The CT Pedosphere concentrates on the interactions of the pedosphere with biosphere, lithosphere, hydrosphere and atmosphere with a special focus on process and structure based functionality. In close collaboration with CT Atmosphere the interactions between of atmosphere and pedosphere will be investigated in relation of water, C and N trace gases, and other matter fluxes, storage changes as well as sink/source dynamics. Data collected by intensive monitoring will be extremely valuable to be used in modelling approaches allowing extrapolating and/ or up-scale (soil) ecosystem processes and related characteristics from the plot scale of intensive test sites to landscape or regional scale.
Soil functions and processes are characterised by experimental approaches and accompanying mathematical modelling on various spatial (micro-scale, macro-scale, lysimeter, field-plot) and time scales with the aim of being able to control and assess matter fluxes and concentrations in biogeosystems. The knowledge of spatial heterogeneity and interaction of processes on local scale is an important challenge to predict the functioning of biogeosystems at larger scales such as the field, farm and catchment scale.
The CT Pedosphere focuses on the scale transition between point/pedon and regional scale. The ultimate goal is to develop an 'effective' one-dimensional approach including the inherent non-linear behaviour of different flux components, especially the onset of vertical preferential flow and lateral interflow and surface runoff. The required parameterization of the unsaturated zone will be based on direct structural soil properties (in contrast to the concept of multi-domain models based on fitted parameters). It will provide residence and travel time distribution within the unsaturated zone in response to external forcing by precipitation. A quantitative understanding of water and matter fluxes through terrestrial systems requires a hierarchical approach because of its hierarchical organization across many spatial scales. The CT Pedology will contribute to the following topics:
- Soil organic carbon pool sizes, fluxes, stabilities and reactivities
- Use of radiolabelled crop residues offers a unique possibility to characterise shifts of carbon stocks and fluxes against the large pool of carbon present in the soil.
- Use of stable isotope labelled crop residues or even plant root exsudates will resolve the chemical structure in various pools. Further, sophisticated respirometric methods will be used to assess the mineralization of organic carbon associated with different soils fractions (Corg - pools).
- In the frame of the climate feedback concept a lysimeter network will be establish (SOILCan) to anticipate a climate change. Lysimeters filled along a temperature and rainfall gradient will be transferred to intensive measurement fields with warmer and dryer conditions than the origin sites. The dryer and warmer conditions will affect the water household, C and N cycles of the lysimeter soil monoliths as well as biodiversity.
- Establishment of intensive monitoring of total soil GHG exchange at sites collocated to climate and EC towers for coordinated observation.
- Dry and wet deposition monitoring of selected test sites.
- Monitoring of soil physical properties (density, texture, etc.).
- Archiving of soil samples of the different intensive test sites
- At the Leipzig-Halle Observatory a specific concept for the in-situ monitoring 'Vadose Zone Monitoring Systems' (VZMS) for agricultural sites
- After geophysical exploration and pedological survey the dynamics of water, carbon, nitrogen and other elements as well as exchange processes with the atmosphere and hydrosphere will be investigated at representative sites in the observatories (catchments).
- Screening of soil chemical parameters, especially nutrients, pesticides and xenobiotika
- Characterisation of SOM in dependence of land use changes and source /sink dynamics of environmentally important C and N trace gases.
- Compilation of soil and area conditions resulting from former land use.
- Integrated modelling of SOM turnover in combination with water and energy fluxes in the soil
- Inversion and validation of models using point measurements of SOM characteristics and CO2 fluxes
- Thomas Pütz (FZJ)
- Heye Bogena (FZJ)
- Steffen Zacharias (UFZ)
- Hans-Jörg Vogel (UFZ)
- Ralf Kiese (KIT)
- Theresa Blume (GFZ)
- Erik Borg (DLR)