Akadama Curious

I have only barely been able to hide my fascination with Akadama…and am seeking people with first hand knowledge of the areas where it is mined and produced. Akadama is a bit of a geological unicorn in terms of its origins and development, which is one reason why it appears to come from but a few localities in Japan. If anyone has some insight to these production areas, the physical setting and proximity or distribution of the various source areas, I would be tremendously thankful for that information.

Some have seen the website I created to document my research into its origin and genesis, with the idea that if we can understand how it was formed, we might find similar earth materials here in the northwest. If you haven’t, here it is: Hunting Oregon Akadama

So Asymmetry friends, can you help me refine the mental model for the origins of this material? Do the Akadama quarry sites occupy low lying terraces along rivers in the Kanuma province only, as I propose in the website? Do the sites occur in other locales or at higher elevations? Any help ground truthing these questions will be greatly appreciated.


So, timing is everything. I had been speaking to a BSOP member last year about my quest, and then discovered from a club newsletter that he had some quality “Oregon Akadama” available. We talked this morning, and now I have an ample supply to study and experiment with.

Location for deposit is still a mystery, but I am impressed by the general observations of the material. It is quite a bit more durable than true Akadama, but is crushable to some extent. I will post some pics before I do some basic backyard tests of porosity/water retention, etc.


I was just going to mention that tidbit from the monthly newsletter. Definitely interested to see what you find out from this Oregon Akadama.


Here is the look of it…

Here is the color compared to true Akadama…


I suspect it is actually residual weathered basalt typical of the Red Hills of Salem or similar. The hardness is far greater than Akadama…plus the dark reddish brown color.

Here is a basic crush test comparison…

The Red Hills form from hundreds of feet of basalt weathered down and compacted. The soils have iron-rich nodules that form within rinds of hydrated oxides. I suspect that is what this may be. When these modules are particularly well developed, they can actually be mineable as iron ore.

The West Hills are known for their soils that support world class viticulture, so might this be a good alternative? I will do some density tests and water adsorption/retention at some point this weekend.


I’m from Mexico City and I’ve been doing research on this subject for the last four years, Akadama comes from Andisols(Kurobokudo 黒ボク土 in Japanese), I recommend you to read Volcanic Ash Soils: Genesis, Properties and Utilization By S. Shoji, it’s a great Book.
Akadama and Kanuma quarry sites and Greenhouses are easy to spot using Google Maps Satellite view in Kanuma, Tochigi Prefecture but are not limited to low lying terraces, Akadama is a commercial term in Gardening but in Japanese Geology is refered as Kanto Loam(関東ローム層) wich is geographically distributed all over the Kanto plain.
I would assume that Akadama and other similar components like Kanuma and Kiryuzuna Pumices can be found in many sites west and east the Cascade range, I suggest you to research Tephra and Ash deposits on those Volcanos such as St. Helens, Mt. Rainier, Mt. Hood, Crater Lake(Mt. Mazama) and others. Most of Oregon’s soils are Andisols so Volcanic deposits might be weathered enough to find excellent components like Akadama, I hope this helped and Happy Hunting, Congratulatios for your site by the way.

This video shows how Akadama is processed from scratch in Japan.

Every year before and after the raining season I drive near Stratovolcanoes to collect Akadama like soil with similar properties and great Cultivation results.


Thanks for the excellent references and the new processing video. That video really brings to life the processing steps, screening and kiln drying. I will definitely look into the Kanto Loam as well as the Shoji book.

I have spent considerable time at each of the volcanoes you mention (with the exception of Ranier) along with several others of note, but not in the time since I began being interested in the soils. That is really too bad. Geologists often focus too much on the rock and not the soils/vegetation that obscures them!

If you have any specific examples of localities that you have discovered in Mexico or elsewhere, I would really like to hear more about that.


Exciting info. I have not hit on an acceptable akadama substitute.
In your analysis scheme…
Would love to see your water retention and CEC info for these.
I would love to see a simple 100x (Maybe a 1000x) microscope shot of these.
A simple surface XRF(hand held x-ray reflectence spectroscope analysis…), would be cheep; and maybe wash soluble elemental lab analysis. To compare… and eliminate possible TOXIC ions… boron…
I’m a science geek. Unfortunately, I don’t have easy access to the above analysis setups anymore, or I would offer… forced redundency… Woohoo!
I am also trying to do a site survey of local clay deposits… Nothing exciting yet. Inland Pacific NW…


@DonPettit I took these pictures in February, just a few kilometers south Popocatepetl Volcano.

‘B horizon(Akadama or Loam)’

Underlayer you can see Yellow and White Pumice deposits

By the end of this month I’ll drive there to bring soil and shot better pictures.

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I am surprised such a deposit would form in more arid areas…but that does look very similar. Look forward to seeing more. Is this the material you said you were growing in now? If so, how is it working?

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Actually I always search locations with cold humid weather as long as is classified as Andisol, this material makes finer roots, compared to other components I’ve tried such as Ignimbrites, Hardpans or Zeolites, it is the closest to Akadama due to the clay size minerals like Allophane and Imogolite(tubular structure gel like mineral).


Mazama pumice and ash deposits (at least most surface deposits) are generally too young to have developed much of a weathered soil profile. Most look like this with just a thin soil horizon.

This rhythmic bedded (pyroclastic surge deposits?) tephra has a slightly more developed zone below the humic layer.

These are from near the south entrance to Crater Lake. Further south, I found a private quarry that I haven’t been able to access yet that has what appears to be a weathered cinder deposit. I haven’t found anything quite like what your example looks like.


Mazama is one of the most voluminous, very impressive. I found some sites that might be useful to refine your search.

Very easy to navigate

I took this picture at a different location, it also shows Tephra sequences, Ash, Paleosols…

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Edgardo, I am extremely interested in known when is the earliest documented use of Akadama or similar aggregate modern substrates in Japan. The reason for the curiosity is that I recently got a copy of the first ever bonsai book published outside Japan or China, from 1902 in Paris and they mention in the repotting section to clean the substrate and add new ‘similar garden soil’ and peat - but no mention of any aggregate substrate. It made me wonder if by 1902 the Japanese were still using normal garden soil. Do you have any information on the history of Akadama? Perhaps that book that you cited mentions something?

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Hello Rafi, I have no idea on when or why Japanese began using Akadama however, Akadama is widely used as general Garden soil, is also sold mixed as aggregate with other components like peat moss, black soil, compost, Pumice, vermiculite, perlite and more depending on the plant species or pH requirements. Japan is a volcanic land so most of its soils are suitable for agriculture. This screen capture is from the 1957 book ‘the art of bonsai’ by Yuji Yoshimura and Giovanna M. Halford.

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