The World’s Longest Conveyor Belt

Satellite image of the Bou Craa conveyor belt

The Bou Craa conveyor belt running through the arid Western Saharan terrain. Credit: Bing maps.

The longest conveyor belt in the world runs 61 miles from the hostile interior of Moroccan occupied Western Sahara to the port city of El-Aaiún. Open to gusty desert winds in many places, the belt’s precious white cargo is strewn across the dusty brown desert, marking  the Earth so profoundly that this massive machine’s outline can be seen from space.

Between around 100 and 55 million years ago, marine waters of the nascent and ever-widening Atlantic Ocean transgressed and regressed over this now dry land. These waters deposited thick muddy sediments containing the decaying tissue, bones, shells, and excrement of dead marine life that had collected and concentrated on the ocean floor over millions of years. As a result, this thick oozing mud, a complex mélange of fetid material, was rich in phosphorus.

Without phosphorus, life itself is not possible. It exists in all living things —in cells, in bones, indeed, even in DNA. For that reason, the mud that formed the hills of Western Sahara so many millions of years ago were full of phosphorus. Now, millions of years later, it is that same phosphorus that we extract from the Earth and load onto a conveyor belt.

Image of the port of El Aaiún viewed form a satellite.

The end of the line: the conveyor belt stretches into the Atlantic Ocean in El Aaiún. Credit: Bing maps.

The white powder that travels along this belt is phosphate. Phosphate, a mineral containing one phosphorus atom and four oxygen atoms, is one of the primary components of agricultural fertilizer. Unlike its counterpart, nitrate, phosphate cannot be synthesized. It forms only in rocks. The only way to get at is to mine it. It is a finite resource, and it is one that our world has come to depend on mightily.

This dependence began between the 1940s and the 1970s, when technological and agricultural advances allowed millions who would have otherwise starved to be fed. Known as the Green Revolution, these advances consisted of the improvement of irrigation systems, the development of high-yield cereal crops and most important, the widespread use the widespread use of synthetic fertilizer.

The component in fertilizer that is commonly assumed to have made the Green Revolution a reality is nitrogen. In 1909, Fritz Haber developed what later became known as the Haber-Bosch process, which made it possible to convert atmospheric nitrogen to a form that could be applied to crops. Its use in agriculture became central when Norman Borlaug, dubbed the father of the Green Revolution, began to advocate its application in the developing world.

But because nitrogen cannot act alone, its increase in fertilizer use spurred another, quieter revolution—a massive growth in the amount of phosphate rock mined for use in fertilizer. Life requires—among other things—both nitrogen and phosphorus. These two elements are the two nutrients that most often limit the growth and expansion of life.

Morocco (and with it Western Sahara), with its massive deposits coupled with minimal domestic needs, is the world’s largest exporter of phosphate. Indeed, much of our world’s food security is tied up in the production of phosphorus from the desolate desert regions of Western Sahara and Morocco, two regions whose boundaries remain contested to this day. This political instability should be cause for some concern—the world’s food supply depends on a steady flow of phosphate from this region.

Bags of fertilizer.

Bags of fertilizer. Credit: Cjp24.

During a worldwide food crisis in 2007 and 2008, the Moroccans repeatedly increased the price of phosphate, blaming the increase on high energy and shipping costs, as well as reduced industry stocks of phosphate. By raising the price on their exports, they drove the rest of the market to increase prices as well.

As a consequence of this and other factors, much of the developing world suffered staggering levels of starvation as price of food rose. Food riots broke out in at least 40 different countries. Thousands of workers rioted in Bangladesh. The prime minister of Haiti was overthrown, largely as the result of food shortages, and in Pakistan, the Pakistani army was deployed to guard food stockpiles.

Beyond political complications, there are other reasons for concern. Most obvious is the fact that phosphate is a finite resource, one that we will run out of someday. When that day comes is a hotly contested academic debate (the safe money seems to be on 300 years), but there is no denying the fact that it is going to run out and that there is no biochemical replacement for it.

It’s a precarious situation, but there are potential solutions. We need to be more judicious with our use of fertilizer—much of the phosphate we add to crops washes away without ever serving a biological role. We also waste many opportunities to recycle the phosphorus we do use back onto crops. Scientists are working on ways to reclaim phosphorus from human and animal waste, just as they are working on ways to make farmlands hold on to their phosphorus more efficiently. These two ends of the equation will help make the agricultural phosphorus cycle a closed loop—the way it is in the natural world.

But we are far from reaching that goal now. There seems to me to be no more potent a symbol of the fragility of our current system than the razor thin outline of a massive conveyor belt bleeding white across the brown arid desert of a poltically contested land. Viewed from space, it looks almost meaningless. But the world literally depends on its constant supply of phosphate. With only a bit of hyperbole, one could say this massive machine is what is feeding the billions of humans who inhabit this planet.


4 Comments on “The World’s Longest Conveyor Belt”

  1. Anthony Tabell says:

    Very good.

  2. […] From photos and satellite images, this conveyor belt in Morocco looks distant and isolated. But in reality, it is the first stretch in a long phosphate chain that eventually makes it way to us. Break it and we, sitting thousands of miles away, will likely feel the consequences. [Amusing Planet, The Sieve] […]

  3. […] From photos and satellite images, this conveyor belt in Morocco looks distant and isolated. But in reality, it is the first stretch in a long phosphate chain that eventually makes it way to us. Break it and we, sitting thousands of miles away, will likely feel the consequences. [Amusing Planet, The Sieve] […]

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