soil biota leading to increase in soil biodiversity
Source of strength for soil aggregates leading to reduction in susceptibility to erosion
Cause of high nutrient and water use efficiency because of reduction in losses by drainage,
evaporation and volatilization
Buffer against sudden fluctuations in soil reaction (pH) due to application of agricultural chemicals
Moderator of soil temperature through its effect on soil colour and albedo (reflective capacity)
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4.2 Impacts of agriculture and measures that could build Soil
Organic Carbon
There are many ways in which agriculture impacts on the capacity to build SOC. In
principal, several factors influence this process reflecting that SOC dynamics is
biologically mediated by a diversity of organisms that inhabit soils (see Section 2.2).
Put simply, what determines the amount of SOC that accumulates is the balance
between the amount of C added to the soil, the amount lost through microbial
respiration and the capacity to build the resistance of what remains (Kirkegaard et al.
2007; Sanderman et al. 2010). Climate, and specifically precipitation and
temperature, exert an overriding control whilst other regulators such as soil type,
particularly particle size, nitrogen inputs, and plant biomass quality and quantity, are
also important because they can be managed to some degree (Parton et al. 1987;
Paustian et al. 1997).
It is also well recognised that land-use change has the most profound and enduring
influence on SOC stocks. A global meta-analysis indicates declines in SOC stocks
after land use changes from pasture to 
             
increase after land use changes from native forest to pasture (+ 8%), crop to pasture
(+ 19%), crop to plantation (+ 18%), and crop to secondary forest (+ 53%) (Guo and
Gifford 2002; Smith et al. 2012).
In Australia, clearing of native vegetation for primarily agricultural purposes has
caused a 40-60% decrease in SOC stocks from pre-clearing levels. Significantly,
some soils are still responding to the initial land-use change with continuing declines
in SOC albeit more slowly under some management regimes (Sanderman et al.
2011) so it is critical that management not be considered only in relative terms (e.g.
stubble retention versus stubble burning) but in the broader context of land-use
change.
Also noteworthy is that while there is a strong theoretical basis for management
strategies that build SOC, this is supported by a limited number of field studies
(Sanderman et al. 2010) that generally lack management history detail (e.g. past and
current management including fertiliser history, rotations etc) that is critical for
estimating SOC build-up (Smith et al. 2012). This reduces confidence in making
quantitative predictions about outcomes of interventions, but there is moderately high
confidence in the efficacy of many approaches (Sanderman et al. 2010).
The relative efficacy of management strategies to mitigate SOC losses and to
potentially build SOC, evaluated below for each of the four main industry groups.
Relationships between land management practices and soil condition
11 | P a g e
Broadacre cropping
Broadacre cropping includes cereals, oilseeds, sugar cane, legumes, hops, cotton,
hay and silage, and contributes around $13 billion or more than 50% of the gross
value of agricultural production in 2009-2010 (ABS 2011b).
Figure 4.1 illustrates the crop management options that are likely to or have been
shown to increase SOC.
Figure 4.1. Crop management practice and relationship with expected Soil Organic Carbon
levels and benefits.
Confidence in SOC benefit based on qualitative assessment of theoretical and evidentiary
lines; L=Low, M=Medium, H=High (figure draws on information from Sanderman et al. 2010,
Scott et al. 2010 and Murphy et al. 2011)
The nearly universally observed reductions in SOC that accompany clearing of
native vegetation for agriculture have been attributed to two broad categories of
process changes: reduced inputs due to harvest and stubble burning; and increased
loss rates of carbon due to disruption of the soil surface, leading to enhancement of
decomposition rates and greater risk of water and wind erosion (Sanderman et al.
2010). The potential approaches to increasing SOC, therefore, focus on reversing
these effects (i.e., increasing inputs and/ or reducing losses). These management
options include varying planting time, sowing rates, nitrogen application, cover and
crop varieties, residue management (e.g. grazing and/ or burning), tillage type and
depth, and length of fallow (Ugalde et al. 2007; Murphy et al. 2011). A combination of
Relationships between land management practices and soil condition
12 | P a g e
these options, and specifically tillage and stubble management practices, can
determine the SOC levels (Sanderman et al. 2010; Scott et al. 2010; Murphy et al.
2011) although Sanderman et al. (2010) warn that the outcomes of changed
management practices is not always predictable quantitatively because of the many
factors that need to be taken into account. Some of these choices affect the stability
of soil, while others affect yield and, therefore, biomass potentially available to the
soil carbon pool.
The amount of carbon available for addition to soils in the form of shoot and root
residues/ exudates depends on how much is removed at harvest. A broadacre crop
such as wheat would produce less than 2 t.ha-1.yr-1 compared to sugar cane which
might generate inputs of 7 t.ha-1.yr-1 (Kirkegaard et al. 2007).
Based on Figure 4.1, long fallow is likely to be associated with lowest expected SOC
levels, and pasture cropping is likely to support the highest expected levels of C.
Expectations for enhanced SOC are now high due to improved adoption of relevant
practices (Barson et al. 2012b). Between 2007-08 and 2009-10 there was a national
10% increase (from 49-59%) in the number of farmers using reduced tillage, or one
pass sowing systems and a 3% increase in farmers using residue retention. This
resulted in residue being left intact over 68% of cropped area or no cultivation apart
from sowing over 76% of cropped area.
Interpreting research on the effects of soil management practices on SOC is
complicated because many studies have not been able to control all variables
(Sanderman et al. 2010). For example, rainfall, soil type, time since last cultivation,
and the depth at which measurements are made all affect SOC accumulation (see
review by Sanderman et al. 2010). How sustained these increases are is also
subject to conjecture as there are limited long-term studies of these systems across
the five broad agro-ecological cropping zones (summer rainfall, Mediterranean west,
moist south east, dry marginal south east and high rainfall zone) and rates of
accumulation are highest in surface soils, which are also most vulnerable to
disturbance. These temporal and regional data are critical in determining the
likelihood of increasing SOC under the proposed management options and explains
the high variability in SOC levels reported for direct drilled, stubble-retained systems
(Mele and Carter 1993; Sanderman et al. 2010; Scott et al. 2010; Dalal et al. 2011).
Apart from the options of direct drilling and stubble retention to build SOC in some
regions, Sanderman et al. (2010) highlighted that the greatest theoretical potential
for building SOC is the addition of organic materials such as manure and green
waste and the inclusion of a pasture phase in a cropping sequence. Due to their
Relationships between land management practices and soil condition
13 | P a g e
relatively recent emergence there is very little scientific evidence that associates
increased SOC in Australian broadacre cropping with practices such as organic
matter amendment (e.g. manure, green waste and biochar) and pasture cropping
(e.g. with perennial species). There is however strong evidence supporting the
feasibility of pasture cropping in broadacre cropping systems (Bruce et al. 2006;
Millar and Badgery 2009; Dolling et al. 2010) and the feasibility of biochar
amendments (Chan 2008; Kimetu and Lehmann 2010; Singh et al. 2010) as
potential strategies for increasing SOC.
If management enables SOC to build up, there is also a nutrient cost reflecting the
heightened demand of soil biota for these nutrients as they decompose additional C
substrates. The deficit created in nitrogen (N), phosphorus (P) and sulphur (S) over
and above crop requirements is 60, 12 and 9 kg respectively per tonne of humus
locked up (Passioura et al. 2008).
Horticulture
In 2009-1
industry based on gross value of production (GVP) of $8.4 billion, ranking third
behind the meat and grain industries (DAFF 2012b).
Horticultural industries encompass a diverse range of fruit and vegetable industries.
The total area under production in Australia is around 250,000 hectares. Generally,
interest in SOC is driven by the need to mitigate greenhouse gas emissions and to
improve soil health and resilience (the capacity to recover after disturbance). A
survey commissioned by Horticulture Australia limited (HAL) in 2000-2003 indicated
that the most important building block for healthy soil, irrespective of soil type,
region, or climatic conditions was SOC.
A comparison of SOC in intensively managed vegetable production sites with

management practices, even for intensive land use for vegetable production, can
sustain soil integrity/ soil he HAL 2003). A recent investigation into on-farm
emissions in Bundaberg regions and in the Lockyer Valley and Bowen indicated that
vegetable production was the highest emitter of C from soils (3.50 tCO2-e.ha-1.year-1)
followed by tree crops (2.85 tCO2-e.ha-1.year-1), then sugar cane (1.91 tCO2-e. ha-
1.year-1) then cane/ other crops (1.16 tCO2-e.ha-1.year-1). This trend was reversed
when calculated as emissions per unit income (e.g. vegetables 41 tCO2-e/$1 million,
fruit trees 221 tCO2-e/$1 million and cane 606 tCO2-e/$1 million). It was concluded
that, despite the high variability in data within a production system, there was
Relationships between land management practices and soil condition
14 | P a g e
significant scope for improvement with carbon fixed in organic matter as a
recommended management option (HAL 2012b).
         -till
techniques and controlled traffic technologies and to add organic materials (such as
organic mulches and biochar) to build SOC (Pattison et al. 2010; HAL 2010, 2011). A
detailed study on the use of organic products (chicken manures, composted green
wastes) for multiple benefits confirmed that additions of organic matter in these ways
both offset carbon losses experienced in conventional approaches to vegetable
management and increased crop productivity by up to 10% when other inputs were
held constant (HAL 2011). A survey of soil management from 2007-08 to 2009-10)
indicated that 28% more horticulturalists used alternate or cover crops and 33%
used mulching or matting (Barson et al. 2012c).
Dairy
In 2010-11 the farm gate value of production for the dairy industry was $3.9 billion
(around 10% of the gross va   
area under production was 4 Mha (Barson et al. 2012a; Dairy Australia 2012).
Generally, dairy systems have higher levels of SOC relative to other agricultural
industries and therefore the focus is less on building SOC and more on maintenance
or loss prevention (MacKenzie 2010). Higher levels of SOC are attributed to a
number of factors such as: higher availability of water (as rainfall or irrigation); ready
supply of nutrients (N and P); higher proportion of perennial species that grow
continually rather than seasonally; minimal disturbance relative to cropping; and
minimal erosion.
