Acid sulfate soils (ASS)
What are acid sulfate soils
Acid sulfate soils are naturally occurring soils which form in waterlogged areas, in the presence of iron, sulfide and organic material. Acid sulfate soils are harmless when covered with water. If exposed to air, through excavation or drainage, they react with oxygen to form sulfuric acid in the soil matrix. This acid, and the associated metals which are released, can be toxic to the marine and freshwater plants and animals, contaminate water supplies and corrode concrete and steel.
Where are they found?
Acid sulfate soils are found in both coastal and inland freshwater areas. In South Australia, such soils have been noted in several locations, including Barker Inlet, several wetlands along the River Murray and Lower Lakes. CSIRO has led the development of an Atlas of Australian Acid Sulfate Soils to identify the extent and severity in coastal, River Murray and other inland environments around Australia.
- Understand what is happening on your farm. Undertake visual observations and test the pH levels in your drainage water and soil.
- Ensure drainage channels, reuse drains and pumps are operating efficiently to keep the acidic groundwater table below the root zone (>0.5 m below ground level) where practical.
- Try to maximise irrigation efficiency on your farm to minimise acid drainage volumes. Provided drainage is adequate, efficient irrigation should be beneficial as this will provide acid-neutralising/alkalinity, leach acid down out of the root zone, and re-establish saturated conditions in the soil.
- Ensure that livestock are kept away from areas containing acidic water. If animals come into contact with acidic water, rinse them off. If they fall ill, call for veterinary advice.
- Where practical, keep acidic water away from metal and masonry infrastructure.
More information on acid drainage water can be found on the Murray–Darling Basin NRM website.
- DEWNR CLLMM Program
- National guidance for the management of acid sulfate soils in inland aquatic ecosystems
- River Murray data
- South Australian Murray–Darling Basin Natural Resources Management Board
- Behaviour and potential impacts of acid drainage plumes being discharged to the Lower Murray
- Ecotoxicological assessment of acid drainage plumes from the LMRIA being discharged to the Lower Murray River
- Guidelines for the Lower Murray Reclaimed Irrigation Area (LMRIA)
- Information Sheet: Lower Murray Reclaimed Irrigation Area technical reports
- Lower Murray Reclaimed Irrigation Area (LMRIA) Acidification Project: A biogeochemical model for assessing and managing acid sulfate soils in the Lower Murray region of South Australia
- Lower Murray Reclaimed Irrigation Area (LMRIA) Acidification Project: Final monitoring report 2013
- Lower Murray Reclaimed Irrigation Area (LMRIA) Acidification Project: Modelling of acid drainage discharges to the Lower River Murray
- Lower Murray Reclaimed Irrigation Area acidification project: Scoping and trialling management options
- Lower Murray Reclaimed Irrigation Area (LMRIA) Acid Drainage Project: Final summary report 2013
- Measurement of sediment acidity fluxes to Boggy and Hunters Creeks
- Acid sulfate soil assessment in Finniss River, Currency Creek, Black Swamp and Goolwa Channel
- Management of acid sulfate soils in the Lower Murray Lakes
- Preliminary assessment of acid sulfate soil materials in Currency Creek, Finniss River, Tookayerta Creek and Black Swamp region
- Management options for acid sulfate soils in the Lower Murray Lakes: preliminary assessment of treatment options
- Acid sulfate soils in subaqueous, waterlogged and drained soil environments of nine wetlands below Blanchetown (Lock 1): properties, distribution, genesis, risks and management
- Acid, metal and nutrient mobilisation following rewetting of acid sulfate soils in Lower Murray
- Community monitoring of acid sulfate soils in the Lower Lakes, South Australia: 4 surveys between August 2009 and June 2010
- Monitoring and assessment of reflooded acid sulfate soil materials in Currency Creek and Finniss River Region, South Australia
- Acid sulfate soils in the Murray–Darling Basin (May 2011)
- ASSAY–Acid sulfate soils newsletter