Technical Abstract: Assessing strategies to help mitigate the rise in atmospheric CO2 includes evaluation of management decisions concerning tillage practices which influence loss of carbon from soil. Information on seasonal CO2 flux patterns as affected by degree of soil disturbance/residue mixing and time of tillage operations are lacking. An experiment was conducted following a grain sorghum [Sorghum bicolor ] (L.) Moench.] crop on a Norfolk loamy sand (Typic Kandiudults) in east-central Alabama to characterize soil CO2 flux patterns as affected by tillage implement [disc-type, chisel-type, and no-tillage] and time of soil disturbance (i.e., fall and spring). Soil CO2 efflux was assessed immediately following fall tillage for a period of about six months; likewise, these measures were also taken in the spring after imposing tillage treatments on another set of undisturbed plots. Concurrent measures were also made on no-tillage plots. Increased CO2 efflux was related to degree of soil disturbance attributed to fall tillage; losses were similar for the chisel and no-tillage treatments and the highest loss occurred for disc treatment; cumulative flux estimates also reflected such differences. With spring tillage, loss of CO2 for the no-tillage and disc treatment were similar, while the chisel treatment exhibited a slightly lower loss. Results suggest that selection of fall tillage equipment that maintains surface residue and minimizes soil disturbance could help reduce CO2 loss. However, such considerations for spring tillage operations would not result in a substantial reduction in CO2 loss. [GRACEnet Publication]