TP3-1: Rhizosphere carbon

Carbon pools and fluxes in the rhizosphere of agroforestry systems

Summary

The objective of this subproject is to characterize the carbon (C) pools and fluxes and microbial activities in the rhizosphere of selected agroforestry systems. Organic substances translocated by roots into the soil are the main source of C and energy for microorganisms responsible for most biochemical reactions, including mobilization of nutrients from hardly available sources, e.g. soil organic matter (SOM), clay minerals, sesquioxides. Therefore, knowledge of the amounts and localization of organic substances added by plant roots into the soil and especially into subsoil is crucial for evaluating many processes including mobilization of nutrients. The difference of agroforestry systems compared to agricultural crops is the presence of multiple interactions between the roots of trees with annual crops or biannual grasses (for grassland). This leads to spatial and temporal niche differentiation in soil including interactions with various microbial groups for acquisition of water and nutrients. However, there is still limited information on these interactions and niche differentiation within the rhizosphere of agroforestry systems.

The main work packages of our subproject are:

  1. analysis of potential activity and kinetics of enzymes responsible for C, N, P and S cycles depending on depth and distance from the short rotation coppice strip;
  2. analysis of the composition of main microbial groups, present under various components of short rotation coppices, which will be done by composition of phospholipid fatty acid (PLFA) approach. This is necessary to characterize the bacteria/fungi ratio under agroforestry components to conclude about the effects of C, nutrients and water budget on microbial composition in soil;
  3. estimation of C input by roots and rhizodeposition into soil for young trees, grasses and crops and analyze their contribution to C sequestration under agroforestry components, using stable (13C) and radioactive (14C) isotopes;
  4. formalize the parameters obtained within the three experimental parts to deliver the process rates and pools for modelling.

These objectives will be conducted at all experimental plots in cooperation with other groups (TP1-1, TP2-1 and TP3-2).

Contact

Prof. Dr. Yakov Kuzyakov

University of Göttingen, Soil Science of Temperate Ecosystems
Büsgenweg 2, 37077 Göttingen, Germany

Phone: +49 (0)551 39 33502
E-Mail: kuzyakov@gwdg.de

Dr. Martin Jansen

University of Göttingen, Soil Science of Temperate and Boreal Ecosystems
Büsgen-Institute
Büsgenweg 2, 37077 Göttingen, Germany

Phone: +49 (0)551 39 33695
Fax: +49 (0)551 39 33310
Email: mjansen@gwdg.de

Anne Schuldt

University of Göttingen, Agricultural Soil Science

Email: anne.schuldt@forst.uni-goettingen.de