Accurate estimation of the carbon abatement potential of a national carbon market upon U.S agricultural lands is needed by climate analysts, policy makers and carbon market organizers. A high resolution integrated socioeconomic-biogeophysical model is created by overlaying soils data and satellite land use data using GIS. The economic component of the model has been disaggregated to the county level, where, in each county, cropping activities have been expanded to include conventional tillage, reduced tillage and no-tillage operations. The model is used to test changes in net carbon flux induced by conservation tillage incentives on existing U.S. cropland in the eight major crops. The maximum technical potential reduction in net carbon flux is estimated to be 34 million metric tons (MMT) below baseline. The economic potential reduction in net carbon flux at incentives below $500 per ton carbon is estimated to be 21 MMT below baseline, and only 4.9 MMT at incentives below $25 per ton carbon. These estimates are considerably less than those previously estimated. High resolution data indicate that the northern corn belt, Red River Valley and Mississippi Delta have the greatest economic potential for carbon abatement. Application of incentives based on gross soil sequestration potential and not net carbon flux leads to leakage in regions where land is reallocated from low input production to higher input carbon sequestering practices.