Plant litter is subjected in soils to contrasted stabilization/degradation processes leading to the formation of soil organic matter (SOM). Soil minerals, nutrient contents and chemical composition of SOM may control these processes. For example interactions with the mineral phase may favor the preservation of specific molecules, such as polysaccharides. On the other hand, it was suggested that slow biodegradation of lignin, the most important aromatic compound in plants, is leading to its preservation. Aliphatic components of SOM were found to accumulate in some soils. The complex interaction between biodegradation of plant litter and its ultimate stabilisation in different soil types is poorly understood. Combining spectroscopic, molecular and isotopic techniques is necessary to elucidate the chemical composition of stabilised SOM and to understand cycling of specific plant litter compounds in soils in order to elucidate their preservation potential. Spectroscopic techniques such as ¹³C and ¹⁵N CPMAS NMR spectroscopy inform on the bulk chemical composition of SOM, whereas molecular markers provide insight into a small but highly specific part of SOM. Isotopic techniques are needed to elucidate the turnover of bulk SOM and molecular compound classes. We combined these complementary methods to (1) compare the chemical composition of OM in soil types under different land-use (2) localize the stabilized carbon pool in bulk soil and particle size fractions of top- and subsoil horizons of acid forest soils, (3) study the influence of N on biodegradation of OM in forest soils; (4) estimate the in situ turnover kinetics of lignin-derived phenols in an agricultural soil. Our results indicate that the bulk chemical composition of stabilized OM in the mineral soil is dependent on soil type and pedogenic processes, whereas these parameters have little influence on biodegradation. Lignin, an aromatic plant litter compound was not found to be stabilized in soil over a decade.