Ökologische Aspekte des Phosphor-Kreislaufs

In contrast to the complex N-cycle with its high number of reactive compounds, the global P-cycle is uncomplicated. There is only one reactive compound (PO₄ ^3?), and the atmosphere is practically not involved. Nevertheless, severe ecological imbalances may be induced by anthropogenic perturbations of the P-cycle, especially in aquatic ecosystems. The present knowledge on the global P-cycle (reservoirs, fluxes, residence times) is summarized and the ecological dimension of increased phosphorus inputs into surface waters is discussed in detail. Exemplary for Germany, the role of agriculture is described in this context. The fact that the rock phosphate resources are principally limited and not renewable is of a high ecological and economical relevance. The expected lifetime of the P-reserves is calculated for different estimate-scenarios concerning the magnitude of reserves and consumption. Measures to reduce the P-surplus in agriculture, to increase the efficiency of P-fertilization, and to recycle P more consequently are therefore highly required.