Abstract: The composition and stability of soil aggregates in sloping yellow soil cropland during the whole maize growing season under natural rainfall conditions were studied in an attempt to reveal the effects of tillage measures and maize growing season on soil aggregates' stability. Cross ridge slope was taken as research object, while longitudinal ridge slope as the control. The study is expected to provide theoretical basis for the study of anti-erodibility of mountain yellow soil in Sichuan Province. Results demonstrated that: 1) The composition and stability of soil aggregate were significantly affected by tillage measures. Compared with that on longitudinal ridge, more soil macro-aggregates were contained on cross ridge slope; the stability of cross ridge slope is better than that of longitudinal ridge slope according to analysis on such indicators as (10,0.25] mm water-stable aggregate (WSA_>0.25), mean weight diameter (MWD), geometric mean diameter (GMD), percentage of aggregate disruption (PAD), fractal dimension (D) of soil water-stable aggregate, and aggregate stability index (ASI). 2) With the advancement of maize growth, the content of soil macro-aggregate and soil aggregate stability both showed a significant increasing trend and reached a maximum value at maturing stage, implying significant influence of maize growing season on soil aggregate's composition and stability. 3) Correlation analysis unveiled that soil aggregate's stability was in extremely significant positive relationships with root density, root surface area and root volume, indicating that root development played an important role on improving soil aggregate's stability. The findings demonstrated that suitable tillage measures and proper planting patterns could effectively prevent and control regional soil erosion.

Key words: sloping yellow soil cropland, soil aggregate's composition, soil aggregate's stability, tillage measures, maize growing season