zeolite

[Stephen Vella]

HI does anyone use zeolite in their potting mixes.

Does it break down fast? Im hoping it would last for at least 4 years.

Also does it contain salts?

cheers

[Lesley Cox]

What is it?

[Stephen Vella]

Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. Also used in agriculture,medicine,nuclear,heating,construction etc

Zeolites can also act as water moderators, in which they will absorb up to 55% of their weight in water and slowly release it under the plant's demand. This property can prevent root rot and moderate drought cycles.

Used in kitty litter.

[Lesley Cox]

So they would be in the product we buy called Chrystal Rain?

[DaveM]

I've not used these in my composts, but...... The zeolite group of minerals have some interesting characteristics to which you refer Stephen. Their structure can be likened to a tight framework which encloses large spaces which are occupied by large cations and water molecules. These cations and water mols have considerable freedom of movement permitting ion exchange and reversible dehydration. (Hence one of the important uses is as a molecular sieve.) In soils zeolites are resistent to breakdown due mainly to its framework structure. But it will aid water management to plants and important plant nutrients such as K and N can be held in those spaces and be available for plant take-up. The large cations present naturally in zeolite include K, Na, Ca, Ba depending on the specific zeolite mineral used in the product. Anyway K and ammonia added to the soil will exchange with cations within the zeolite.

See this web site for more info.
http://www.zeolite.com.au/products/agriculture.html

[Maren]

Is it commercially available for horticultural purposes? what are the trade names? google does not prove helpful.

I have been using chempak Ultrasorb for a while but I believe that's just expanded clay. This is also used in cat litter, which I use liberally when breaking in a new bed ion my allotments. It is a natural claybreaker and has quite a pleasant perfume - for a while anyway.

[Martin Baxendale]

I have a feeling the Moler expanded clay granules I buy from Viresco Uk Ltd used to be described as being zeolite granules:

http://www.viresco-uk.com/information/horticultural_growing_media.asp#moler

[maggiepie]

Is this similar to Diatomaceous earth?

It is also used as an absorbent in garages etc.
I have a big bag of it and have used it in the past to try and root cuttings. It fizzes when you add water to it.
Am referring to the granules not the powdered form.

I've also been wondering if I could add it to potting mix.

[Lori S.]

Zeolites are a group of minerals whose ion exchange capacity gives them special properties, as has been said, while diatomaceous earth is the hard body parts (tests) of tiny siliceous-shelled organisms, usually marine but there are also some species that inhabit fresh water.

Also, zeolites aren't expanded clay... "clay" is another different group of minerals. 

[Lesley Cox]

I wish I hadn't asked.

[Martin Baxendale]

Lori, you're right. I remember now that the zeolite sold by Viresco was another product of the type you describe.

Helen, yes you can add the granules to compost mixes. Good for drainage and aeration.

[maggiepie]

Helen, yes you can add the granules to compost mixes. Good for drainage and aeration.

Thanks Martin, that's good to know.

[Stephen Vella]

Thanks for the responses.

David M thanks for the link...and explains some questions I had in mind.

Helen the kitty litter products Ive seen seem to break down to a white silty looking mess and not what i would recommend for potting mixes, well not long term.

Maren theres no trade names that I know of but only as zeolite. Zeolite was mixed into a soil media for a green roof at work. From memory it was mixed with red lava rock, bark fines, sand, perlite, coco fiber and gravel..maybe something else. I'm going to have a better look and see what the gardener has to say. I'm wanting to use it in a cypripedium mix. I was hoping it was free of salts. Sounds like it works like Seramis 

I haven't personally used zeolite in a potting mix but was recommend from a soils representative/salesman.

Lesley I don't know crystal rain. Zeolite looks like a white fine gravel and is very hard.

cheers

[Stephen Vella]

Maren the trade name looks to be "Escott Zeolite"

After reading the web site It mentions that this particular zeolite is mined in northern NSW Australia and is low in sodium, suitable for horticulture/potting mixes, comparing it to other zeolite mined in other parts of the world

cheers

[Regelian]

Zeoliths are a group of alumisilcates, a bit like clays, that have the interesting property of adsorbing selective materials/molecules (molecular sieves).  There are over 40 natural zeoliths and many have been synthesised for specific purposes.

Their adsorbtive qualities (versus aBsorbtive.  Think of a sponge, which aBsorbs water.  You can wring the water back out.  ADsorbtion chemically binds and the material will NOT wring out) vary with two of the most commonly found zeoliths in commerce being kitty liter (mixed with a diatomatious earth) and aquarium zeolith (clinoptilolith).  These zeoliths adsorb ammonia in large amounts.  In kitty litter this has the desirable effect of preventing the strong odor associated with a cat-box, while in the aquarium/water purification ammonia is one of the main waste products that needs to be removed.

What is fascinating with this adsorbtion is; ammonias make for a wonderfull home to nitrifiing and denitrifiing bacteria!  As bacteria are the machines behind the nitrogen and carbon cycle, their management is adventageous.

Additional properties of the clintinoplith group is their ability to store water (in German they are called "boiling stone", as they give off water when heated. Zeo is Greek for boil. lith is stone, as you know), as well as adsorb potassium, calcium and a few other similar metals.  They act as storage areas for these usefull products.  This can be a problem with certain types of plant culture, as, if a fertilizer with calcium (as for many geophytes) is used, the zeolith will tend to adsorb the calcium.  The same with ammonium-based fertilisers.  A two-edged sword.

I have not used them in potting mixes, but I do dump the spent zeolith from my aquariums into the rockery, where they aid in porosity and water retention without promoting root rot.  Is this advantageous?  I can't say, other than no negative effects are noted and I hate to waste a potentially still usefull material. I could imagine them being usefull in smaller amounts for various reasons, much as active carbon or perlite.