The United States has only 12 phosphorus mines. The supplies from the most productive mine, in Florida, are declining rapidly -- it will be commercially depleted within 20 years. The United States exported phosphorus for decades but now imports about 10 percent of its supply, all from Morocco, with which it signed a free trade agreement in 2004.
The effects of this resource shortage will be felt long before the last phosphorus atom is extracted from the last mine. Increased demand for fertilizer and the decreased supply of phosphorus exports will result in higher prices, significantly affecting millions of farmers in the developing world who live on the brink of bankruptcy and starvation. Rising fertilizer prices could tip this balance.
Already, signs are emerging that our current practices cannot continue for long. Between 2003 and 2008, phosphate fertilizer prices rose approximately 350 percent. In 2008, rising food prices sparked riots in more than 40 countries. Although the spike in fertilizer prices was only partially responsible for the higher food prices, the riots illustrate the social upheaval caused by disruptions to the world's food supply. The 2008 food riots were only stopped by government promises of food subsidies -- a viable strategy only as long as governments can afford the ever-increasing costs of food support.
Establishing a reliable phosphorus supply is essential for assuring long-term, sustainable food security. We need to dramatically reduce the demand for phosphate rock by eliminating our wasteful practices. This will require a combination of low-tech and high-tech solutions, including efforts to prevent soil erosion, development of more-targeted methods of fertilizer application, and the creation of new, phosphorus-efficient crops, which produce a larger yield per phosphorus unit applied. Fortunately, unlike fossil fuels, phosphorus can be used over and over -- this is what occurs in natural ecosystems, where it is recycled innumerable times from its first mobilization from the Earth's crust to its eventual deposition into lake and ocean sediments.
If we fail to meet this challenge, humanity faces a Malthusian trap of widespread famine on a scale that we have not yet experienced. The geopolitical impacts of such disruptions will be severe, as an increasing number of states fail to provide their citizens with a sufficient food supply. This dark scenario need not, however, be our fate. If we are successful in rising to the phosphorus sustainability challenge, as well as other aspects of sustainable agriculture, we can look forward to a future in which families, communities, and countries are healthy and secure in their nutrition and where all live in a world with cleaner rivers, lakes, and oceans.