<p>Soil is a huge carbon (C) reservoir, but where and how much extra C can be stored is unknown. Here, using 5089 observations, we estimated that the uppermost 30&nbsp;cm of Australian soil holds 13&nbsp;Gt (10–18&nbsp;Gt) of mineral-associated organic carbon (MAOC). Using a frontier line analyses, described in Viscarra Rossel et al. (2023), we estimated the maximum amounts of MAOC that Australian soils could store in their current environments, and calculated the MAOC deficit, or C sequestration potential. We propagated the uncertainties from the frontier fitting and mapped the estimates of these values over Australia using machine learning and kriging with external drift (KED). The maps show regions where the soil is more in MAOC deficit and has greater sequestration potential. The modelling shows that the variation over the whole continent is determined mainly by climate, linked to vegetation, and soil mineralogy. We find that the MAOC deficit in Australian soil is 40&nbsp;Gt (25–60&nbsp;Gt). The deficit in the vast rangelands is 20.84&nbsp;Gt (13.97–29.70&nbsp;Gt) and the deficit in cropping soil is 1.63&nbsp;Gt (1.12–2.32&nbsp;Gt). Our findings suggest that the C sequestration potential of Australian soil is limited by climate.

This dataset list soil characteristics observed in Rangeland sites across Australia by the TERN Surveillance Monitoring team, using standardised AusPlots methodologies. <br /> Soil observations are recorded at each site as part of the AusPlots Soil and Landscapes method. Observations on the soil surface conditions are also recorded as part of the AusPlots Plot description method.<br />

The soil in terrestrial and blue carbon ecosystems (BCE; mangroves, tidal marshes, seagrasses) is a significant carbon (C) sink. National assessments of C inventories are needed to protect them and aid nature-based strategies to sequester atmospheric carbon dioxide. We harmonised measurements from Australia's terrestrial and BCE and, using consistent multi-scale spatial machine learning, unravelled the drivers of soil organic carbon (SOC) variation and digitally mapped their stocks. The modelling shows that climate and vegetation are continentally the primary drivers of SOC variation. But the underlying regional drivers are ecosystem type, terrain, clay content, mineralogy, and nutrients. The digital soil maps indicate that in the 0-30&nbsp;cm soil layer, terrestrial ecosystems hold 27.6&nbsp;Gt (19.6-39.0&nbsp;Gt), and BCE 0.35&nbsp;Gt (0.20-0.62&nbsp;Gt). Tall open eucalypt and mangrove forests have the largest mean SOC per unit area. Eucalypt woodlands and hummock grassland, which occupy vast areas, store the largest total SOC stock. These ecosystems constitute important regions for conservation, emissions avoidance, and preservation because they also provide additional co-benefits.

The map gives a modelled estimate (probability) of the spatial distribution of rock outcroppings across Australia.<br></br> This product was produced in the development of the updated soil thickness map of Australia, details of which are published in Malone and Searle (2020; https://doi.org/10.1016/j.geoderma.2020.114579). This product is the output from Model 1 of aforementioned paper and uses the Rock Properties database provided by Geoscience Australia which gives the locations of sampled rock outcrops across Australia (http://www.ga.gov.au/scientific-topics/disciplines/geophysics/rock-properties). Filtering this dataset resulted in 14616 rock outcrop locations within areas where relief >300 m. A machine learning model was used to find relationships between observed data and associated environmental covariate data to inform the mapping of rock outcrop occurrence across Australia.<br></br> Detailed information about the Soil and Landscape Grid of Australia can be found at - <a href="https://esoil.io/TERNLandscapes/Public/Pages/SLGA/index.html">SLGA</a><br /><br /> <ul style="list-style-type: disc;"><li>Attribute Definition: Probability of rock outcrops;</li> <li>Units: 0-1;</li> <li>Period (temporal coverage; approximately): 1950-2021;</li> <li>Spatial resolution: 3 arc seconds (approx 90m);</li> <li>Total number of gridded maps for this attribute: 1;</li> <li>Number of pixels with coverage per layer: 2007M (49200 * 40800);</li> <li>Data license : Creative Commons Attribution 4.0 (CC BY);</li> <li>Target data standard: GlobalSoilMap specifications;</li> <li>Format: Cloud Optimised GeoTIFF;</li></ul>

