To improve the farmland soil fertility and provide suggestions for better field management for more carbon sequestration, effects of land use and rice straw incorporation models on mineralization of soil organic carbon were quantitatively investigated. The CO₂-C evolved from the soil was measured during incubation of the undisturbed soil column mulched or incorporated with ¹⁴C labeled rice straw over a 100-day period. Results show that straw carbon participated in carbon mineralization, contributing 34.74% in paddy mulched with straw (SM), 17.85% in paddy incorporated with straw (SI), 35.68% in upland (SM) and 36.06% in upland (SI) of the ¹⁴C-labelled rice straw carbon applied in either way after 100 d incubation. Meanwhile, 0.99%~1.17% and 2.25%~2.53% of the native soil organic carbon (SOC) in the paddy and upland soil was mineralized, respectively. Rice straw application model and land use and their interaction all showed significant effects on mineralization rate and accumulative mineralization rate of applied rice straw carbon (p<0.01). However, only land use (p<0.01) did on mineralization rate of SOC and accumulative mineralization rate of SOC. Application of rice straw did not affect much the total soil accumulative carbon mineralization rate except in upland (SI) because straw in the soil inhibited decomposition of native SOC, thus reducing the 100d cumulative mineralization rate by 13.95% in paddy (SM), 15.68% in paddy (SI), 11.04% in upland (SM) and 3.34% in upland (SI). Comparatively, Straw incorporation in paddy fields and straw mulch in upland fields are better straw application models and more favorable to accumulation of SOC. The mineralization rate of either applied rice straw carbon or native SOC in paddy soil is obviously lower in paddy soil than in upland soil, which is one of the main reasons why the content of soil organic carbon is generally higher in paddy soil than in upland soil within the same landscape.