Strukturelle und funktionelle Charakterisierung von mikrobiellen Gemeinschaften in ökologisch und konventionell bewirtschafteten Agrarböden

Summary

Soil samples from the DOK long-term field trial were investigated to study influences of different farming systems on structure and function of soil microbial communities. The DOK long-term field trial in Switzerland consists of plots managed bio-dynamically (D), bio-organically (O), conventionally (K) and of those which are managed conventionally but only receive mineral fertilizer (M).
In spring 2003 soil samples from these differently managed plots were taken. All investigated fields were planted with winter wheat in 2003, but with different croppings in 2002: potato and maize cultivation, respectively. Analyses of phospholipid fatty acids (PLFA) and phospholipid etherlipids (PLEL) were carried out to determine bacterial, eukaryotic and archaeal phenotypic diversity. By combining this technique with isotope ratio mass spectrometry (GC/MS-C-IRMS) it was possible to analyse simultaneously 13C/12C ratios in PLFA and PLEL biomarkers for functional analyses of the soil microbiota.
First results revealed differences in the total microbial biomass and community structure among the compared farming systems. Furthermore, the incorporation of the maize derived carbon could be detected in several PLFA at the natural abundance level. This may be an indication for the role of different microbial groups during organic matter degradation.