Soil acidity

Indicator description

Soil acidity is a widespread and generally under-reported environmental problem in the Region, and in much of Australia. Although it is a natural process, soils can become more acidic more quickly under some landuses and land management strategies.

Agricultural landuses, which remove nutrients through crops or livestock, are one of the main ways in which soils are acidified in rural Australia. The result can be loss of agricultural productivity, to the point where some types of agriculture (e.g. cropping) are not possible. This indicates a decline in the health of the land in State of the Environment reporting.

Other activities which can cause soils to acidify include mining, disposal of industrial waste, and exposure of potential acid sulphate soils. Disturbance of potential acid sulphate soils can have adverse effects on biodiversity, and on the condition of marine, estuarine and stream waters. Because of this, it is important to identify and manage potential acid sulphate soils appropriately.

Acidity is reported in terms of pH. Soils of a pH less than 7.0 are considered to be acidic, soils of pH 7.0 are considered neutral, and soils of a pH greater than 7.0 are alkaline. Although different plants require different soil pH levels to thrive, most agricultural crops and pastures will start to suffer if the soil acidity falls below a pH of 5.5.