Abstract: The key to estimating dissolved and non-dissolved inorganic carbon in saline-alkali soil is understanding the processes of carbonate accumulation. In order to effectively quantify inorganic carbon composition and their ages in saline-alkali soil，the paper introduced a convenient way to determine soil dissolved and non-dissolved inorganic content in these soils. Dynamics of soil inorganic carbon was separated by leaching soil，and inorganic carbon ages were determined by 14C isotope technology in this study. The results showed that average values of both dissolved and non-dissolved inorganic carbon contents in saline soil were higher than in alkaline soil.  Through analyzing dissolved and non-dissolved inorganic carbon storages in saline and alkaline soil profiles at different depths，the paper found that there was significant soil dissolved inorganic carbon and soil non-dissolved inorganic carbon storage below 1 m depth：SIC and SDIC storage below 1 m depth accounted for more than 80% of that for the soil profile，and more than 50% carbon storage was below 3 m depth. At the same depth，the dissolved inorganic carbon storage is approximately 30% of the non-dissolved inorganic carbon storage. Clearly，most of this dissolved inorganic carbon cannot be in a stable form. The mean resident time of carbon in the saline and alkaline soil profiles were more than 10 000 years，and the mean resident time of soil dissolved inorganic carbon was significantly shorter than soil inorganic carbon. These conclusions were indicated that the faster turnover and higher input rate of soil dissolved inorganic carbon was proved though soil dissolved inorganic carbon storage was small in saline-alkali soils. So，soil dissolved inorganic carbon as an important fraction of the modern carbon cycle contribution is obvious higher than soil inorganic carbon.

Key words: dissolved inorganic carbon, ¹⁴C isotope, inorganic carbon content, inorganic carbon storage