Keywords: Phosphorus fertilisation, phosphorus cycle, equilibrium fertilisation, phosphorus management, manure.
The global flow of phosphorus is essentially linear and irreversible. After being mined, phosphorus is applied to agricultural soils where it is taken up by crops or where it accumulates in the soil. Crop produce is directly or indirectly consumed by humans. The major part of the phosphorus consumed by humans is excreted again in faeces, ending up in sewage. Finally, phosphorus-containing effluent from sewage treatment works finds it way to the sea. Due to this one-way-traffic of phosphorus fluxes, new phosphorus has to be introduced into the system as necessary. The products used for this, however, largely originate from finite reserves which are estimated to become exhausted within one to two centuries.
There are two major problems: application rates are unnecessarily high in countries such as the Netherlands and phosphorus is hardly recycled despite its finite character. In the paper the reasons why phosphorus application rates in the Netherlands have become so high is analysed. Strategies to reduce phosphorus inputs and to increase recycling of phosphorus are also presented and discussed.
J J Neeteson, J J Schröder, A L Smit, J F F P Bos and J Verloop, Plant Research International, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, Netherlands.
23 pages, 10 figures, 4 tables, 37 references.