Relationships between the content and quality of the soil organic matter in arable soils

The soil organic matter (SOM) content and its quality have been evaluated in the 475 topsoil samples from ordinary farm fields. The selected sites range from 151–888 m above the sea level, they include the main taxonomical soil units existing in the Czech Republic, and also differing texture classes, forming thus a continuous climate and pedosequence. Total organic C and N content, as quantitative parameters of the SOM and the C/N ratio, decomposable C content, hot water soluble C content, the DRIFT spectra and hydrophobicity index as qualitative parameters of the SOM were determined. The relationships between the qualitative and quantitative SOM properties were evaluated using linear regression and correlation over the whole dataset and also within the specific soil texture categories and categories according to the altitude of sampling sites.