Soil organic matter composition in three humus profiles of the western Taurus, Turkey, as revealed by wet chemistry and CP/MAS C-13 NMR spectroscopy

In this study three soil profiles located in the Western Taurus (Turkey) at different altitudes (10, 1900, and 3080 m a.s.l.) were compared with respect to their soil organic matter characteristics. The soil sample were fractionated by density to plant residues, slightly altered plant material,organo-mineral complexes, and organic-free minerals. Bulk samples and fractions were analyzed for C and N, the bulk samples additionally for total sugars, lignin signature, and bulk soil organic matter composition by CP/MAS C-13 NMR spectroscopy. The first step of litter decomposition and humification is a very strong degradation of polyaccharides without the loss of O-alkyl structures. This process is slowing down very fast and the polysaccharides are stabilized. Lignin is decomposed as fast or even faster than polysaccharides. The data obtained by wet-chemical analysis and by NMR spectroscopy are not or only weakly correlated to each other. This leads to the conclusion that the two types of methods give complementary rather than equivalent information. For the study of soil organic matter it is important to combine different methods and to draw the advantages of either type.