Acid Sulphate Soils

What Are Acid Sulphate Soils?
Acid sulphate soils (ASS) are the common name given to soils containing iron sulfides. Acid sulfate soils were naturally formed within the past 10,000 years after the last major sea level rise when sulfate in sea water mixed with land sediments to produce iron sulfides in the waterlogged sediments. In the undisturbed stateacid sulfate soils do not cause harm as the water in the soil prevents oxygen from reacting with the iron sulfides. However, when exposed to air by excavation or the lowering of the watertable they may form sulphuric acid. The acid can move through the soil, acidifying surface waters and reducing agricultural productivity.

Sunshine Sugar is aware of the link between a healthy environment and agricultural productivity. As such, we are committed to protecting and improving the soil and water quality on farms and to protect the surrounding ecosystems for current and future generations by minimising the production and outflow of sulphuric acid from the acid sulphate soils that occur beneath much of our cane land.

How Does NSW Sugar Manage Acid Sulphate Soils?
The NSW sugar industry’s objective is to ensure that the activities of its members do not contribute to or exacerbate acid sulphate runoff. To this end, the member farmers have adopted current Best Practice Guidelines for Acid Sulphate Soils (May 2000), which establishes farming methods to prevent acid runoff.

All grower members of the New South Wales Sugar Milling Co-operative Ltd (NSWSMC), of which there are over 600, are signatories to a Memorandum of Agreement that individually confirms this commitment to the Best Practice Guidelines for Acid Sulphate Soils. The Co-operative will refuse to accept or pay for cane from land where the Co-operative concludes that the landholder continues to refuse to comply with established best practice.

The scheme includes the assessment of all cane farms in NSW for the real or potential risk of acid sulphate soils and the development and instigation of acid sulphate management plans on all cane farms in NSW. An Agricultural Officer from the NSWSMC or BSES Limited (Bureau of Sugar Experiment Stations) develops the plans in conjunction with the land manager.

The key management strategies include avoiding acid sulphate soils by building shallower drains or constructing drains away from affected areas or neutralising the acid content by applying lime to drain spoil or exposed sides of drains that may constitute a hazard.

The project is self-regulated and a Memorandum of Understanding (MOU) between the NSW Department of Natural Resources and NSWSMC sets out procedures and obligations of self-regulation.

A Transparent and Independently Audited System
Under the terms of the MOU, an independent audit and compliance process is specified and an assessment of acid management practices by NSWSMC members is undertaken annually. The audit teams consist of representatives from the following:

• NSW Department of Primary Industries
• NSW Department of Natural Resources
• BSES
• NSW local council staff (6 local council areas)
• New South Wales Sugar Milling Cooperative

Recognition
The NSW Sugar Industry was awarded the RiverCare 2000 Gold Award in 1998 for their project "Reducing the Outflow of Acid Sulphate Soils in NSW Canelands". These awards recognise the highest standards of work carried out by community, education and business groups to improve water quality and river restoration.

The NSW acid sulphate project won the industry/primary category in the NSW state-wide competition. The award recognised the sugar industry’s efforts in managing these naturally occurring soils to reduce the outflow of acid and to improve the quality of the rivers.

Receipt of this award was widely publicised in the media on the north coast of NSW and raised the awareness of the community and other industry to the work undertaken in the canelands of NSW. This awareness is a key component of the industry's acid reduction strategy.

Further information about acid sulphate soils, including copies of the guidelines may be obtained by contacting Sunshine Sugar.

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