Loss of soil carbon from dairy soils does occur and has been attributed to loss of
ground cover due to high stocking rates, leaching of organic acids below the root
zone, and to cultivation associated with planting of annual grasses in dryer or
drought prone regions such as in northern Victoria (MacKenzie (2010) reviewed
experimental results from several countries as well as Australia). Management
options to prevent loss of carbon in dairy pasture soils are: 1) to reduce
decomposition; 2) to improve the rate of addition of organic materials; and 3) to
reduce soil disturbance/ increase ground cover (Watson 2006; MacKenzie 2010;
Barson et al. 2012a). These options are summarised in Table 4.2 together with the
likelihood of adoption.
Relationships between land management practices and soil condition
15 | P a g e
Table 4.2 Dairy pasture management options to conserve soil carbon (drawing on a research
review by MacKenzie (2010) and a survey of practices by Watson (2006))
Management
option
Rationale
Slow the rate of
decomposition
of soil carbon
Clay soil tends to protect organic
matter more effectively from
decomposition than sandy soil.
Subsoil modification of hard pan or
sodic/ Al toxic layers to encourage
root penetration to deeper (cooler)
layers
Organic materials such as biochar,
waxy plant materials, and composted
manure have chemical structures can
potentially reduce the rate of organic
carbon decomposition in soil
Increase the rate
of addition of
plant biomass
Use of ameliorants such as gypsum
(for sodic soils) and lime (for acid
soils) to increase plant productivity
Use of essential elements (e. g. N, P,
S, K, Ca) to increase C
transformations and optimise
productivity
Reduce soil
disturbance
(pugging, tillage)
increase ground-
cover
Livestock management (stocking
rates/ grazing intensity to protect
ground cover)
Pasture renovation (increasing
perennials in sward composition).
In terms of current trends in management (2007-08 to 2009-10), dairy farmers are
increasingly monitoring ground-cover (up from 72% to 88%) but fewer are setting
ground-cover targets (38% to 27%) (Barson et al. 2012a).
Grazing
Livestock grazing is the most widespread Australian land use, covering more than
336 Mha or about 40% of the total area of Australia. Meat and wool production
contribute almost 30% to the gross value of agricultural production (ABS 2011a).
These enterprises encompass three broad systems; i) the native pasture dominant
Relationships between land management practices and soil condition
16 | P a g e
systems, principally occurring in the rangelands of central and northern Australia, ii)
the permanent perennial grass-based pasture zones of south-eastern Australia and
iii) the more intensive mixed wheat-sheep farming systems of southern Australia that
are based on improved pastures and fallow rotations (Scott et al. 2000; Australian
State of the Environment Committee 2011).
Grazing by livestock (e.g. beef and sheep) can impact directly on SOC and nitrogen
cycling by modifying plant biomass inputs into soil (shoot and root material) and by
reducing ground cover and thereby exposure of SOC-rich surface layers to wind and
water erosion (Earl and Jones 1996). Grazing can also impact indirectly on SOC by
modifying soil structure (density and aggregate stability), moisture and temperature
influencing soil faunal and microbial diversity and activity (Southorn and Cattle
2004b; Teague et al. 2011).
Management options to increase SOC have focussed on three strategies: 1)
increased productivity (irrigation and fertilisation); 2) time controlled (TC) or rotational
grazing; and 3) shift to perennial species (Sanderman et al. 2010). Research on the
impacts of these options on SOC is rare (Sanjari et al. 2008; Sanjari et al. 2009),
despite the extensive research effort in sustainable grazing systems and,
specifically, increasing the perenniality of pasture systems (Kemp and Dowling 2000;
Mason and Kay 2000; Michalk et al. 2003)       
grazing systems referr        
  -      

including SOC (Earl and Jones 1996; McCosker 2000; Sanjari et al. 2008; Sanjari et
al. 2009; Sherren et al. 2012). A small number of studies in south-eastern
Queensland and northern NSW of TC grazing have reported increases in herbage
mass, SOC, nitrogen (Sanjari et al. 2008), ground-litter (Earl and Jones 1996;
Sanjari et al. 2008), and reduced runoff and soil loss (Sanjari et al. 2009) compared
to continuous grazing. Longer monitoring periods would increase confidence in these
data (Sanjari et al. 2008; Sanjari et al. 2009).
4.3 Evidence of the efficacy of practices to increase soil organic
carbon
In theory, the two main ways to build soil C are to reduce gaseous loss as either CO2
and CH4 by reducing soil disturbance and to increase C inputs either in the form of
more plant biomass (which may require measures to overcome other constraints to
plant growth) or in the form of other organic materials (manures, biochar etc). In
practice, only the cropping industries (broadacre and horticulture) have opted for
Relationships between land management practices and soil condition
17 | P a g e
reducing disturbance of surface residues and increasing inputs through plant residue
retention and through the addition of organic residues as strategies to increase SOC.
The grazing industries (including dairy) have focussed more on maintaining SOC
through indirect means such as increasing ground cover and arresting acidification.
The efficacy of practices to increase SOC is highly variable and is dependent on soil
type (particle size) and climate (regional precipitation patterns) (Smith and Belvins
1987; White 1990; Mele and Carter 1993; Kirkegaard et al. 2007). The consensus is
that, in most of the cereal cropping areas in Australia (rainfall of 250-600 mm), the
potential for reduced or no-tillage (direct-drilling) and stubble-retention to store
carbon and mitigate greenhouse gas emission is limited, in contrast to areas with
higher rainfall and greater biomass production (Sanderman et al. 2010; Chan et al.
2003). In a review of stubble retention systems in southern Australia, the higher SOC
levels under stubble retention practices (relative to stubble burnt treatments) was not
attributed to the sequestering of C but rather to the slower rate of decline under
stubble retention compared to burning (Scott et al. 2010). The higher levels of SOC
in surface soils of no-till systems can be associated with other benefits such as
increased infiltration, reduced disease, conservation of nutrients and increased
earthworm densities (Carter and Steed 1992; Roget 1995; Simpfendorfer et al. 2004;
Scott et al. 2010) which may represent a more sensitive, yet indirect measure of the
benefits of SOC increases with minimum tillage and stubble retention.
For horticulture, dairy and grazing industries, evidence of the efficacy of
management strategies to increase soil C is difficult to find in the primary literature.
For the grazing industries, only a very small number of studies have measured
changes in SOC directly (Sanjari et al. 2008) and the confidence in these data was
low due to the relatively short time frame for monitoring differences in TC and
continuous grazing systems.
The general principles that have been demonstrated in using broadacre cropping
industries as the model can also be applied more broadly. Empirical data have
increased confidence in the application of models to predict soil C build up (e.g.
CENTURY/ROTHC), which can be useful when it is not possible or affordable to
collect SOC data.
Relationships between land management practices and soil condition
18 | P a g e
Box 4.1: Managing Soil C through a systems approach
System goal
To increase soil C or slow down its decline.
Considerations
1. Increase inputs by growing more biomass (relative to removal), adding fertiliser
and ameliorants as required, growing perennials or increasing crop frequency, and
adding organics (mulch, manure, compost). These practices are interactive and
probably cumulative. Appropriate performance indicators would be water-use
efficiency and nitrogen-use efficiency, as an optimal balance between carbon and
nutrients improves water-holding capacity of soil, microbial involvement in carbon
and nitrogen cycles, and efficiency of nitrogen use for growth by plants. These
actions potentially apply to cropping, horticulture, grazing and dairy.
2. Reduce decomposition by: avoiding excessive soil moisture and waterlogging;
eliminating tillage, burning and erosion; reducing NO3 fertilisers, changing to NH4
fertilisers, organics or legumes; and encouraging free-living N fixation. These actions
are applicable across industries.
3. With 1 and 2, operate at a stable soil C level, not increasing. This level needs to
be determined but will be higher for currently degraded soils. Maintenance inputs
depend on soil C levels, lower is better. Soil C also ties up large amounts of
nutrients. Should our goals be equilibrium soil C and increased C cycling of the C
inputs from 1 and 2? It is difficult to increase C inputs and soil C in cropping
industries with the high product removal required for viability and efficiencies.
Recommended practices
Zero tillage, increased crop frequency or perennial pastures to increase biomass
production and retention, residue retention or managed grazing pressure, improved
agronomy, organic fertilisers, no burning.
Performance indicators
Annual water-use efficiency and nitrogen-use efficiency, carbon and nutrient cycling
(most relevant at farm scale), percentage ground cover (most relevant at farm to
regional scales), and productivity (relevant at farm to regional and national scales).
Conflicts
Availability and costs of machinery for managing minimum till can be a limiting factor.
Incentives may be needed to move some farmers from traditional practices.
Management inputs can be high to achieve enhanced SOC.
Relationships between land management practices and soil condition
19 | P a g e
5. Soil pH
5.1 Nature of the issues
Soil pH (potential hydrogen) is the test used to assess the concentration of hydrogen
ions in soil solutions of water (pHW) or calcium chloride (pHCa). Ideally, soil pH for
crop and pasture production should be in the range of pH 5.5 to 7.5Ca in the top soil,
and no less than pH 4.8Ca in the subsoil (Dolling et al. 2001; Gazey and Davies
2009). Soil acidification, a key soil condition indicator (NLWRA 2007) is measured by
a decline in pH over time. This can occur in the surface and subsurface layers of soil.
There are several major causes for the acidification of agricultural soils: removal of
agricultural products (most plant and animal products from farms are slightly
alkaline); excessive accumulation of organic matter, which contains organic acids, in
some circumstances (even though soil carbon also plays a key role in buffering
against pH change); excessive use of nitrogenous fertilisers, especially those that
lead to release of ammonia into the soil; leaching of fixed, fertiliser and urine-N as
nitrate from surface layers to lower layers before plants can utilise it (Scott et al.
