Dynamics of soil organic carbon in different-sized aggregates under splash erosion

Purpose Soil erosion drastically perturbs the global carbon cycle, and splash erosion is the first critical stage of soil erosion by water. Thus, studying the soil organic carbon (SOC) dynamic caused by splash erosion is essential. Methods Simulated rainfall splash experiments were conducted on three cultivated soils with different SOC contents (black soil, purple soil, and red soil) to investigate the dynamics of SOC related to splash erosion, and the splash distance was 0-5, 5-10, 10-17, 17-28, 28-40 cm, respectively. Results SOC was unevenly distributed and enriched in different-sized aggregates. The enrichment ratio of SOC (EROC) was basically greater than 1 and increased as the splash distance increased. Moreover, the variation of EROC differed from that in the aggregate enrichment ratio (ERA), and the EROC in large macroaggregates (> 0.5 mm) decreased with increasing ERA. The weight proportion of SOC mobilization with different-sized aggregates was consistent with the mass percentage of aggregates. Specifically, there was a significant positive exponential relationship between SOC mobilization and the aggregate mass of the greatest proportion, indicating that the mobilization of SOC was mainly affected by the aggregate mass of the greatest proportion. Conclusions Our findings indicated that SOC migration can be realized by aggregates transport under splash erosion, indicating that improving soil structure will help to reduce SOC migration and even loss.