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

Abstract

Core Ideas The 7Be technique can quantify soil and SOC redistribution under short‐term erosion. The heavy erosion happened in the up‐middle and down‐middle location of the slope. Depending on the weather, plowing can result in a substantial increase in 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 (7Be) 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°) 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 7Be 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.