Changes in soil organic carbon in croplands of China:II Estimation of soil carbon sequestration potentials

China is a key player in world agriculture,thus the enhancement of the capacity of soil carbon sequestration in croplands of China would be important to influence on global greenhouse gases mitigation.Based on the first and the second national soil inventory database,and data collected from previous field measurements through literature reviews.This study estimated the potentials of soil organic carbon(SOC)sequestration according to SOC spatiotemporal changes in regional croplands of China over the last two decades.The estimated potential of soil carbon sequestration could be up to 668 Tg C,assuming under the certain conditions in the 1980s(with unchanged cropland-use patterns,tillage and fertilization practices).This suggests that the soil in croplands of China would sequester up to 668 Tg C to reach a relatively stable soil carbon equilibrium under the certain condition,meaning that the soil would be a carbon source to the atmosphere in 1980s and afterwards.The study could help provide the method and base for the evaluation and the estimation of the potentials of soil carbon sequestration in croplands of China.