[Objective] In calcareous soil, CO₂in rhizosphere soil comes from at least three sources, i.e., respiration of roots, decomposition of soil organic C (SOC) and dissolution of soil inorganic C (SIC). Owing to technical limitations in partitioning CO₂ by source, how rhizosphere effects affect SOC decomposition and SIC dissolution is still an issue not yet clarified. Therefore, an in-lab pot experiment using calcareous soil collected from a farmland of North China to grow maize in an attempt to investigate rhizosphere effects of summer maize plants on release of CO₂ from SOC and SIC, using the IsoSource model to partition CO₂ in the rhizosphere by source.[Method] At the end of the elongation (24-53 days), heading (54-66 days) and grain-filling (67-99 days) stages of the summer maize, destructive sampling of maize rhizospheres was carried out separately for analysis of content of ¹³C from root, SOC and SIC, separately. During the period from the beginning of the elongation stage to the end of the maize growth stage, soil respiration and ¹³C content in the soil with or without maize planted was monitored at a three-day interval with the aid of the IsoSource software.[Result] Results show that to the total soil CO₂ emission, root respiration contributed 48.0%, SOC did 31.2% and SIC did 20.8%. During the period from the elongation stage to the end of the summer maize season, CO₂ emission from SOC and from SIC in the pot with maize planted was 65% and 156% higher than their respective ones in the pot without maize planted.[Conclusion] This experiment indicates that SIC plays a significant role in stabilizing global C pool and regulating atmospheric CO₂ concentration. If the contribution of SIC to soil CO₂ emission in calcareous soils is ignored, the amount of CO₂from SOC decomposition may be overestimated, which will inevitably affect quantification of the priming effects of SOC. This study will help reduce uncertainties in of soil C budgeting for farmlands of calcareous soil in North China.