Out of joint

The global cycles of nitrogen and phosphorous

Published: Wednesday 30 June 2004

-- THE twenty-first century's just begun, and already its ecological contours have begun to appear. Hollywood has declared global warming will occur, spectacularly. But the day after tomorrow might bring about on Earth another -- much less monitored, even lesser talked about -- survival-threatening event: 'elemental wars' over nitrogen and phosphorous.

The more-yield-per-hectare mentality was a product of the post-World War II agricultural imagination. Its translation into bumper crops was predicated on an essential input: nitrogen- and phosphorous-based fertilisers. So began the increasingly urgent hunt for these two elements, the first synthesized out of thin air, the second scooped out from below. So, now, a situation where overuse of the first, and increasingly fraught availability of the second, are just beginning to throw our century out of joint.

Today nitrogen, available in plenty and supposed to render soil more fertile, is an established ecological scourge in the West, and as its use skyrockets in developing countries, poised to become so here. It is wreaking havoc in coastal, forest and freshwater ecosystems, and generously egging on the greenhouse effect. Our nitrogen intake comes from the food we eat; we excrete most of it. But this excreted and potentially usable nitrogen finds its way, not back to the land as it should, but into water via sewage systems: this is where the disruption of the nitrogen cycle is most visible.

And phosphorous? Available but dwindling, it has become the pretext for territorial conflict and is at the centre of an intense and emergent global politics to control its production and distribution flows. Worryingly enough, global policy is yet to factor phosphorous into its profound calculations.

Phosphorous is non-renewable; because it is basic to food security, its use cannot be discounted. But can such use not be made sustainable? While this is a question experts have still to mull about, the way out of the nitrogen nightmare is clearer: plug the disrupted cycle, by sending the wealth of nitrogen that today flows away as waste back to the land. In both cases, it is clear that their use ought to be restrained.

Will that happen? Now, that's a blockbuster of a question.

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