Biogeochemical processes in peatlands are primarily controlled by the soil properties peat. While dependant on botanical origins and degree of decomposition, these properties are highly variable. The degree of decomposition can be used as an indicator for the ecological, hydrological and carbon storage functions of peat and peatlands. A commonly used field test for classification of peat decompositions is the Von-Post method, which is a test performed by squeezing an egg-sized sample of peat and observing the quality of the evacuated liquid and the remaining solids and any possible residue or paste. However, as such the test is subjective, and the result depends on the personal judgement of the sampler.

This study was carried out to prove that peat fiber content is an objective indicator of degree of decomposition of different peats using nearly a hundred different peat samples taken from different locations around Europe. Each sample was diluted into a (NaPO3)6-solution, sieved and dried, and the dry weights were compared with an undiluted, unsieved dried control. The dry mass in the sieve divided by the dry mass in the control represented the fiber content mass percentage (FC) of each sample. The measurements were carried out in triplicates.

The collected data was compared against pre-existing set of soil profiles and other information gathered by previous projects of Thünen institute. The study found that across the set of different peat samples the ones with higher degree of decomposition in general had a lower FC. The samples also had a lower total organic carbon (TOC), Carbon-Nitrogen ratio (C/N), as well as porosity and saturated water content (θs) and hydraulic conductivity (Ks), as suggested by previous studies. However, the FC results had a high level of variance within the triplicates due to the heterogeneous nature of natural peat, leading to large error margins. Therefore, more repetitions, perhaps with larger sample masses are required for more accurate results.