Diatomite comparisons?

[Woody11]

Hi Scott

I don't mean to offend but the ability to keep pot temps even is not confined to akadama. See, I agree with what you are saying with regards to the importance of keep pot temps constant and even. But, diatomite is porous like akadama.

Diatomite is inherently porous. That's why it's used in filter media and as an absorbant in spill kits.It's porous like a sponge. At one point in my life, I even was trained to use as Fuller's earth (basically ground up diatomite) to absorb chemical warfare agent on personal clothing and equipment.

Thus all the properties that akadama has in terms of keep pot temps even and constant apply to diatomite as well. The air content of diatomite which makes it light for its volume (i.e. low density) is because it is quite porous. This air content gives it the qualities of being a good insulator much like the old fashioned Thermos flasks.

Also, the water absorption qualities of diatomite also gives it the favourable insulation qualities. This also applies to akadama. See as the water evaporates in the persence of warm weather, it evaporates and takes heat with it (Latent heat of evaporation). It's the same process how sweating cools the body. I use diatomite a lot more these days and with the warm weather up in Townsville, I see it's benefits quite clearly.It's great during the dry weather in being able to rewet easily but drains well during the Wet.

Why pumice is a poorer insulator is because it usually is composed of a glass-like silicate material. There are various forms of pumice, but they are all composed of various forms of this silicate. Unfortunately, this silicate material heats up easily hence it's a poor insulator against heat in bonsai pots.

But what about diatomite? Isn't it composed of 90% silica! That's pretty close to silicate isn't it? Hmmm not really. It's like the difference between coal and diamonds. Both are essentially carbon but in different forms - very different properties. (If you don't believe me, try presenting your significant other with a coal solitaire ring vs a diamond ring - you'll probably get very different responses despite the current high price of coal on the commodities market). Diatomite seems to absorb less heat than pumice.

So in summary, diatomite is porous like akadama. It has similar temperature insulating properties. Unlike akadama though, diatomite doesn't break down over time. The only thing I am personally not clear on is the cation exchange ratio (CEC) of akadama vs diatomite. I suspect they are both quite low.

Whether the Japanese would use it is another question. The Japanese are sticklers for tradition,but there was a time before akadama after all. The Japanese would have migrated to akadama when they realised it's benefits. Maybe the same would occur if diatomite was available to them.

I don't mean to offend by posting this alternative view. That's not my point. All I wish is that, information posted on forums try a stay as factually correct as possible so everyone benefits. The information generally posted on Ausbonsai I think is more accurate than compared with other forums I visit and I think that is an important quality.

If anyone has an alternative view and disagrees with what I've posted above, please speak up. I'm always trying to improve my scientific understanding of what we do in bonsai.

[Scott Roxburgh]

No offence taken mate, it seems that you have quite a good grasp on the geology/chemistry. Although I did not say that temp moderation was confined to Akadama.

I do not know why pumice and diatomite are different, perhaps someone more qualified can provide input. I found them to perform much the same.

I am not stating that diatomite is no good, its better than potting mix. I have used it, but it did not suit me.

From personal experience, I have found that Akadama/pumice performs better

Edit: Just found out that the Japanese do have diatomite, Mt Sylvia no less, and they still use Akadama There must be something there?

[shanemartin]

What are the favoured fertilisers to use in conjunction with 100% Diatomite, or the same combined with typical soil mixes?

[Scott Roxburgh]

You can use most types of ferts, I use miracle gro, powerfeed, nitrosol, Charlie carp and a fert cake of cottonseed meal and blood and bone

[Joel]

The only thing I am personally not clear on is the cation exchange ratio (CEC) of akadama vs diatomite. I suspect they are both quite low.

Hi Woody11,
Nicely written summary. I would like to add that I strongly suspect akadama has a higher CEC due to it being a clay product, and clay naturally has high CEC due to it being highly coloidal. I have never seen any numbers to crunch though.

Edit: Just found out that the Japanese do have diatomite, Mt Sylvia no less, and they still use Akadama There must be something there?

