Environment

Soils

Land and soil capability classification is a major tool to assess the sustainability of land management practices in New South Wales.

Land capability is the inherent physical capacity of the land to sustain a range of long term land uses and management practices without degradation to soil, land, air or water resources. The management of land within its capability is vital for sustainable use of soil and land resources.

The Land and Soil Capability (LSC) map includes specific assessment of a number of land and soil limitations that have a large impact on land management and land degradation. The LSC system defines land and soil capability classes based upon both on-site and off-site limitations of the land. It assesses the impact of land use and land management practices and specifies the general level of inputs, expertise and investment required for sustainable management without causing land degradation.

Within each class there are limitations caused by differences in climate, soil type, existing erosion, slope, landform position, acidity, salinity, drainage, rockiness and a range of other physical factors. Each limitation has to be managed to avoid land degradation and to make full use of the potential of the land.

The higher the LSC class number, the greater the limitations on land use. Higher classes require higher levels of input, expertise and investment to manage the land sustainably. For example, in marginal cropping land (Class 4), if the potential for erosion by water is not managed, significant erosion will degrade the soil on-site and can also lead to problems of sedimentation and water turbidity off-site. However, on such land, water erosion can be controlled by readily available and widely accepted land management practices. The costs, technology and management practices to overcome limitations also need to be considered. In theory, it is possible to overcome most limitations with sufficient investment and technology inputs, but most often this is not economically viable.

The LSC map is used to assess the sustainability of land management practices. High impact practices can lead to long term decline in agricultural productivity, damage infrastructure such as buildings and roads, and reduce the health of natural ecosystems. Management practices that may harm the land include:

• over-cultivation – exposes the soil to erosion, reduces levels of soil organic matter and nutrients and can cause soil structure decline.

• over-grazing – reduces ground cover, exposes the soil to erosion, and can change pasture species composition to less palatable species and reduce soil organic matter.

• burning stubble – exposes the soil to wind and water erosion and reduces soil organic matter.

• soil compaction from machinery and stock – compacted layers restrict root growth and water infiltration and can increase greenhouse gas emissions, especially nitrous oxide.

• Clearing trees and perennial pasture – changes the hydrology of the landscape and can activate salinisation processes resulting in increased salinity levels or salt loads in streams. It can also cause waterlogging and increased erosion, especially gully erosion, in sensitive areas.

• removing organic matter and soil nutrients via agricultural and forestry products – means long term decline in the nutrient content and physical condition of soils.

• clearing of native vegetation from environmentally sensitive areas such as sand hills and stream banks can destabilise these areas making them susceptible to severe erosion and degradation.

The LSC map is based on the best available soils maps for NSW. The map classes were determined by a number of climatic, geomorphic and environmental factors. An area of land is assigned a class based on its unique features using the criteria shown in the LSC class table.

It is important to note that acid sulfate soils are not considered in this particular assessment. The LSC map shows the highest or the most limiting class for each map unit.

Department of Environment, Climate Change and Water