Rock minerals — also known as volcanic rock dust, rock powder, stone dust and stonemeal — are the secret, essential ingredients often lacking in conventional plant fertilisers.
While the manures and organic fertilisers many gardeners use are big on macronutrients such as nitrogen, phosphorus and potassium, they often pull up short when it comes to trace elements vital for healthy plants.
In fact, eight of the 17 elements essential for plant growth are micronutrients: boron, chlorine, cobalt, copper, iron, manganese, molybdenum and zinc.
As plants grow, they take up what minerals are