Of all the elements of critical importance to plants, phosophorus is the least commonly found, and sources are rarely available locally. Of all the phosphatic fertilisers used, Europe and North America consume 75% (and get least return from this input because of overuse, over-irrigation, and poor soil economy). If we really wanted to reduce world famine, the redirection of these surplus phosphates to the poor soils of Africa and India (or any other food-deficient area) would do it. Forget about miracle plants; we need global ethics for all such essential soil resources. As long as we clear-cultivate, most of this essential and rare resource will end up in the sea.
table 8.1 - Permaculture: A Designers' Manual (1988)