A modified model for estimating soil redistribution on grassland by using 7Be measurements

Background and aims

⁷Be has been used as a powerful tracer for estimating short-term soil redistribution by virtue of its short half-life. However, the existing conversion model associated with this radionuclide means that it can only be applied to bare soils because vegetation will intercept a large proportion of ⁷Be fallout. A modified model which takes into consideration the impact factor of vegetation was reported in this paper and the estimation of soil redistribution was compared by using both the conventional and the modified models.

Methods

Field experiment on ⁷Be distribution in above-ground grasses and soils was carried out on a 100 m² grass-covered slope. The vegetation interception factor (P) was determined and the soil redistribution rates were calculated by using the previous model and the modified model.

Results

The result shows that nearly 40 % of the atmospherically deposited ⁷Be will be sequestered by leaf surfaces of herbaceous plants. Soil loss rates on grassland will be remarkably overestimated by using the previous model.

Conclusions

The net soil loss estimated from the modified model is more accurate than that derived from the conventional model and the modified model will be more appropriate to estimate soil redistribution rates on soils with significant vegetation cover by using ⁷Be technique.