The Sacramento-San Joaquin ? in California was drained and converted to agriculture more than a century ago, and since then has experienced extreme rates of soil subsidence from peat oxidation. To reverse subsidence and capture carbon there is increasing interest in converting drained agricultural land-use types to flooded conditions. Rice agriculture is proposed as a flooded land-use type with CO 2 sequestration potential for this region. We conducted two years of simultaneous eddy covariance measurements at a conventional drained and grazed degraded peatland and a newly converted rice paddy to evaluate the impact of drained to flooded land-use change on CO 2, CH 4, and evaporation fluxes. We found that the grazed degraded peatland emitted 175-299 g-C m -2 yr -1 as CO 2 and 3.3 g-C m -2 yr -1 as CH 4, while the rice paddy sequestered 84-283 g-C m -2 yr -1 of CO 2 from the atmosphere and released 2.5-6.6 g-C m -2 yr -1 as CH 4. The rice paddy evaporated 45-95% more water than the grazed degraded peatland. Annual photosynthesis was similar between sites, but flooding at the rice paddy inhibited ecosystem respiration, making it a net CO 2 sink. The rice paddy had reduced rates of soil subsidence due to oxidation compared with the drained peatland, but did not completely reverse subsidence.
