Search

Although soil erosion and land use change have long been focuses in carbon research, the combined influence of soil erosion and vegetation rehabilitation on aggregate stability and the associated soil organic carbon (SOC) and total nitrogen (TN) remains unclear. The current study evaluated the effects of soil erosion on aggregate stability and the associated SOC and TN dynamics in relation to vegetation rehabilitation after the implementation of the “Grain-for-Green” project in the hilly Loess region. A check dam sediment sequence was dated using 137 Cs activity and erosive rainfall events. The SOC and TN in the bulk soil and aggregate fractions were measured in soils from rehabilitated grasslands and sloping croplands and in sediments retained by the check dam. The results showed that vegetation rehabilitation led to 78%, 27% and 9% average increases in the macroaggregate amount, mean weight diameter (MWD) and mean geometric diameter (MGD), respectively. In addition, rehabilitation resulted in the highest SOC and TN concentrations and contents in macroaggregates among all the aggregate size fractions. Soil erosion facilitated the modification of the aggregate size distributions along with soil mineralization and induced the incorporation of deeper SOC-poor soils during transport. These processes resulted in the aggregate-associated SOC and TN concentrations and contents in the sediments being significantly lower than those in the eroding sloping cropland soils. The highest reductions were found in microaggregates, which exhibited decreases of 48% and 44% for SOC and TN, respectively. Moreover, reaggregation and gully soils incorporated during soil erosion led to higher values of macroaggregate amount and aggregate stability at depositional sites than those at eroding sloping cropland sites in this study. Our study contributes to the understanding of the effects of soil erosion and vegetation rehabilitation on SOC and TN dynamics, which is crucial for understanding the restoration efficiency in soil erosion control and ecosystem security evaluation. [ABSTRACT FROM AUTHOR]

• Splash erosion affected the redistribution of soil particles and SIC. • The redistribution of splashed material and SIC varied with soil type. • SIC had sorting and enrichment characteristics. Splash erosion caused by raindrops is the first stage of water erosion that detaches and transports soil particles. As an important component of soil particles, soil inorganic carbon (SIC) contains little information on its redistribution during splash erosion. In this study, two soils, purple soil and loess, were selected and placed in a soil tray with a diameter of 20 cm at the center of a splash tray, and a rainfall simulator was used to simulate three raindrop energies in experiments to investigate the migration of soil particles and SIC. The results showed differences in the amount and selective migration of splashed material between the soils, which was evident in the obvious sorting of the particle size of purple soil with distance and the insignificant change of loess soil. The SIC sorting characteristic performed differently in the two soils, that is, the SIC content of purple soil increased with particle size, while that of loess was the opposite. The enrichment and depletion of SIC during splash erosion varied with soil type, and differed from the general enrichment of soil organic carbon (SOC). The SIC enrichment ratio (ER IC) of purple soil was generally > 1, whereas the ER IC values of loess were < 1. In addition, multiple linear regression (MLR) models were established to predict the SIC content of splashed material. Rainfall splash plays an important role in SIC migration and may further affect the carbon cycle. These preliminary results provide a basis for further study of SIC response to rainfall splash. [ABSTRACT FROM AUTHOR]