Science Interviews


Fri, 6th May 2016

The phosphorus famine

Dr James Dyke, University of Southampton

Listen Now    Download as mp3 from the show Phosphorus: Essential to All Life But Are We Running Out?

You need phosphorus to live and we're running out. When will we start to see Dandelionsupplies dwindle and is there anything we can do? Dr James Dyke is the co-chair of Sustainability Science Southampton explained to Kat Arney the predicament we face...

James - Well, the vast majority of phosphorus comes from phosphate rocks. So phosphorus is not a particularly rare element in the earthís crust . About 1% of the earthís crust is comprised of phosphorus, so that translates to something like 1,000 billion, billion tons of phosphorus. So thereís a lot of phosphorus around. Unfortunately, there are not a lot of high concentration deposits of phosphorus and itís those high concentrations deposits that thus far weíve entirely relied on to power our agricultural system.

Kat - So to just draw a parallel with something like oil. Are there particular places in the world that are the phosphate capitals of the world where this stuff can be mined?

James - There are, and thereís actually many fewer places so, in terms of the good quality phosphate deposit, youíre looking at China, the United States, Morocco and a couple of other countries that have about 85% of the entire reserves of phosphorus.  In Morocco and the Western Sahara alone, youíre looking at about 75% of all the known high quality phosphorus reserves.

Kat - That to me seems kind of risky. Itís always risky when you hear about an essential resource that is concentrated just in one or two places in the world.

James - It might be, mighten it? You might think that certain wars have been fought over getting hold of oil.  Weíve seen armed conflicts for water. So one of the concerns is when we see these high concentration deposits that begin to be depleted, we could be looking at just a handful of countries largely controlling the worldís supply of phosphorus.

Kat - Bring on the phosphorus warsÖ NOT!  Again, to draw another parallel with oil, thereís been a lot of discussion about peak oil - have we reached that? How many fossil fuels are left in the ground? Where are we in terms of phosphorus, of phosphate thatís left?

James - Ah well, that is the 6 million dollar question, isn't it? So it will depend widely on who you ask. If you talk to the International Fertilizer Development Centre, it thinks we will not see any constraints on phosphorus supply for a matter of centuries, maybe up to 300 years. If you were to go and look at the United States Geological Survey figures from just a few years ago, they will be giving peak phosphorus, so the maximum rate of phosphorus and thereafter the amount that we produce is going to get smaller every year, theyíre going to put that at as little as 2030. So, in as little as a few decades we could see a continual and progressive decline in our ability to extract phosphorus from rocks.

Kat - In that case, if that scenario is actually the one thatís correct, this is actually quite an urgent problem but then, what happens to it. Itís made into fertilizer, it goes onto the fields. Then what happens - why do we lose it out of the cycle?

James - Yes, you would think that given that itís actually crucial for all human life, at least, and all life on the surface biosphere weíd be a bit more careful with it. But when you look at how much we waste, itís an extraordinary amount. Itís about 80% of the phosphorus thatís initially used, initially dug out of the ground, is wasted before a human actually consumes it. So there are many points at which itís wasted; itís wasted initially when itís dug up and processed, there are losses there. There are losses when we put it on the field; soil erosion it gets blow away by the wind, it gets washed away by water. Then when we grow the crops thereís significant amounts of food thatís lost globally. So about 30% of global food produced is lost before it gets to market and then, when itís bought it  in developed nations, we waste a lot of food because we buy too much food and then we throw that food away.

At each point on that process we are losing those phosphorus elements.  I mean, we canít ever run out of phosphorus, it doesnít leave the earth but weíre continually diluting that easy to get, high concentration deposits.

Kat - And in terms of the stuff that we put on the fields that gets leeched away or lost, where does that end up?

James - Well, unfortunately, for many habitats it ends up in water courses. In certain countries, particular regions of China letís say, thereís a large amount of input of phosphorus fertilizer on the lands. Unfortunately, soil management is quite poor, large amounts of soil end up in the water laden with phosphorus, it runs down through rivers into lakes and there it produces eutrophication events. It promotes so much algae, the algae clog up the surface of the lake, they fall down to the bottom, they produce these low oxygen situations which rapidly kill all the large plants and fish. They go from nice productive aquatic environments that can produce fish for human as well as other wildlife to these rather unpleasant green, stinking lakes which can stay in that state for a very, very long time after the input of phosphorus is stopped. So itís a real ecological problem.

Kat - So how should we be viewing phosphorus if it can cause this eutrophication? Is it a pollutant, is it a finite resource, is it precious? How should we be viewing it?

James - Well itís both. Itís absolutely crucial for life but itís also an incredibly damaging pollutant that we put into our water courses so, itís a finite resource in the sense of the high concentration deposits. There should be enough that would last us, but we need to do a much better job in managing the reserves that we have, and then also making sure that we donít lose so much and then end up using it, essentially, as a pollutant.

Kat - What can we do to lessen this problem?

James - Well, thus far weíve looked at it as a supply site problem. So, the increase in phosphorus, when you look back over time, itís undergone this kind of exponential increase since the second world war but really, ultimately, what we need to be doing is taking some more inspirations from the biosphere. Phosphorus is a limiting nutrient for all life on earth and the biosphereís figured out how to recycle phosphorus so itís ultimately going to be reducing the losses from the system. So thatís more recycling, more careful application, and much less amount of food that weíre going to waste.


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