Phosphorus has been used extensively for over 100 years as a fertiliser in modern industrial agriculture. This underappreciated resource is still decades from running out. This paper published in Scientific American advises us to act now to conserve it, or the future agriculture could collapse.

As complex as the chemistry of life may be, the conditions for the vigorous growth of plants often boil down to three numbers, say, 19-12-5. Those are the percentages of nitrogen, phosphorus and potassium, prominently displayed on every package of fertilizer. In the 20th century the three nutrients enabled agriculture to increase its productivity and the world