Understanding soil organic matter concentration (SOM) and chemistry in different peatlands can help design appropriate management practices for sustainable use of peatland agroecosystems. However, detailed information on characteristics of SOM concentration and chemistry is not available for most peatland agroecosystems in general and in northern Germany in particular. In this study, we investigated the SOM concentration and chemistry of drained and rewetted percolation mires, forest and coastal peatlands. We used simple chemical analysis, pyrolysis field ionization mass spectroscopy (Py-FIMS), and carbon and nitrogen X-ray absorption near-edge structure (XANES) spectroscopy. The total organic carbon (Corg), total nitrogen (N), and total sulfur (S) contents were significantly (P < 0.05) different among the peatlands. The Corg at the surface horizons ranged from 164 to 373 g kg−1, and these values were lower than that of the subsurface horizons of the studied peatlands except for the drained alder carr forest and coastal peatlands. The Py-FIMS indicated that the labile SOM compound classes (carbohydrates, phenols, and lignin monomers, and amino acids, peptides, and amino-sugars) and stable SOM compounds classes (lignin dimers, heterocyclic nitrogen compounds, and nitriles) were abundant at the surface horizons. However, the stable compound classes such as lipids, alkanes, alkenes, fatty acids, n-alkyl esters, and suberin were more abundant at the subsurface horizons than the surface horizons. The carbon K-edge spectra revealed that aromatic C, carboxylic C, O-alkyl, and aliphatic C were the predominant C functional groups, whereas N K edge spectra indicated that the amide group was the predominated N functional group. The SOM concentrations and some compound classes were higher in the rewetted sites of alder carr forest peatland (more carbohydrates, suberin and fatty acids) and of percolation mires (more lignin dimers, lipids and alkylaromatics). The results indicate that the effects of rewetting peatlands on SOM concentration and chemistry depend on peatland type.
