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Basalt Powder?

Posted by mauirose 11 (My Page) on
Wed, Mar 18, 09 at 2:46

looking for some information on how to use basalt powder? i have heard that it is a useful amendment for highly weathered tropical soils, raising pH and increasing the CEC, and that the effect is suprisingly persistent. Truth or hype?


Follow-Up Postings:

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RE: Basalt Powder?

Adding Basalt to your soil would be like adding more sand to that soil. There really is no added benefit to adding Basalt to soils that need lots of organic matter.


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RE: Basalt Powder?

There has been a fair amount of research into this subject - apparently quite a few slicate rock dusts will act similarly, increasing CEC, lowering pH and providing a range of trace minerals.

From ATTRA:
A number of other rock dusts and powders are occasionally available in various parts of the country; sometimes the results from local trials are reported in national or international publications, but it is important to remember that what applies in one region may not be pertinent in another. Additionally, when dealing with natural materials like rock, there is very little product consistency from one batch to another; results from one trial may not be transferable to other situations.

Basalt dust, if available at a reasonable cost, can provide a wide range of trace minerals to agricultural systems over a period of several years; as with most rock powders, transportation costs are a major factor in determining cost-effectiveness. Most of the rich volcanic soils of
the world are derived from basalt, which gives some indication of basalt's agronomic value, and even when too expensive for land application, basalt dust can benefit farm systems when mixed with manure in the composting process.

Any rock, of course, can be ground into powder, if the price is right. Various people have proposed additions to the soil of assorted rock dusts, or even powdered gravel. One rationale for this is the paramagnetic property that some rock minerals add to the soila factor believed to be associated with high fertility. ATTRA has additional information on paramagnetism in soils for those interested.

The issues with many of these tests and trials is that they've been conducted under greenhouse conditions, so there may be a great deal of variability experienced in the field. And the consensus seems to be one would need to use a substantial quantity of these rock dusts or powders to effect any measurable change in soil condition.

I've attached an excerpt (.pdf file) from a University of Guelph publication that might shed further light.

Here is a link that might be useful: Rocks for crops


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RE: Basalt Powder?

Basalt varies too much to tell what minerals it can contain. It can also be acid or basic. However, I did a test with the red lava rocks used for landscaping. They are a type of basalt. Where I used the dust and fine particles the plants appeared to be more vigorous that ones I did not apply the dust to.

I will admit this was not a scientific test but for my own study of how different things effect plants. If you have it use it in a small area and see what happens.

With all rock dusts please use a mask over your nose and mouth while using it. The small particles can remain in your lungs forever. They may cause health problems.


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RE: Basalt Powder?

The material in Volcanite by Garden-Ville, is basalt.


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RE: Basalt Powder?

no arguing the benefits of organic matter just that it burns up so FAST

gardengal thanks for that link. Sounds encouraging but wow, check out those application rates!

maifleur plants do seem to grow better in cinder. Always thought it was the way it opens the soil but maybe more going on than just that. Thanks for the tip on face masks.

dchall-have u tried Volcanite?


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RE: Basalt Powder?

I've searched everywhere for local sources of Volcanite but I guess I'll have to order from that site


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RE: Basalt Powder?

I did an experiment with radishes and Volcanite. Didn't see any difference from the control pots. The soil was pure unadulterated Wal-Mart potting soil. It has been suggested that I try the same experiment with compost in the soil and volcanite on top.


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RE: Basalt Powder?

Rock dust could certainly be good in highly-weathered soils. The minerals in highly-weathered soils have been broken down and leached out. Adding ground up rock adds fresh mineral material that has not been subjected to the weathering and leaching that the parent soil has been subjected to.

OM burns up fast in tropical soils. You still need to add OM, but it's not a substitute for adding rock dust.

I have the opposite problem here, in my cold recently-glaciated soils. Inadequate weathering! leaves my soil sandy and gravelly. No clay particles to speak of, or humus, so little CEC. These are the soils that benefit from lots of OM but not rock dust. Hawaiian soils will be very different from Washington soils.


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