Are We Heading Toward Peak Fertilizer?

You've heard of peak oil—the idea that the globe's easy-to-get-to petroleum reserves are largely cashed, and most of what's left is the hard stuff, buried in deep-sea deposits or tar sands. But what about peak phosphorus and potassium? These elements form two-thirds of the holy agricultural triumvirate of nitrogen, phosphorus, and potassium (also known as NPK, from their respective markers in the periodic table). These nutrients, which are essential for plants to grow, are extracted from soil every time we harvest crops, and have to be replaced if farmland is to remain productive.

For most of agricultural history, successful farming has been about figuring out how to recycle these elements (although no one had identified them until the 19th century). That meant returning food waste, animal waste, and in some cases, human waste to the soil. Early in the 20th century, we learned to mass produce N, P, and K—giving rise to the modern concept of fertilizer, and what's now known as industrial agriculture.

The N in NPK, nitrogen, can literally be synthesized from thin air, through a process developed in the early 20th century by the German chemist Fritz Haber. Our reliance on synthetic nitrogen fertilizer (as its known) carries its own vast array of problems—not least of which that making it requires an enormous amount of fossil energy. (I examined the dilemmas of synthetic N in a 2011 series at Grist.) But phosphorus and potassium cannot be synthesized—they're found in significant amounts only in a few large deposits scattered across the planet, in the form, respectively, of phosphate rock and potash. After less than a century of industrial ag, we're starting to burn through them. In a column in the November 14 Nature, the legendary investor Jeremy Grantham lays out why that's a problem:

These two elements cannot be made, cannot be substituted, are necessary to grow all life forms, and are mined and depleted. It’s a scary set of statements. Former Soviet states and Canada have more than 70% of the potash. Morocco has 85% of all high-grade phosphates. It is the most important quasi-monopoly in economic history.

What happens when these fertilizers run out is a question I can’t get satisfactorily answered and, believe me, I have tried. There seems to be only one conclusion: their use must be drastically reduced in the next 20-40 years or we will begin to starve.

Why listen to this guy? Grantham, cofounder and chief strategist for the Boston firm Grantham Mayo Van Otterloo, has avoided or at least foreseen every bubble from the Japanese equity/real estate craze of the '80s right up to our own real estate mania of the 2000s. Back in fall 2007, with the S&P 500 near all-time highs and months before the Bear Stearns nosedive, Grantham was publicly foretelling financial gloom and doom.

Grantham is also known for his real talk on climate change. The Nature piece I quoted focuses on that topic, and advises scientists to "be arrested (if necessary)," in order to inspire policy action on the climate crisis. And in a characteristically blunt November letter to his firm's investors, Grantham argued that "we should not unnecessarily ruin a pleasant and currently very serviceable planet just to maximize the short-term pro?ts of energy companies and others." That's more clearly stated than you'll get from any high-profile Democratic pol—and this from a financial titan, no less.

So, given his record of prescience and gift for getting to the heart of the matter, we should probably listen to Grantham when he says that our agricultural system is lurching toward collapse.