2000; NLWRA 2001; Gazey and Davies 2009). Understanding the causes will be
critical for addressing questions on the efficacy of remedial action in different
agricultural land-use scenarios.
The effects of acidification are not easily recognised and hence it is commonly
described as an insidious problem in that plant symptoms are less visual and easily
misdiagnosed, and production declines are gradual (Scott et al. 2000). Impacts can
be on-site and related to plant, animal and soil biological performance or off-site,
though the link to stream and groundwater acidification is speculative (Cregan and
Scott 1998). On-site impacts are usually associated with increases in aluminium (Al)
and manganese (Mn) levels with plant toxicity symptoms emerging and a reduction
in nutrients such as calcium (Ca), Magnesium (Mg), and Potassium (K) with plant
deficiency symptoms emerging (Slattery et al. 1989). The reduction in plant biomass
production has a major knock-on effect; it reduces the quantity and quality of plant
residue entering soils and hence SOC levels and all the associated critical functions
(see Section 4, Table 4.1).
Acidification occurs in surface and in subsurface soils. According to the National
Water and Land Resources Audit of 2001 (NWLRA 2001), half of the non-rangeland
agricultural land in Australia is acidic (surface pHCa      
level to prevent subsurface acidification. This area, estimated to be of the order of
about 49-50 Mha, is 5 times greater than the area affected by salinity. About half of
Relationships between land management practices and soil condition
20 | P a g e
this, or approximately 17 Mha, has pHCa      
action. In WA, almost 8 Mha of the 13 Mha under dryland agriculture are at risk of
acidification (Holmes et al. 2011). In southern Australia, subsoil acidity occurs on
about 24 Mha (Li et al. 2010).
Ten years on, the State of the Environment report (Australian State of the
Environment Committee 2011) highlights that the severity and extent of acidification
has increased in many regions, due, it says, to inadequate treatment, intensification
of land management, or both. Although, for three of the four main agricultural
industries, the number of businesses applying lime or dolomite to their holdings
increased between 1995-96 and 2009-10, the totals by 2009-10 were only between
17 and 21% and most of that increase had occurred by 2001-02 (DAFF 2012a). For
cropping, this increase was from 8 to 17% between 1995-96 and 2001-02, rising to
19% by 2009-10 (DAFF 2012a; Barson et al. 2012b). Dairy and horticulture started
at higher percentages but achieved much smaller increases (DAFF 2012a).
Of even greater concern is the largely unknown extent of subsoil acidification and the
intergenerational issues that will arise if this develops to levels where mineral
dissolution occurs and soils are beyond remediation. It is clear that subsoil testing to
raise awareness of the issue is a critical first step with early evidence of a change in
attitude and intention in farmer groups (e.g. Nyabing group) in WA (Wilson et al.
2009; Gazey et al. 2012).
5.2 Impacts of agriculture and measures that could arrest soil
acidification
Broadacre cropping, horticulture, dairy, and grazing all contribute to soil acidification.
The Australian State of the Environment Committee (Australian State of the
Environment Committee 2011) listed the following summary observations:
Soil acidification is widespread in the extensive farming lands (cropping,
sheep and cattle grazing) of southern Australia;
Rates of lime application are well short of those needed to arrest the problem;
Acidification is common in intensive systems of land use (tropical horticulture,
sugar cane, dairying);
Acidification is limiting biomass production in some regions, but the degree of
restriction is difficult to estimate;
Carbon losses are most likely occurring across regions in poor condition, and
soil acidification is a major constraint on storing carbon in soils in the future.
Relationships between land management practices and soil condition
21 | P a g e
Acidification risk areas based on topsoil data from major agricultural land-use
categories have been identified (based on a 5 km grid) as a priority for remedial
management (Wilson et al. 2009). The specific agricultural activities that increase
soil acidity are the use of high-analysis nitrogen fertilisers, the large rates of product
removal, and the farming of soils that have a low capacity to buffer the decrease in
pH (e.g. infertile, light-textured soils) and the soil already has a low pH (Helyar et al.
1990; Helyar 1991; Wilson et al. 2009).
The five primary actions to address soil acidification are to:
soil test for pH
add lime at rates that are effective for arresting acidification
add lime at high rates, sufficient to reverse acidification in soils that have
already acidified
use acid-tolerant plant species where available (as a short-medium term
measure).
land retirement (this could be considered where it is uneconomic to apply lime
and where the benefits of arresting acidification are judged to be sufficiently
important this has not occurred anywhere in Australia to date to our
knowledge).
Testing surface and subsurface pH by farmers, on-farm, is the precursor to
implementing remedial action. The number of landholders who undertake pH testing
has declined slightly (from 07-08 to 09-10) across all industries (grains, horticulture,
dairy and grazing) with Queensland being the exception with slight increases in all
but the grazing industries (Barson et al. 2011, 2102a, b, c). Lime addition and use of
acid tolerant species are complementary actions with the fifth action, land-use
change, being a more extreme option and not usually considered. The use of acid
tolerant species, although a relatively straightforward and cost-effective option, does

 most widely used remedial action is to
add lime to increase surface soil pH and gradually subsurface pH. Information on the
neutralizing values of liming material (Goldspink and Howes 2001) and the
recommended rates to apply in pasture and cropping systems (Slattery et al. 1989;
Gazey and Davies 2009) are readily available and supported by online lime
calculators for choice of lime, amount to add, and economic benefit (e.g.
http://www.aglime.com.au/liming; http://www.soilquality.org.au).
Relationships between land management practices and soil condition
22 | P a g e
The adoption of these five primary remedial actions is ultimately influenced by return
on investment which is set by regional factors of soil type and rainfall (Helyar 1991;
Gazey and Davies 2009; Holmes et al. 2011). The impacts of soil acidification and
practices that are available to address this widespread problem will now be
considered in the context of the four main industry groups.
At a national scale, protocols for monitoring soil pH are established (Grealish et al.
2011) but an organised national monitoring system has yet to be implemented.
Broadacre cropping
A consequence of the intensification of broadacre cropping over the past 10-15
years (see Section 4.2) is greater N-fertiliser use and greater product removal
leading to increased rates of soil acidification. Liming is regarded as an economically
viable option for broadacre cropping, and a lime application strategy must account
for a range of factors including type of crop and level of production, type of lime and
amount applied, soil texture and rainfall (Slattery et al. 1989; Helyar 1991; Helyar et
al. 1992; Gazey and Davies 2009).
The key management messages for broadacre croppers are that:
Lime rates should be matched to the soil type and soil pH. The lime
requirement (as dolomite or limestone) to raise pH by about one unit varies by
soil type, with rates increasing from about 1.5 to 2.5 t/ha of good quality lime
on sandy soils to up to 6 t/ha on clay soils (Slattery et al. 1989; Aitken et al.
1990; Gazey and Davies 2009).
Varying the rates of lime applied to soils has proved more cost effective than
uniform application. This accounts for paddock variability in soil type (see
above) and to variable rate N fertiliser applications (Bruce et al. 2006).
Soil samples to assess pH should be taken to depth (down to 30 cm) and
composited to account for spatial variability (Slattery et al. 1989; Holmes et al.
2011) and to assess the occurrence of subsoil acidification (Gazey et al 2012)
Soil pH should be monitored every three to four years to assess the impact of
management and amelioration treatments (Holmes et al. 2011).
Lime rates should also consider the crops grown to account for varying tolerances
and for loss of alkalinity through product removal (Slattery et al. 1989) and to N
fertiliser rates to account for increased acidity through nitrate-N drainage (Bruce et
al. 2006).
Relationships between land management practices and soil condition
23 | P a g e
Horticulture
The use of high analysis N fertilisers and the high rate of product removal are
features of most horticultural enterprises. Horticulture Australia limited (HAL) reports
that 11 of the 21 horticultural industries supported by HAL have undertaken soil
research (e.g. strawberries, citrus, bananas, blueberries, deciduous orchards,
macadamias, and nursery, potatoes, processing tomatoes, turf and vegetables) to
counter the problems associated with high fertiliser inputs and product removal. Soil
acidification has been identified as one of the six main issues of concern
(Horticulture Australia Ltd 2008).
The key management options for mediating soil acidification in horticulture are
similar to those for broadacre cropping with liming a key strategy. Nationally about
20% of horticultural businesses apply lime/ dolomite and 25% use pH and nutrient
testing (Barson et al. 2012c). Horticulturalists tend to use burnt lime (CaO) which
reacts more quickly with water (Goldspink and Howes 2001). For intensive industries
such as vegetable growing, the high N fertiliser use coupled with irrigation represents
a significant risk for acidification through nitrate leaching below the root zone. In
extensive perennial-based dryland systems, (e.g. orchards and vineyards),
particularly those located in the high rainfall zone, the use of acid tolerant species
such as chestnuts and the liming of soils for grape production is recommended
(McCarthy et al. 1992; Scott et al. 2010). The recommended pHCa for grapevines is
5.5 to 7.5. Outside this range they are likely to suffer toxicity (Al) or deficiency (Fe,
Cu, Zn and Mn) (White 2009). Data recording the extent to which lime is applied
under vine in Australia is difficult to find.
For many horticultural industries, the cost of liming is relatively small in relation to
yield profit              
acidification compared to the broadacre cropping industry. As with broadacre
industries, liming can be an effective and profitable management strategy for
mitigating surface soil acidification provided appropriate rates are applied that
account for regional and local (management) factors of soil and plant type and N-
fertiliser regimes.
Dairy
Eight of the major dairying areas in Australia occur in the higher rainfall zones (600
mm) of southern Australia (Southern Queensland and Northern NSW) and southern
Western Australia. Around 63% of intensively managed grazing, including dairy
pastures, area is at low risk of soil acidification (particularly in SA and NSW) and
Relationships between land management practices and soil condition
24 | P a g e
21% is at high risk (particularly in WA and Vic) (Barson et al. 2012a; Dairy Australia
2012).