This is Version 2 of the Australian Soil Sand Content product of the Soil and Landscape Grid of Australia. It supersedes the Release 1 product that can be found at https://doi.org/10.4225/08/546F29646877E The map gives a modelled estimate of the spatial distribution of sand in soils across Australia. The Soil and Landscape Grid of Australia has produced a range of digital soil attribute products. Each product contains six digital soil attribute maps, and their upper and lower confidence limits, representing the soil attribute at six depths: 0-5&nbsp;cm, 5-15&nbsp;cm, 15-30&nbsp;cm, 30-60&nbsp;cm, 60-100&nbsp;cm and 100-200&nbsp;cm. These depths are consistent with the specifications of the GlobalSoilMap.net project (https://esoil.io/TERNLandscapes/Public/Pages/SLGA/Resources/GlobalSoilMap_specifications_december_2015_2.pdf). The digital soil attribute maps are in raster format at a resolution of 3 arc sec (~90 x 90&nbsp;m pixels). Detailed information about the Soil and Landscape Grid of Australia can be found at - https://esoil.io/TERNLandscapes/Public/Pages/SLGA/index.html <ul style="list-style-type: disc;"><li>Attribute Definition: 20&nbsp;um - 2&nbsp;mm mass fraction of the < 2&nbsp;mm soil material determined using the pipette method;</li> <li>Units: %;</li> <li>Period (temporal coverage; approximately): 1950-2021;</li> <li>Spatial resolution: 3 arc seconds (approx 90&nbsp;m);</li> <li>Total number of gridded maps for this attribute: 18;</li> <li>Number of pixels with coverage per layer: 2007M (49200 * 40800);</li> <li>Data license : Creative Commons Attribution 4.0 (CC BY);</li> <li>Target data standard: GlobalSoilMap specifications;</li></ul>

This map gives a modelled estimate of the spatial distribution of Pedogenon soil classes across Australia.<br><br> Pedogenon mapping is a method for stratifying the landscape (similar to soil-landscape units), which can be used to assess past soil change with a space-for-time substitution approach.<br><br> Pedogenon classes are a conceptual taxa that aim to define groups of homogeneous environmental variables. These groups are created applying unsupervised classification to a set of state variables, proxies of the soil-forming factors for a given reference time. The assumption is that the soil-forming processes within these classes (i.e., pedogenons) have been relatively similar over pedogenetic time and thus have developed soils with similar properties. Pedogenon classes can afterwards be divided into subclasses along a gradient from less (i.e., remnant pedogenons) to more anthropogenic pressure on soils (i.e., pedophenons), in an analogous way to the concept of genoform and phenoform (Rossiter and Bouma, 2018). The assessment of changes in soil condition can be done with a space for time substitution within and across pedogenon classes. The conceptualization and methodology for pedogenon mapping and using the classes as basis to assess changes in soil condition are explained with more detail in two publications (Román Dobarco et al., 2021a; Román Dobarco et al., 2021b).<br><br> Detailed information about the Soil and Landscape Grid of Australia can be found at - <a href="https://esoil.io/TERNLandscapes/Public/Pages/SLGA/index.html">SLGA</a>.<br><br> <ul style="list-style-type: disc;"> <li>Period (temporal coverage; approximately): 1950-2022;</li> <li>Spatial resolution: 3 arc seconds (approx 90&nbsp;m);</li> <li>Number of pixels with coverage per layer: 2007M (49200 * 40800);</li> <li>Data license : Creative Commons Attribution 4.0 (CC BY);</li> <li>Target data standard: GlobalSoilMap specifications;</li> <li>Format: Cloud Optimised GeoTIFF;</li></ul>

This is Version 2 of the Australian Total Soil Nitrogen product of the Soil and Landscape Grid of Australia.<br></br> It supersedes the Release 1 product that can be found at https://doi.org/10.4225/08/546F564AE11F9<br></br> The map gives a modelled estimate of the spatial distribution of total nitrogen in soils across Australia.<br></br> The Soil and Landscape Grid of Australia has produced a range of digital soil attribute products. Each product contains six digital soil attribute maps, and their upper and lower confidence limits, representing the soil attribute at six depths: 0-5&nbsp;cm, 5-15&nbsp;cm, 15-30&nbsp;cm, 30-60&nbsp;cm, 60-100&nbsp;cm and 100-200&nbsp;cm. These depths are consistent with the specifications of the GlobalSoilMap.net project (https://esoil.io/TERNLandscapes/Public/Pages/SLGA/Resources/GlobalSoilMap_specifications_december_2015_2.pdf). The digital soil attribute maps are in raster format at a resolution of 3 arc sec (~90 x 90&nbsp;m pixels). An additional measure of model reliability is through assessment of model extrapolation risk. This measure provides users a spatial depiction where model estimates are made within the domain of the observed data or not.<br></br> Detailed information about the Soil and Landscape Grid of Australia can be found at - <a href="https://esoil.io/TERNLandscapes/Public/Pages/SLGA/index.html">SLGA</a><br /><br /> <ul style="list-style-type: disc;"><li>Attribute Definition: Total soil nitrogen;</li> <li>Units: % (percentage of fine soil mass);</li> <li>Period (temporal coverage; approximately): 1950-2021;</li> <li>Spatial resolution: 3 arc seconds (approx 90&nbsp;m);</li> <li>Total number of gridded maps for this attribute: 24;</li> <li>Number of pixels with coverage per layer: 2007M (49200 * 40800);</li> <li>Data license : Creative Commons Attribution 4.0 (CC BY);</li> <li>Target data standard: GlobalSoilMap specifications;</li> <li>Format: Cloud Optimised GeoTIFF;</li></ul>

