Q. So, what is the deal about rock dust?
A. There is something of a buzz going around about rock dust for growing vegetables – as if it’s a new discovery.
The statement is made (https://news.independent.co.uk/uk/environment/story.jsp?story=622128) that “By spreading the dust we are doing in minutes what the earth takes thousands of years to do, i.e. putting essential minerals in the rocks back into the earth.”
This is not new science. Jacob Mittleider has been teaching for over 40 years that “the only difference between dirt and rocks is the size of the particles.” And that leeching, flooding, erosion, and crop removal, which have been going on for thousands of years, make it necessary to replace the minerals lost by adding them back using ground-up rocks. Furthermore, commercial fertilizer companies have been grinding up rocks into dust, bagging it, and you and I have been spreading it on our lawns and gardens for over a hundred years.
The big difference, as I see it, is that we have learned which rocks to grind up, and in what ratios to apply them to our soil in order to give the plants exactly what they need, and the rock dust proponents say nothing about that.
Suppose the quarry from which you obtain your rock dust happens to be a limestone quarry. You will be blessed with an abundance of calcium and magnesium. Since all gardens need these minerals, and most do not get them, you will experience an improvement in your crop yield. But what about the other 11 elements the plants need to receive from the soil? And what if the quarry is granite instead of limestone? Or what if the rock dust chosen contains heavy metals, or other harmful materials?
Compost is cited as the only other thing needed – except for the statement “using little more than,” at one point in the article. That “little” could make all the difference. What “little” else are they using?
Rock dust, compost, and “little more”, are all three unknown quantities insofar as the nutrition they provide to your plants as well as the other, possibly harmful, elements they are introducing into your garden.
The Food For Everyone Foundation teaches people to take the guesswork out of gardening; that healthy plants must have 16 elements; that 3 are provided in the air; that the other 13 must come from the soil; that they are needed in certain ratios, and that they are needed throughout the plants’ growing cycle – not just once at the beginning.
I encourage all who read this to continue using rock dust that has been certified to contain only the minerals your plants need, in the ratios needed, and thereby be assured of “a great garden in any soil.