Objective Understanding the accumulation, distribution, and characteristics of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) is essential for clarifying the formation and stabilization mechanisms of soil organic carbon (SOC) pools.

Method This study investigated typical dryland red soils derived from four parent materials (Quaternary red clay, sandstone, slate, and granite) in the WeiShui River Basin of Hunan Province. The contents and distribution ratios of POC and MAOC, as well as their relationships with SOC and soil texture were analyzed.

Result The results showed that MAOC constituted the dominant fraction of SOC across the studied soils. Parent materials significantly (P < 0.05) influenced SOC and MAOC contents but exhibited no significant effect (P > 0.05) on POC. The contents of SOC and MAOC in dryland red soils developed from slate and sandstone weathering materials were significantly (P < 0.05) or obviously higher than those developed from Quaternary red clay and granite weathering materials. Furthermore, parent materials also significantly (P < 0.05) affected the distribution ratios of POC and MAOC in dryland red soils. The red soil developed from granite weathering materials had the highest POC distribution ratio, which was significantly (P < 0.05) higher than that of sandstone weathering materials, while its MAOC distribution ratio showed the opposite trend. Correlation analysis indicated that both SOC and MAOC had a significant positive correlation with soil silt content.

Conclusion In summary, parent materials significantly influenced SOC and MAOC in dryland red soils, with silt content was a key factor for the variability of SOC and its component accumulation across dryland red soils derived from different parent materials.