Short-term erosion rates from a 7Be inventory balance

Detailed soil erosion studies benefit from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for Be-7 was used to calculate sediment erosion in a 30.73 m(2) plot during a series of runoff-producing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, Iowa, USA. The inventory balance included determination of the pre- and post-storm Be-7 inventories in the soil, the atmospheric influx of Be-7 during the event, and profiles of the Be-7 activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the Be-7 inventory balance was 0.058 g cm(-2), which is 23 per cent of the annual average erosion determined using Cs-137 inventories. The calculated erosion from the mass balance is similar to the 0.059 g cm(-2) of erosion estimated from the amount of sediment collected at the outlet of the 6 ha field during the study period and the delivery ratio (0.64). The inventory balance of Be-7 provides a new means for evaluating soil erosion over the time period most relevant to quantifying the prediction of erosion from runoff. Copyright (C) 2003 John Wiley Sons, Ltd.