Australian Natural Resources Atlas

The ASC represents the current method of classifying and describing soils in Australia. It is a general-purpose system that was devised to replace the older national systems.

The ASC is described in detail in Isbell (1996). It has been in common use only since 1996. Most agencies are working towards incorporating it into their descriptions. Because it is of relatively recent origin, only 45,000 of 164,000 soil profiles compiled in ASRIS have been classified using ASC.

The ASC can be used at various levels of detail. It has multiple-categories, similar to the Order, Family, Genus and Species used in botany. These categories are defined on the basis of horizons and their arrangement in an exposed soil profile. Classes are based on real soil bodies and are mutually exclusive. The allocation of 'new' or 'unknown' individuals to the classes is by means of a key.

The Factual Key (Northcote 1979) was the most widely used soil classification scheme prior to the ASC. It dates from 1960 and was essentially based on a set of about 500 profiles largely from south-eastern Australia. It is an hierarchical scheme with 5 levels, the most detailed of which is the principal profile form (PPF). Most of the keying attributes are physical soil characteristics, and can be determined in the field.

The major divisions within the Factual Key are:

The amount of existing data classified using the Factual Key means that it is still an important standard for soil description. Almost 69,000 of the soil profiles in ASRIS have been allocated to a PPF, compared to 45,000 classified using the ASC. The Northcote Factual Key formed the basis for characterising soils in the Atlas of Australian Soils.

There is no simple translation between ASC and the Factual Key, since the two are fundamentally different in the way they classify soils.

McKenzie et al (2000) have compiled tables that provide estimates of typical ranges for soil physical and nutrient properties associated with each PPF, based on 7000 soil profiles held within CSIRO's soil database. These tables have been an important input in preparing the maps of soil properties presented in ASRIS.

The map below shows the soils of Australia classified using Principal Profile Forms of the Northcote Factual Key.

Soil classification used in the Australian Soil Resources Information System

The table below shows the number of soil profiles in the Australian Soil Resources Information System (ASRIS) point database classified using the major soil classification schemes.

Maps compiled in ASRIS included descriptions using many different soil classification systems. For each state, the best available data were compiled which provided a consistent classification scheme and related tables of soil properties. These were:

• for WA, mapping based on WA Soil Groups
• for SA, mapping based on SA Soil Groups
• for the eastern states and the Northern Territory, maps based on Principal Profile Forms (PPFs) of the Northcote Factual Key, and interpretative tables of soil properties for PPFs (McKenzie et al 2000).
• where other data were not available, the Atlas of Australian Soils (based on Northcote PPFs).