| A field experiment was conducted to investigate the effect of long-term continuous cropping cotton on organic carbon and soil aggregate composition in Manas River oasis. Five patterns were conducted, including continuous cropping cotton, corn rotation, soybean rotation, corn and soybean intercropping and no-tillage. The results showed that the size distribution of soil mechanical aggregate stability was the highest for those between 53 and 250 μm, accounting for 39%～53%, while that of the water-stable aggregates was the lowest. The mechanical aggregate stability size of ＞250 μm showed significant difference among planting patterns, with an order of soybean rotation＞corn rotation＞no-tillage＞continuous cropping cotton＞corn and soybean intercropping. Soil aggregate index of soybean rotation and corn/soybean intercropping decreased by 18.7% and 15.6% in early spring, respectively. The contents of soil aggregate organic carbon and microbial biomass carbon are mainly in the size of >250 μm, being higher than that in microaggregate. The content of soil organic carbon showed an order of soybean rotation＞corn rotation＞continuous cropping＞no-tillage＞corn and soybean intercropping. Compared with rotation patterns, soybeans and corn rotation showed positive effect on stable aggregate formation, which can be used as a reasonable short-term crop rotation patterns. |