Chestnut Soils: A Comparison Study by Diffuse Reflectance and Attenuated Total Reflection FTIR spectroscopies with Fractionation

Abstract

For wet-sieving fractionated aggregates of chestnut soils (20-1000 μm) with different agricultural use (a fallow and arable land) and depth profiling, attenuated total reflection (ATR) and diffuse-reflectance (DRIFT) modalities of IR spectroscopy were used for distinguishing differences in the mineral and soil organic matter (SOM) composition. Among fractions, the differences are minimal, and the fraction of 20-400 μm bearing the maximum information volume. Both modalities are complementary: ATR provides more information on the carbonate/silicate matrix and the changes in the range of 1600-200 cm -1 , while DRIFT provides higher sensitivity in the hydrogen-bond and organic carbon ranges (3800-2700 cm -1 ) and more differences in the carbonate range (1600-1400 cm -1 ). Most changes between the agricultural-use samples are observed in upper horizons Ap, in the SOM range (3000-2800 cm -1 ), although slight (arable land shows significantly lower amounts of total organic carbon) and in the carbonate range (1600-1300 cm -1 ). The increase in carbonate contents with the horizon depth was found for both samples, with no significant changes in the silicate part were found.