widespread eutrophication of aquatic and terrestrial ecosystems (e.g. Carton and Jarvis, 2001). This is however not the only reason to advocate more efficient fertiliser use in agriculture Most inorganic phosphate fertilisers such as triple-phosphate and diammonium phosphate contain rather high concentrations of cadmium1 and other toxic metals, and subsequent fertiliser application has led to substantial accumulation of toxic metals such as cadmium in agricultural topsoils (e.g. Spijker, 2006, Van der Veer, 2005, Nziguheba and Smolders, 2008). Like phosphate, cadmium also has a tendency to accumulate in the topsoil layer. As a consequence, the concentrations of cadmium in Dutch agricultural topsoils are now two to three times higher compared with naturally prevailing concentrations (e.g. Spijker, 2006, Van der Veer, 2005). Farmers have to use P from animal manure more efficiently. This goes at the expense of P from fertilisers. However, the input of Cu and Zn becomes therefore higher than crops need. Cd can be a environmental issue but the risk declines due to a lower use. 41 1 An overview of cadmium concentrations in different inorganic phosphate fertilisers can be found in Van der Veer (2005), MMF (2008) and Nziguheba and Smolders (2008). Pagina 50

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