By Mallchin
East Sussex,
United Kingdom 
How effective is volcanic rock dust as a soil improver. Suppliers claim that root growth and water retention is greatly increased. Has anyone used it that can confirm or comment
7 Jun, 2011
Answers
That is what I was going to ask...
7 Jun, 2011
Soils derived from volcanic rocks are supposed to be very fertile - hence the popularity of the farmlands on the slopes of Mount Etna, for example. I don't know of any soil conditioners based on volcanic dust though. Crushed rock is supposed to release trace elements.
7 Jun, 2011
Adding rock dust to your soil is similar to adding lime plus some minor trace elements. If your soil is already good and fertile then you do not need the rock dust. It is not something that I bother with.
7 Jun, 2011
its good for stopping aeroplanes.never thought about it in the garden.
7 Jun, 2011
We use a form as a grit to improve drainage in clay soils, and to improve nutrient retention in potting composts. Itcan also be used as a kind of natural slow release micronutrient fertilizer. Note that most kinds eventually break down into clay in alkaline conditions, or a fine silica dust (podzol) in acid conditions.
11 Jun, 2011
There seems to be a bit missing from your question - effective when used for what?
7 Jun, 2011