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1387.3 - Queensland in Review, 2003  
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 13/05/2004  Ceased
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Contents >> The Queensland Environment >> Salinity in Queensland, 2002

Salinity is increasing across Australia. It is already having a significant impact on the environment, the quality of inland waters, civil infrastructure and agricultural production.

In the ABS 2002 Land Management and Salinity Survey, 1,969,000 hectares (ha) of agricultural land in Australia were identified as showing signs of salinity. Of these, 821,000 ha were so affected as to be unusable for agricultural production.

Although the area of land currently affected by salinity in Queensland is less than in most other states, a report by the State of the Environment Advisory Council in 2002 predicted that the affected area could increase significantly in the next 50 years (footnote 1).

This article analyses the salinity problem in relation to Queensland agriculture, providing comparisons with other Australian states and territories. Links to further information on the topic are provided at the bottom of the article.

WHAT IS SALINITY?
SALINITY IN QUEENSLAND
COMPARISON OF DATA FROM DIFFERENT SURVEYS
FURTHER INFORMATION
DEFINITION OF TERMS

WHAT IS SALINITY?

Salinity is the term used to describe the salt content of soil or water. While soluble salts are often naturally found in water and soil, the concentrations are usually not high enough to produce negative consequences for the environment, for flora and fauna, and for people.

The problem occurs when the levels of underground water-tables rise and these naturally occurring salts remain on the surface in increased amounts after the water evaporates. The resulting concentrations of the salts can then be sufficiently high to be toxic to most plants, which in turn impacts on the rest of the environment.

There are two types of salinity, Dryland salinity and Irrigation salinity (footnote 1).

Salinity is exacerbated by human activity such as agriculture. Contributing factors include excessive land clearance and large scale planting of pasture and crops that use relatively little water. Salinity has also increased as a result of recent land use changes. Some of the causes of salinity originated over 100 years ago and therefore are difficult to repair easily (footnote 2).

SALINITY IN QUEENSLAND

In 2002, Queensland had approximately 107,000 hectares or 0.1% of agricultural land showing signs of salinity, 37.4% of which was unable to be used for agricultural production.

The area of salinity affected land in Queensland, in hectares and as a percentage of all agricultural land, is considerably lower than most other states and territories. However, in 2001 the National Land and Water Resource Audit predicted that, by the year 2050, under current use, the affected area will have increased significantly (footnote 2).
Queensland is a partner with the Australian Government and the other states and territories in the National Action Plan for Salinity and Water Quality (NAP). This plan supports land management actions by regional communities and land-holders in the catchments highly affected by salinity.

Of the 21 priority regions identified by the NAP for the management of salinity, four affect Queensland. These four regions are: Burdekin Fitzroy, Lockyer-Burnett-Mary, Border Rivers, and Condamine-Balonne-Maranoa. The regions of Border Rivers and Condamine-Balonne-Maranoa are also part of New South Wales.


ABS LAND MANAGEMENT AND SALINITY SURVEY, 2002, QUEENSLAND

In 2002, Queensland had 993 farms and 107,000 ha of agricultural land showing signs of salinity representing 3.4% of the state's farms and 0.1% of the state's agricultural land. This included 102,000 ha of non-irrigated farmland and 5,000 ha of irrigated farmland.

These figures compare favourably with those from other states, with only Tasmania and the Northern Territory having less agricultural land showing signs of salinity. As shown in the summary by state below, Queensland had the fifth largest area of agricultural land and the sixth largest percentage of agricultural land showing signs of salinity.

A total of 40,000 ha of land in Queensland was unable to be used as a result of salinity. This represented 37.4% of the land which showed signs of salinity, but only a negligible percentage of the state's total agricultural land (less than 0.01%).


LAND SHOWING SIGNS OF SALINITY - SUMMARY BY STATE(a)

Farms with land showing
signs of salinity
Proportion of total
farms in state(b)
Land showing
signs of salinity
Proportion of total
farm area in state(c)
Salinised land unable to be
used for production

State

no

%

'000 ha

%

'000 ha

NSW/ACT
3,108
7.4
124
0.2
44
Vic.
4,834
13.7
139
1.1
60
Qld
993
3.4
107
0.1
40
SA
3,328
21.6
*350
0.6
105
WA
6,918
51.3
1,241
1.1
567
Tas.
390
9.1
6
0.3
2
NT
8
2.0
2
-
2
Total Australia
19,579
13.9
1,969
0.4
821

(a) The ABS conducted the Land Management and Salinity Survey in May 2002. This collection was targeted at the population of farm establishments which had indicated in the 2001 Agricultural Census that they had land affected by salinity or used salinity management strategies. The survey results are based on a sample of about 20,000 farm establishments and the results were weighted to cover the full population. Care should be taken in the interpretation of the data, particularly for items with high relative standard errors (RSE). For further information on these, refer to: Salinity on Australian Farms, 2002 (cat. no. 4615.0).
(b) Farms with land showing signs of salinity as a proportion of total farms in the state/territory/Australia. Source for the denominator is data from the ABS 2001 Agricultural Census.
(c) Land showing signs of salinity as a proportion of total farm land in the state/territory/Australia. Source for the denominator is data from the ABS 2001 Agricultural Census.

