adrift

I wouldn't lose sleep over it, but ... no guarantees. Each volcanic chain, indeed, each volcanic event, can emit a different composition of materials. What a volcano blew out for the prior 100 years that was beneficial could be toxic (excessive sulfur or fluorine) the next time.

The materials ejected from a volcano do often make a good soil conditioner by adding trace minerals, and providing a light and porous substrate. Typically you will find silicates, calcium and aluminum oxides, and a few others in the rock (lava). On the other hand, ash is often quite acidic, contains a lot of sulfur and sometimes fluorine. Good when you need it, bad when you have it. But, volcanic soils typically are low in phosphorus, even to the point of absorbing it from fertilizer. But every volcano is different...

None of this provides nitrogen, which you currently say comes from dung. (And the atmosphere via a several step chemical process driven by soil microbes.)

You, with uncharacteristic insistence, ask what this means to Ecuador. If the population remains steady, then Richard's comments mean nothing to you. You provide nitrogen with dung, and add trace minerals from volcanic deposits. In short, you recycle all the elements "the old fashioned way", not "the NASA way."

But populations don't remain steady in most cases. Human societies seem to expand or die out. Perhaps that should say expand then die out. Examples otherwise are rare. Anywho, expansion of Ecuador's population will at some time mean that chemical fertilizers are needed to increase yield per area of land to meet the need for food.

Richard makes the point (and I don't know enough whether to agree or disagree) that resources for chemical fertilizers (I assume that he means phosphate and potash) are finite and non-renewable. This would be a problem for "western" society which demands (and achieves) tremendous yields per acre. If western cultures run into this wall they will either find a way to overcome it (perhaps using the recycling Richard mentions, perhaps some other way) or famine will return to the west. With even a small amount of luck, Ecuador will have time to adapt since they are not stretching the "system" the way the US is.

It is only sort-of correct that fossil fuel does not make up a part of fertilizer (fossil fuels being various forms and purities of hydrocarbons, meaning made of chains of carbon atoms with attached hydrogen atoms, but containing very little nitrogen). However, we do use a tremendous amount of energy (today coming from many sources, but heavily hydrocarbons) to produce nitrogen compounds for fertilizer (ex. ammonia, NH3) from atmospheric nitrogen in what is known as the Haber process. Also, we currently use methane (derived from natural gas) as the source of hydrogen for the Haber process. Hydrogen could be obtained at higher cost from hydrolysis of water.

(Google "Haber process", but here is a start: Haber process: Definition from Answers.com )

So if we do run out of fossil fuels without a replacement energy source to power the Haber process for fixing nitrogen, we become dependent on natural supplies for not just two, but all three parts of the fertilizer trinity. (Nitrogen and potassium from salt petre (KNO3), phosphorus from rock phosphate, potassium from potash and its compounds, but potassium should be available from sea water (at greater cost) for quite some time.)

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