Acidification of Western Australia’s agricultural soils and their management

Document Type

Conference Proceeding

Publication Date


Conference Title

Australian Society of Agronomy 13th Annual Conference 2006: Groundbreaking Stuff

Place of Publication

Perth, WA


Subsurface acidity; liming; pH; deep ripping; aluminium toxicity


Agricultural Science | Agronomy and Crop Sciences


About one-third or 5.3M ha agricultural soils of Western Australia (WA) are prone to or have subsurface acidity. These soils have acidified since being cleared for agriculture. Susceptible soil types include the deep sands, sandy earths, gravels and duplex soils with low clay and organic carbon content and low pH buffering capacity. Acidic layers often form between 30-40 cm. As the pH (measured in 0.01 mol CaCl2) declines to <4.5 aluminium (Al) solubility increases and becomes toxic to root growth. Surface liming can prevent and correct subsurface acidification but it can take >5 years to raise the soil below 10 cm. Prevention of subsurface acidification by surface liming can give wheat yield responses of 30% after 8 years in one trial at Bindi Bindi. Attempts to more rapidly ameliorate subsurface acidity with direct placement of lime behind deep ripping tines have had mixed success but in one trial at Bodallin subsurface liming increased wheat and barley yields by 30-40% within the first three years. Currently the most practical and efficient management option is to use surface liming to prevent and correct subsurface acidification. The use of crops and varieties tolerant to Al toxicity in soils where the subsoil acidity exists is essential.