Using natural gas as your source of energy, you can synthesise nitrogen right out of the air. But you cannot synthesis the other two ingredients in the holy plant growing triad: phosphorous and potassium.
Oil, because we have used up so much of the stuff in the safe places to get to it, is now found in a variety of sometimes scary places. Phosphate is less easily found, and all of it is one somewhat scary place.
Tom Philpott, Mother Jones, 28 November 2012
These two elements [, phosphorous and potassium,] 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…
our friendly neighbor Canada sits on a vast potash stash. But phosphate rock is largely concentrated in Morocco—and not just anywhere in Morocco. It's in the country's Western Sahara region, on highly disputed land. In a superb 2011 piece in Yale Environment 360, the environmental writer Fred Pearce explained:
The Western Sahara is an occupied territory. In 1976, when Spanish colonialists left, its neighbor Morocco invaded, and has held it ever since. Most observers believe the vast phosphate deposits were the major reason that Morocco took an interest. Whatever the truth, the Polisario Front, a rebel movement the UN recognizes as the rightful representatives of the territory, would like it back.