Due to diminishing returns from milk production dairy farmers nationally have
intensified and diversified their production to remain profitable. This has been done
by increasing stocking rates, growing irrigated annual fodder crops, moving to mixed
livestock systems of beef and dairy, and increasing nutrient inputs (Gourley et al.
2007; Bolland and Russell 2010). Many dairy farms also report significant nutrient
surpluses, either as a result of high N application rates or by importing feed on farm
(Gourley et al. 2007). The net effect of these activities is significant acidification,
particularly in light textured soils where soil buffering capacity is low. The situation is
particularly serious in south-western Australia where most soils used for dairy
production have acidified from pHCa values 5.56.5 to pHCa 3.74.5 (McArthur 2004).
Aluminium toxicity, induced by soil acidification, is a major problem for dairy
production (Bolland and Russell 2010) and is ameliorated by applying sufficient lime
to raise the pH of the top 0.10    (Whitten et al. 2000). The rate of
change was slow, with pHCa of 5.5 achieved in individual paddocks 911 years after
the liming program started, with 29% of paddocks not achieving this level despite
additions of between 1221 t/ha lime (Bolland and Russell 2010).
Grazing
Acidification-remediation actions for grazing lands are confined to permanent pasture
and mixed farming zones, and subsequent discussion will focus on these systems.
Under grazed permanent pastures, nitrate leaching is considered to be the largest
contributor to acidification (Ridley and Coventry 1995). In south eastern Australia
(e.g. NSW southern Tablelands and north-eastern Victoria), Scott et al. (2000)
highlighted three characteristics of acidification; i) the rate of pH decline is slow (50
years or more) and even slower on strongly acidic soils ii) acidity problems are more
quickly apparent on light textured soil and iii) soil can be acidic to depths of 60 cm.
The options for managing acidification under grazing systems are listed in Table 5.1
together with the associated constraints (Scott et al. 2000). These options are
related to increasing perennial pasture content for better uptake of nitrate and for
better year round biomass production (Section 4). Specifically there are four listed: 1)
to sow perennial grass species rather than annual to access nitrate and prevent
leaching; 2) to incorporate agroforestry systems, again to increase rooting depth and
nitrate uptake; and 3) to reduce stocking rates on pastures with a high component of
native grasses, to maintain vigour of native grasses. This last option will only
constitute a minor component of grazing systems (less than 10%) and will therefore
Relationships between land management practices and soil condition
25 | P a g e
not apply in many cases. Ultimately liming at higher rates is the major solution to
reduce soil pH below 10 cm and benefit-cost scenarios for different soil types and
rainfall distributions must be articulated.
Table 5.1 Options for management of soil acidity and feasibility in permanent and mixed
grazing systems (adapted from Scott et al. 2000)
Option
Feasibility
Considerations
1. Modifying
the grazing
system
change
pasture
species
and/or
grazing
manage
ment
use less
fertiliser
Limited (in
permanent
pasture
systems due
to cost and
management
skills, and
also limited
to area). This
option will
also only
reduce
acidification
Perennial species (e.g. native grasses)
some scope but very high establishment costs
Modification of animal camping behaviour
high investment in labour, management skills and fencing
Increase stocking rate
likely if farmers more able to afford lime
Reduce stocking rate
likely where there is a reasonable proportion of summer-active
native grasses
profitability likely lower except maybe for fine wool production
Fertiliser use
avoid elemental S and NH4+- fertilisers, otherwise must apply
lime to balance (3-7 kg per kg S and N respectively)
2. Breeding
and selecting
plants for
tolerance
Feasible in
permanent
and mixed
grazing
systems but
is a
temporary
solution only
Selection of Aluminium tolerant species - most ryegrasses, native
grasses, oats and triticale are highly tolerant but can mask and
intensify developing problem and does not negate need for lime
Breeding must consider other traits such as palatability, persistence
and the response of the rhizobial symbiont to acidity.
Selection of aluminium tolerant plant varieties and rhizobial strains
can be useful as a short medium term solution (Ridley and
Windsor 1992) but can exacerbate acidification in the long-term.
3. Correcting
acidity by
lime
application
Highly
feasible but
amounts
required and
time taken
dependent
on soil type
and grazing
system
(permanent
or mixed)
Lime (carbonate) movement is slow
takes time to move into soil profile, depends on porosity, can
be facilitated by tillage and/ or soil fauna
higher clay and organic matter soils resist change
higher lime rates increase pH to greater depth
surface applied lime increases profile pH to greater depth than
incorporated lime(Ridley 1995)
Response of subterranean clover-based pastures to liming is
promising
sub clover response but variable in magnitude and time;
the required 30% increase in stocking rates for economic
response has been reported (e.g. Book Book NSW)
some nutrients less available limiting rhizobial survival
sub clover response less reliable where lime surface applied
but likely a matter of time (Ridley and Windsor 1992)
Response of perennial-based pastures to liming is promising
Phalaris, cocksfoot (DM increases) (Ridley and Windsor 1992)
Plant yield response is often related to depth of lime incorporation
and to rate of application
the rate of lime required varies with soil type (Ridley 1995)
Managemen
t option
Feasibility
Considerations
4. Changing
land-use
Technically
feasible,
politically
very difficult!
Forestry/ land retirement means acidification slowed/ less relevant
forestry is too costly on slopes >20%, location of infrastructure
for harvesting trees
Land retirement will require public funding
Horticulture and cropping means lime amendment is economically
achievable (refer above section)
Relationships between land management practices and soil condition
26 | P a g e
5.3 Evidence of the efficacy of practices to increase soil pH
This section will address the issue of efficacy against the 4 practices listed above.
Test soil for pH
The motivation to test soil requires knowledge of the problem (why it is necessary),
instruction on a statistically meaningful sampling design (how to collect the sample),
awareness and instruction on best course of action to increase soil pH, and
knowledge of economic benefits couched in realistic timeframes. Commercial soil
testing facilities are readily available and instruction on testing design is established
or under refinement to take greater account of spatial variability and temporal factors
that account for the slow rate of change in soil pH (Holmes et al. 2011). Yet soil
testing for pH (monitored since 2007/08) has declined in 2009-10 (Barson et al.
2011; 2012a; b; c). Reasons for this decline are unclear and are likely to be complex
and multifaceted (Pannell and Vanclay 2011). Significant motivation will be
generated by the promotion of regional data demonstrating the significant benefits to
be derived from managing soil pH and the development of a 20-year, $75 million
national soil pH monitoring program (noting that this national program is separate
from programs aimed at encouraging local testing) (Grealish et al. 2011).
Add lime at rates that are effective for arresting acidification
There is compelling evidence to support the view that the management of soil
acidification by liming surface soils can yield significant benefits for broadacre
cropping industries. In a long-       h

on the limed (2-3.6 t/ha) treatments. Sensitive (barley and wheat) and acid tolerant
cereal varieties (e.g. Dollarbird) also yield more (1.6-2 t/ha more) in limed soils (Li et
al. 2001; Carr et al. 2006). Lime-induced yield increases of a similar magnitude have
been reported widely in southern Australian broadacre cropping systems in plot trials
(Coventry et al. 1987; Coventry et al. 1989; Slattery et al. 1989), even in the
presence of soil borne diseases (Coventry et al. 1987). According to Li et al. (2010),
this success, combined with strong grain prices resulted in anecdotal reports of
exponential increases in lime applications in the area in the 1990s.
A more recent case study conducted in the Gabby Quoi Quoi Catchment of the Avon
River basin in Southern WA, highlighted the increases in soil pH values measured at
approximately 300 sites over a 7-year period (1999-2006) after liming (Carr et al.
2006). This study reported that 75% of the topsoil and 85% of the mid-soil sampled
in 1999 had pHCa values lower than 5.0, with 15% of these soils having pH values
less than 4.0. Re-sampling in 2006 has showed an overall increase in soil pHCa with
Relationships between land management practices and soil condition
27 | P a g e
60% topsoil and 69% mid-soil being less than 5.0Ca and no samples found to be
below pH 4.0. Yield responses were also measured in wheat ($28/ha), barley
($53/ha) and lupin ($5/ha), although in the latter crop, lime costs were not covered
by the increased yield.
In the diverse industries that are collectively grouped into horticulture, the addition of
lime is viewed as one of the management strategies for improving the overall health
of soils. There are no accessible studies available on the effects of lime rate on
biomass production in this industry. The high inputs applied and the short growth
phases of vegetable production systems means that the lime-induced response is
difficult to assess. Lime addition is therefore seen more as a general soil health
maintenance activity (AusVeg 2010).
Despite positive yield responses, national trends in lime/ dolomite use (Barson et al.
2011; 2012a; b; c)         
change since 2000/01 or there has been a slight decline depending on industry and
state. Many suggest that this could be related to the 10 years of drought during this
period. For cereals (majority of broadacre cropping) nationally there was an increase
in the percentage of farmers using lime/ dolomite from 1995/96 to 2000/01 but not
much change since (except in WA and Tasmania) (Barson et al. 2012b). A project in
the WA wheatbelt (where sandy soils are at high risk) is showing that 50% of soils
tested have subsoil acidification problems, around 40% of broadacre croppers in WA
are liming, but lime use is less than half the amount required to manage soil
acidification (Gazey et al. 2012; Chris Gazey, DAFWA, pers. comm.) For the dairy
industry the results are similar, except that liming has decreased in Tasmania and
WA since 2000/01 (Barson et al. 2012a). In horticulture there was little change in the
  et al. 2012c).
In the grazing industries the percentage of beef cattle/ sheep businesses (outside
the rangelands) liming declined between 2007/08 and 2009/10 (Barson et al. 2011).
Add lime at high rates, sufficient to reverse acidification in soils that have already
acidified
The target values required to arrest acidification are generally high and followed by
lower maintenance levels (Li et al. 2010). National lime use estimates from the

a total of 4,136,312 tonnes of lime and 302,333 tonnes of dolomite were used in the
broadacre cropping, dairy, horticulture and more intensively managed beef cattle/
sheep grazing industries in 2007-08 (Michele Barson, DAFF, pers. comm.) This is
Relationships between land management practices and soil condition
28 | P a g e
considerably less than the projected requirement for nine million tonnes nationally
(Webb et al. in preparation).
