Saturday, June 6, 2009

Phosphate and fertility

When I was a child my family frequently took trips though the Tennessee country side on the way to visit relatives. We often drove by tobacco plots. On such occasions, my mother would talk to us about the effects of tobacco on soil fertility. Mother said that tobacco robbed the soil of trace minerals and the trace minerals it needed to sustain plant life. My mother also talked about soil erosion, and told us all sorts of other neat things she learned in her college botany classes in the 1930's. Unfortunately the other energy writers on the Internet appear to have had mothers who ignored discussion soil conservation issues on family trips.

One of those trace minerals that mother talked about is phosphate, and ironically my father worked for a brief time as a chemist for a phosphate mine near Bartow, Florida in the 1940's. Phosphate is a disappearing resource, and as the song goes, "we've got trouble right here in River City".

As the SNB phosphate recovery web site tells us:
The demand for phosphate is increasing. Global stocks are finite. According to experts all the phosphate in the world will have been used within the foreseeable future. The majority of estimates are a maximum of 100 years, and the consequences will be enormous, especially for food production. A shortage of phosphate will result in large-scale famine and political turmoil. What makes the problem serious is that there are no alternatives for phosphate.
SNB adds:
Our bodies need phosphor and extract it from our food. Plants also need phosphor to live. Under normal circumstances plants extract phosphor from the soil, but intensive farming is rapidly exhausting this phosphate. This is why phosphate is added to the soil in the form of artificial fertiliser in order to compensate for the shortage and maintain our food production. In the Netherlands and the majority of countries in Europe we have done this to such a great degree that the soil currently contains more than sufficient phosphate. Nevertheless, this quantity will also become depleted if we do not continue to supplement it. In other parts of the world, such as Africa, artificial fertiliser is far less readily available and the soil is poorer. The end of the stocks is on the horizon. The problem is even more acute due to the fact that demand for phosphate is increasing. This is because of the growing world population, increasing consumption of meat and the cultivation of energy crops.

Besides the fact that we extract phosphate from our food, we also use phosphate in the pharmaceuticals sector and industrial and household cleaning. However, consumption for the purpose of food production is by far the most important. Approximately 80% of all phosphate is used for this purpose.
The SNB account continues:
Australian research conducted by Dana Cordell shows that approximately 14.9 million tons of phosphate ore is mined worldwide. Of this, 3.5 million tons of phosphate finds its way into our food. Eventually, three million tons of phosphates are released through human waste. If we recover this 3 million tons of phosphate we will have covered 20% of our worldwide phosphate requirement. The Netherlands uses relatively little artificial fertiliser because we produce a relatively large quantity of animal manure. This means that the percentage in the Netherlands is even 50%.

Approximately 11.4 million tons is lost worldwide. This is due to over-fertilisation. If too much phosphate is released onto the soil a large amount is lost due to erosion and precipitation. It is also essential that a solution is also developed for this. However, in this web site we concentrate on the recovery of phosphate from waste water. Phosphates can be recovered at several points in the waste chain:
There you have the whole story. We need phosphate. Not a lot, but life requires phosphate. There is not a whole lot of it compared to the human appetite for it. We are using it up. If we don't do something different, it will be gone. We live in a way that makes phosphate a necessity. We cannot live without it. The phosphate supply is an issue that is not quite as urgent as CO2/AGW but serious enough to draw the attention of this post and others as well. We need to start thinking and talking about solutions. Solving the phosphate problem is not an option.


Soylent said...

As long as there's plenty of energy I'm rather a lot more sanguine about phosporus than you are.

It is true that phosphate consumption is currently growing. However, we're some ~30-40% below the all-time high, so it's not all that calamitous.

The average abundance of phosphorus in the Earth's crust is 0.1% so there's certainly no shortage of phosphorus; it's a matter of how much of it is feasible to mine at what price, what co-products you can get and what rates you can extract it at.

The definitions of reserve and reserve base contains an unstated assumption, a price ceiling or an ore-grade floor at which a resource is assumed to not be viable to recover. If the price is free to increase and there is abundant energy and skilled labour available recoverable phosphate can increase.

This argument hinges on a particular distribution into various ore-grades for phosphorus and can't find any information online to check it out. To give the extreme case in which this argument is totally wrong; those 0.1% could be distributed into 0.1% ore that will never be viable to mine and a tiny amount of almost pure phosphate rock with nothing in-between.

