Land capability and soil health
The physical attributes of the land (landform, geology and soils) determine its capability to accommodate various kinds of land uses that in turn impact on natural processes such as nutrient movement, plant growth, and surface and subsurface flow of water. The capability of land to support a given type and intensity of use without its ability to carry out these natural processes being damaged must be taken into account when developing planning and management strategies, assessing developments, and managing land in accordance with current best practice.
The land is a dynamic and rich biological system. Soils contain a living biomass of microbial populations including fungi and bacteria that play a critical role in cycling nutrients, establishing plants and forming soils, and in geochemical transformations. Decayed living material forms the organic matter that supports the microbial populations, stores and buffers nutrient concentrations, influences water storage, and is a major factor in determining overall soil structure and erodability.
In addition, the carbon stored in soil is becoming a key issue in mitigating climate change – soil holds more carbon as plant organic matter than plants and atmosphere combined. Even when it is burnt much of the soil’s carbon is still held as charcoal. Carbon is also retained in the fibrous root mass of grasslands. In future, land capability assessment will likely need to take account of stored carbon.
The impacts of dryland, irrigation and urban salinity are evident across many rural areas in Australia, including the major catchments surrounding the ACT that provide a watershed to the Murrumbidgee River. Although salinity is not currently considered a major problem within the ACT, this situation may change, particularly with continued urban development and the likely adoption of water re-cycling at both the centralised and decentralised scale. The Council will adopt a watching brief in relation to the need for a specific salinity target and re-evaluate the need for a target in five years’ time.
Actions to address issues of concern for ACT land
Land capability: identify land capability so that land use can be matched to capability; better understand the ‘cumulative impact’ of long periods of altered land use
Soil fertility: ensure that soils do not lose their fertility
Acid soils: identify areas of acid soils
Salinity: understand the risk of salinity and reduce recharge wherever possible by increasing perennial vegetation in potentially saline catchments; reduce the amount of salt entering rivers from sewage treatment
Erosion: maintain adequate ground cover to reduce erosion by either wind or water; ensure a minimum of erosion occurs on land being developed for urban or other infrastructure
Land use: ensure universal adoption of best practice
Climate change: identify opportunities for mitigating climate change by storing more carbon in the soil; modify land use practices in order to retain resilient landscapes as the impacts of climate change unfold.
