The exponential growth in global food production has not only sent the price of fertilisers skyrocketing, but could lead to a world shortage of phosphate within decades. Beyond a temporary market spike driven by richer developing countries and increased supply of biofuels, researchers are warning that the world could face dwindling supplies of phosphate by 2040 unless steps are taken to use it more efficiently and recover it from human waste. But unlike oil, which can be managed by substituting other sources of energy, there is no substitute for the critical role of phosphate in plant development and production. Mineral...