If energy remains cheap and abundant I believe the distinction between the "developing world" and the "developed world" will be gradually erased. I don't think paying as much as several times more for food will seriously hurt anyone but at the very margins of society, where as today it would lead to widespread starvation in the worlds poorest nations.

I expect precision farming(clamp down on application of excess phosphorus by applying it only when and where it is needed the most) and no-till agriculture(wastly reduces soil errosion) to become increasingly ubiquitous; the former driven by moore's law and the latter by the cost of liquid fuels and soil erosion.

There have been pilot trials for phosphate recovery techniques in municipal waste treatment facilities which have been somewhat successful(both biological and chemical precipitation techniques). They were driven by a wish to reduce euthropication, which happily coincides with the long-term goal of phosphate recovery.

It's extremely dicey to prognosticate today what's going to happen a mere 100 years into the future. For all I know we could invent some really clever set of processes and technologies to separate and extract each element, obviating the need to mine ore and making it viable to mine anything including plain old bed-rock.

As a general rule I'm far more afraid of the problems no-one is worrying about or aware of.

bobcat said...

Maybe these people are on to something about making agriculture much more efficient. You can read about them by clicking here

Warren Heath said...

Charles, don’t worry about it. The EU/Greens already have that problem covered. They will have governments pay farmers to dump landfill on their farmland. There must be loads of phosphates in that landfill. Heck, I bet a farmer could attach scoops to the blades of their Wind Turbines, dump the landfill underneath them, and the Wind Turbine will pick up the landfill and spread it all over. Of course current regulations, will probably make the farmland too contaminated for food crops, with heavy metals and other noxious substances in the landfill, but the EU/Greens have that problem resolved as well. The farmers don’t need to grow food crops anymore. They can grow any old scrap biomass like switchgrass, weeds, brush and send it to the cellulose ethanol plant and the noxious Coal Burning power plant. Once the Thermal Power plant starts burning biomass, according to the EU/Greens it is magically transformed into a Carbon Neutral Green Power Plant.

Farmers will be made in the shade, with royalties from Wind Turbines and Transmission lines on their property, payments for landfill disposal, and heavily subsidized prices for biomass. And after thirty years or so, when the Wind Turbines are dead, and nobody can afford to repair them, they will make good structures to grow grapevines on. The survivors of the World Economic collapse, can grow grapes on Wind Turbine towers, make Wine and drink all day & night to drown their sorrows. And the dead Power Transmission lines will make great clotheslines since people won’t be able to afford to use clothes dryers, assuming there is any power left for the general populace. But you say, the grapes will contaminated with heavy metals and other toxins from all those years of dumping landfill on the soil, and likely the general populace will only live for maybe 40 years instead of 85 years. The EU/Greens are way ahead of you on that one, if people only live half as long they will emit half the GHG emissions, and Europe will easily meet the Kyoto limits. And I bet those Wind Turbines will become places of worship for a new Temple of The Wind religion, where survivors can tell fables about how their ancestors sacrificed everything to erect those holy cathedrals.

Of course, those who are responsible for that misery, will be living in the lap of luxury in their enormous fenced in compounds, guarded by Blackwater, chuckling about how they caused THE GREATEST SCAM EVER! No Wind Turbines or Solar Panels in those compounds, they will be powered by small reliable Nuclear Reactors, that may only need refueling once every 50 years.

Charles Barton said...

I plan more posts on phosphate. Soylent, thank you for your particularly helpful comments.

Anonymous said...

Charles, Thanks for the info on phosphates. As a biologist, I would conclude that plankton and seaweeds could efficiently sequester phosphates from water. After harvest, the aquatic growth could serve as fertilizer for cropland. Municipal digester sludge is already recycled on farmland. Waste from cattle, hog and poultry feeding as well as from dairy operations is also being recycled. If an industrial society has energy, it should be in a position to maintain agricultural productivity for many generations to come. It would be interesting to learn just what the minimal loss threshold for phosphate would be if there is abundant cheap energy for recapture. You have brought light on an issue that will play a significant role in the quality of life for future generations.

John Tjostem

bobcat said...

I am sorry that my link did not work. I will try again. The link I was trying to post about more efficient agriculture can be found by using the link below.,0,4784175.story

One of these days I will master html tags.


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