10 July 2011

Phosphorus and food's future

James Elser, Ph.D.
What can we do about phosphorus and food's future?

The 15th element in the periodic table is not something that comes to mind for most people when they reflect on causes of global food crises of the past. Overpopulation, climate change, crop disease, and soil erosion are more likely to deemed as the instigators of disaster scenarios.

However, phosphorus is essential for every living thing on this planet and, according to estimates, the world's phosphorous -- needed for fertilizing plants -- will peak within half a century.

It turns out there's so much biological demand for phosphorus that it's a limiting factor for life on this planet. The critical nature of phosphorus for the future of crops was well emphasized when Franklin Deleanor Roosevelt was president, but lately government leadership has yet to bring more awareness to the problem of dwindling supplies.

James Elser, Ph.D., hopes that will change.

"That's my dream, that President Obama will say the word 'phosphorus.'" he said, jokingly (or maybe not so much).

Elser, who as a child once wished to become a priest, is on a lifelong journey to save humankind from an entirely different, serious calamity: soaring food prices and widespread world hunger because of phosphorus unavailability.

As an ASU life sciences professor, he studies and teaches "biological stoichiometry," a theory that has it that the existence of living systems depends upon the balance of multiple chemical elements (such as carbon, nitrogen and phosphorus) that make up ecology and evolutionary dynamics.

On Sunday, July 10, Elser presented on "Phosphorus, Food, and Our Future," for the Humanist Society of Greater Phoenix in Mesa, Ariz.

Most people might think of phosphorus as a mineral needed in minor amounts daily – along with calcium – to keep their bones healthy and strong. It's needed nutritionally to hold your jeans up, but that’s not all.

"The running joke is that phosphorus holds your genes up. It holds DNA together, every base pair," Elser said. "Ribosomes, needed to make proteins, are also very rich in phosphorus."

The story of phosphorus, he explains, actually begins earlier, in the stars where phosphorus was made, then appears in plants that become our food and eventually as a major element in our own DNA and bones.

What’s the source of all the phosphorus we now eat?

Rewind back to the 60s, one of the key features of the "green revolution" – along with high-yield crops and improved irrigation – was creation of phosphorus- and nitrogen-rich fertilizer. The source of the phosphorus: mines.

Mining phosphorus has sustained us for some time, but we're running out. Whatever phosphorus available is "all we’re going to get," Elser said, and efforts to make it synthetically as in the stars have failed.

The problem lies in the fact that geological sources of phosphorus are not widely distributed. They are primarily found in sedimentary remains. In other words, they are a fossil resource and not renewable.

"We don't have 20 million years to wait for [dinosaurs to die off again and give us more phosphorus], do we?" Elser said.

Most of the phosphorus we obtain for food in the U.S. comes from a mine near Tampa, Florida and production isn't meeting internal demand.

In the future, it's likely we'll import most of our phosphorus from Morocco. The country was recently found to contain the greatest reserves of phosphorus. Morocco has enough a reserve to export its "white gold" (as Bloomberg BusinessWeek once called it) for the next 300 to 400 years bringing a lot of promise to the country’s future.

What it will cost to other countries, however, may be bad news in times of global food insecurity for a rising global population that will reach near 11 billion people by 2050. Take particular countries such as China, which use up to 39 percent of the world's phosphorus, who will need to depend on Morocco's export.

"Those people are going to need to eat and make bones," Elser said. "And as they become more affluent, they’ll want to add more meat to their diets."

Meat is a particularly phosphorus-intensive product, which brings up yet another reason for eating lower on the food chain as a way to support sustainability. This doesn't mean becoming vegetarian, Elser says, but he suggests considering at least becoming a "demitatarian"—making menu choices involving servings with half the normal meat portions.

Another major source of phosphorus in the diet is processed foods, particularly soft drinks containing phosphoric acid. Limiting these foods could, in fact, be a bit healthier for people too.

However, dietary restrictions alone won't cut our dependence on phosphorus imports. The fact is, most of the phosphorus mined and used on our wheat and corn crops is lost to erosion and runoff.

"It goes downstream," Elser says.

Downstream means it becomes a pollutant leading to eutrophication, a situation where fertilizer in lakes and oceans becomes a feast for phytoplankton creating large dead zones.

Dead zones? How could it be that what’s necessary for life be deadly? The reason is because resulting algal blooms suck up all the oxygen and drive other life forms into non-existence.

Farming methods that limit fertilizer use, control erosion, and reduce runoff could go a long way to prevention of phosphorus loss meanwhile controlling pollution.

The other thing that's coming is biofuels, which is thought to help us with our climate problem, but the problem with that scenario is that these crops will require fertilizer. The growing demand on fertilizer increases demand on phosphorus.

"The numbers are not small," Elser said.

Demand spikes of fertilizer for biofuel production will contribute to rising food prices that could produce a situation similar to the 2008 food crisis. This is a concern, Elser says, because hungry people are likely to drive unrest, including terrorism, and compromise food security around the world.

Elser says we need a new form of alchemy—by solving the problem of waste and dead zones through making them into resources and productive zones. It’s a "reduce, reuse and recycle" type of solution.
His research involves several areas of science including geology, biology, and agricultural technology.

Recycling phosphorus has to do with making a resource of crop, animal, food, and human waste. If we're getting energy and phosphorus out of waste, even urine (sterile and containing about two-thirds of phosphorus lost from the body), we could do a lot to save phosphorus.

In Switzerland, for example, they’ve put in measures such as toilets that capture urine for recycling phosphorus. Elser says toilets are "a way forward for the developing world and the developed world" and even Bill Gates has invested in developing toilets that hold onto phosphorus for South Africa.

He adds that we need to re-imagine and re-engineer other ways of creating cities and infrastructure to hold onto and reuse our phosphorus.

"We don’t have a human phosphorus cycle [or loop]," Elser said. "Cycles are sustainable. We’ve forgotten that. That’s what we need to create."

Some examples of how to re-engineer a food system include localized agriculture that makes it easier to keep phosphorus, technology to reduce erosion, and using phosphorus-collecting toilets.

Genetically engineering crops and animals to use phosphorus more efficiently may be solutions too, Elser told me. For example, "enviro pigs," are pigs engineered to produce the enzyme phytase to break down phytate and, some GM crops can better extract nutrients from the soil as many wild plants do.

"We've kind of bred plants to be stupid, selecting them for production with fertilizer," Elser told me. Compare these plants to some that grow in some of the harshest landscapes on Earth. The genes of those plants could be introduced to reduce need for fertilizer.

Will people in the U.S. need to worry about phosphorus and soaring food prices any time soon? Elser isn’t worried about the developed world so much as underdeveloped nations.

"My worry is that they can’t afford phosphorus now," Elser said.

What about recovering phosphorus from dead zones and other measures to obtain phosphorus from rock? The problem with dead zones, Elser said, is that they are deep and wet. And, rocks just don’t contain enough of a concentration making it worth doing.

“It took tens of hundreds of millions of years was used to reorganize matter into Morocco," he said. "The phosphorus is still there. But when we distribute it everywhere, it becomes more difficult."

Interested in more information on the problem of phosphorus? Get updates from Elser's Web site at http://sustainablep.asu.edu/ or follow @sustainP.

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