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An Element of Concern, Phosphorus: Food and our Future

December 31, 2010

If lake water turns (blue)green, it is overloaded with fertilizers like P

In the mid 80-ies, the high levels of phosphorus (P) in the surface waters caused a dramatic increase in eutrophication of lakes, rivers, and coastal regions in Europe, especially in the lower countries… Because algae like P.

Legislation kicked in, P wasn’t allowed anymore in detergents, and…over time, the environment improved.

P was not in the news for many years.

2011 may become a year where you might read and hear more about P….

….because there isn’t enough of it?…Because algae like P?

All life on earth is organic


Which means it is built around a central chemical element, carbon (C). The formula for living biomass is quite simple, something like CxHyOzNqPr.

The capitals C, H, O, N and P represent the elements that make up most, like more than 99%, of the biomass of anything that is alive, and the non-capitalized letters x, y, z, q and r represent numbers. The numbers express the exact ratio of how the elements (carbon, oxygen, nitrogen, phosphate) are blended together to make a particular life form. Buy the way, the numbers decrease from x (the highest) to r (the lowest). So the formula shows what is called the composition stoichiometry of the elements that make up biomass.There are several ways to present the stoichiomerty. One can choose r equal to one, so that the formula emphasizes how many of the other elements are present relative to the limiting element (which is P). The formula is also known as a C-mole of biomass, when you choose x to be one. If you want to read more about what one can do with composition stoichiometry, read my article ‘From Electrons to Biomass‘.

Of all elements that make up most of the living biomass, P is present in the smallest amount. In a situation where all elements are present in abundance, one kg of P will have the potential to make the biggest amount of biomass. It is like P has the highest leverage potential to make biomass.

Without P, nature cannot synthesize a new cell, or keep a cell’s machinery going. P is present everywhere, it is very difficult to find or create an environment where P is absent. But if living material is present, it will acquire as much P from the environment as is needed to stay alive and to proliferate.

In agriculture, the biggest progress in productivity was made when farmers started to add fertilizers onto the fields, and P is one very important fertilizer. The yield of plant produce will increase dramatically if we add more P onto the land (proof of its leverage function).

With ever more demand for plant material (as feed, food, and, alas, also as biofuel), there is an ever increasing demand for P. We currently consume P as we do with  everything: we dig it up from places where there is plenty, and consume it. If we need more, we dig up more.

Ah, a familiar procedure. You need oil, you pump it up. You need wood, you log it. You need fish, you catch it. You need water, you take it. You need land, you grab it. You need money, you print it….

All these actions have one thing in common, they are linear, with a source and sink. You don’t need to be a genius to understand that since the earth has physical limits, so have the sources. Likewise, sinks are limited in size, and nobody really wants to live in a sink (even if we would, we couldn’t).

So, as evidenced headline news at increasing rate and intensity, more and more commodities appear in the spotlight as becoming limited. In case of P – without discussing here if the reserves are enough for 40 or 400 years – it is a fact that large economies start preparing game strategies on how to play the game of selling P at highest possible margins.

If this was the entire story, it wouldn’t look good for an optimistic scenario where we can make food, feed and organic raw materials forever by producing marine phytoplankton – you need P to get these small plants growing. And by the way, the take up the P much more efficient than land-plants can do, and second, you can fully recycle the water in which they grow, so phytoplankton systems do  prevent P from entering the environment in an uncontrolled way.

But it is not the entire story. P is not really destroyed when it is consumed. It just serves some function in one or the other biological compartment. It is taken up, stays where it is for a while and is secreted again. In simple words, what other non-plant organisms excrete is the source of P for those organisms that are plants. One’s dead is the other’s bread.

The solution to decreasing resources is as simple as it is self-evident: close cycles, look at nature how it has closed cycles, apply engineering ingenuity and competence and perform the same process, but now at controlled conditions and much higher efficiencies than nature does.

The normal phosphorus cycle will not be good enough to provide sufficient P for engineered applications, but looking at the natural cycle should give enough inspirations and ideas where to look for more P.

Some countries are beginning to address the potential threat of long-term phosphorus scarcity, such as China and Sweden. The United States, the largest consumer of phosphorus, has, however, largely ignored the issue, which is why ASU scientists and students launched the Sustainable Phosphorus Initiative on Earth Day in 2010. This effort was spearheaded by

James Elser (Regents’ Professor in the School of Life Sciences in ASU’s College of Liberal Arts and Sciences), Daniel Childers (Professor in the School of Sustainability and senior sustainability scientist with  the Global Institute of Sustainability) and Mark Edwards, (Professor with W.P. Carey School of Business) have initiated the Sustainability Phophorus Initiative on Earth Day in 2010, from the terrestrial agricultural perspective – I hope they will soon see the marine agricultural perspective too.

“We need to be asking how we can achieve sustainable P by closing the P cycle in human and agricultural waste streams,” Elser says. “Our hope for this Summit is that we and our students can help better define the problems and turn an idea into creative solution building with the international community.”

Elser has a really good point here. I wish him all best luck with his initiative.

via An element of concern: Phosphorus, food and our future.

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