Abstract:Through filed sampling and laboratory analysis, the composition and fractal features of profile soil micro-aggregates in purple hilly area with different land use types were studied. The results showed as follows: Among woodland, pepper filed, dry land, paddy and citrus orchard, micro-aggregates of 0.25~0.05 mm was dominant, followed by micro-aggregates of 0.05 to 0.01 mm, which appropriated 18.80% to 35.57% of the total samples, the least were <0.001 mm, which proportion was between 0.33% and 2.57%. In 0—20 cm soil layer, the annual mean weight soil surface area (MWSSA) sequence was woodland (161.04 cm2/g)>citrus orchard (134.49 cm2/g)>pepper land (117.31 cm2/g)>paddy (100.67 cm2/g)>dry land (96.94 cm2/g). In this layer, the MWSSA of woodland micro-aggregates was significantly higher than other land use types,which aggregate state and aggregate degree superior than others as its aggregate state showed a 16.55%, 20.15%, 11.23% and 7.68% higher than pepper filed, upland, paddy and citrus orchard, respectively. In 20—40 cm soil layer, the fractal features D of each land use type is like citrus orchard (2.41)>woodland (2.40)>pepper field (2.32)>paddy (2.31)>upland (2.12), the D value of upland is significantly lower than other lands. The fractal features of these five land correlate with the result of factor analysis, though some inconsistent exist. Hence, the fractal features of micro-aggregates in different land use type can be, to some extent, seen as an index to characterize superior or inferior of soil physical properties, fertility level and corrosion resistance.