Relationships between soil organic carbon fractions and their thermal stability in forest soils (Bavaria, Germany)

Abstract

Several methods for soil organic matter (SOM) fractionation have been developed to better understand e.g. SOM turnover, carbon sequestration, and impact of land use. Most of these fractionation methods are expensive and time-consuming, particularly combined chemical-physical fractionation approaches. This study aims to assess thermogravimetry as a simple and rapid alternative. The dynamics of mass losses of 49 samples from forest mineral topsoil A horizons and subsoil B horizons in Bavaria (Germany) were recorded and related to soil properties and five chemical-physical fractions of SOM. The samples have been fractionated using the approach of Zimmermann et al. (2007). A regression analysis indicated limited predictability of these fractions using thermal mass losses in single temperature intervals. However, if two temperature intervals were combined, the coefficients of determination increased up to 0.88 (p < 0.0001, e.g. for the pool representing intermediate turnover). The fast, reliable, and inexpensive thermal analyses make this method attractive for a combination with chemical-physical fractionation.