Indicators of Catchment Condition in the Intensive Land Use Zone of Australia – Soil acidification hazard

\n\nIt should be noted that this data is now somwhat dated!\n\nAustralia has naturally and widely occurring acid soils, but the extent has\nbeen increased by agricultural practices since European settlement,\nprincipally through the export of calcium in agricultural products, the use of\nacid-producing fertilisers, the widespread use of legumes, the leaching of\nsoluble anions (particularly nitrates) below the root zone of annual crops and\npastures, and insufficient use of lime to replace lost calcium (SoE, 1998).\n\nAcidification impacts on biophysical condition by producing soils that are\nsuitable only for a narrow range of plants and few crops (which typically\nprefer a soil pH of 5.5 a 7.0) and limits crop productivity and agricultural\nflexibility.\n\nDrainage waters have a lower base status and are likely to have low biotic\nrichness.\n\nThe Digital Atlas of Australian Soils (1:2M) has been assessed in terms of\nacid buffering capacity.\n\nThe NLWR land-use map (1:1M) has been used to determine areas of intensive\nagriculture.\n\nIntensive agriculture is defined as cropping and improved pasture practices,\nas these land-uses tend to involve significant fertiliser use.\n\nWhere these land-use practices coincide with areas with an inherently low acid\nbuffering capacity (i.e. most vulnerable to acidification), a soil\nacidification risk is defined.\n\nThe methodology is sound, but data reliability is low.\n\nThe indicator assumes that naturally acidic soils are at risk of greater\nacidity through intensive land-use activities.\n\nThis indicator cannot be interpreted unequivocally because land management\npractices are ignored.\n\nThe indicator has not been validated against the assessment question.\n\nThe main areas of acidification hazard are in the temperate and Mediterranean\nclimate zones of southern Australia.\n\nThe affected areas include most of the ILZ in Western Australia (Albany Coast,\nFrankland, Donnelly, Blackwood, Busselton, Collie, Murray, Avon, Greenough,\nMurchison basins) and Victoria (Campaspe, Loddon, Portland), southeastern\ncatchments in South Australia (Glenelg, Fleurieu Peninsula, Myponga and\nWakefield).\n\nThe tablelands and western slopes of New South Wales show areas of higher\nacidity hazard in the finer scale assessments.\n\nTasmania, Queensland and the Northern Territory are rated in the better\ncategories.\n\nData are available as:\n\n * continental maps at 5km (0.05 deg) cell resolution for the ILZ;\n * spatial averages over CRES defined catchments (CRES, 2000) in the ILZ;\n * spatial averages over the AWRC river basins in the ILZ.\n\nSee [further metadata](http://data.daff.gov.au/anrdl/metadata_files/pa_iccilr9ab\n__07721axx.xml) for more detail.\n\n