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The objective of the present research was to determine the influence of soil management (moldboard and chisel plow and no-tillage systems) and the application at a rate of 30 t ha-1 of thermally-dry sewage sludge (TSS) on soil labile C pools (water-soluble organic C, carbohydrates and phenolic compounds), microbial biomass C (MBC) and CO2 fluxes in a longterm field experiment under semi-arid conditions. Unamended soils were used as control in both conventional and conservative management. All examined parameters were monitored during 12 months. Soil tillage exerted a significant influence on soil CO2 fluxes and affected the dynamic of labile C pools and soil organic matter contents. Results indicated that TSS enhanced soil CO2 fluxes and caused a significant increase of MBC and labile organic C fractions in chisel and notillage soils in comparison with moldboard plow soils. TSS provoked a general increase of all examined parameters in soils, which indicate a global revitalization of soil microbial metabolism in response to the fresh input of organic C that are energy sources for microbial growing. [ABSTRACT FROM AUTHOR]