SREL Reprint #1999
Soil Contamination of Plant Surfaces from Grazing and Rainfall Interactions
T. G. Hinton*, J. M. Stoll & L. Tobler
Paul Scherrer Institute, Villigen, CH-5232 Switzerland
ABSTRACT
Contaminants often attach to soil particles, and their subsequent environmental
transport is largely determined by processes that govern soil movement. We
examined the influence of grazing intensity on soil contamination of pastures. Four
different grazing densities of sheep were tested against an ungrazed control plot.
Scandium concentrations were determined by neutron activation analysis and was
used as a tracer of soil adhesion on vegetation. Soil loadings (g soil kg-1 dry plant)
increased 60% when grazing intensity was increased by a factor off our (p =
0.003). Rain and wind removed soil from vegetation in the ungrazed control plots,
but when grazing sheep were present, an increase in rain from 0.3 to 9.7 mm
caused a 130% increase in soil contamination. Multiple regression was used to
develop an equation that predicts soil loadings as a function of grazing density,
rainfall and wind speed (p = 0.0001, r2 = 0.78). The model predicts that if grazing
management were to be used as a tool to reduce contaminant intake from
inadvertent consumption of resuspended soil by grazing animals, grazing densities
would have to be reduced 2.5 times to reduce soil loadings by 50%.
SREL Reprint #1999
Hinton, T.G., J.M. Stoll, and L. Tobler. 1995. Soil contamination of plant surfaces from grazing and rainfall interactions. Journal of Environmental Radioactivity 29:11-26.
