Victoria’s land and soil

Victoria’s land is used for a variety of purposes. Although land used for urban and irrigated agriculture activities each account for only 5% of the total land area of Victoria, their impacts on Victoria’s environment are significant. This is because of the degree of land change they require and the resources they consume.

Victoria’s soils are subject to various pressures, including clearing, cropping, grazing and fire.

Good soil health is vital for Victoria’s agriculture, native ecosystems and ecosystem services.

Healthy soils support essential ecosystem services, such as the production of food, fibre, timber and clean water, as well as the decomposition and detoxification of wastes.

Soil acidification impacts include a reduction in plant growth and productivity, decreased availability of nutrients, reduction in soil biological activity, loss of vegetation, and increased risks of soil structure decline and erosion. 

Salinity refers to the presence of salt in soils as a result of raised water tables. While Victoria has large naturally occurring saline areas, most salinity has been caused by, or exacerbated by, the clearing of native vegetation (dryland salinity) and excess irrigation (irrigation salinity).

The most recent monitoring results were included in the 2013 State of the Environment report, and are set out below.

Land use

  • The area of parks and reserves, irrigated agriculture and urban land have all increased since 2007, with decreases in state forest and dryland agriculture.
  • Victoria’s public land is mainly divided between parks and reserves (18% of Victoria’s total area) and state forests (14% of Victoria’s total area), which account for 90% of Victoria’s public land.
  • Agriculture accounts for 56% of Victoria’s total area, making it the dominant land-use type in the state.
  • The area of parks and reserves has increased with a corresponding decrease in the area of state forest due to the transfer of state forest into the reserve system.
  • Irrigated agriculture has increased with a corresponding decrease in dryland agriculture. This is likely driven by water trading which is producing significant land-use change in irrigation areas.
  • Urban areas have increased with population growth driving urban expansion in Melbourne and regional centres, as well as in coastal areas.

Area affected by salinity

  • Around 247,000 hectares are affected by dryland salinity, 2% of the total area of dryland agriculture in the state. Regions most affected include Victoria’s north (particularly the Mallee) and west, and near Sale in the state’s east.

Estimate of area affected by dryland salinity (data from 1976-2011)

Source: DEPI


 

  • The spread of dryland salinity in Victoria slowed or receded in many areas during the recent dry period due to lower groundwater tables. However, the area impacted by salinity is likely to increase with the recent return to wetter conditions.
  • Western Victoria is generally more severely affected by salinity than eastern Victoria, largely because it is flatter and poorly drained, and also because conversion of native vegetation to agriculture has been much more extensive in western Victoria.

Soil health

  • At least 60% of Victorian soils are prone to erosion and soil structure decline. The recent drought conditions experienced across much of Victoria reduced the threat of water erosion (primarily in cropping regions) and soil acidity. However, the extended dry is likely to have increased wind erosion because of the decrease in vegetative cover.

Main image: Indigo Skies Photography