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The fact that our overreliance on fossil fuels is quickly draining easily accessible resources is becoming more known in the public. Now there is talk on several scientific and environmental radio shows that warn of declining phosphorus reserves.
The concern over a possible phosphorus shortage may seem contradictory to observations of increased algal blooms and eutrophication of inner water streams – a phenomenon where increased chemical nutrients in the environment lead to algal blooms and suffocation of aquatic life with detrimental  consequences to the environment – which at least in part are caused by increased bio-available phosphorus.

All this lead me to the question: Is there really a phosphorus shortage?

Phosphorus is the 15th element on our periodic table. In nature phosphorus never exists in its elementary form due to its reactivity [1]. Phosphorus is one of the essential elements of life because it is part of many structures in living cells from simple bacteria to complex multi-cellular organisms such as plants and animals.  For instance, the cell membrane containing each cell consists of phospholipids, and the backbone of the information carrying molecules DNA and RNA consist of phosphate groups as well.  For this reason, plants require phosphorus when growing: They absorb it through the roots in the soil. Animals, too, require phosphorus. But different from plants which can derive the needed phosphorus from the environment, animals rely mostly on other animals or plants to take up phosphorus by eating them.

What is the link between fertilizers and phosphorous?

Knowing that phosphorus is an essential element of life probably makes it less surprising to find that it is part of any fertilizer.
The interesting question was to ask where the phosphorus comes from. Historically, animal or human feces were commonly used for fertilizers because they naturally contain phosphates (and other essential nutrients of course). In fact, it was through boiling, filtering and processing of about 60 buckets of urine, how Henning Schmidt discovered phosphorus back in 1669 [2].  Today, organic matter has in many parts of the world been superseded by the use of modern synthetic fertilizers which use phosphate rocks as a source for raw material, which, interestingly, are only found in a few countries such as China, Russia, Morocco and part of the United States [1].
Phosphate rock, just like coal, oil, and other forms of fossil fuels, is a non-renewable natural resource. And this is the crux of the matter: Because we rely so much on synthetic phosphate fertilizers, the rate at which we consume the phosphate rock is rapidly increasing while the natural stocks are decreasing. In this context, Hubbart’s name is frequently mentioned who first observed and predicted in 1949 that oil will at some time reach a maximal rate of production when about 50% of the resources are still in the ground, after which production rates will go down. However, if demands are going up at the same time and costs for the raw material will likely increase as well [3,4,5]. This, Hubbart called “peak oil”, but it appears that the same fate will be true for phosphate rocks as well: There will be “peak phosphorus” in form of phosphate rock deposits that are quickly declining. But there is one big difference, however: Unlike oil, where alternatives exist for sources, there is no alternative for phosphorus. It is essential for life.

“Where do eutrophication and algal blooms come from?”, you ask…

 This leaves us with the question why algal blooms and eutrophication are happening more and more often? Ironically, it is in some parts due to excessive phosphorus leaking into water streams. Overfertilization, discarded animal feces, and human feces in large cities often lead to phosphorus leakage into the natural water cycle where they stimulate excessive algal growth. The problem is partly due to the current economic model which currently promotes a very linear and inefficient use of phosphorus. Simplified, phosphorus is added to plants, which will then be eaten by food stock animals or humans. Humans and animals then use some of the phosphorus for their own body and excrete the rest again. A lot of it nowadays is flushed away, into the waste water stream where it is not always cleaned before release. This leads to the aforementioned problems.


There are a couple of interesting observations to make:
1.)    The poorest agricultural lands are being exploited because those who can afford it first need to import phosphorus and from one of the other countries. The farmer then applies the fertilizer to grow crops, exports these crops (and thus part of the phosphorus goes away although it is most needed in the poorer country.
2.)    So ironically, although phosphate rock deposits are rapidly declining, the concentrations of phosphates in the water is partly to blame for current problems. What then is the solution to the dilemma? Instead of the often linear processes which includes mining/manufacturing/discarding, new methods of phosphorus recovery should be searched and applied.
3.)    Declining phosphorus reserves, and the resulting price increases will also affect 1st and 2nd generation biofuel production.

Literature Cited:

3.)    Cordell, D., Drangert, J.-O., and White, S., (2009) The Story of Phosphorus: Global food security and food for thought. Global Environmental Change, 2009. 19(2009): p. 292-305

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