Fig. 5. Schematic illustration of possible spatial orientations of organic matter (OM), consisting of the carbon backbones chains (solid gray) and the functional groups (solid black circles) toward the mineral surface depending on the relations between the number of OM molecules the mineral surfaces and the SOM/mineral ratio (adopted from Falbe and Regitz, 1998). The suggested ranges of SOC contents are related to the soils of this study.