It is highly likely that these estimated lime requirements reflect the response of the
more recalcitrant soils in south western Australia in broadacre and dairy industries
where field studies indicate that it may take in excess of 11 years (and likely much
more) and between 1221 t/ha lime to raise the pHCa to 5.5 (Bolland and Russell
2010).
Use acid-tolerant plant species where available
There is good information available about the natural acid tolerance (and associated
Al and Mn tolerance) of a range of pasture and crop plants (Slattery et al. 1989;
Duncan 1999). The DAFWA Farmnotes soil acidity series (DAFWA 2012) also
contains this information. No information was available on the combined use of this
acid tolerant species and liming but it could be assumed that both practices are used
in many regions that are at high risk of acidifying.
5.4 Concluding remarks
There is compelling evidence to show that liming surface soils increases yields of a
wide variety of grasses and legumes. This is based on intensive R&D effort in the
80s-90s on long-term trials in the high rainfall and temperate zones of southern
Australia, and more recently in the 1990s-2000s in southern WA field trials.
Examples of information packages available are the Department of Agriculture, and
Food Western Australia soil acidity series (DAFWA 2012) covering issues such as
lime storage, liming rates and quality and expected and actual yield responses. For
broadacre cropping and high return industries such as horticulture and dairy, liming
can be an effective and profitable management strategy for mitigating surface soil
acidification provided appropriate rates are applied that account for regional and
local (management) factors of soil and plant type and N-fertiliser regimes.
The efficacy of practices to reduce subsoil acidification is less well established and
only demonstrated on a small subset of soil types, but according to Anna Roberts
(pers. comm.) the principles are simple 
rainfall and therefore could be 
extended time frame for change and the high rates required to shift pH in some soils
(of heavier texture) this is a remaining challenge for achieving improvements in soil
pH condition. Once subsoil pH testing is adopted more broadly, the mitigation of
subsoil acidity with more appropriate lime application rates and frequencies can be
implemented in the high-risk agricultural regions.
Relationships between land management practices and soil condition
29 | P a g e
Box 5.1: Managing Soil pH through a systems approach
System goal
To increase soil pH or slow its decline by managing nitrogen in plant systems.
Considerations
1. Reduce NO3 availability by using legumes, NH4 and organic forms of N fertiliser,
and maximising N uptake by crops and pastures.
2. Reduce NO3 leaching by maintaining drier soils and reduced fallow lengths
(perennials and higher crop frequency).
3. Balance anion removal in products by liming, presumably this is forever.
Acidification is a constraint to production and C storage, there is reluctance by
growers to use more lime and lime application for many farmers is driven by rules of
thumb.
These responses are consistent with the soil C responses, provided lime application
can be incorporated.
Recommended practices
Apply lime effectively, use organic and NH4 fertilisers, use more legumes, perennials
and increased crop frequency, test soils regularly where pH<6.
Performance indicators
Trends in soil pH (relevant to support decisions at local to national and international
scales), productivity (relevant locally to nationally), leaching of nitrates to subsoil and
waterways (relevant locally and regionally).
Conflicts
Suitable machinery for applying lime, especially at depth, higher management inputs
required to apply lime at sufficient quantities in some areas and the costs of these
inputs encourage some farmers to increase cropping and grazing pressure to
maintain cash flow.
Relationships between land management practices and soil condition
30 | P a g e
6. Wind erosion
6.1 Nature of the issues
          usually
brought about by wind and/ or water. The extent to which soils are susceptible to
wind erosion depends on a range of factors, including climatic variability, ground
cover, topography, the nature and condition of the soil, and the energy of the wind.
Soil particles behave differently depending on the strength of the wind and how well
the soil surface is protected by ground cover. As wind erosion intensifies, aggregates
can break or abrade, releasing dust into the air (Leys et al. 2010). Land management
can either moderate or accelerate wind erosion rates, largely depending on how it
            
surface, and structures that reduce the force of wind (i.e., windbreaks). Grazing by
stock, native animals (e.g., kangaroos) and feral animals (rabbits, camels, horses,
goats) have major impacts on ground cover and soil physical properties. Such
impacts have been exacerbated by the establishment of watering points that allow
these animals to be active throughout previously dry landscapes in many parts of
Australia (James et al. 1999; Landsberg et al. 2002). The changes in land cover

of wind (and water) erosion (Beadle 1948; Yapp et al. 1992; Edwards and Pimentel
1993; Ludwig and Tongway 1995; Wasson et al. 1996; Campbell 2008; Hairsine et
al. 2008; Leys et al. 2009).
The on-site impacts of wind erosion include soil loss, reduction in soil nutrients and
organic matter (including soil organisms), release of soil carbon to atmosphere,
undesirable changes in soil structure, reduced water infiltration and moisture-holding
capacity, and exposure of unproductive saline and acid subsoils (Morin and Van
Winkel 1996; Belnap and Gillette 1998; Pimentel and Kounang 1998; Lal 2001; Leys
et al. 2009; McAlpine and Wotton 2009). Off-site impacts include negative impacts
on the global climate through positive radiative forcing of dust, physical impacts of
dust storms on buildings and equipment, and health impacts of dust for people (Leys
et al. 2009). The limited data available suggest that the off-site costs of wind erosion
can be many times greater than the on-site costs. Williams and Young (1999)
estimated direct market values for on-site costs of wind ersosion in South Australia
to be $1-6 million per year, compared with an estimated $11-56 million cost per year
for off-site costs (largely associated with human health). The costs borne by Sydney
       torm in 2009, including costs associated with
Relationships between land management practices and soil condition
31 | P a g e
cleaning premises and cars, disruptions to transport and construction, and
absenteeism were estimated to be $330.8 million, while losses of soil fertliser and
carbon to landholders were estimated at $9 million (Tozer 2012). On the other hand,
transport of eroded soil can provide important inputs to nutrient budgets of systems
that can trap dust, such as forests and woodlands (McTainsh and Strong 2007).
Several major initiatives have been put in place to improve Australia’s ability to
monitor wind erosion and to identify priority areas for remedial action (Leys et al.
2010; McTainsh et al. 2012; Smith and Leys 2009). This will be especially important
in the future as climate change is likely to increase the likelihood of soil erosion, due
to increased incidence of droughts and reductions in crop production and ground-
cover (Leys et al. 2009; Soils Research Development and Extension Working Group
2011). Historically, wind erosion has been particularly active in times of drought. In
the 1940s and again in 2002 and 2009 there were heightened concerns due to dust
storms hitting major Australian towns and cities (McTainsh et al. 1990; McTainsh et
al. 2011). Wind erosion appears to have been reduced substantially since the 1940s,
primarily due to better management of vegetation cover on agricultural lands
(Australian State of the Environment Committee 2011), but it is expected that the
incidence of huge dust storms, like those in 2002, will increase in the future (Leys et
al. 2009).
6.2 Land management practices in relation to wind erosion
Approaches to reducing wind erosion address three major aspects (Carter 2006):
Ground cover
Soil looseness
Wind velocity
Ground cover is important as it reduces wind speed at the soil surface and captures
soils particles mobilised by wind. Soil looseness increases when there is too little
vegetation cover, soils are dry, the type of soil contains small particles and/ or the
surface is smooth. Maintaining soil moisture, avoiding trampling of exposed or
susceptible soil by stock and maintaining rough soil surface are all ways to reduce
soil looseness (Findlater et al. 1990; Carter et al. 1993; Moore et al. 2001; Carter
2002; 2006; McTainsh et al. 2011). While the velocity of wind is determined by the
weather, it can be moderated locally by creating windbreaks.
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32 | P a g e
Cropping and mixed farming
Recent surveys of past soil erosion, using measurement of 137Caesium in soils, have
concluded that levels of combined water and wind erosion from cultivated land and
rangelands are relatively similar, and as much as eight times greater than from
uncultivated areas and forests (Loughran et al. 2004; Bui et al. 2010). Regions with
the largest impacts of wind erosion tend to be focused in arid and semi-arid
rangelands of south-western Queensland, western NSW, north-central and north-
eastern South Australia and western Western Australia, posing particular challenges
for grazing enterprises (Leys et al. 2010). The semi-arid agricultural lands of eastern
West Australia also have areas of high and very high wind erosion, compared with
the generally low erosion levels in the non-agricultural lands of western South
Australia, the northern Northern Territory and eastern Western Australia (Leys et al.
2010).
The process of cultivation of soil is a key factor affecting potential for both wind and
water erosion in broadacre cropping (Freebairn 1992a; b; Freebairn and Loch 1993;
Moran 1998; Barson and Lesslie 2004). The effects of cultivation have been likened
to a fire passing through ploughed soil, disrupting the activities of soil organisms,
oxidising organic matter, reducing soil fertility and often leading to soil structural
problems (Australian State of the Environment Committee 2011). Some of these
effects can be offset by addition of fertilisers and organic matter, but structural
problems are much harder to address. The combination of soil type, moisture, tillage
practice, and associated activities like clearing of deep rooted perennials, burning of
crop residues, and running of grazing animals on the land can lead to the sorts of
structural changes that encourage bare soil (Bartley et al. 2006).
The types of land management recommended to reduce wind erosion in cropping
and mixed farming zones (McTainsh et al. 2011) include:
Maintenance of adequate plant residue cover for soil erosion protection
through the adoption of stubble retention systems;
The adoption of minimum/ zero tillage systems that protect against erosion
and maintain or improve soil structure;
Avoidance of cultivation in high erosion risk periods;
Reduction in burning stubbles;
Use of chemical fallowing rather than tillage;
Integrated feral fauna and flora control programs, including biological controls;
Fencing to land class through a developed farm plan;
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33 | P a g e
Retention of boundary tall perennial vegetation;
Avoiding grazing erosion-prone areas by fencing these areas;
Intensive strip grazing/ cropping;
Land reclamation of degraded areas for both production and conservation
uses;
Involvement of agricultural commodity industries in promotion of better land
management practices.
