Pastures represent a significant portion of the rural landscape in the southeastern US, yet remain understudied agro-ecosystems in terms of the effects of rising atmospheric CO2 concentration. Therefore, in 2005 we initiated a long-term (10 yr) study of bahiagrass (Paspalum notatum Flüggé) response to elevated CO2 using open top field chambers on a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults). Plants were exposed to ambient or elevated (ambient + 200 μmol mol−1) CO2. After a one-year establishment period, a management (M) treatment was applied where half of all plots received N [(NH4)2SO4] at 90 kg ha−1 three times yearly plus P, K, and lime as recommended by soil testing; the remaining plots received no fertilization. These two treatments represent managed and unmanaged pastures, both of which are common in the Southeast. Prior to M treatment initiation (establishment phase) biomass production was unaffected by CO2 treatment. Harvests after M treatment initiation (Spring 2006) showed strong effects of fertilizer addition on cumulative forage biomass production (˜231.8% increase); the main effect of CO2 was also significant (˜13.8% increase with elevated CO2). Significant M x CO2 interactions showed that CO2 had no impact on bahiagrass production with no fertilizer added (as observed in establishment year); however, forage production was increased (˜15.3%) under elevated CO2 with fertilizer addition. These findings highlight the importance of soil fertility management to enhance pasture productivity under rising atmospheric CO2 levels.