I first came across Rock Dust around a year ago while researching soil remineralization. Most beginners will inevitably reach a point when they start looking to improve their growing medium and that’s usually after the first season of growing.
Rock Dust comes with some bold claims. It is said to help build soil, increases pest resistance, increases crop yields and increases microorganism diversity, and amount. Also known to help with water retention in soil and removes the need for chemical fertilizers. Rock dust as it has up to 70 minerals and trace elements that increase nutrition in plants. This helps to produce nutrient dense healthy plants and widely used in organic farming. It is environmentally friendly and does not leach into the water table, so thumbs up there. Basalt and Granite often contain the most minerals where as Limestone tends to have the least.
So what is Rock Dust? Essentially it is a waste product from the mining industry and can be free if you are able to collect from a quarry. It comes as small pebble like pieces of crushed rock as well as a fine powder.
Those that wish to remineralize a 6ft x 4ft raised bed with soil, I would recommend around 5 to 10 pints. Depending on what soil type and condition your dealing with it’s simply a case of using your judgment. I tend to use a 4 to 1 ratio, that’s 4 cups of dust to 1 cup of pebbles. Trace minerals in the powder are absorbed slightly easier by the plants. Small pebbles provide a slower release as well as drainage. If you are growing into compost that has had a season of plants sucking the life out of it, then you should thinking about increasing the amount you add slightly. I did a number of split tests last year, which seemed to suggest that Rock Dust works well just not on seedlings.
Until next time. Learn as you go & learn as you grow.
Your friendly Suburban Farmer – Edible Gardens Team
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