Wetlands Reserve Program (WRP) has converted considerable area of cropland to wetland in the United States since the 1990s, yet its effect on soil organic carbon (SOC) sequestration received only limited attention. SOC content at four soil depths (0-10, 10-20, 20-30, and 30-40 cm) were measured in study sites with different soil series (Latanier, Gallion and Sharkey) in St. Landry Parish, Louisiana, to quantify SOC dynamics as a function of three contrasting land use types (forest, cropland and WRP). The results showed that for all the three soil series SOC contents of WRP were significantly lower than those of forest at 0-10 cm depth but not at 10-20 and 20-30 cm depths. SOC contents of WRP were significantly higher than those of cropland at all the four depths for Latanier and Sharkey but not for Gallion, due to different crop types and agricultural managements. SOC sequestration rate of WRP for Latanier and Sharkey were 284 g C m^-2 yr^-1 and 135 g C m^-2 yr^-1 respectively. These findings highlight the importance and potential of WRP as a soil carbon sequestration strategy.