Subsoil acidity is a major constraint to crop productivity in the high rainfall zone (500-800 mm) of south-eastern Australia. Soil acidification is accelerated by nitrate leaching under certain crop rotations, by the use of ammonium-based fertilisers, and by the regular removal of plant products, such as grain or hay. The major constraint to plant production on acid soils is aluminium toxicity which inhibits root growth even at very low concentrations.

The aim of this project is to manage subsoil acidity through innovative amelioration methods that will increase profitability and sustainability on farms. Although the surface application of lime is a common practice used to combat soil acidity, lime movement is very slow and takes years to have an effect. This project will investigate more aggressive ways of ameliorating subsoil acidity, such as the deep placement of lime to the subsoil where it is most needed, with or without organic amendments to achieve more rapid changes to pH at depth. Other novel materials, such as calcium nitrate fertiliser, nano-lime and silicate-based materials, either separately or in combination, will be tested in different soils with different crop species in both controlled environments and under field conditions.