Salinity
What is salinity?
Salinity refers to the presence and concentration of soluble salts in solution, the soil, or other medium. Soil salinity occurs when salt that is normally locked within the soil profile rises to the surface.
Soil salinity is defined as the amount of soluble salts present in the soil, primarily composed of ions such as chlorides, sulphides, carbonates, sodium, potassium, calcium, and magnesium, aluminium, zinc, iron and manganese.
Salinity can be classified into two different types- Dryland and Irrigated
What causes soil salinity?
Soil salinity can come from both natural and human-induced processes:
Natural Processes:
- Weathering of Rocks: Salts can be released from the weathering of parent rocks and minerals over time.
- Evaporation: In arid and semi-arid regions, high evaporation rates can lead to the accumulation of salts at the soil surface as water evaporates, leaving salts behind.
- Saltwater Intrusion: Coastal areas may experience salinity due to the intrusion of seawater into freshwater aquifers.
Human Activities:
- Irrigation: Excessive irrigation can lead to salinization, especially if the irrigation water contains dissolved salts. When water evaporates, the salts remain in the soil.
- Improper Drainage: Poor drainage can cause waterlogged conditions, allowing salts to rise to the surface.
- Use of Salt-Based Fertilizers: Some fertilizers can contribute to increased salinity levels in the soil.
- Clearing of deep-rooted vegetation across the landscape- Removes the deep-rooted perennials that keep the water table and salts at the lower depths cause water tables to rise and evaporate leaving high concentrations of salt at the soils surface.
How does it affect the land and productivity?
In general, high salinity levels can lead to many negative effects on farming land, including:
- Reduced Crop Yields: Salinity can significantly decrease agricultural productivity,
- Degradation of Soil Health: Salinity can destroy soil structure, reduce water infiltration, and increase erosion potential.
- Nutrient Deficiencies: Salt-stressed plants may experience nutrient deficiencies, affecting their growth and health.
How does it affect the natural environment?
Not only does salinity negatively affect farming and production it also has a significant impact on the natural environment.
- Waterways and wetlands can turn from freshwater to saline
- Potentially turning diverse natural environments into saline environments.
State Salinity Strategy Biological survey of the WA wheatbelt- 2004
Dryland Salinity | Heartland Journeys
Studies on distribution and scale of the issue
Salinity was first reported in WA streams of WA prior to 1900, and even then, the connection was made between an increase in salt in waterways and the removal of trees from the landscape (Stream salinity status 2025).
Intensive agricultural practices are generally located within the South-West Land division, spanning approximately 30 million hectares (or 12% of the WA landmass) from Geraldton in the north across to Esperance in the south.
Of this area, approximately 1.75 million hectares has been classified as being salt affected, which affects the productivity and biodiversity of these areas.
Salinity and land management on Western Australian Farms
Mapping salt-affected land in the South-West of Western Australia using satellite remote sensing- 2022
Government response over the years
Salinity came to the forefront of landcare action in the late 1990s and early 2000s. For a number of years State and Federal strategies and programs provided encouragement that government, industry, land managers and the community could work together over the 30 years that followed to make a big difference in combating salinity. Sadly, programs have not continued, and successive governments have provided little guidance on the issue since.
In late 2018 the WA Auditor General conducted a review of management of salinity that slammed the State government for its lack of action on salinity in south-western Australia.
Report Overview
‘Dryland salinity has been developing since large scale clearing began. It is estimated to affect between 1 and 2 million hectares (up to 10% of total land) in the agricultural regions of the South-West, and cost $519 million per annum in lost agricultural production. Salinity also damages infrastructure, adding further costs, impacts on water resources and reduces biodiversity.
Predictions are that, without some level of intervention, the area of land affected by salinity could more than double over the next 50 to 100 years. Intervention on such a scale is a huge task and needs to be balanced against the possible cost, which could also be large.’
Salinity has been developing since large scale clearing in the South-West agricultural regions began and is forecast to continue to expand for another 50 years or more. Estimates are that it affects between 1 and 2 million hectares, potentially rising to 5 million, and costs over half a billion dollars a year in lost agricultural production alone.
The scale of the problem is daunting, but so is the scale of the action that would be needed to eliminate salinity. It would require re-planting 80% of the Wheatbelt, a huge task, requiring significant investment that would make broad scale agriculture, as it currently exists, impossible.
