Heavy-metal balances of agro-ecosystems in the Netherlands

Abstract

In this paper, heavy-metal flows (cadmium, copper, lead, and zinc) of arable, dairy and mixed farming systems in the Netherlands are studied. Farm-gate and field-scale balances are calculated. On the field-scale, static and dynamic balances are distinguished. By determining the characteristic metal flows, it becomes possible to differentiate between farming systems and to select the most viable options for sustainable heavy-metal management. The crop rotation and the choice of fertilizers clearly influence the heavy-metal balance of arable farming system. In dairy farming systems, the role of feed management is very important, but the effects on the heavy-metal balance are not always straightforward. Mixed farming systems compare favorably with specialized (arable or dairy) farming systems with regard to heavy-metal accumulation. Due to the internal cycling of feedstuff and manure, less inputs are required and thus the import of heavy-metal containing raw materials and products is minimized. Uncertainties related to the calculation of heavy-metal balances are discussed.