The measurement of aggregate stability is often used as indices of charactering soil anti-erodibility and soil quality. The sensitive aggregate stability test

Le Bissonnais method

was used to assess aggregate stability and its breakdown mechanisms of Ferrisols in the present study. The measured aggregate stability indices by Le Bissonnais method were highly significantly linearly correlated with the aggregate amount with 0.25 mm in diameter

mean weigh diameter (MWD) and percentage of aggregate disruption determined by conventional wet sieving method. The aggregate size distribution (ASD) of dry 5~2 mm

2~1 mm

and 1~0.5 mm aggregates after fast wetting (FW)

slow wetting (SW) and wet-stirring (WS) treatments was significantly affected by treatment method and initial aggregate size. The FW treatment had the largest aggregate disruption

while WS treatment had the lowest aggregate disruption. It suggested that the aggregate breakdown in the Ferrisols was mainly caused by the entrapped air pressure in the soil porosity and clay different swelling when fast wetting. There was a significant relation between >0.25 mm aggregate content and organic matter

and similarly between aggregate MWD and organic matter. Results showed that the organic matter is the main cementing and stabilization agent of aggregate formation in the Ferrisols. The aggregate stability indices in the Ferrisols were significantly negatively related to clay content

and no relationships between aggregate stability and free iron content were been found.