The takeover sprung upon Potash Corp of Saskatchewan, Canada, by BHP Billiton of Melbourne, Australia, is a seismic shift in the future of food. Demand for potash, a mineral salt that is mined and used as crop fertiliser, has risen because the world needs to produce more food to feed an increased population, and there is limited land for cultivation. Added to this is the rising wealth of highly populated countries in Asia, with a growing appetite for meat. If you want to produce a lot of meat, you need a lot of grain – 7kg for every 1kg of beef – and the broad view is that to achieve this, you need large quantities of NPK – or fertiliser that combines nitrogen with potassium, the latter found in potash.