Overall, about 90% of the phosphorus entering the system
is lost into the environment. Because of the increasing
scarcity of high-grade phosphate reserves, and the huge
problem of losses to surface waters and subsequent
nutrient pollution and eutrophication (see section 4.2,
4.3), it is imperative that we “close the loop” on the losses of phosphorus. In order to achieve a sustainable use of phosphorus, two main strategies should be apply to any
system (options for closing the phosphorus cycle are
developed further in Section 5):