Acid Sulphate Soil Treatment, Queensland

ProjectNew South Wales State Government

What is Acid Sulphate Soil?

Acid sulfate soils (ASS) occur naturally over extensive areas of low-lying coastal land, and may be found close to the natural ground surface but may also be buried at depth in the soil profile.

Acid sulfate soils (ASS) are coastal and near-coastal soils, sediments or other materials containing iron sulfides. They are environmentally benign when left undisturbed, but when exposed to oxygen the iron sulfides break down, releasing sulfuric acid and soluble iron. Both substances have considerable ability to degrade the natural and built environment, and the acid may additionally mobilise other pollutants (e.g. aluminium, lead, zinc) if present in the soil.

Parts of central Queensland also contain ASS at sites such as bottom sediments in drains, dams, constructed and natural waterways, swamps and billabongs, periodically stagnant creeks and places with perched watertables.

How is Acid Sulphate Soil Managed?

As stated in the Queensland Acid Sulfate Soil Technical Manual: Soil Management Guidelines, where disturbance of ASS is unavoidable, preferred management strategies include neutralisation.

Neutralisation of ASS involves the thorough mixing of suitable alkaline materials into the soil. The amount of neutralising agent added must be sufficient to neutralise all existing acidity that may be present and all potential acidity that could be generated from complete oxidation of the sulfides over time.

The materials required for neutralisation and the rates at which application is required are determined by soil testing specialists, and upon their recommendation, a number of processing options are available for carrying out neutralisation.

Voight Contracting provide bulk haulage services to transport various neutralising materials to the treatment site. Our fleet of tipper trucks (with dog trailers) are modern, safety-compliant, and well-maintained. In particular, Voight Contracting take extra care to ensure our trucks and the loads of materials being carted are clean, hygienic and loads are free of contaminants. Live GPS monitoring of our trucks ensures we can make deliveries to your project on time.

What is Agriculture Lime (Ag-Lime)?

Agricultural Lime (Ag-Lime) is a neutralising agent used to treat acidic soils. By composition, high quality aglime may be 98% calcium carbonate (CaCO3) and hence has a neutralising value of 98%. Ag-Lime is mildly soluble in pure water, with a pH of ~8.3; application rates will depend on the purity and fineness of the product.

How is Ag-Lime applied to treat soil?

Not only can Voight Contracting deliver Ag-Lime (and other materials, such as Gypsum, Bentonite and Dolomite) to your site, Voight Contracting also specialise in the treatment of Acid Sulphate Soils.

Once Ag-lime has been delivered to your site, specialist contractors are required because of the specialist equipment needed to spread and incorporate these large quantities over (spreading) and through (incorporation) the soil’s surface.

Voight Contracting provide heavy-duty tractors with spreaders (and offset disc ploughs) to spread and incorporate the lime into the soil’s surface. Spreading Ag-lime allows the lime to leach into the soil’s surface more slowly over-time (for example, with subsequent rainfall).

However, as Ag-Lime is relatively insoluble, for maximum benefit, spreading and incorporation of the soil helps to ameliorate and enrich the soil’s sub-surface, assisting the Ag-Lime to dissolve more quickly and improving and neutralising the soil’s condition. All of our tractor operators have many years’ experience in the treatment of soils and undergo training to ensure they work with your site’s safety at the forefront of our on-site operations.

Who do I call to find out more about Supply, Delivery, Spreading and Incorporation of Agricultural Lime?

Need more information on how to treat Acid Sulphate Soils, or the benefits of applying Ag-Lime to your soil? 

Call: Steve Voight, Managing Director at Voight Contracting directly on 0419 009 867, or call the Voight Contracting office on 07 3801 8229 (email