institute of soil ecology

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Soil Functions and Material Fluxes

Head:          Prof. Dr. Jean Charles Munch
Telephone   +49 (0)89 3187-4065
Fax              +49 (0)89 3187-2800
Email          

The overall aim of the research approaches in this group is to develop an improved understanding in the identification of possible impacts of physical and chemical stress factors (such as drying, flooding, frost-thaw, changes in pH, chemical pollution and inappropriate farming methods) on the ecosystem soil. The soil and its micro-organisms are considered to form an organic unity, which exchanges both energy and matter within themselves and with their immediate environment. The specific research goal is to clarify the processes, which control the fluxes and the ecological effects of environmentally important gases and the dissolved organic mater (DOM). Key elements of this research are:

  • Investigation of the uptake and release of environmentally relevant trace gases (N2O, C02, CH4) by soils in microcosms, lysimeters, and cultivated fields
     
  • Description of the dynamics of the nutrient pool components, such as microbial biomass, organic substrate, N (15N) and C (13C) in microcosm and field experiments. This endeavour has been documented in several of the publications (e.g. by Ruser, Wessels-Perelo, Yevdokimov) listed below. This group is especially suited to accomplish this, because the Institute´s impressive stable isotope facilities are imbedded in it. Furthermore, the facilities of the Dept. of Environmental Engineering enable the labelling of vegetation to also attain this goal.
     
  • Determine the suitability of DOM as a sensitive indicator of soil quality. This is being done within the framework of a European Commission project "Indicators and thresholds for desertification, soil quality, and remediation (INDEX)", which is being coordinated by this group.
     
  • Two studies, one with support of the German Research Association, have been initiated to improve our understanding of diffusion processes in soils. This is critical, since it is through these processes that sequestration and availability of matter function.
     
  • This indicator approach has already been applied with some success to the GSF project "Glyphosate-Gene Transfer Project". It is common to assess the impact of pesticide application on the biota and on groundwater quality. It is far less common to assess possible impacts on the physicochemical state of a soil. To close this gap the soil quality indicators, which are being developed within INDEX, are being applied here. The results are still very preliminary, but one year after the application of glyphosate, both the soybean plants and the soil´s physicochemical state appeared to have deteriorated.
     
  • The influence of clay minerals on DOM composition and preservation has been initiated in conjunction with the Japanese Universities of Kyoto and Kyushu. Some samples have been taken and are being processed, but data are not yet available.
     
  • Doctoral studies by J. Junkers and J. Akagi have been completed in which, the interaction between the heavy metal, copper, and DOM have been clarified. In them one can clearly see that copper interacts with the more humified material with a one-site binding. As a result the interaction is less with DOM, which is freshly excreted by roots. To what extent this has an effect on plant-metal interactions needs to be clarified.
     
  • Considerable basic research has been and will be done to clarify the sources and sinks of DOM as well as its temporal and spatial variability. The dissertation of K. Zelles and research by A. Embacher have shown that DOM in a field can be quite variable and that this variability can be described by using geostatistical tools. However, the dissertation of J. Akagi suggests that this variation is due to physical perturbations such as drying, freezing, ploughing, etc. She also showed that DOM fresh from roots is quickly transformed presumably by microbial activity but at the same time efficiently sequestered and protected by the soil matrix. In fact she found that even after 50 years DOM substrate was still available in a soil. The doctoral study by M. Marx also showed that on the one hand fresh root exudated organic carbon was incorporated in the microbial biomass while on the other hand it was also very efficiently sequestrated.