* The relative standard error of this estimate exceeds 25%. Figures should be used with caution.

Source: Salinity on Australian Farms, 2002 (cat. no. 4615.0).


Of Queensland agricultural land that showed signs of salinity, around 62% was in Queensland's four NAP regions (Burdekin Fitzroy, Lockyer-Burnett-Mary, Border Rivers, and Condamine-Balonne-Maranoa). The following table provides specific data on the extent of salinity in the Queensland NAP regions.



LAND SHOWING SIGNS OF SALINITY - FARMS IN QUEENSLAND NAP REGIONS(a)




Irrigated farms


Non-irrigated farms


Farms with land
showing
signs of salinity

Proportion of total
irrigated
farms in region

Land showing
signs of salinity


Farms with land
showing
signs of salinity

Proportion of total
non-irrigated
farms in region

Land showing
signs of salinity


NAP region


no.


%


'000 ha



no.


%


'000 ha



Border Rivers(b)

*13

1.7

na


*137

5.0

na

Burdekin-Fitzroy

*56

4.0

1


*96

3.0

**35

Condamine-Balonne-Maranoa(b)

*13

1.2

*1


*132

2.6

*28

Lockyer-Burnett- Mary

87

3.3

1


168

3.8

*1



(a) The ABS conducted the Land Management and Salinity Survey in May 2002. This collection was targeted at the population of farm establishments which had indicated in the 2001 Agricultural Census that they had land affected by salinity or used salinity management strategies. The survey results are based on a sample of about 20,000 farm establishments and the results were weighted to cover the full population. Care should be taken in the interpretation of the data, particularly for items with high relative standard errors (RSE). For further information on these, refer to: Salinity on Australian Farms, 2002 (cat. no. 4615.0).
(b) Includes part of NSW

* The relative standard error of this estimate exceeds 25%. Figures should be used with caution.
** The relative standard error of this estimate exceeds 50%. This estimate is so unreliable that it is not useful for most purposes.

Source: Salinity on Australian Farms, 2002 (cat. no. 4615.0).



Salinity management

Queensland farmers are using a variety of methods to manage salinity levels.

Queensland farms had 331,000 ha of crops, pastures and fodder plants for salinity management, the fifth largest area of all Australian states. A total of 126,000 ha of trees has been planted in Queensland for salinity management or prevention of salinity, more than any other state and territory except Western Australia. A total of 27,000 ha of land was fenced for salinity management or prevention of salinity.

Queensland had 15,000 km of earthworks (levees/banks and drains) constructed for salinity management or prevention of salinity.


SALINITY MANAGEMENT STRATEGIES BY STATE(a)(b)

Crops, pastures
and fodder plants
Trees
Land fenced
from grazing
Earthworks

State

'000 ha

'000 ha

'000 ha

'000 km

NSW/ACT
1,096
91
17
43
Vic.
*680
40
40
37
Qld
331
126
*27
15
SA
452
14
29
*13
WA
633
500
352
98
Tas.
*7
5
1
*3
NT
*6
-
-
-
Total Australia
3,205
776
466
208

(a) The ABS conducted the Land Management and Salinity Survey in May 2002. This collection was targeted at the population of farm establishments which had indicated in the 2001 Agricultural Census that they had land affected by salinity or used salinity management strategies. The survey results are based on a sample of about 20,000 farm establishments and the results were weighted to cover the full population. Care should be taken in the interpretation of the data, particularly for items with high relative standard errors (RSE). For further information on these, refer to: Salinity on Australian Farms, 2002 (cat. no. 4615.0).
(b) Any land management practice undertaken wholly or partly for the management or prevention of salinity


* The relative standard error of this estimate exceeds 25%. Figures should be used with caution.

Source: Salinity on Australian Farms, 2002 (cat. no. 4615.0).


Potential growth of the salinity problem in Queensland

While the Queensland salinity problem appears small compared with some other states, it is expected to worsen greatly if the factors that cause salinity are not addressed. The NLWRA has estimated that dryland salinity will affect 3 million hectares of land by 2050 (footnote 2).


