To evaluate the respiration and temperature dependence of each component of a managed C3coolseason turfgrass (Kentucky bluegrass, Poa pratensis) field and to elucidate the characteristics of the carbon budget, respiratory CO2 fluxes from leaves, non-assimilatory organs, and decomposition (soil heterotrophic respiration) were measured using a closed dynamic chamber method. Analysis of temperature dependence using the Arrhenius function was performed for partitioning of the components of ecosystem respiration. The activation energy for respiration was 40,200 J mol.-1 for non-assimilatory organs, 41,600 mol-1 for leaves, and 69,800 mol-1 for heterotrophic respiration. Total ecosystem respiration at 25°C was 9.0 μmol m-2 s-1 in June 2006 and 8.2 μmol m-2 s-1 in August 2007. Leaf, non-assimilatory organ, and heterotrophic respiration at 25°C was 1.7 (19%), 4.8 (53%), and 2.5 (28%) mol m-2s-1, respectively, in June 2006, and 1.8 (22%), 4.1 (50%), and 2.3 (28%) mol m-2 s-1, respectively, in August 2007. A large proportion of non-assimilatory organ respiration coincided with the non-assimilatory organ biomass. At the study site, soil respiration as the sum of non-assimilatory organ and heterotrophic respiration formed 78-81% of the total ecosystem respiration, and the proportion of autotrophic respiration (non-assimilatory organ respiration) to total soil respiration was 64-66%. The total ecosystem respiration and soil respiration were very large in comparison with the values reported for other ecosystems. © 2010, The Society of Agricultural Meteorology of Japan. All rights reserved.