Dynamic (redox) interfaces in soil - Carbon turnover in microbial biomass and flux into soil organic matter

• Applicant: Dr. Anja Miltner
• Subject Area: Soil Sciences
• Term: from 2007 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 40976892

Existing models of soil organic matter (SOM) formation consider plant material as the main source of SOM. Recent results from nuclear magnetic resonance analyses of SOM and from own incubation studies, however, show that microbial residues also contribute to a large extent to SOM formation. Scanning electron microscopy showed that the soil mineral sur-faces are covered by numerous small patchy fragments (100 - 500 nm) deriving from microbial cell wall residues. We will study the formation and fate of these patchy fragments as continuously produced interfaces in artificial soil systems (quartz, montmorillonite, iron oxides, bacteria and carbon sources). We will quantify the relative contributions of different types of soil organisms to patchy fragment formation and elucidate the effect of redox con-ditions and iron mineralogy on the formation and turnover of patchy fragments. The develop-ment of patchy fragments during pedogenesis will be followed by studying soil samples from a chronosequence in the forefield of the retreating Damma glacier. We will characterize chemical and physical properties of the patchy fragments by nanothermal analysis and microscale condensation experiments in an environmental scanning electron microscope. The results will help understanding the processes at and characteristics of biogeochemical interfaces.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1315: Biogeochemical Interfaces in Soil
• Participating Person: Professor Dr. Matthias Kästner