Grazing/ pastoral enterprises
Livestock grazing has been associated with a decline in native perennial cover and
an increase in exotic annual cover, reduced litter cover, reduced soil cryptogam
cover, loss of surface soil microtopography, increased erosion, changes in the
concentrations of soil nutrients, degradation of surface soil structure, and changes in
near ground and soil microclimate (Eldridge 1998; Evans 1998; Yates et al. 2000;
Jansen and Robertson 2001; Landsberg et al. 2002; Sparrow et al. 2003; Dorrough
et al. 2004; Hunt et al. 2007; Department of the Environment 2009).
Recommendations for countering the effects of grazing on soil erosion involve
reducing grazing pressure, keeping animals away from riparian areas, and managing
movements of cattle using watering points (Andrew 1988; James et al. 1999;
Dorrough et al. 2004; Hunt et al. 2007; McTainsh et al. 2011). Rotational grazing and
cell grazing have been shown to be profitable approaches to managing the impact of
grazing on pastures and, therefore, ground cover (McCosker 2000; Southorn and
Cattle 2004a; Crosthwaite et al. 2008). McTainsh et al. (2011) note that pastoral
industries have improved in a variety of ways since the 1940s, including better
control of total grazing pressure (native, feral and domestic stock).
6.3 Evidence of the effectiveness of management practices for
reducing wind erosion
Evidence for the effectiveness of measures to reduce wind erosion come from two
types of studies: experimental studies showing relationships between soil movement,
wind speed and the state of the soil surface; and evidence of reduced incidence of
dust storms as land management practices have improved from the 1940s to the
present.
Numerous studies have been performed in Australia, and in comparable ecosystems
in other parts of the world, to show that increasing ground cover reduces losses of
soil due to both wind and water erosion (Eldridge 1993; Eldridge and Greene 1994;
Relationships between land management practices and soil condition
34 | P a g e
Erskine and Saynor 1996; Scanlan et al. 1996; Carroll et al. 2000; Loch 2000; Yates
et al.        et al. 2004; Heywood 2004;
Greenway 2005; Bartley et al.    et al. 2006; Raya et al. 2006;
Silburn et al. 2011). Increasingly, evidence is being documented from on-ground
initiatives by individual land managers (Jenkins and Alt 2007; Jenkins and Alt 2009).
In semi-arid environments, it has been concluded that ground cover of around 50%
is required to keep wind erosion to a minimum (Findlater et al. 1990; Leys 1992;
Rosewell 1993; Scanlan et al. 1996; Leys 1998; Loch 2000; Leys et al. 2009; Silburn
et al. 2011) (Figure 6.1).
Figure 6.1: Erosion rates in relation to ground cover when four different wind speeds were
applied to lupin residues (Findlater et al. 1990)
The general relationships between ground cover and soil erosion have been known
for over 20 years. The main focus of research and development during the past two
decades has been on how to achieve ground cover cost-effectively. This is
discussed in the following section on water erosion.
The second line of evidence for the effectiveness of better land management
(ultimately resulting in improved ground cover) for reducing wind erosion comes from
comparisons of Dust Storm Indices (DSI) between the 1940s and the present
(McTainsh et al. 2011). DSI provides a measure of the frequency and intensity of
wind erosion activity. McTainsh et al. (2011) showed that mean on-site wind erosion
in the 1940s was almost 6 times higher than in the 2000s, and the mean maximum
DSI for the 1940s was 4 times that of the 2000s. There are also significant regional
differences: wind erosion in the 1940s was much more active in the Mulga, Riverina
and Central Australia than in the SA and WA rangelands, and the decrease in wind
Relationships between land management practices and soil condition
35 | P a g e
erosion between then and the 2000s was much more pronounced in the east and
centre of the continent (McTainsh et al. 2011). Uptake of measures to improve
ground cover was discussed in Section 4 and is also considered in Section 7.
Although there have been high rates of adoption among farmers (D'Emden and
Llewellyn 2006; Llewellyn and D'Emden 2009; Llewellyn et al. 2012), it has not been
complete, and so risks of both wind and water erosion remain high in some areas
(McTainsh et al. 2011).
Box 6.1: Managing wind erosion through a systems approach
System goal
To reduce soil loss from wind erosion.
Considerations
1. Wind speed is reduced by high cover (from soil C actions) and tree windbreaks
(probably down fence-lines for operational efficiency). Maintaining ground cover of at
least 50% will reduce the risk of soil loss through wind erosion.
2. Particle availability is reduced by limiting concentrated stock movements and
tractor operations on very dry surface soils which can generate clay sized particles.
Recommended practices
As for soil C, acidification and water erosion practices.
Performance indicators
Dust monitoring (DEHNSW 2012).
Conflicts
In many cases major changes are needed from traditional practices to ones that
build and maintain high levels of ground cover in all seasons and in wet and dry
years.
Relationships between land management practices and soil condition
36 | P a g e
7. Water erosion
7.1 Nature of the issues
Water erosion of soils occurs when soil particles are detached and carried away by
water flowing across a landscape. In some cases soil loss is uniform (sheet erosion).
In other cases small channels are formed (rill erosion). When the velocity and
volume of water are high enough, and the soil surface is vulnerable, deep channels
can be cut (gully erosion). Tunnel erosion occurs when the subsoil is removed while
the surface soil remains relatively intact, producing tunnels under the soil, which
eventually cause the surface to collapse (Coles and Moore 2001).
Like wind erosion (Section 6), the on-site impacts of water erosion include soil loss,
reduction in soil nutrients and organic matter (including soil organisms), release of
soil carbon to the atmosphere, undesirable changes in soil structure, reduced water
infiltration and moisture-holding capacity, and exposure of unproductive saline and
acid subsoils (Morin and Van Winkel 1996; Belnap and Gillette 1998; Pimentel and
Kounang 1998; Lal 2001; Leys et al. 2009; McAlpine and Wotton 2009). Off-site
impacts include sedimentation of waterways and impacts on quality of surface water
and groundwater (turbidity, nutrient and other chemical loads).
Erosion from hillslopes by water is complex and multifaceted (Figure 7.1). It is
determined by the combined effects of:
the strength of water flow (influenced by the amount and rate of rainfall, the
length and steepness of slopes, the degree to which the energy of raindrops
is dissipated by ground cover, and whether the water encounters obstacles to
its flow)
the predisposition of soil particles to be dislodged (affected by soil type,
ground cover, structural properties of the soil that affect the infiltration rate of

the presence of obstacles to the flow of sediment from a site (e.g., its
roughness and the presence of obstacles such as fallen timber, plant stems or
contour banks created to limit erosion).
Relationships between land management practices and soil condition
37 | P a g e
Figure 7.1: Factors influencing soil erosion by water. Figure was derived from various
publications cited in the text
By far the strongest factor mitigating water erosion is ground cover: typically, 20-30%
cover reduces erosion by 80-90% across a range of soils and land uses (Freebairn
et al. 1986; Freebairn and Wockner 1986; Freebairn 1992b; Littleboy et al. 1992;
Freebairn et al. 1993; Freebairn 2004; Gerik and Freebairn 2004; Silburn et al. 2007;
Freebairn et al. 2009). Ground cover can be grasses, herbs, trees, dead plants with
root systems still intact, dead plant material (especially branches) lying on the
surface, or even stones. The mechanisms by which ground covers prevent erosion
are a combination of physical binding (by roots), slowing of over-land flows (by
plants, fallen timber, litter, and stones as physical barriers) and dissipation of the
energy of raindrops (by foliage) (Freebairn and Wockner 1986; Brandt 1988; Hall
and Calder 1993; Daily et al. 1997; Loch 2000; Phillips et al. 2000; Freebairn et al.
2009; McAlpine and Wotton 2009).
It is estimated that current rates of soil erosion by water across much of Australia
exceed soil formation rates by a factor of at least several hundred and, in some
areas, several thousand (Australian State of the Environment Committee 2011). As a
result, the expected half-life of soils (the time for half the soil to be eroded) in some
upland areas used for agriculture ranges from less than a century to several hundred
years. While the time for total loss of soil is estimated to range from 100-500 or more
years in different parts of Australia, it is expected that crops and other plants will
respond to small changes in depth of topsoil, so that many areas are at risk of critical
decline in productivity in much less than 100 years (Bui et al. 2010). Areas at highest
Relationships between land management practices and soil condition
38 | P a g e
risk include Coastal Queensland, the Wet Tropics, Mitchell Plains grasslands, New
England Tablelands, and Victoria River basin in the NT. The 2011 State of the
Environment     s,
the majority of the landscapes have been eroded (by combined wind and water
erosion) to the extent that plant growth and agricultural yields have been adversely
affected (Australian State of the Environment Committee 2011). In the other 13, it
was concluded that management and monitoring are needed or the system of land
use will be threatened in the long term.
Drought predisposes land systems to erosion by both wind and water because of
reduced soil cover. Major soil erosion accompanied the intense rainfall events and
floods that broke the drought of the late 2000s in southern Queensland (Australian
State of the Environment Committee 2011).
7.2 Land management practices in relation to water erosion
Land uses that affect water erosion do so primarily via their effects on ground cover,
evaporation of soil moisture, soil structure, compaction by heavy equipment or
running of stock, and creation of contours that control water flow (Australian State of
the Environment Committee 2011).
Broadacre cropping
Many of the effects of cultivation on susceptibility to wind erosion (Section 6) also
apply to water erosion. Water erosion associated with cropping was recognised as a
serious issue in the 1930s (Carey et al. 2004). Different studies report sediment
yields from cultivated basins of between 2 and 21 times those from undisturbed
native forests (Neil and Galloway 1989; Neil and Fogarty 1991; Erskine et al. 2002),
although it should be noted that good land management can keep these figures
within the low end of this range (Erskine et al. 2002). Soil conservation structures
(contour banks and grassed waterways) were designed to reduce the slope length
and thus net water erosion. These have been implemented extensively in Australia,
but have not been sufficient to bring soil erosion within acceptable limits (Freebairn
et al. 1993; Freebairn et al. 2009).
