%0 Journal Article
%T Investigations into Soil Composition and Texture Using Infrared Spectroscopy (2¨C14£¿ m)
%A Robert D. Hewson
%A Thomas J. Cudahy
%A Malcolm Jones
%A Matilda Thomas
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/535646
%X 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£¿¦Ìm was observed. Preliminary efforts at deriving a spectral index for the soil organic carbon content, based on 3.4¨C3.5£¿¦Ìm fundamental H¨CC stretching vibration bands, were also undertaken with limited results. 1. Introduction Mapping and analysing soils for their composition and textural characteristics typically involves extensive field work and laboratory techniques that are traditionally time consuming. However the measurement and determination of soil texture and composition is important for the mapping of areas vulnerable to soil erosion, driven by water and wind. Coarser-textured soils are more resistant to detachment and transport via raindrops, thus less affected to water-assisted erosion [1]. Soils with a silt content above 40% are considered highly erodible while clay particles can potentially combine with organic matter to form aggregates or clods which assist in their resistance to erosion [1]. Also, studies of the critical shear wind velocities required for transportation of different-sized soil particles indicate, those with diameters between 0.10 to 0.15£¿mm are the most vulnerable to wind erosion [1]. Another motivation to determine a soil¡¯s texture and composition, including mineralogy, is with the aim to measure a soil¡¯s ability to retain water or enable drainage. Clay minerals such as montmorillonite can exhibit swelling behaviour, absorbing and storing water, within their layered lattice structure [2]. Such finer textured clay rich soils can offer more water for plant growth than sandy soils. Sandy soils are more vulnerable to drought than clayey soils, storing
%U http://www.hindawi.com/journals/aess/2012/535646/