There is no way that buying our diatomite is even close to the price of their akadama. Akadama is VERY abundant and cheap in Japan. ALso, I suspect it holds nutrients better. That is why I use zeolite in my mix. I am not saying I agree with Ken's argument - I have no idea of the preference of others (or their optimum growth rate, soil temperatures, climate, microclimate, species, fertilising and water regimes etc). I'm just saying these are a few things to consider.

Joel

[Craig]

ALso, I suspect it holds nutrients better.

As far as i'm aware Joel Akadama doesn't hold/store, nutrients only water is that wrong

[kcpoole]

Edit: Just found out that the Japanese do have diatomite, Mt Sylvia no less, and they still use Akadama There must be something there?

That is interesting Scott, and I would love to know what they have found different, As I have mentioned before, I have done side by side tests of plants in different mixes and found for the several trees type I have done, that diatomite give s me better growth rates than akadama.

Ken

[Craig]

ALso, I suspect it holds nutrients better.

As far as i'm aware Joel Akadama doesn't hold/store, nutrients only water is that wrong

So i've been doing some homework and answered my own answer

I also found this great article about Akadama,

Quote" The name Akadama comes from the Japanese words for red and ball. It is a volcanic clay that is mined from a depth of about three meters from old Japanese Cryptomeria forests. The deeper it is mined the harder it becomes. It is then dried and baked to remove any organic matter and diseases. Finally it is crushed, sieved and graded into different particle sizes and then bagged up. It is used by many bonsai growers for its ability to retain water and nutrients while still providing porosity and free drainage. When wet it darkens making it easy to see when it has dried out which is a useful benefit for growers.

Akadama has a very good CEC (Cation Exchange Capacity) value which means that it will pull out of the water any cations, eg Mg++, Ca++, K+, etc and hold onto these making them available for the plant's roots. The Akadama works similar to a cation exchange resin used in domestic water systems for softening water except rather than exchange magnesium and calcium for sodium ions, it exchanges magnesium, calcium, etc for hydrogen ions. The exchanged hydrogen ions then react with any bicarbonates in the water causing the KH and pH to drop. Also due to magnesium and calcium being held by the Akadama the GH will drop as well. After a period of time and a few water changes the water parameters will settle down.

Being a baked clay Akadama is very porous which means that there should be very good water circulation through the substrate helping prevent any dead spots and providing plant roots with nutrients."

Is that what it does as soil??

to credit the site i found it - http://www.theplantedtank.co.uk/akadama.htm .

[nevilleh]

from another post


Re: maidenwell mine

Postby Mojo Moyogi » Yesterday, 11:38 pm
Comparison of Maidenwell and Mt Silvia Diatomite, from the Mt Silvia website: http://www.mtsylviadiatomite.com.au/mod ...

[Scott Roxburgh]

Edit: Just found out that the Japanese do have diatomite, Mt Sylvia no less, and they still use Akadama There must be something there?

There is no way that buying our diatomite is even close to the price of their akadama. Akadama is VERY abundant and cheap in Japan. Joel

True.

[nevilleh]

We see plenty of "clays" in Australia that might be used in Bonsai some of which can be found in kitty litter. Non clumping kitty litter is generally made of zeolite, diatomite or sepiolite, so might be a cheap source. Another type is called Attapulgite clay. However, they are highly variable in composition and my contain many types of clays - those that swell in water and break down.

True Attapulgite clay is composed of smectite - most commonly bentonite which are swelling clays. It is the swelling action that causes the eventually breakdown of the pellet. The best minerals for bonsai soil mixes as far as I can see are those which don't swell but have 'cavities" in their chemical structures that take in water and let it out when drying. The structures do not become weaker during this process and so should keep their shape and size over time. The key factor in their formation is temperature.

Both zeolite, pumice and diatomite are such minerals and have been used successfully in bonsai potting mixes

Zeolite minerals are formed at temperatures somewhat greater than normal clays which are often formed at surface by weathering (like the Attapulgite). Zeolites are formed in volcanic terrains where the heat of magma chambers kms below the surface drive the circulation of hot water through the rock. In this case volcanic rock (lavas and ash formation) are transformed by the heat and water to clays. As it forms at higher temperatures 60ºC - 150ºC the zeolite has a strong structure. As a result it is harder therefore somewhat more resistant to breaking down when it absorbs some water.

