so i live in southern japan and we've got a volcano that recently awakened and has been spewing lots of ash. some areas have already received a foot of ash but my area has only gotten a light dusting. farmers closer to the volcano have lost crops of leafy veggies due to the accumulations and locals are already predicting the upcoming rice season to be poor.
i had thought that volcanic ash would make a good fertilizer/soil amendment and was planning to use some in my field, but local wisdom here says otherwise. are volcanic soils so different from volcanic ash? what about the daikons they grow on a nearby volcano that reach 100lbs.?!
any wisdom much appreciated.
@Pattimair, every element that you can imagine is in that soil, and what makes it special is that there is a high surface area to volume ratio because of the jagged shape the ash takes as it solidifies. First everything that's too abundant and soluble washes away and then you are left with the things that are moderately soluble, things that plants have evolved to love.
i collected a couple bags of this stuff and it was surprising heavy. it's sand-like in texture and appearance - most of the ash had been taken away by the wind. a farming friend said all the good stuff had burned away during the explosion......though I'm doubtful.
i guess i'll just pile it up in the field for a year and experiment from there.
Does the content of the ash vary from place to place?
yes, from volcano to volcano and possibly from even eruption to eruption( not 100% sure on that )
@Soil, I'm not sure I'd say that the problem is it being too fertile, I think it's more an issue of too many toxins being highly available.
i guess you could say it that way. too concentrated basically. too fertile might not have been the best word to use but i think it got my point across.
I am exprapolating from this thread what to do about the lava rock I'm dealing with. I believe it is good stuff, just needs time.
the lavarock actually needs to sit out and bake in the sun for some time before you can use it. i have a friend in hawaii who explained to me why but it slips my mind at the moment. something almost like allelopathy in plants.
i think contacting a local company that is dealing with the volcano would be of great help, you could tell them that your a farmer and are interested in what the ash mineral content is because im sure they have tested it already if they are on top of things.
This thread seems related to a question I have had about lava rock. In my area in the Northwest homeowners sometimes buy red lava rock for mulch instead of bark or compost. I understand that volcanic soils are fertile so I wonder if the lava rock, which is already in place, will provide favorable conditions for the garden beds I'm building on top.
When I lived in 'country' on the beautiful isle known as Oahu we used to take actual lava rock from a 'special source' which turned out to be very air lava rock. We would cut the rock, and use it to start seedlings in because it made the very best and safest seedling starter out there. The roots of what we were planting at the time would grow through it, and break it down over time. Photos of this era are lost. ((Most likely a good thing)).
The lava rock in the NW is very helpful. sepp holzer's videos can illustrate this on YouTube, but to quickly toss ideas out. The lava rocks can be used to encourage varied microclimates in order to create warmth for plants, protect from the frost (like this mornings) and so on.
What minerals does the ash provide? Does the content of the ash vary from place to place? Do lava and ash have similar content?
RZA are you aware of previous ash deposits in the area you garden? Has it been fertile for you?
Everything as I understand it. Volcanic rocks are rich in trace elements and minerals that have been leached out of many soils.
If I were to pick a soil like substance that was the most unlike volcanic ash it would either be the crushed quartz landscaping rock, or volcanic rocks.
Most volcanic soils (andisols) do have fairly good fertility for 500 or 1000 years after the last eruption. They typically have a very light nature and high surface area, which is good in many ways (the minerals are more available, until the are gone).
Fluoride is the big issue in the short run. Major eruptions in Iceland since it was settled killed or stunted the grass, made the sheep sick with fluorosis, and people starved.