(Co)investigater from the Department: 
Project description: 

Presence of plants significantly affects soil processes.  Plants release organic compounds from their living roots, which modify physico-chemical conditions in surrounding soil and influence a composition and functioning of soil microbial community. The enhanced activity of rhizosphere microbial community results in decomposition of stable soil organic matter and release of nutrients, which are then available for plant roots. The project aims to determine relations between plant C:N stoichiometry and soil microbial activity. We hypothesize that there is a coupling between the C:N stoichiometry of plant tissues and composition of their metabolic pools and rhizodeposition (namely root exudation). The C:N ratio of root exudates would significantly affect soil microbial activity, production of extracellular enzymes and thus decomposition of soil organic matter. These relations will be studied for two plant species differing in their exploitation type (conservative versus competitive). We will shift plant C:N stoichiometry through foliar N application in different dosages, while maintaining the same initial conditions of N availability in soil. Keeping this design, the only input of N to the soil will be via the plant. Then we will determine how increased plant N affects plant functional traits and how these will be mirrored in soil microbial community using biochemical and analytical methods including labeling with stable isotopes C and N, plant metabolomics and molecular techniques.

Project goals: 

This research project aims to determine the connection between plant C:N stoichiometry, plant functional traits affecting belowground flux and fate of photoassimilates, and their effect on soil C and N cycling and sequestration to facilitate predictions of how possible environmental changes affect soil C cycling and storage.