One of the largest sinks of organic carbon on the global scale is the organic matter stored in soils, it contains about 1500 Gt C in the top one meter. Changes in the size and the turnover rate of the soil carbon pools could possibly have an effect on the atmospheric CO2 concentration and the global climate. Stabilization of soil organic C (SOC) is pre-requisite for long-term C sequestration to mitigate climate change. Stabilization of SOC means the decrease in the potential loss of organic C by microbial respiration, erosion or leaching. Sorption to mineral surfaces is considered to be the most effective mechanism that protects SOC against microbial degradation. The stabilization of SOC is not only influenced by the amount (i.e., soil texture) of but also the type of clays present. The sandy clay loam soils of Pattambi, Kerala stabilized more silt+clay protected C than sandy loam soil of Bhubaneswar, Odisha. The smectic clays are more potent in accumulation and sequestration of SOC in black cotton soils of India. Sorption is influenced by the chemical properties of a mineral, mainly the surface chemistry, which includes the surface structure of the mineral, and is also influenced by the physical properties, e.g. the specific surface area (SSA) and the porosity. Soil organic matter sorption seems to increase with increasing specific surface area (SSA) of soil minerals. SSA in soils can be related to the oxide content. Ligand exchange occurs mostly in acid soils and soils which are rich in oxides. Perhaps ligand exchange is more relevant in subsoils, because of the smaller surface loadings. The bonds by ligand exchange are very strong, they are able to outlast over 100 years. In neutral and alkaline soils mostly Ca2+ und Mg2+ occur, whereas in acid soils additionally Fe3+ and Al3+ form cation bridges with SOM by electrostatic bonding. The coordination complexes of the Fe3+ und Al3+ ions are considerably stronger in comparison to those with Ca2+. Ligand exchange is considered to be the most efficient binding mechanism at lower pH values on porous clay minerals. As pH increases, adsorption of SOM to mineral surfaces generally decreases. The pH affects the surface charge of variable-charge minerals, e.g. Fe and Al hydroxides. On hydroxylated surfaces, the net surface charge becomes increasingly negative as pH increases. Increase in temperature will cause reduction in stabilization due to desorptive effect of greater affinity molecules from soil mineral surfaces. Mineral characteristic exerts control on top soil organic carbon pool, such information is crucial to assess the site specific potential of afforestation to mitigate global warming. So this provides scope for development of a method that can predict capacity of different soils to stabilize the SOM.

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