Dec05

Plant phracking pops peak phosphorus?

Author // Dr. Robert S. Zeigler Categories // Bob's blog

OK, I could not resist the urge to have some phun with phonetics. The topic at hand was inspired by an article that IRRI’s Chief Information Officer (read: Chief IT Geek) circulated around to IRRI senior management last week. It was an article published in Mother Jones magazine on “Peak Phosphorus.” I occasionally read Mother Jones articles on line. While it is often characterized as a raving left-leaning publication, I have always found its articles to be intellectually stimulating, often targeting important topics that are ignored by more mainstream media. I don’t always agree with their positions, but they are always challenging.

In this article the author warned that the world is rapidly depleting its known phosphorus reserves and, worse, these reserves are in only a very few locations making global phosphorus supplies particularly vulnerable to disruption. This is a concern of course, because phosphorus, along with nitrogen and potassium, comprise the “big three” of essential nutrients that all plants require in relatively large quantities. If phosphorus supplies become short, then agricultural productivity worldwide could suffer badly. Crops grown in acid soils, common in tropical regions, are particularly vulnerable because phosphorus is bound in chemically inaccessible forms in the soil. But, what does this have to do with fracking?

Hydraulic fracturing of subsurface rocks – usually thousands of feet below the surface – is a technology that frees previously inaccessible petroleum and/or natural gas trapped in rock and allows it to be pumped to the surface. It is a pretty blunt instrument in that water, chemical solvents and other matrix compounds are pumped into wells at enormous pressure causing the rock to fracture. Petroleum and natural gas then flow through the cracks and into the well bore and then are removed. It is a pretty messy affair that is more than a little controversial; but I am not writing to defend the practice. I want to illustrate a point.

A decade or so ago there was talk of “peak oil” and the price of natural gas was climbing rapidly as supplies were tight. Projections into the future all showed declining reserves and seriously rising prices. But, today across the US fracking is becoming widespread with states like North Dakota and Pennsylvania now experiencing a petroleum boom that would have been unimaginable 15 years ago. So, today, natural gas prices in the US are dropping rapidly and there is talk of the US actually becoming an oil and gas exporting country in a few years. Whether you like fracking or not, it is indisputable that a new extraction technology has completely changed the global equation of petroleum and gas supplies.

But what does this have to do with peak phosphorus and global food security? Well, last September IRRI scientists and their partners published a paper in Nature in which they describe a gene from a traditional rice variety that is able to grow in very low phosphorus soils and produce a good yield (see my blog “Whose line is it, anyway? ”). The mechanism appears to be that the gene (Pstol1) promotes much more vigorous root growth that allows the plant root system to more effectively penetrate and explore the soil volume to extract what phosphorus is there. There may also be a role for root exudates that make the soil phosphorus more chemically available to the plant. In my mind this is the plant kingdom’s equivalent of “fracking”.

If this rice gene can be transferred to other crops, especially cereals and legumes, this would have a massive impact on global agriculture. Imagine maize farmers in Sub-Saharan Africa not having to worry about applying phosphorus fertilizer to their nutrient-poor acid soils. Or, farmers in the US, China, Europe, Latin America, and Australia having only to add minimal amounts of phosphorus to their crops. The economic and environmental advantages would be enormous. Especially considering that pollution of water bodies with phosphorus fertilizers is a serious problem worldwide.

Indeed, the concerns over “peak phosphorus” would recede. Soils that have lots of phosphorus locked up would see this phosphorus freed for use by plants. So, much like hydraulic fracking is freeing petroleum and natural gas from solid rock, Pstol1 may well free phosphorus from soils where it is tightly bound.

Some brief reflections on another key nutrient, nitrogen, are in order. In the late 19th century it is likely that if anyone thought about such things using today’s words, the world would have been facing a “peak nitrogen” crisis. Like today’s dependence on a few phosphorus deposits from the Western Sahara and Canada, at that time the world depended on nitrate deposits largely from the Chilean desert for its inorganic nitrogen fertilizer. With global population growth already accelerating, the Malthusian prediction of population collapse was built on the assumption that global food supplies could not keep up. Yields were limited by fertility and nitrogen fertilizer supplies were the chief culprit. Thus, predictions of famine were reasonable based on the assumption that future technologies would be the same as those technologies at hand at the time. Of course, the Haber-Bosch process changed all that at the beginning of the 20th century. That process converts atmospheric nitrogen (another extremely abundant form of an essential nutrient that is useless to plants) into ammonia, a readily usable from of nitrogen easily converted to other nitrogen fertilizer types1.

So, fracking and Haber-Bosch represent transformational technologies that rendered predictions based on current trends completely irrelevant. And, Pstol1 may be the next in line. The same can be said for the semi-dwarf varieties and the Green Revolution they created: Predictions of widespread famine that made up part of my undergraduate reading list (see Paul Erlich’s “The Population Bomb ” and the Paddock brothers’ “Famine 1975! America's Decision: Who Will Survive? ”, among others) never came to pass. Thanks to the creation of new, transformational technologies.

My main message here, then, is that we seem to repeatedly fall into the same old trap of assuming that all trends will continue on the same path. But, time and time again we see right before our eyes that technological change is not linear. Indeed the purpose of institutions like IRRI is to make sure that exactly the opposite is true. We are here to break trends, to make what seems to be impossible, possible, and thereby solve some of the world’s most challenging problems. And these are not solved by looking in the rear–view mirror as we drive into the future.


1 In one of life’s supreme ironies, an early major application of the Haber-Bosch process was to create abundant and cheap explosives for Germany in the First World War. These guys are right up there with Alfred Nobel; and fittingly, they each won a Nobel Prize in Chemistry for their discoveries and engineering (1918 and 1931, respectively).

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About the Author

Dr. Robert S. Zeigler

Dr. Robert S. Zeigler

Dr. Robert "Bob" Zeigler is an internationally respected plant pathologist with more than 30 years of experience in agricultural research in the developing world. He is the first Director General Emeritus of IRRI.

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