Soil organic carbon in clay and silt sized particles in Chinese mollisols: Relationship to the predicted capacity

Soil organic carbon (SOC) associated with clay plus silt sized particles ( 20 μm were relatively low and similar amongst all the Black soils. In contrast, SOC in the fraction > 20 μm varied considerably amongst the Baijiang soils. Soils which have the SOC associated with clay plus silt size fraction in amounts approaching or exceeding the protective capacity in general were those which had C accumulation in the > 20 μm size fraction. Since the SOC in Black soils has already decreased to about 50% of the protective capacity, there may be a greater potential for sequestering C in these Black soils than in the Baijiang soils.