Management of water erosion on cropping lands has increasingly focused on
methods of planting and managing crops and controlling weeds that involve little or
no tillage, retention of stubble after harvesting, inclusion of a pasture phase between
crops and minimisation of the effects of machinery by controlled traffic
methodologies (Freebairn et al. 1993; Freebairn 2004; Li et al. 2007; Silburn et al.
2007; Llewellyn and D'Emden 2009; Llewellyn et al. 2012). Creating raised beds for
Relationships between land management practices and soil condition
39 | P a g e
crops in waterlogged areas can create an erosion hazard unless slopes and ground
cover are managed carefully (Hamilton et al. 2005; Wightman et al. 2005)
Over the last 20 years new tillage practices have been developed that maximize
water infiltration and reduce runoff; new row spacing and plant arrangement
schemes have been developed to reduce soil temperatures and soil evaporation
losses. Crop modelling and weather prediction capabilities have been developed to
advise farmers on the opportune time of sowing that ensures adequate supply of
stored soil water in combination with sufficiently high growing season rainfall
probability required to satisfy the crop growth requirements and the farm 
goal (Gerik and Freebairn 2004; Australian State of the Environment Committee
2011; McTainsh et al. 2011). While including a pasture phase between crops is
considered advantageous in managing ground cover, the potential effects of stock
on the soil surface during this phase can potentially pose similar problems to those
faced on dairy farms, especially if soils are wet (see below).
The uptake of minimum tillage approaches has required two major innovations:
equipment capable of planting in stubble; and effective methods for weed control
without disturbing the soil (Freebairn 1992; Freebairn and Loch 1993). The advent of
better ways to manage heavy vehicles (controlled traffic) has also contributed to
reducing runoff-driven erosion (Li et al. 2007).
Horticulture
As a form of cropping, horticulture faces many of the same risks as broadacre
cropping in terms of encouraging soil erosion. The hardening of soils in many
orchards (coalescence) restricts the growth and function of tree roots and infiltration
of water to roots (Cockcroft 2012). Two key management innovations in orchards
have been control of machinery traffic to minimise soil compaction, and
establishment of ground cover plants that both minimise erosion and contribute to
the soil ecosystem (Wells and Chan 1996; Dewhurst and Lindsay 1999; Firth et al.
1999; Zwieten et al. 2001; Reid 2002; McPhee 2009; Loch 2010; Slavich and Cox
2010; HAL 2012a). Increased ground cover is correlated with higher diversity of soil
organisms, which has been found to have beneficial effects on water infiltration (and
therefore reduced run-off erosion) promotes natural pest control (Colloff et al. 2003;
Colloff et al. 2010).
Dairy
Many dairy farms combine the running of dairy cattle with beef cattle, cropping and/
or irrigated pasture production (Ashwood et al. 1993). To maintain high production of
milk, pastures are fertilized. Key challenges for such enterprises include controlling
Relationships between land management practices and soil condition
40 | P a g e
sediment (along with nitrogen and phosphorus) losses into waterways, which can be
exacerbated by compaction and disturbance of soil by the feet of grazing animals
(Nash and Murdoch 1997; Fleming 1998; Fleming and Cox 2001; Fleming et al.
2001; Aarons et al. 2004; Nash et al. 2005; Barlow et al. 2007; Chan 2007).
Irrigation itself has the capacity to increase soil erosion by accelerating mineral
weathering, transporting and leaching soluble and colloidal material, changing soil
structure, and raining the local water table, thereby increasing the risk of salinity
(Heywood 2004; Jenkins and Alt 2007; Jenkins and Alt 2009). Irrigation also has the
capacity to reverse soil preparation measures such as the tillage that precedes
planting.
Grazing
Livestock grazing is the most widespread Australian land use (Section 4). Impacts of
livestock grazing on ground cover were discussed in Section 6. These impacts affect
vulnerability of landscapes to both water and wind erosion. In addition, as discussed
above, grazing during a pasture phase between cropping could increase vulnerability
of soils to water erosion by disrupting soil structure and reducing ground cover.
7.3 Evidence of the effectiveness of management practices for
reducing water erosion
As mentioned in Section 6, there is an extensive literature showing that increasing
ground cover reduces losses of soil due to both wind and water erosion (Eldridge
1993; Eldridge and Greene 1994; Erskine and Saynor 1996; Scanlan et al. 1996;
Carroll et al. 2000; Loch 2000; Yates et al.      
Zuazo et al. 2004; Heywood 2004; Greenway 2005; Bartley et al.
et al. 2006; Raya et al. 2006; Jenkins and Alt 2007; Jenkins and Alt 2009; Silburn et
al. 2011). Box 7.1 gives an example of how ground cover management, climatic
            

Like wind erosion (Section 6) there is a small number of studies that have focussed
on the minimum extent of ground cover needed to avoid soil erosion. While different
combinations of cover-types have different effectiveness, largely depending on the
proportion and pattern of bare ground (Greene et al. 1994; Ludwig et al. 2005), some
broad guidelines about effective cover have been developed. In general, a higher
proportion of cover (70% - Figure 7.2) is recommended to manage water erosion
than for wind erosion (50% - Figure 6.1) (Findlater et al. 1990; Rosewell 1993;
Scanlan et al. 1996; Loch 2000; Silburn et al. 2011). For environments where rainfall
Relationships between land management practices and soil condition
41 | P a g e
is moderate to high, and/ or slopes are steep, 80-100% ground cover is
recommended (Leys 1992; Lang and McDonald 2005). The standard of 70% is being
applied widely by catchment management authorities in northern NSW (Central West
Catchment Management Authority 2008; Namoi Catchment Management Authority
2010).
Box 7.1: The Gascoyne Catchment A Case Study of Water Erosion
Three record flooding events in the Gascoyne Catchment, Western Australia, in the
summer of 201011, resulted in massive plumes of soil spreading into the ocean at
the mouth of the Gascoyne River (Waddell et al. 2012). The amount of soil lost
during one of the flooding events was an estimated 2,250,000 tonnes. Restoration of
damaged land in the Carnarvon area after the three floods required 140,000 tonnes
of topsoil. It was concluded that the poor state of the landscapes in the catchment
resulted in very much higher losses of soil than would have occurred in a catchment
with good ground cover, although the extent of the additional losses could not be
determined. The flooding also resulted in damage to infrastructure in the Carnarvon
horticulture area.
The Ga
protected from erosion by a covering of stones, but other parts have been heavily
grazed and are highly degraded. This results in the rapid transfer of sediments and
large amounts of water into the lower parts of the catchment. Downslope of the
upland areas the landscape is dominated by extensive sheet wash plains. These
areas are sources of browse for stock and have been over-utilized, leading to soil
instability, when water flows from the upland areas, disrupted water flows and
nutrient cycles, and erosion where stock have disrupted the soil surface. As the
catchment goes through dry periods, grazing pressure in this part of the catchment
increases, making erosion risks worse. I     
alluvial plains are stabilised to some extent by buffel grass, but this is susceptible to
fire, the risk of which increases in dry periods. As recovery of these sorts of systems
is slow, the challenge of returning this catchment to a state that is resilient to the
effects of water in the landscapes, and to climate variations in general, is major.
Relationships between land management practices and soil condition
42 | P a g e
Figure 7.2: Generalised relationship (based on several empirical studies) between ground
cover and annual average soil loss from vertisol soils on the Darling Downs, Queensland,
with the influence of ground cover management illustrated (Freebairn and Silburn 2004)
The main focus of research and development during the past two decades has been
on how to achieve appropriate proportions of ground cover cost-effectively. In
grazing systems, removal of stock has been shown to allow recovery of ground
cover, if conditions are favourable for regrowth of pastures, but recovery of full soil
functionality, especially organic matter content, can take years to decades (Braunack
and Walker 1985; Basher and Lynn 1996; Lal 1999; Silver et al. 2000) and the short-
term and longer-term reduction in financial returns can be a disincentive for graziers
(Lilley and Moore 2009). Maintaining a diversity of species, especially native plants
and soil organisms, at landscape scales, is argued to be an important component of
ground cover strategies in grazing systems, as this provides ready sources of
species to re-establish ground cover communities after disturbances such as fires
and drought (McIntyre 2002; Colloff et al. 2010). Restoring and maintaining plant
species diversity and community structure is likely to provide greater resilience of
ground cover to climatic and other shocks. This will probably require strategies that
capture resources, such as water, seeds, nutrients and carbon, increase their
retention on-site, and improve microclimate, in addition to removing stock (Yates et
al. 2000).
Across Australian states, 30-80% of horticultural businesses reported using
alternative or cover crops between main crops or using mulching and/ or matting to
provide ground cover between crops in 2009-10 (Barson et al. 2012c). The
proportion of grazing (beef cattle/ sheep) businesses across Australia monitoring
ground cover levels has increased from 70% in 200708 to 79% in 200910, but the
Relationships between land management practices and soil condition
43 | P a g e
percentage of businesses setting ground cover targets decreased from 40 to 31% in
the same period (Barson et al. 2011). Similar trends were seen for dairy businesses
(Barson et al. 2012a).
Detailed research on reduced-tillage approaches has been conducted across
Australia (Hamblin et al. 1982; Hamblin 1984; Freebairn et al. 1986; Hamblin et al.
1987; White 1990a; Buckerfield 1992; Freebairn 1992; Kingwell et al. 1993; Schmidt
and Belford 1993; Schmidt et al. 1994; Felton et al. 1995; Thomas et al. 2007).
