Soil is a critical resource for water, carbon, energy and nutrient cycling. It provides fundamental support for nearly all coastal land ecosystems, and is a complex ecosystem in itself. Soil quality is determined by a combination of physical, chemical and biological properties. There are several ways to measure soil quality; commonly used indicators include sheet erosion, wind erosion, gully erosion, pH (acidity), organic carbon concentration, structure, salinity and acid sulfate oxidation status (Chapman et al. 2011). Soil quality is important for the microbial communities responsible for nutrient cycling (see Microbial processes and nutrient cycling). The natural quality of Australian soils is generally low because they are deficient in phosphorus, a vital nutrient for vegetation.
The recently developed Soil and Landscape Grid of Australia now provides a nationally consistent soil and landscape database. Development of the grid began in 2011, led by the Terrestrial Ecosystem Research Network in collaboration with researchers from CSIRO; the University of Sydney; Geoscience Australia; and Australian, state and territory government agencies. It combines historical data with new data generated from sampling, laboratory sensing, modelling and remote sensing, and provides access to the best available information about Australian soils and landscapes. Data for at least 11 soil attributes and 8 landscape attributes are available at 90 metre × 90-metre resolution (approximately 2 billion pixels in total), and each pixel also contains estimates of uncertainty. The grid is being used for a wide range of applications, providing information to urban and regional planners, land managers, farming groups, scientists and engineers.
One of the major soil issues for the Australian coast is acid sulfate soils. These occur when soils containing iron sulfide minerals are disturbed and exposed to air, creating sulfuric acid that can leach into waterways and decrease pH (Fitzpatrick et al. 2010). Acid sulfate soils are a natural phenomenon, but are exacerbated by human disturbances such as drainage of floodplains and wetlands. Some efforts have been made to remediate areas affected by acid sulfate soils, such as in the East Trinity Reserve near Cairns, Queensland, and vegetation communities here are responding to large-scale mitigation works (Newton et al. 2014). Hazard maps are required to provide information on the spatial distribution of acid sulfate soils (e.g. Naylor 1995), although little new information has been collected during the past 5 years and at the field or farm level.
In coastal–estuarine landscapes that are inherently rich in sulfidic sediments and saline watertables, natural resource management data need to be collected to describe the heterogeneous nature of the soil, the underlying regolith and interactions with groundwater. This is because these areas are used for agriculture but, increasingly, also for urbanisation. Geophysical methods, such as electromagnetic induction, are being used to value-add to the limited soil data because they are a cost-effective way of mapping the areal distribution of soil salinity and soil acidity (Huang et al. 2014). Increasingly, they are also being used to generate electromagnetic conductivity images (EMCI) of the soil continuum in 2D (Goff et al. 2014). More detailed work using 3D and 4D EMCI, akin to magnetic resonance imaging (MRI) scanning in health care, has also been shown to be able to measure and map beach face salinity (Davies et al. 2015).
See the Land report for more detailed information on soil.