Treatment of Acid Sulphate Soils
Acid sulphate soil (ASS) is the common name given to soils and sediments containing iron sulfides, the most common being pyrite. When exposed to air due to drainage or disturbance, these soils produce sulphuric acid from reacting with oxygen, often releasing toxic quantities of heavy metals to the wider environment.
Excavation of potential acid sulphate soils (PASS) can lead to the creation of actual acid sulphate soils (AASS). To reduce the possibility of potential acid sulphate soils becoming actual acid sulphate soils, there are four main management techniques used to minimise this possibility and its effects:
– Minimising disturbance
– Neutralisation
– Reclaiming land
– Water cover
In many cases minimising disturbance is not possible especially in relation to construction projects. Reclaiming land and water cover are based on removing the possibility of oxygen coming into contact with the sulphate within the soil, but in many circumstances is not possible. Therefore neutralisation is the only management technique available in many situations where acid sulphate soil is present.
The way in which acid sulphate soil is neutralised is relatively simple in that a highly basic material, such as lime, is mixed with the acid sulphate soil. The amount of lime required to be mixed with the acid sulphate soil is determined by analysing a sample of soil to calculate actual acidity and relating the amount of lime required to be added to effectively neutralise the soil.
In many cases of acid sulphate soil treatment, agricultural lime (Ag lime) is used to neutralise the soil. However, there are other reagents available, which are effective such as hydrated lime, mixtures of hydrated lime and Ag lime, and also lime slurries, which can be added as a liquid.
Pacific Fertiliser can supply and deliver bulk or bagged lime products and other products such as hydrated lime to address your acid sulphate soil issues in NSW, QLD and VIC. We also have equipment and staff to spread, incorporate and mix materials into the treatment areas.
We can work in accordance with your ASS Management Plan (generally provided to you by soil analysis contractor such as SESL etc) and ensure that the correct addition rates of lime (or other product) with homogenous mixing into the soil at correct depths, to provide the best result on your project.