The State Salinity Strategy, which stopped 10 years ago, reflected the fact that salinity is a shared problem. It is not spread evenly through the landscape and managing it often relies on action by landholders whose land is not salt affected.
Recovering the landscape completely would take decades and comes with its own significant impacts. But agencies, landholders and communities can adapt to salinity and mitigate its spread and impact through well informed, well targeted, collaborative local action. For agencies to play an effective role in this, they need good information on the extent and impact of salinity, to understand the best options in tackling it, and they need to build effective partnerships to get things done.
Source: Western Australian Auditor General’s Report, Management of Salinity, Report 8, May 2018.
Other Past Government documentation
Many of the documents that were created in the past have been challenging to find. Here are just a few that might be of interest as to what past commitments have been.
Salinity in Action- March 2000
Salinity Investment Framework - Phase 2- 2006
Salinity Management program- 2006
Current situation
Unfortunately, the Government continues not to provide sufficient funding to landholders to adequately continue to address this growing issue on a broadscale approach. Instead, they are looking to continue monitoring, to ensure that salinity data is accessible to landholders, to promote evidence-based faming, to invest in innovative and science-based salinity mitigation approaches.
Future approaches will include the integration of salinity management into broader landscape restoration and sustainability markets (from a presentation through the- Great Southern Salinity Summit- March 2026)
- Strategic Landscape Restoration- Restoring degraded lands at a landscape scale
- Integrated Environmental and Economic Goals- Aligning environmental repair with economic and social outcomes
- Climate resilience and adaptation- Addressing climate variability impacts
- Creating shared value and Market Alignment- promoting nature positive markets
Landholders have been working to find alternative methods of funding in order to address salinity impacts on their properties by working together to find solutions.
Options for salinity and land management for landholders
Understanding the original cause of the salinity and landuse, will help to determine what the potential treatment and management strategies may be undertaken to ameliorate the salinity issue.
Assessing saline areas in Western Australia | DPIRD
Measuring and assessing soils | DPIRD
In general, agricultural solutions to the management of salinity fall into two separate categories, plants and engineering solutions.
Engineering solutions can include the following
- Deep drains
- Other engineering solutions -siphons, dams, relief wells
- Surface water control- contour banks
Integrated Saltland rehabilitation - Katanning Research Station
Pumping Groundwater- DPRID factsheet
Siphons for Managing Groundwater discharge and salinisation- DPRID factsheet
Relief wells for water resources and managing salinity and water- DPIRD factsheet
Plant based solutions can include the following
- Perennial pastures- lucerne, saltbush, deep rooted plants
- Trees – can be planted for both productive and biodiversity outcomes, such as alley farming, Brushwood, oil mallees, Tagasastes
https://youtu.be/QdPMVGfIjRs?si=PN53IKUkgC6awOA4 - Saltbush seedling system
https://youtu.be/k4__Vh6wryA?si=jrJQpwZngSg16lv1 - A Niche Seeding Saltbush System
Puccinellia for dryland salinity management- DPIRD factsheet
Pasture legumes and grasses for saline land in WA - DPIRD factsheet
Additional resources and case studies
Salinity Manual series — Gillamii Centre
Saltland Genie- An application providing the latest information on profitable saltland solutions for your property.
Case studies on dryland salinity from farmers in Western Australia. | DPIRD
For more factsheets from the DPIRD library check out- https://library.dpird.wa.gov.au/nrm_factsheets
On the 19th March - the Gillamii Centre hosted the Great Southern Salinity Summit. To check out the presentations from this event click here.
For additional salinity case studies click here.
Information on WISALTS
A major player in the fight against salinity, Whittington Interceptor Sustainable Agriculture Land Treatment Society (WISALTS) has recently folded and generously donated their remaining funds to the WA Landcare Network.
Harry Whittington OAM (1921-1999) devoted most of his life developing innovative solutions to the growing salinity problems in the Wheatbelt and South Western Australia. In 1978, a group of farmers were convinced by Harry’s ideas and formed the WISALTS organisation.
WISALTS have ensured their valuable collection of resources is housed in a special collection in the Murdoch University Library – Agriculture, Environment and Health Studies Collections so that researchers, landcarers and the general public can have access to these important documents.
Access the WISALTS Special Collection here https://www.murdoch.edu.au/library/resources/special-collections/agriculture-environmental-health-studies-collections