We used Digital Soil Mapping (DSM) technologies combined with collations of observed soil colour data from TERN's Soil Data Federation System, to produce surface and subsoil maps of soil colour at a 90&nbsp;m resolution.<br><br> The map gives an estimate of the spatial distribution of RGB soil colour across Australia.<br><br> Detailed information about the Soil and Landscape Grid of Australia can be found at - <a href="https://esoil.io/TERNLandscapes/Public/Pages/SLGA/index.html">SLGA</a>.<br><br> <ul style="list-style-type: disc;"> <li>Period (temporal coverage; approximately): 1950-2020;</li> <li>Spatial resolution: 3 arc seconds (approx 90&nbsp;m);</li> <li>Number of pixels with coverage per layer: 2007M (49200 * 40800);</li> <li>Data license : Creative Commons Attribution 4.0 (CC BY);</li> <li>Target data standard: GlobalSoilMap specifications;</li> <li>Format: Cloud Optimised GeoTIFF;</li></ul>

This is Version 2 of the Depth of Regolith product of the Soil and Landscape Grid of Australia (produced 2015-06-01).<br><br> The Soil and Landscape Grid of Australia has produced a range of digital soil attribute products. The digital soil attribute maps are in raster format at a resolution of 3 arc sec (~90 x 90&nbsp;m pixels).<br><br> <ul style="list-style-type: disc;"><li>Attribute Definition: The regolith is the in situ and transported material overlying unweathered bedrock;</li> <li>Units: metres;</li> <li>Spatial prediction method: data mining using piecewise linear regression;</li> <li>Period (temporal coverage; approximately): 1900-2013;</li> <li>Spatial resolution: 3 arc seconds (approx 90&nbsp;m);</li> <li>Total number of gridded maps for this attribute: 3;</li> <li>Number of pixels with coverage per layer: 2007M (49200 * 40800);</li> <li>Data license : Creative Commons Attribution 4.0 (CC BY);</li> <li>Variance explained (cross-validation): R^2 = 0.38;</li> <li>Target data standard: GlobalSoilMap specifications;</li> <li>Format: Cloud Optimised GeoTIFF;</li></ul>

This is Version 2 of the Australian soil pH (CaCl₂) product of the Soil and Landscape Grid of Australia.<br><br> It supersedes the Release 1 product that can be found at https://doi.org/10.4225/08/546F17EC6AB6E<br><br> The map gives a modelled estimate of the spatial distribution of the pH of soils across Australia.<br><br> The Soil and Landscape Grid of Australia has produced a range of digital soil attribute products. Each product contains six digital soil attribute maps, and their upper and lower confidence limits, representing the soil attribute at six depths: 0-5&nbsp;cm, 5-15&nbsp;cm, 15-30&nbsp;cm, 30-60&nbsp;cm, 60-100&nbsp;cm and 100-200&nbsp;cm. These depths are consistent with the specifications of the GlobalSoilMap.net project. The digital soil attribute maps are in raster format at a resolution of 3 arc sec (~90 x 90&nbsp;m pixels). An additional measure of model reliability is through assessment of model extrapolation risk. This measure provides users a spatial depiction where model estimates are made within the domain of the observed data or not.<br><br> Detailed information about the Soil and Landscape Grid of Australia can be found at - <a href="https://esoil.io/TERNLandscapes/Public/Pages/SLGA/index.html">SLGA</a><br><br> - Total number of gridded maps for this attribute: 24.<br> - Number of pixels with coverage per layer: 2007M (49200 * 40800).