The richest deposits in North America are found in Florida and in eastern North Carolina, though output from these deposits has dropped by as much as 20 percent in the last few years.

Morocco commands the largest deposits, about 32 percent of the world’s share. Other major deposits are found in Western Sahara, South Africa, Jordan, Syria and Russia.

The Times also reports that a global struggle to secure depleting supplies of phosphorus is already well under way. For example, China, which possesses an estimated 13 billion tons of phosphate rock, has imposed a 135 percent tariff on phosphate rock exports — an action that sent ripples through the world economy.

It’s also buying up as much phosphorus as it can secure from foreign sources, including the United States, Mitchell says.

Skeptics may contend that humans have travelled down a similar road before. In the 19th century, for example, farmers were running critically short of guano, which then served as the primary source of nitrogen fertilizer. At about the time supplies approached depletion, with the specter of food shortages and famine looming, two German scientists stepped forward with a method for extracting nitrogen from the air.

However, phosphorus, by its nature, can’t be synthesized, Mitchell says.

If there is any good news, it’s that phosphorus, unlike energy produced from fossil fuels, isn’t irretrievably lost.

“We can destroy fossil fuels by burning them,” Mitchell says. “But you can’t destroy phosphorus — it’s going to remain in the biosphere somewhere, in plants and animals or in minerals in the soil.”

Likewise, he points to research that has demonstrated consistently that cropland with adequate stocks of phosphorus can remain under cultivation for years, if not centuries, without depletion of these stocks.
“That’s because plants don’t take up nearly as much phosphorus as they do potassium or nitrogen,” Mitchell says.

Even so, Mitchell predicts that effective stewardship of this rapidly depleting resource will become a major worldwide preoccupation over the next few decades.

Consequently, he says that old standby farming methods such as soil testing will take on renewed significance. For that matter, so will precision agriculture, which up to now, has been viewed primarily as a cost-saving measure.

Some experts are even calling for the formation of an international body to monitor the use and recycling of phosphorus.