Abstract: Taking the typical coal mining subsidence basin of Jiuli mining area of Xuzhou city as the research object to analyze the effect of coal mining on carbon reserves of farmland soil.So,the sampling scheme of subsidence basin soil organic carbon library is designed, the soil organic carbon content is measured in laboratory,the soil organic carbon library of subsidence basin is built,the organic carbon reserves changs of subsidence basin before and after coal mining subsidence are analyzed.The research results show that,the soil organic carbon density of the slope areas is accordance with the one in control area under the condition of coal mining subsidence undisturbed.The soil organic carbon density of the slope areas decreased at first then increased along with the subsidence depth after the mining subsidence. The organic carbon reserves of soil carbon library of the subsidence basin is 560.4 t before mining subsidence,however,after mining subsidence,the organic carbon reserves is 530.9 t.Therefore,the influence of coal mining on the farmland soil organic carbon reserves is carbon loss (carbon source) effect.

Key words: Coal mining subsidence, Farmland soil carbon library, Carbon density, Evaluation model of carbon reserves