Conservation tillage has been shown to dramatically reduce soil erosion and provide
benefits for production in most areas (Freebairn et al. 1986; Freebairn 1992; Radford
et al. 1993; Thomas et al. 2007). No-tillage and reduced tillage (stubble mulch)
practices with stubble retention have generally resulted in greater fallow efficiency
(gain in soil water during the fallow per unit of rainfall), soil water storage and grain
yield, compared with conventional tillage practices, which incorporated stubble into
the soil, although lower grain protein content has also been reported for some
locations (Freebairn 1992; Radford et al. 1993).
These results are supported by around 20 commercial-scale, development and
extension experiments across a range of crops and environments in the grain
growing areas of Queensland since the 1970s, in which mean grain yield was 9%
greater under no-tillage than with stubble incorporation (Thomas et al. 2007). There
is some evidence that yield responses are likely to be greater where soil water
supply limits yield (Freebairn et al. 1986; Thomas et al. 2007). While it is likely that
these general trends will apply in other places with different soil types and production
systems, the researchers caution against uncritical generalization without further
experimentation (Freebairn et al. 2009).
Case studies in Queensland indicate that these benefits can be turned into
significantly improved profits from no-tillage compared with traditional tillage,
especially when economies of scale can be achieved by applying the same labour
and machinery over large areas, and when controlled traffic management is used
(Wylie 1997; Gaffney and Wilson 2003).
Some limitations of conservation tillage have been identified. The reduced surface
roughness produced by no-till management can lead to enhanced run-off and
sediment movement in areas where maintaining high biomass of plants is difficult, or
where low cover results from crop failure or grazing (Freebairn et al. 2009). In these
cases, some tillage might be required to create surface roughness. Since one role of
tillage is weed and disease control, crop rotation and other approaches to weed
control, such as inversion ploughing every 8-10 years to bury weed-seeds, are
Relationships between land management practices and soil condition
44 | P a g e
especially important in no-till systems (Douglas and Peltzer 2004; Thomas et al.
2007).
As discussed in Sections 4 and 5, the adoption of some form of minimum tillage has
increased over the past two decades.
In southern Australia, key factors that have influenced adoption of minimum tillage
approaches include machinery costs, perceived lack of convincing evidence of
results, and concerns about herbicide resistance and weed control (D'Emden and
Llewellyn 2006; Llewellyn and D'Emden 2009; 2010; Llewellyn et al. 2012). The main
reasons given by adopters for limiting their use of no-tillage approaches include
herbicide resistance, weed control issues, soil physical constraints, pests and soil
disease. Adoption of no-tillage approaches appears to be leveling out at about 90%
of farmers in many regions of Australia (Llewellyn et al. 2012).
Box 7.2: Managing water erosion through a systems approach
System goal
To reduce water erosion by reducing suspended sediment and transported
sediment.
Considerations
1. Maintain ground cover at better than 50% to reduce raindrop impact and
production of suspended sediments. Maintaining good ground cover will also
increase biomass available for soil carbon.
2. Increase infiltration (reduce runoff) with adequate ground cover, manage soil
moisture to avoid excessive decomposition and waterlogging (as for carbon
management), and reduce compaction by using Controlled Traffic (CT) approaches.
3. Where appropriate, manage runoff with designed layouts (controlled traffic
farming, diversion and contour banks) to prevent flow concentration (spread runoff
evenly across the land). Runoff velocity is then unlikely to reach erosive levels in our
landscapes. CT wheel tracks are designed to carry runoff to safe disposal areas
(typically diversion channels).
Recommended practices
Soil C and acidification practices, controlled traffic and designed layouts, ground
cover management.
Relationships between land management practices and soil condition
45 | P a g e
Performance indicators
Water erosion control (especially percentage groundcover, turbidity of off-flows,
water quality) (relevant at local to regional scales), access and timeliness (relevant at
farm scale).
Conflicts
In many cases major changes are needed from traditional practices to ones that
build and maintain high levels of ground cover in all seasons and in wet and dry
years.
Relationships between land management practices and soil condition
46 | P a g e
8. Ecosystem services and resilience of soils
8.1 The concept of ecosystem services
The concept of ecosystem services evolved to bridge the perceived gap between
economics and ecology. To achieve this it has been necessary to consider at some
length how to define and classify ecosystem services so that they not only make
sense to a range of stakeholders, but also can be used unambiguously in economic
valuation and environmental accounting. Because this process has involved multiple

 (Costanza et al. 1997; Daily 1997; de Groot et al.
2002; MA 2005; Wallace 2007; Costanza 2008; Fisher et al. 2009; TEEB 2009;
Dominati et al. 2010; Maynard et al. 2010; UK National Ecosystem Assessment
2011b; Nahlik et al. 2012; Robinson et al. 2012). Typologies of ecosystem services
have remained fluid with the recognition that services must be identified in relation to
those receiving the services, and that this relationship differs with different groups of
people, different places and different purposes for considering ecosystem services
(de Groot et al. 2002; Costanza 2008; Fisher et al. 2009).
As our focus in this report is on the links between land management, soil condition
and benefits to humans, we have adapted four recent approaches for
conceptualising these relationships into the framework shown in Figure 8.1.
Figure 8.1 incorporates several recent conventions designed to reduce inconsistency
of terminology and ensure that the direct and indirect contributions of ecosystems
are not confused in economic evaluations and environmental accounting:
Ecosystem services are defined and described (Table 8.1) in terms of what
possibilities soil ecosystems make available to humans, without the need for
intervention by humans
1
; the benefits to humans are identified separately, and
require actions or the articulation of needs by humans (Boyd and Banzhaf
2007; Fisher et al. 2009; Haines-Young and Potschin 2009).
We have avoided distinguishing between ecosystem processes and functions,
referring only to processes. Ecosystem processes are defined as
transformations of inputs into outputs and ecosystem services are defined as
the flows that arise from these processes and are of benefit to humans
(Dominati et al. 2010).
1
             
ecosystems utilized (actively or passively) to produce human well-et al. 2009)
Relationships between land management practices and soil condition
47 | P a g e
We have distinguished between final ecosystem services (those that can be
turned directly into benefits by humans) and intermediate ecosystem services
(those that support other services but are not used directly for benefit by
humans) (de Groot et al. 2002; Boyd and Banzhaf 2007; Fisher et al. 2009;
TEEB 2009; Bennett et al. 2010; Dominati et al. 2010; Johnston and Russell
2011; UK National Ecosystem Assessment 2011b).
For consistency with other typologies, we have adopted the broad organising

2005; De Groot et al. 2010; Dominati et al. 2010).
Figure 8.1: Conceptual relationship between land management, soil structures and
processes, ecosystem services, benefits to humans and human wellbeing
This diagram draws on several key publications (MA 2005; Haines-Young and Potschin 2009;
Bennett et al. 2010; Dominati et al. 2010)
Although it is potentially confusing to distinguish between final and intermediate
ecosystem services, we agree with advocates of this approach that: (i) being strict
about final services is essential to avoid double counting of benefits in economic
assessments, such as we perform in this report; and (ii) there is a need to recognise
a level of aggregation of processes above that of nutrient, water and carbon cycling
and the like, by which soils support the final services produced by broader
ecosystems.
Relationships between land management practices and soil condition
48 | P a g e
8.2 Relating soil ecosystem processes to services and benefits
The roles of soils in supporting natural and agricultural ecosystems have been
recognised for some time and their importance for providing ecosystem services has
been discussed in various recent syntheses (Daily et al. 1997; Wall and Virginia
2000; Balmford et al. 2002; De Groot et al. 2003; Swinton et al. 2006b; Dale and
Polasky 2007; Kroeger and Casey 2007; Swinton et al. 2007b; Turner and Daily
2007; Weber 2007; Bennett et al. 2010; Robinson et al. 2012). Figure 8.2 and Table
8.1 draw on a number of these syntheses.
Figure 8.2: Interrelationships between living and non-living components of soils, major
processes, ecosystem services, benefits to humans and who the beneficiaries are
The diagram synthesises frameworks by: Palm et al. (2007); Kibblewhite et al. (2008a);
Bennett et al. (2010); Dominati et al. (2010); UK National Ecosystem Assessment (2011a)
Relationships between land management practices and soil condition
49 | P a g e
Figure 8.2 and Table 8.1 illustrate the complex interrelationships between the living
and non-living components of soil, the processes and ecosystem services these
interactions generate and the benefits derived by a range of beneficiaries, and seek
to simplify this compl
services and benefits. This figure also emphasises the underpinning importance of
 -living components), which is the
key to long-term sustainable management of soils, and maintenance of soil
resilience (Lal 1997; Dominati et al. 2010; Sylvain and Wall 2011; Robinson et al.
2012).
Table 8.1: Description of the broad groups of ecosystem services provided by soils*
Ecosystem
services
Description of services and benefits
Provisioning
services
Provision ecosystem services are those that either directly provide products that
people value or can be used to produce things of value.
Products from soils include clean water, bush foods (e.g., witchety grubs,
mushrooms), timber, and chemicals and genetic material that might be developed
as pharmaceuticals or used in genetic and other technologies in the future.
Fertile soil can be used by humans to grow crops. Soil fertility is maintained by a
range of processes, including nutrient cycling (distribution of carbon, nitrogen and
phosphorus throughout soils by a range of soil organisms), gaseous exchange with
the atmosphere (extraction and release of nitrogen and carbon), and the
engineering activities of earthworms, insects, fungi and other species (which
maintains soil structure, porosity and water-holding and infiltration capacities).
By supporting the growth of native forests, woodland and grasslands, soils
contribute to the ecosystem services that native vegetation provides, including the
provision of fodder for stock.
It is often overlooked that the formation of soil by natural processes provides to
foundation for anchoring structures such as houses, other buildings and other
infrastructure.
Provision of
fertile soil,
natural
products and
clean water
Support for
native
vegetation
Maintenance
of genetic
diversity
Support for
structures
Regulating
services
Regulating ecosystem services are so named because they control biophysical
processes in ways that can be beneficial to humans.
The structural properties of soils, determined living and non-living components
below ground and the vegetation component of the soil-plant ecosystem above
groun