Energetic eco-physiology of the soil microbiota in two landscapes of southern and northern Germany

Interactions between microbial communities and organic matter were analyzed for soils from the project regions 'Ecosystem Research in the Agricultural Landscape/FAM, Munich' in southern Germany and 'Ecosystem Research in the Bornhoved Lake district' from northern Germany using ratios between microbi al biomass content (C-mic), microbial metabolic quotient (qCO(2)) and organ ic carbon content (C-org). In the agricultural soils in southern Germany, t he qCO(2)/C-org ratio differed significantly with respect to agricultural m anagement in contrast to ecophysiological C-mic/C-org ratio. In addition, C -mic/C-org ratio decreased from 39 to 21 mg C-mic g(-1) C-org and qCO(2)/C- org ratio increased from 72 to 180 mg CO2-C g(-1) C-mic h(-1) (g C-org g(-1 ) soil)(-1) with increasing soil depth. For the upper soil horizons from th e landscape in northern Germany the two quotients differed significantly wi th reference to land use showing highest microbial colonization under grass land and lowest under beech forest. In contrast, C use efficiency was lowes t in arable field under maize monoculture and highest in a wet grassland ha ving a high organic C content.