Kitchen Garden Forum

I have just read the article about rockdust in the January KG (saved it for Christmas, you see!). Has anybody used rockdust and DOES it work? I am tempted to try it if I can find a local supplier.

I've been wondering the same thing. After all the rain we've had, I can't help feeling that all our soils will have been badly leached of much of the goodness and nutrition in them this winter. I can't see that giving it a try will do any harm. One can always treat part of a growing area and do a comparison.

Pretty sure that if you search you'll find at least one comprehensive previous thread on this.

Search for it as two words and tick the search option to return topics not posts.

Two on "Rock Dust" in General Chatter and similarly in Best Practices, third there with a ? and a fourth on "Quarry Dust".

Of forum members Natures Babe has mentioned it fairly frequently and Primrose threatened to try it, as did several others.


Personally I think people are worrying too much about leaching of minerals, unless they are on sand.

Isn't sand worn down rocks? Wonder how the mineral content of sand compares or will a lot have been washed away and it be mainly silica?

Thanks for the reminder, Peter. I have looked at the archive but I don't think there is a definitive answer to the question: does it really improve the soil or is there no difference?

We have lots of quarries in our area and could readily obtain "quarry dust" but as they are mostly lime stone, I think the result would be rather different from the basalt rock dust mentioned in the article and available commercially.

I've not got round to reading the December mag. yet, but have just looked up a bit more info on the rockdust. Pinetum Products sell it for £11 to collect or £19.50 delivered and show a full list of all the minerals and the quantities they occur in the rockdust they sell. They have had it analysed.

It sounds a good idea as I'm sure some minerals must get depleted if you are constantly harvesting from the same area, and also different parts of the country will have more or less of certain minerals depending on their geology.

PLUMPUDDING wrote:Isn't sand worn down rocks? Wonder how the mineral content of sand compares or will a lot have been washed away and it be mainly silica?

Sand is mainly silica and no use as a nutrient. The rock dust that is marketed by Seer is crushed volcanic rock and has many essential trace elements in its make up. Soils derived from volcanic rock are generally very fertile and I suppose that is the thinking behind selling the stuff to gardeners. I used it in my potting mixes this year with excellent results but I'd have to agree with Peter that if you have a normal soil it shouldn't be deficient in minerals unless you've cropped intensively and never put anything back.

Unless you have had a full soil analysis and your soil is found to be deficient of the said trace elements supposed to be in 'Rock Dust'
I would avoid it like the plague.
Generally speaking an unnecessary expense and would suggest that the use of an all purpose fertilizer will do just as well at a quarter of the price and you at least know that the fertilizer will assist your crops.
JB.

Thank you, everybody. As our soil is quite healthy and gets regular feeds of cow manure and home-made compost, I will spare myself the expense.