Soil mapping at the local- (paddock), to continental-scale, may be improved through remote hyperspectral imaging of surface mineralogy. This opportunity is demonstrated for the semiarid Tick Hill test site (20 km2) near Mount Isa in western Queensland, which is part of a larger Queensland government initiative involving the public delivery of 25,000 km2 of processed airborne hyperspectral mineral maps at 4.5 m pixel resolution to the mineral exploration industry. Some of the "soil" mineral maps for the Tick Hill area include the abundances and/or physicochemistries (chemical composition and crystal disorder) of dioctahedral clays (kaolin, illite-muscovite and Al smectite, both montmorillonite and beidellite), ferric/ferrous minerals (hematite/goethite, Fe2+-bearing silicates/carbonates) and hydrated silica (opal) as well as "soil" water (bound and unbound) and green and dry (cellulose/lignin) vegetation. Validation of these hyperspectral mineral products is based on field sampling and laboratory analyses (spectral reflectance, X-ray diffraction, scanning electron microscope and electron backscatter). The mineral maps show more detailed information regards the surface composition compared with the published soil and geology (1:100,000 scale) maps and airborne radiometric imagery (collected at 200 m line spacing). This mineral information can be used to improve the published mapping but also has the potential to provide quantitative information suitable for soil modeling/monitoring.

Geoscience Australia and CO2CRC have constructed a greenhouse gas controlled release reference facility to simulate surface emissions of CO2 (and other GHG gases) from an underground slotted horizontal well into the atmosphere under controlled conditions. The facility is located in a paddock maintained by CSIRO Plant and Industry at Ginninderra, ACT. The design of the facility is modelled on the ZERT controlled release facility in Montana, which conducts experiments to develop capabilities and test techniques for detecting and monitoring CO2 leakage. The first phase of the installation is complete and has supported an above ground, point source, release experiment, utilising a liquid CO2 storage vessel (2.5 tonnes) with a vaporiser, mass flow controller unit with a capacity for 6 individual metered gas outlet streams, equipment shed and a gas cylinder cage. Phase 2 involved the installation of a shallow (2m depth) underground 120m horizontally drilled slotted well, in June 2011, intended to model a line source of CO2 leakage from a storage site. This presentation will detail the various activities involved in designing and installing the horizontal well, and designing a packer system to partition the well into six CO2 injection chambers. A trenchless drilling technique used for installing the slotted HDPE pipe into the bore hole will be described. The choice of well orientation based upon the effects of various factors such as topography, wind direction and ground water depth, will be discussed. It is envisaged that the facility will be ready for conducting sub-surface controlled release experiments during spring 2011.

This report deals with the problem of detecting electrically resistive bodies of small size buried at shallow depths in wet soils. Detection was attempted by means of measurements made on the surface of the soil using the electrical resistivity method. The present report can be regarded as an extension of an earlier one (No. 1943/64B). The purpose of the new tests was twofold. Firstly it was proposed to make tests of 'normal' resistivity effects using a constant electrode arrangement and measuring the resistivity at closely spaced points on water saturated soils. The second part of the testing programme was contingent on the first part proving that under saturated conditions soil resistivities were sufficiently constant to warrent an attempt being made at detection. If this condition of constancy existed, it was proposed to extend the work of the tests, reviewed in the previous report, to actual field conditions. This has been done and the present report deals with the results obtained.

Our planet provides everything we need for our lives, including the food we eat. As the human population increases and expectations for lifestyle quality increases, so too do the pressures placed on our planet to provide that food. We therefore need to be better at producing food and understanding how that links to our scientific understanding of our planet. For National Science Week 2021, the Geoscience Australia public seminar (co-sponsored by the ACT Division of the Geological Society of Australia and the ACT Branch of the Australian Marine Sciences Association) will present four speakers to demonstrate how geoscience is integral to the provision of our food. Steve Hill – The Long View: Across many disciplines of geoscience and different spatial scales, geology, soils and even plate tectonics influence our food (and wine). Andrew Carroll – Finding Important Seabed Habitat (FISH): Did you know that seabed mapping data directly contributes $9 billion to the Australian economy each year and employs over 56,000 people? For the fishing and aquaculture sectors, seabed mapping is valued at $3 billion. However, only one quarter of Australia’s seabed is mapped! Learn how GA is addressing this challenge to support the rapid growth of Australia's Blue Economy. Claire Krause – Food at Scale: In a country as big and dynamic as Australia, producing food is no small task. Satellite imagery is being leveraged to map, monitor and understand Australia’s food production regions and to identify and manage challenges in the sector. Anna Riddell – From Paddock to Plate with Positioning: Have you ever wondered how your food arrives on your plate and the role that navigation satellites play? Positioning is becoming ubiquitous in everyday life and even has a part in enabling our food to be grown, harvested and transported.

Iron (Fe) oxide mineralogy in most Australian soils is poorly characterised, even though Fe oxides play an important role in soil function. Fe oxides reflect the conditions of pH, redox potential (Eh), moisture and temperature in the soil environment. The Fe oxide mineralogy exerts a strong control on soil colour. Visible-near infrared (vis-NIR) spectroscopy can be used to identify and measure the abundance of certain Fe oxides in soil as well as soil colour. The aims of this paper are to: (i) measure the hematite and goethite content of Australian soils from their vis-NIR spectra, (ii) compare these results to measurements of soil colour, and (iii) describe the spatial variability of hematite, goethite and soil colour, and map their distribution across Australia. The spectra of 4606 surface soil sample from across Australia were measured using a vis-NIR spectrometer with a wavelength range between 350-2500 nm. We determined the Fe oxide content from characteristic absorptions of hematite (near 880 nm) and goethite (near 920 nm) and derived a normalised iron oxide difference index (NIODI) to better discriminate between them. The NIODI was generalised across Australia with its spatial uncertainty using sequential indicator simulation. We also derived soil RGB colour from the spectra and mapped its distribution and uncertainty across the country using sequential Gaussian simulations. The simulated RGB colour values were made into a composite true colour image and were also converted to Munsell hue, value and chroma. These colour maps were compared to the map of the NIODI and both were used for interpretation of our results. The work presented here was evaluated using existing studies on the distribution of Fe oxides in Australian soils.

