Title : Soil organic carbon sink and losses in sloping erosion-prone farmland
Abstract:
Soil organic carbon (SOC), primarily accumulated in the surface layers of sloping farmland, experiences disrupted distribution due to soil erosion, significantly affecting its lateral transport and vertical sequestration within the soil profile. To gain a deeper understanding of interaction between erosion and carbon cycle, the study evaluated spatial variations in erosion-deposition rates, SOC content and fractions across two tillage practices: inclined slope-ridge tillage (SRT) and cross-ridge tillage (CRT), by integrating Caesium-137 (¹³?Cs) technique with advanced wavelet analysis theory. The findings revealed lower ¹³?Cs inventories for both SRT (732.96 Bq·m?²) and CRT (1000.98 Bq·m?²) compared to the reference value (2468.77 Bq · m ? ² ), confirming the occurrence of erosion. However, CRT exhibited a significantly lower erosion rate (3056.65 t·km²·a?¹) than SRT (4409.04 t·km²·a?¹), highlighting its greater effectiveness in mitigating soil and water losses. Wavelet analysis further revealed periodic erosion-deposition patterns under both tillage practices, which corresponded to variations in SOC and its fractions. A significant negative correlation was observed between SOC content and cumulative mineralization with the soil erosion rate. Correlation analysis confirmed that SOC fractions play a crucial role in driving SOC mineralization and are closely linked with SOC dynamics. Random forest importance ranking analysis identified the average annual soil erosion rate, SOC, and dissolved organic carbon (DOC) content as the most significant factors affecting SOC mineralization under SRT. The findings suggest that CRT is more effective in reducing soil erosion by modifying microtopography, thereby minimizing the migration of mineral-associated organic carbon (MAOC) and enhancing SOC retention. This research contributes to the development of sustainable land management practices in the region, mitigating the adverse effects of erosion on the carbon cycle.
