Isotope Biogeochemistry and Gas Fluxes

 

The focus of our work is the investigation of key processes that regulate the flux of elements and water within the soil-plant-atmosphere continuum (SPAC) of agricultural landscapes. For this purpose, isotope techniques, methods for measuring gas fluxes and plant physiological studies are combined. The targeted combination of these approaches and their further development within the framework of interdisciplinary and multiscale projects enables the integrative analysis and quantification of element and water fluxes along the SPAC as well as the elucidation of their regulation. Currently, the working group is focusing on the role of erosion for C and N dynamics in agricultural landscapes, on the importance of rhizosphere processes for rhizodeposition and nutirient uptake, and on the water balance and water use efficiency of ecosystems.

C and N dynamics in agricultural landscapes 

Erosion causes a steady shift of topsoil particularly on croplands. This results in an increasingly intense, small-scale pattern of terrain positions characterized by strong differences in soil properties. The goal of our studies is to determine how these differences in soil properties affect C and N fluxes and stocks in the soil, as well as the function of these positions as sources and sinks of greenhouse gases. Special emphasis is placed on accurately quantifying the influence of soil heterogeneity and erosion state on fertilizer N dynamics and N use efficiency in the soil-plant system and the fate of assimilates in the soil.

Rhizosphere processes 

The root system of plants and the release of carbon compounds into the rhizosphere (root exudation) play a critical role in the uptake of nutrients from the soil. These effects are strongly interlinked with the flow of soil water, as this in turn exerts a strong influence on the distribution of root exudates and the availability of nutrients in the rhizosphere. To date, we have only fragmentary knowledge of the spatiotemporal dynamics of root exudate movement in the rhizosphere and how it interacts with soil water fluxes and root uptake of water and nutrients. Thus, our goal is to elucidate these relationships using isotopic techniques and rhizosphere imaging techniques.

Water balance and water use efficiency of ecosystems​ 

Extreme hydrological events, such as droughts, heavy rainfall and floods, are already affecting ecosystem C sequestration and the productivity of agricultural sites. To assess the extent to which impairments will continue to increase as a result of climate change, a much more comprehensive, quantitative, and process-based understanding of water fluxes in the soil-plant-atmosphere continuum along spatiotemporal scales from the individual plant to the landscape level is needed. We aim to contribute to this primarily by closely linking carbon and water budgets. We therefore combine novel high-frequency and automated gas flow and isotope techniques with other methodologies from the spectrum of ecosystem physiology and ecohydrology to gain an improved understanding of dynamic SPAC process feedbacks and their effects on water and carbon budgets and thus the resilience of agricultural and other ecosystems.

Core Infrastructure:

Carbon c​rane 

Stable isotope laboratory 

Radionuclide laboratory 

Incubation facilities