The national picture
GroundCover™ Issue: 51
The parliamentary inquiry heard evidence that acid soil programs in NSW, WA and SA have brought beneficial changes in land use, with substantial increases in liming.
Cost-benefit analyses of the programs in WA and NSW, which combined research and extension, concluded that they will deliver lasting benefits to farmers. All three programs strongly emphasised liming.
The National Land and Water Audit reports that the largest area of strongly acidic surface soils (pH 4.3 to 4.8) occurs in NSW, with five million to seven million hectares affected.
According to the Australian Soil Resources Information System, the largest areas of land affected by moderately acid topsoils (pH 4.8 to 5.5) are in WA (seven million hectares) and NSW (11 million). But commercial soil testing indicates the figures are actually much higher.
For NSW, estimates of the total cost of soil acidity range from $90 million to $380 million annually. The Acid Soil Action program (1997-2003) was modelled on a successful salinity extension program, "Salt Action". Lime use increased by 25 percent.
In WA, the Integrated Soil Acidity Research, Development and Extension Project (1992-2002) supported a promotional extension campaign, "Time to Lime". During the campaign (1994-2002), annual lime use increased from 150,000 tonnes to more than 800,000 tonnes. The number of farmers using lime rose from 1353 to 3292.
Acid soils in SA affect more than 2.5 million hectares, far exceeding the 325,000ha affected by salinity. But, as in Victoria, salinity and water issues have attracted greater state and federal funding.
The State Government project "Balancing Acidity in South Australian Soils" ran for three years from 1998, to tackle worsening acidity, gaps in farmer knowledge and low levels of lime application. Lime use doubled, but is still below the rate required to maintain the pH of acid-prone soils.
Tasmania and Queensland have no framework or policy for dealing with acidification. In Tasmania, liming has been widely adopted as a regular part of farming. Queensland has more than 500,000ha of agricultural land at risk from soil acidification, but only one catchment has an acid soils strategy.