We describe a model to predict soil-regolith thickness in a 128,000 ha study area in the central Mt Lofty Ranges in South Australia. The term soil-regolith includes the A, B, and C soil horizons to the lower boundary of the highly weathered bedrock zone (R horizon). The thickness of the soil-regolith has a major control on water holding capacity for plant growth and movement of water through the landscape, and as such, it is important in hydropedological modelling and in evaluating land suitability, e.g. for forestry and agriculture. Thickness estimates also have direct application in mineral exploration and seismic risk assessment. Geology and landscape evolution within the area is complex, reflecting the variable nature of bedrock materials, and the partial preservation of deeply weathered profiles as a consequence of weathering processes dating to the Cenozoic, or possibly older. These characteristics, together with strong climatic gradients across the area, make the study area an ideal location to understand the environmental and landscape evolution controls on weathering depth. The area also features weathered landscape analogues to many parts of southern Australia. We use a digital soil mapping piecewise linear decision tree approach to develop the model to predict soil-regolith thickness. This model is based on relationships established between 714 soil-regolith thickness measurements and 28 environmental covariates (e.g. rainfall, slope, gamma-ray spectrometry). The results establish a correlation R2 of 0.64, based on a 75:25% training:test data split. These results are encouraging, and are a significant advance over soil depth mapping by traditional soil-landscape mapping methods.

This report deals with an investigation of the electrical resistivities of a variety of wet surface soils, gravels and sands. The work may be regarded as preliminary to an investigation by Mr. R.F. Thyer into the detection of electrically resistive bodies buried in wet soils at shallow depths. It was required to determine the range over which the resistivities of surface soils vary, and also the changes that may be expected in any one type of soil between measurements made within any 1 foot of each other. Measurements were made in four localities, three being in the bed or on the banks of the Molonglo River, where the surface materials are sand, gravel, silts, and in some places, clay. The fourth locality was near the head of Sullivan's Creek, where the soil is a heavy black clay.

Recently, continental-scale geochemical surveys of Europe and Australia were completed. Thanks to having exchanged internal project standards prior to analysing the samples, we can demonstrate direct comparability between these datasets for 10 major oxides (Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SiO2 and TiO2), 16 total trace elements (As, Ba, Ce, Co, Cr, Ga, Nb, Ni, Pb, Rb, Sr, Th, V, Y, Zn and Zr), 14 aqua regia extracted elements (Ag, As, Bi, Cd, Ce, Co, Cs, Cu, Fe, La, Li, Mn, Mo and Pb), Loss On Ignition (LOI) and pH. It is useful to compare these new datasets, covering 12 million km2, with compositional estimates from other continents, the upper continental crust and, indeed, published average world soil values. Comparison with other continental datasets is hampered by differences in sampling strategies (media, depth, etc.), sample preparation (esp. sieving), sample analysis (total vs partial analysis), and data reporting (means vs medians). Overall, it appears that different continents have distinct geochemical characteristics. Using upper continental crust concentrations to estimate 'average' global soil compositions is over-simplistic and unwarranted. We propose a set of Preliminary Empirical Global Soil reference values from 2 continental-scale geochemical surveys (PEGS2) based on the median values measured for Europe and Australia, for the elements listed above. These empirical values can be significantly different to previous (theoretical) world soil values. For instance PEGS2 values are systematically lower in Al2O3, CaO, Fe2O3, P2O5, Ba and Sr than previous estimates.

Geoscience Australia and the CO2CRC have constructed a greenhouse gas controlled release facility at an experimental agricultural station maintained by CSIRO Plant Industry at Ginninderra, Canberra. The facility is designed to simulate surface emissions of CO2 (and other greenhouse gases) from the soil into the atmosphere. CO2 is injected into the soil is via a 120m long slotted HDPE pipe installed horizontally 2m underground. This is fitted with a straddle packer system to partition the well into six CO2 injection chambers with each chamber connected to its own CO2 injection line. CO2 was injected into 5 of the chambers during the first sub-surface release experiment (March - May 2012) and the total daily injection rate was 100 kg/d. A krypton tracer was injected into one of the 5 chambers at a rate of 10 mL/min. Monitoring methods trialled at the site include eddy covariance, atmospheric tomography using a wireless networked array of solar powered CO2 stations, soil flux, soil gas, frequency-domain electromagnetics (FDEM), soil community DNA analysis, and krypton tracer studies (soil gas and air). A summary of the findings will be presented. Paper presented at the 2012 CO2CRC Research Symposium, Sunshine Beach, 27-29 November 2012.

Spectral data from airborne and ground surveys enable mapping of the mineralogy and chemistry of soils in a semi-arid terrain of Northwest Queensland. The study site is a region of low relief, 20 km southeast of Duchess near Mount Isa. The airborne hyperspectral survey identified more than twenty surface components including vegetation, ferric oxide, ferrous iron, MgOH, and white mica. Field samples were analysed by spectrometer and X-ray diffraction to test surface units defined from the airborne data. The derived surface materials map is relevant to soil mapping and mineral exploration, and also provides insights into regolith development, sediment sources, and transport pathways, all key elements of landscape evolution.