Assessing land use potential
The potential of our land and soils to support particular uses has shaped the nature and development of our landscapes, industries, population growth and urban areas. Land use potential information supports policy development, planning and on-ground decision making, and should be consulted when new uses of land are being considered.
Most land in South Australia is affected by soil conditions, topographic features or climatic conditions which limit land use options and productive potential. The State Land and Soil Information Framework datasets are used to show the location, extent and severity of important soil and land limitations, for example:
- high levels of susceptibility to erosion
- strong levels of acidity
- high levels of salinity
- high susceptibility to waterlogging
- low plant-available water holding capacity
- natural physical or chemical barriers to root growth (also known as impeding layers or subsoil constraints)
- low inherent fertility
- steeply sloping land
- excessive surface rockiness
- impeding layers that restrict irrigation drainage.
Land with a high potential for a large variety of uses requires many factors to be acting in harmony. However, a single factor such as a limitation pertaining to a particular soil or land attribute (as per the examples given above), can represent a key constraint to potential uses of land. To help understand this, the analogy is commonly made to an upright wine barrel, where storage capacity represents land use potential, and the sides (staves) of the barrel represent each (potentially) limiting factor. If one stave is shorter than the others, this limits storage capacity. By analogy, the most limiting factor (eg adverse soil or land condition) will limit land use potential.
The DEWNR Soil and Land Program has developed modelling methodologies that use available soil and land attribute spatial datasets to assess the potential of land for specific uses. Other spatial datasets such as rainfall can also be incorporated within such models (in which case the term ‘land use suitability’ is used). These are predominantly ‘most limiting factor’ models, where land and soil conditions are matched against conceptual criteria such as the landscape and soil conditions favoured by a particular plant species, and particular limiting conditions (eg high salinity levels) dictate the final land use potential category.
Five categories are used to highlight levels of potential or suitability, from low to high (as per FAO 1976). These are provided as mapping or data outputs.
The DEWNR Soil and Land Program has developed a range of land use potential models (listed below), which have been funded on a project-by-project basis. All models and their outputs are considered preliminary as they are yet to be extensively ground-truthed.
Food and Agriculture Organization of the United Nations, 1976, A framework for land evaluation, Food and Agriculture Organisation of the United Nations, Rome, FAO Soil Bulletin 32
Preliminary ‘land use potential’ models
- faba beans
- field peas
- durum wheat
- maize, millet and sorghum (irrigated).
Perennial horticultural crops
- grape vines
- grape vines (mechanically harvested)
- ‘Terra Rossa’ soil identification (for wine grapes)
Annual horticultural crops
- dryland lucerne
- dryland lucerne (acid soil tolerant varieties)
- irrigated lucerne
- dryland phalaris
- irrigated perennial ryegrass (high value)
- dryland perennial ryegrass
- dryland strawberry clover
- irrigated subterranean clover
- summer fodder
- irrigated white clover
- dryland grazing.
Alternative crops, fodder species and native plants
- Atriplex nummularia (old man saltbush)
- Eremophila glabra (emu bush)
- Rhagodia parabolica (fragrant saltbush)
- Rhagodia preissii (mallee saltbush)
- Tasmanian blue gum
- radiata pine.
Non-standard soil and land attributes and other models
The soil and land attribute datasets have previously been used to support a range of projects to inform management, policy decisions, land use or infrastructure development. These have been designed to meet individual customer needs, such as identifying high-value primary production areas, arable land, suitability for farm dams, risk of soil structure decline due to irrigation, potential soil biological activity levels, corrosion potential to infrastructure, and assessing risk to infrastructure due to soil reactivity potential (shrink-swell characteristics).