Welcome to the lunch seminar: From plants to the soil - the nature of soil organic matter with Carsten Müller, Technical University of Munich, Chair of Soil Science.
Soils represent the largest terrestrial carbon reservoir, thus by far exceeding the amount of carbon stored in plant biomass. However, the dominating primary source of soil organic carbon are plant derived organic compounds. The amount and composition of plant residues entering the soil differ between above and belowground sources. Especially root derived organic matter, root exudates and cell fragments from living roots, and decaying roots comprise an important soil carbon source forming spatially distinct hot spots of microbial activity. At such hot spots interactions between microbiota, organic matter and mineral particles are thought to control the long-term fate of soil carbon. The rhizosphere thus represents a soil volume hosting the complex interplay of biological, chemical and physical soil processes determining the fate of soil organic matter.
The lecture will span from the chemical composition of fresh plant residues and their fate during microbial decomposition, to the long-term storage of specific soil organic carbon fractions. A special emphasize will be put on the integration of quantitative bulk analyses into a conceptual understanding of soil functioning as determined by soils intact 3D structure.