Linking Abiotic Characteristics of Functional SOM Fractions to Biotic Parameters and to Microbial Use

摘要

Soil organic matter (SOM) is heterogeneously distributed among soil compartments into pools of different quality and stability. Approaches based on chemical and/or physical principles of fractionation techniques enable measuring the quantity and quality of the various SOM pools. They enable to distinguish between labile and stabilized carbon pools that rely to soil functions. Previous research on agricultural soils of temperate European regions allowed discriminating the impact of management practices on a hot water extractable fraction (HWE) of the SOM [1] which is assumed to be highly degradable. In contrast, SOM associated to clay particles and to soil fractions with high densities is of special importance for stability and resilience of soil structure and properties [2]. Long-term field experiments are among the best means to predict impacts of soil management on soil organic carbon (SOC) storage. Recent studies use natural isotope ~(13)C/~(12)C ratios as an in situ marker to characterize storage and turnover of relic and newly formed SOC pools [3]. The soil microbial community regulates all transformation processes of SOM and can be considered to be a key component of the active SOM pool. The main objective of the presented work is to link abiotic characteristics of SOM fractions to the biological processes by analyzing the age, source and availability of C in SOM fractions as well as the structure of microbial community associated to the fractions.