Analysis of Soil Organic Carbon Functional Groups by FTIR Method among Land Use Types in Semi-arid Region of Kadapa, Andhra Pradesh

Soil organic carbon is an important component of soils as it determines the soil fertility and soil carbon sequestration potential. The SOC comprises of components of plant and animal litter present at varied decomposition stages. FTIR Spectroscopy was used to identify different functional groups of soil organic carbon components across the four land use types. FTIR method measures the absorbance of IR radiation (4000 cm^-1 - 400 cm^-1) by which functional groups (C-O, C=O, C=C, C-H, N-H) associated with soil organic carbon. A total of 72 soil samples were randomly collected from the four selected study areas and composite soil sample was prepared. Aliphatic -CH stretching was found in all land use types at 2925 - 2300 cm^-1. The presence of aromatic phenolic compounds 1410–1380 cm^-1with (-CO, OH) groups of humic acid, Si-O mineral groups 798–779cm^-1were reported in all four land use types. While the band 779–798 cm^-1 which corresponded to the stretching vibrations of the Si-O mineral group is observed in all the four land use types. The results suggest that although SOC content is varied across the four study sites, the decomposition products featured more or less same re-synthesized products showing similar peaks in the FTIR spectral graphs.