Slough sewage works
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Phosphorus: Flushing away our future?

21 February 2014 Last updated at 18:55 GMT

Justin Rowlatt speaks to chemist Andrea Sella to find out just why phosphorus is so vital to sustaining life, and modern agriculture.

He also hears from Jeremy Grantham, a voice from the world of high finance, who warns that pretty soon Morocco may find itself with the dubious honour of a near-monopoly of the world's remaining phosphate supplies.

And Justin travels to Slough, near London, to take a look at one new way of staving off the dreaded day when the world eventually runs out of the stuff.