COMPARISON OF THE ABS SURVEY WITH OTHER SALINITY SURVEYS

Due to the different scopes, concepts and methodologies of the various studies on salinity, it is very difficult to compare results in a meaningful way. The table below shows the figures from the ABS Land Management and Salinity Survey, the Prime Minister's Science, Engineering and Innovation Council Survey (PMSEIC), and the National Land and Water Resources Audit (NLWRA).

In the ABS Land Management and Salinity Survey, farmers identified the affected land and reported on both dryland and irrigated salinity. The Prime Minister's Science, Engineering and Innovation Council based its estimates on expert assessments of the area affected by salinity and included non-agricultural land. The National Land and Water Resources Audit estimated the risk of land becoming affected by salinity using information on water table height. The area at risk of salinity is not equivalent to the area showing signs of salinity, but the two are correlated.

Although the magnitudes of the figures differ vastly, trends are similar. In all three studies, Western Australia is the state most affected by salinity and Northern Territory, the Australian Capital Territory and Tasmania are the least affected. See below for links to organisations that have conducted salinity research.


AREA AFFECTED BY SALINITY, COMPARISON OF SURVEY RESULTS WITH OTHER ESTIMATES

PMSEIC 1999
NLWRA 2001
ABS 2002

Area of salinity
affected land (a)

Area at risk
of salinity (b)

Area showing signs
of salinity(c)

State

'000 ha

'000 ha

'000 ha

NSW/ACT
120
181
124
Vic.
120
670
139
Qld
10
na
106
SA
402
390
*350
WA
1,802
4,363
1,241
Tas.
20
54
6
NT
-
-
2
Total Australia
2,476
5,658
1,969

(a) As determined by experts.
(b) As estimated from water table heights.
(c) As reported by farmers.

* The relative standard error of this estimate exceeds 25%. Figures should be used with caution.

Note: The ABS conducted the Land Management and Salinity Survey in May 2002. This collection was targeted at the population of farm establishments which had indicated in the 2001 Agricultural Census that they had land affected by salinity or used salinity management strategies. The survey results are based on a sample of about 20,000 farm establishments and the results were weighted to cover the full population. Care should be taken in the interpretation of the data, particularly for items with high relative standard errors (RSE). For further information on these, refer to: Salinity on Australian Farms, 2002 (cat. no. 4615.0).

Source: Salinity on Australian Farms, 2002 (cat. no. 4615.0).



DEFINITIONS OF TERMS

Water table

Water not used by plants or lost by evaporation and drainage seeps through the soil until it reaches a dense rock or clay layer. The soil above then fills up with water. The water table is the top of the saturated soil (footnote 3).

Dryland salinity

Dryland salinity is caused when the rising water-table brings natural salts in the soil to the surface. The salt remains in the soil and becomes progressively concentrated as the water evaporates or is used by plants. One of the main causes for rising water-tables is the removal of deep rooted plants, perennial trees, shrubs and grasses and their replacement by annual crops and pastures that do not use as much water (footnote 1).

Irrigation salinity

Irrigation salinity occurs when irrigation water soaks through the soil area where the plant roots grow, adding to the existing water. The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries and the underground water-table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated (footnote 1).


FOOTNOTES
(footnote 1)
1. National Action Plan for Salinity and Water Quality http://www.napswq.gov.au
(footnote 2)
2. NLWRA (National Land and Water Resource Audit) 2001, Australian Dryland Salinity Assessment 2000, NLWRA, Canberra. The NLWRA's salinity projections are based on a range of assumptions and data including an assumption of a continued rate of increase and no change to water balances.
(footnote 3)
3. New South Wales Government Department of Infrastructure, Planning and Natural Resources. Access information on salinity in NSW from www.dipnr.nsw.gov.au then follow the links >>go to information on natural resource management> Catchment/Salinity > Salinity in NSW.


FURTHER INFORMATION

ABS Sources

Information from the ABS Salinity on Australian Farms, 2002 (cat. no. 4615.0), can be accessed in: the media release for the publication; and main features of the salinity survey.

General information about salinity can be found in the following ABS Yearbook Australia articles: Feature Article: Environmental Impacts of Agriculture ; Australia's Land Resources: an Overview.

See the following for more general environment articles which include salinity:


A good source of free ABS information on the environment and a huge range of other information is the on the ABS web site. This provides summaries of data from many ABS publications. To view main features of environment publications select 46. Environment and then the article of interest.

For the latest news on ABS Environmental Statistics see the 6 January 2003 issue of the ABS Environmental Statistics Newsletter.

Non-ABS Sources

Natural Resources and Mines
Waterwatch Queensland.
National Action Plan for Salinity and Water Quality
Australia's National Dryland Salinity Program
National Land and Water Resources Audit
Prime Minister's Science Engineering and Innovation Council


Link to the Queensland in Review contents page


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