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Applied and Environmental Soil Science
Volume 2012, Article ID 535646, 12 pages
Research Article

Investigations into Soil Composition and Texture Using Infrared Spectroscopy (2–14 m)

1School of Mathematical and Geospatial Sciences, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia
2CSIRO Earth Science and Resource Engineering, P.O. Box 1130, Bentley, WA 6102, Australia
3Geological Survey of Queensland, Level 10, 119 Charlotte Street, Brisbane, QLD 4000, Australia
4Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia

Received 17 February 2012; Accepted 27 August 2012

Academic Editor: Sabine Chabrillat

Copyright © 2012 Robert D. Hewson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The ability of thermal and shortwave infrared spectroscopy to characterise composition and texture was evaluated using both particle size separated soil samples and natural soils. Particle size analysis and separation into clay, silt, and sand-sized soil fractions was undertaken to examine possible relationships between quartz and clay mineral spectral signatures and soil texture. Spectral indices, based on thermal infrared specular and volume scattering features, were found to discriminate clay mineral-rich soil from mostly coarser quartz-rich sandy soil and to a lesser extent from the silty quartz-rich soil. Further investigations were undertaken using spectra and information on 51 USDA and other soils within the ASTER spectral library to test the application of shortwave, mid- and thermal infrared spectral indices for the derivation of clay mineral, quartz, and organic carbon content. A nonlinear correlation between quartz content and a TIR spectral index based on the 8.62 μm was observed. Preliminary efforts at deriving a spectral index for the soil organic carbon content, based on 3.4–3.5 μm fundamental H–C stretching vibration bands, were also undertaken with limited results.