Pumice is a volcanic rock that forms by rapid cooling of lava as it hits water. It is high in silica (50 -90%) depending on the type of lava it is. The process of rapid cooling traps water vapour in the rock that is formed (generally quite round bubbles - geologists call them vesicles). They are so plentiful that the pumice feels very light. As the rock contains lots of little holes it is able to hold significant amounts of water - and because it is hard it doesn't break down easily. Again it is a great bonsai soil media - holds a lot of water and is light.

Diatomite is a naturally occurring sedimentary rock forming in marine basins from the accumulation of diatoms, a type of hard shell algae (often looking like hollow tubes when you see them under a microscope). It is composed of 80-90% silica, so it is tough as well as being light because of its high porosity - which sucks in water - and as such is also a great bonsai soil media.

See the attached document which contains both analyses of Mt Silvia and Maidenwell.

With such high silica contents it is very likely that pH of diatomite will be around neutral (rainwater is often thought to be at a pH of 7 but isn't because dissolved carbon dioxide forms a dilute acid - pH 6 to 6.5). Most plants thrive - they like rainwater in a soil that is less than 7 . Both mt silvia and Maidenwell diatomites contain clay contaminants that because of cation exchange properties that make a mixture of silica and clay more acidic. However, because of the small amount of clay relative to silica pHs should be only a little less than 6.0. Because the Mt Silvia diatomite contains more CaO and MgO (alkalis) you would predict it would have a higher pH than the MW diatomite, but not a lot because of the higher silica content.

Note that some plants, such as rhododendron, camellias, azaleas, blueberries, ferns, spruce, pines, firs, and red cedar prefer soil that is more acidic, with a pH of 4.0 to 5.0. Other plants, such as beech tolerate soils with a pH 7.0 to 8.0 (so you would add some lime to that soil) . Above a pH 8.5, the soil is too alkaline for most plants, while if the soil pH is below 3.5 it will be too acid.

Grant upload a document some time ago (also attached below) with measured pH's of various bonsai media.

Kanuma - ph 5.5
Akadama - pH 5.5
Mt Silvia Diatomite pH 6.0
Maidenwell Diatomite pH 5.5
Zeolite ph 5

Attapulgite ph 8 (so don't use kitty litter in bonsai mixes....)

So in a long winded way I have come to my point - Mt Silvia and Maidenwell diatomites will function in a very similar way - and are therefore interchangeable.

[Scott Roxburgh]

Thanks Neville, I was hoping you would chime in with some cold hard facts.

It is interesting to see that the to my ungeological eye, the diatomite seem to be much the same but have varied water holding capacity.

A lot to digest

Thanks

Scott.

[GavinG]

OK, just to put the cat among the pigeons, if akadama is just fired clay, why is crushed brick any different? Anyone compared it to akadama?

Gavin

[NBPCA]

OK, just to put the cat among the pigeons, if akadama is just fired clay, why is crushed brick any different? Anyone compared it to akadama?

Gavin

Hi Gavin,

Crushed brick was tested and in some ways it is similar to Akadama and in other ways different in the tests. It did not absorb/hold as much water as the Akadama even though the air filled porosity was the same.In one mix of 50% perlite/50% crushed brick it stayed too dry.

In use I would treat Crushed brick as a gravel replacement rather than a complete potting media which Akadama can be. The so called Chinese Akadama; which is just round balls of fired clay; in use performed well.

Crushed brick I imagine is fired to a higher temp than Akadama and doesn't break down.

Grant

[Shane Martin]

A pH of 6 is really not very acidic, given that neutral is 7.. SO Only a smidge on the acidic. I always use Mt Sylvia because it is accessible for me and it is also cheap. Works well. I literally grow everything in it. Pines, Junipers, Azaleas, Figs, Elms, Maples, Murrayas, Swampies, Crab apples. I haven't got any redwoods or camelias in i yet. Redwoods because they arrived in the mail in the middle of one week and I didn't have any diatomite, and camelias cause none have been repotted since I bought them, still in their nursery pots.
But that's the only reaosn. It is great stuff

Nathan, are you using Mt Sylvia at 100%, or in proportion with another bonsai mix.