Soil organic carbon in Ultisol landscapes: Influence of erosion rates, soil development, depth, and hillslope properties

Key Points

• To quantify soil organic carbon stocks and examine their relationships with erosion rates and soil properties in Ultisol landscapes.
• Analyzed SOC stocks from 30 soil pits in low-order watersheds
• Measured erosion rates using 10Be isotopes
• Examined soil depth, clay content, and pedogenic iron concentrations
• Compared SOC across different hillslope positions and aspects
• SOC stocks are higher in basins with lower erosion rates
• Well-developed soils show greater SOC due to higher clay and iron content
• SOC density varies more with erosion rates than with hillslope aspect or position
• Significant SOC storage is found below 30 cm depth, often underestimated in surface samples