Many have predicted there will be wars over water and oil, but one Arizona State University professor says phosphorus should be added to that list.

"There will be wars over water and oil. And right along with that, there will be wars over phosphorus," said Mark Edwards, a marketing professor and co-organizer of Arizona State University's Sustainable Phosphorus Initiative.

In 2009, a pair of Australian scientists published studies suggesting that demand for phosphorus could exceed supplies as early as 2035. Using the term "peak phosphorus," an analogy to peak oil, they relied partly on a Geological Survey estimate that the world had 16 billion tons of minable phosphate rock.

Phosphorus is often overlooked of the big three macronutrients because supplies of nitrogen and potash are readily available with no shortages projected anytime soon. However, the supply of phosphate rock is not as plentiful.

Scientists have estimated that minable supplies may not be sufficient to meet worldwide demand within decades. The situation could lead to higher food prices, famine and worse.

Despite Edwards’ prediction, others disagree. Robert Shirley, with PotashCorp, says phosphate supplies will not run out anytime soon and the thought that it will is inconceivable.

PotashCorp estimates that the Aurora, N.C., mine will be productive for at least 49 years, and while some people can think about the global implications of a possible shortage, Shirley focuses on how crucial phosphorus is to the local economy.