Impact of sugarcane cropping duration on soil aggregate stability and erodibility in subtropical regions

A comprehensive understanding of aggregate dynamics is the foundation for establishing sustainable sugarcane production systems, especially in vulnerable red soil ecosystems. While existing studies have established a basic understanding of aggregate formation and stabilization, the functional relationship between aggregate stability and erosion resistance under extended sugarcane monoculture remains inadequately characterized. We employed an integrated methodology combining dry/wet sieving, the Le Bissonnais method and scanning electron microscopy to quantitatively evaluate the soil aggregate stability and erosion resistance across six distinct cultivation chrono-sequences (3–32 years) and two soil depths (0–15 cm and 15–30 cm) in the sugarcane cultivation area of Qingshui Village, Wuxuan County, Guangxi Zhuang Autonomous Region, China, aiming at providing insights for developing soil conservation strategies in sugarcane cultivation systems. The results reveal three core findings. First, planting years significantly influence the proportions of soil aggregates with varying particle sizes. Under the treatments with Le Bissonais methods, the mean weight diameter (MWD) under fast wetting, disturbance after pre-wetting, and slow wetting decrease with increasing planting years, while the relative dissipation index, relative mechanical fragmentation index, and erodibility factor (K) exhibit varying degrees of change, indicating progressive soil structural degradation and increased erosion susceptibility. Second, long-term sugarcane monocropping leads to declining soil organic carbon, liquid limit, plastic limit, and clay content, likely due to factors such as soil-forming materials and rainfall. Concurrently, the increased sand content and porosity weaken interparticle bonding and reducing aggregate stability over time. Third, correlation analysis demonstrates that MWD and geometric mean diameter (GMD) under disturbance after pre-wetting and slow wetting treatments show strong positive correlations with soil organic carbon, pH, clay content, liquid limit, and plastic limit but negative correlations with sand content, total porosity, and capillary porosity. Furthermore, K is significantly negatively correlated with soil physicochemical properties as well as GMD and MWD. These results help us understand the mechanism of aggregate stability variation in sugarcane-cultivated red soils and support the development of soil conservation strategies for sustaining sugarcane productivity in subtropical regions.