Soil aggregates play a central role in the soil organic carbon (SOC) sequestration. To understand the stabilization process of exogenous easily decomposable organic C in soil and aggregates, 13C-glucose was supplied to arable soils following a 20-year application of compost (CM), inorganic NPK (NPK) and a control (no fertilizer, CK). Soil was fractionated into large macroaggregate (>2000µm), small macroaggregate (250-2000µm), microaggregate (53-250µm), silt fraction (2-53µm) and clay fraction (CNPK>CCK over the entire incubation. The content of glucose-derived 13C in large and small macroaggregates decreased gradually, but steadily increased in the silt and clay fractions in all treatments over the 30-day incubation period. However, glucose-derived 13C in microaggregates remained at the constant level during the incubation. Our findings indicate that the proportion of 13C protected from dissolving in water during wet-sieving increased with the incubation, and the exogenous easily decomposable organic C could be more effectively maintained in organic C-rich soil (CM) than in organic C-poor soil (CK or NPK). Clearly, glucose-derived 13C was sequestrated and stabilized gradually in soil by redistribution from macroaggregates to silt and clay fractions.
