Variability of Beryllium-7 and Its Potential for Documenting Soil and Soil Organic Carbon Redistribution by Erosion

Limited understanding of the redistribution of soil and soil organic C (SOC) within landscapes and their corresponding delivery ratios is available. To improve this assignment, the beryllium-7 (Be-7) technique and a simple conversion model were used to estimate soil and SOC redistribution rates on a sloping cropland plot (5 m wide and 15 m long with a slope of 10 degrees) in the hilly red soil region of southern China. Results showed that the soil erosion and deposition rates were relatively consistent with the magnitude of a rainfall event, and the estimated net soil and SOC losses were close to the measured values. These findings suggested the potential of Be-7 measurements in quantifying soil and SOC redistribution patterns associated with short-term erosion from heavy rainfalls. The spatial redistribution patterns of soil and SOC presented alternating erosion-deposition patterns from the slope crest to the bottom. Heavy erosion occurred in the upper-and lower-middle regions of the slope. The estimated net soil and SOC loss were 1.14 kg m(-2) and 23.00 g m(-2) for tillage from spring to summer (S-S, March-July 2013), clearly exceeding the soil (0.017 kg m(-2)) and SOC loss (0.43 g m(-2)) observed for no tillage from summer to winter (S-W, July 2013-January 2014). The sediment delivery rates in the two periods were calculated to be 64.41 and 2.51%, respectively, and the SOC delivery rates were estimated to be 58.17 and 6.48%, respectively. Depending on the weather conditions, tillage can result in a substantial increase in soil and SOC loss under traditional land use.