A/Prof. Carsten W. Mueller1
1Technical University of Munich, Freising, Germany
Due to its large interface between soils and plants, the rhizosphere, the volume of soil around living roots directly influenced by root activity, plays a key role in soil formation. Especially the root derived input of organic carbon into the soil matrix triggers a multitude of soil processes. The soil structure formation, i.e. aggregation of solid soil particles into three dimensional clusters, is the key process for the formation of a soil’s pore space and specific surface area, determining the air, water and nutrient balance and thus shaping both plant and microbial habitats. The formation of associations built by the interaction of minerals with organic matter supplied by rhizodeposition or decaying roots together with microbial residues is unique to soils. The high input of organic carbon in the rhizosphere (both from plants and microorganisms) in contrast to root free bulk soil, promotes the formation of micro- and macro-aggregates, and thus the development of a 3D soil structure with positive effects on soil carbon sequestration. As the rhizosphere is a hot spot for organic carbon input and microbial activity, it becomes evident that it also plays a special role for the long term carbon sequestration at greater soil depth. Results from a number of studies will presented on the importance of roots and the rhizosphere on soil organic matter cycling and sequestration. This will reach from using artificial root systems at the lab scale to determine the effect of root exudates on soil aggregate formation and microbial community structures, up to the field scale exploring the major role of roots for soil organic carbon stability.