Uncertainty assessment in modelling cadmium and zinc accumulation in agricultural soils

The sustainability of current land use in agro-ecosystems can be assessed with respect to heavy-metal accumulation in soil by balancing their input and output fluxes. Even small heavy-metal accumulation rate in soils may lead to a violation of soil quality standards in the future. To undertake suitable preventive measures against heavy-metal enrichment in soil, estimated input and output fluxes need to be reliable. For this task we developed an empirical stochastic model that considers heavy-metal inputs by agricultural management as well as outputs, such as crop removal and leaching. In order to quantify the uncertainty in model output, we propagated the uncertainty in model parameter using a Latin Hypercube sampling strategy. In this paper we present the regional cadmium and zinc balances for the test region Sundgau, Switzerland, and the contribution of uncertain input parameters to the total variation of the net heavy-metal fluxes as determined by uncertainty analyses.