・ Volcanic ash may be natural fertilizer through weathering ( efflorescence )
Natural volcanic ashes are quite full of adsorption, they fall with various metallic ions and gases.
During an eruption, not only large quantities of vapors but also various gases such as carbon dioxide, nitrogen, hydrogen sulfide, sulfur dioxide, chlorine are issued from a crater.
They selectively adsorb various matters dependently on individual natures.
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After the eruption, for a while from the fall, those volcanic ashes are harmful for plants because of contained toxic metallic ions and gases.
But, as a long time goes from the accumulation of volcanic ashes, its chemical nature varies from alkalescence to acidity.
Furthermore, those volcanic ashes gradually weather and begin to show various properties according to climates proper to the region.
Namely, due to physical and chemical actions such as raining, sunbeam, heat, snow and frost or biological actions with microbes, bugs and various plants & animals, toxicities of volcanic ashes are neutralized, those ashes are purified and those materials themselves change into different compositions from original states.
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Therefore, in most of lands over volcanic ashes, transmuted fertile soils are found out.
In some regions, completely barren lands could be changed into even jungle-covered lands.
We think that such cases are originated in effective fertilizer-ingredients issued from volcanic ashes under weathering-metamorphosing processes.
It seems that features of transmuted volcanic ashes remarkably depend on each climate proper to individual region, compositions and characters of fallen volcanic ashes, its fertilizing-effects also have diverse aspects.
At present, we don't know about conditions and actions to transmute some volcanic ash into an other material and how to bring fertilizing effects to the land in detail ( in 2009 ).
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By the way, it's probable that nitrogen gives main influence on fertilizing effects of volcanic ash.
When volcanic ashes are released against the air from a volcano and drift in the air, they effectively adsorb nitrogens in the earth's crust and the air.
Just after the fall or for a while from the fall, those volcanic ashes cause damages for plants because of contained noxious matters.
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However, as those volcanic ashes are gradually weathered, much fertilizing-effects appear.
Because adsorbed nitrogens effectively work.
By the way, as an extremely strong fertilizer also withers plants, the concentration of the nitrogen fertilizer must be moderately diluted to obtain best effects.
Therefore, it's often reported that the more distant the interval from a crater gets and the longer the time from the fall of volcanic ash becomes, the higher the fertilizing effect also is.
It's probable that such a spatio-temporal 'distance' contributes to the dilution of the concentration.
Really, it's probable that volcanic ashes work as natural nitrogen fixater to produce nitrogen fertilizers.
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Furthermore, the same mechanism as this case holds in snow.
Namely, the same as volcanic ash, snow also has very subtle and complex crystalline structure at micro level and it's full of adsorption.
In snowing, the snow takes in large quantities of nitrogens from the air through adsorption and then it brings fertilizing-effects to the soil.
Following cases are presented as such evidences.
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