Characterisation of a humus profile under beech forest by using wet‐chemistry and CPMAS ¹³C NMR‐spectroscopy in consideration of spatial heterogeneity

Three of ten macromorphologically similar humus profiles of a Dystric Cambisol under a beech forest were randomly chosen and the litter and humus layers were characterized by wet‐chemistry and CPMAS 13 C NMR‐spectroscopy. The spatial heterogeneity of the litter and humus layers was high for the bulk density and for the sugar and starch fraction; lowest coefficients of variation were obtained for the chemical shift range of O‐Alkyl‐C. The spatial heterogeneity of the layers did not differ by means of all chemical methods. Changes in the chemical composition at the beginning of humification were high from the fresh fallen litter (Ln‐layer) to the morphologically only slightly altered litter in the L‐layer, whereas the changes in the litter and humus layers from the L to the Ohf‐layer were minor. However, the organic matter of the first mineral horizon was characterized by a decrease in lignin and cellulose. With wet‐chemistry and 13 C NMR‐spectroscopy similar results were obtained for polysaccharides whereas results which can be attributed to changes in lignin deduced by the methoxyl content differed from each other.