This project aimed to reduce the erodibility of high risk landscapes through an increase in the area of land planted to perennial pasture species, which are both more productive and more persistent when not constrained by acidity and aluminium toxicity. To achieve this, the project aimed to increase awareness, knowledge and understanding of soil acidification and management options for topsoil and subsoil acidity.
Traditional blanket-rate lime practices do not address the issue of increasing subsoil acidity, nor target areas where acidity is most severe, and the project explored dual-depth grid soil mapping in combination with variable rate lime application for more effective and longer-term management of soil acidification.
The project aims to increase the area of land planted to perennial pasture species, as well as increase the area of soil limed to at least pH 5.2 in the topsoil (0–10cm). Grass and legume-based pastures limed using tailored rates will be more productive as a result, with pasture legumes and their rhizobia able to supply more fixed nitrogen (N) for the benefit of the mixed sward.
Based on intensive soil sampling, the project aimed to develop property soil nutrient and liming plans that identify the constraints, including soil acidity, that can influence the establishment and maintenance of perennial pasture systems. By ensuring that soil fertility and plant nutrition are understood and managed by the landholder, the focus can be on the prevention of soil erosion and the management of acidification.

• Dual-depth (0–10cm, 10–20cm) grid soil sampling was used to map surface and subsoil pH across 45 properties and 2210ha of farmland in the eastern Riverina area of southern NSW.
• Soil sampling showed an average variation in pH of 0.8–1.0 pH units across a paddock in both the surface and sub-surface layers, with marked differences in soil pH between the two sampling depths.
• Exchangeable aluminium (Al) levels increased rapidly in the soil sample where pH was lower than 4.6, with minimal amounts of exchangeable aluminium detected where soil pH was greater than 4.6.