Last summer I picked up a 10 pound bag of Azomite rock dust from Amazon for around 20 bucks. I know it sounds crazy to buy rock dust but this stuff sounded pretty amazing. It comes from a desert in Utah that was once an ancient seabed where the ash and other material from a volcanic eruption had settled.
Most fertilizers replenish nitrogen, phosphorus, and potassium (NPK), but generally don’t add secondary nutrients, micronutrients, or any of the other trace minerals and elements that plants need. Azomite contains around 70 and seems to be the best and least expensive way to replenish them in soil.
With that said, I’m guessing that good quality potting soil already has what plants need, at least before it gets used up. But my property is basically built on compacted construction debris with a layer of crappy St. Augustine grass on top. And even if some of the minerals are already there it looks like there isn’t any harm in adding more. I’ve been using it in my containers, around my Kratom tree, and scratching it into my herb garden and everything is growing well.
You don’t need to use too much of it. I do a few heaping tablespoons around my tree, and a couple teaspoons scratched into to top of containers. Still have about half the bag, and that’s after a year of using it and giving some away.
Do your plants really need everything in Azomite? Probably not, but they definitely need some. The importance of minor nutrients has been known for a couple centuries. There’s an old theory called ‘Law of the Mimimum’ that essentially applies the saying “a chain is only as strong as its weakest link” to cultivation. You can add all the major nutrients your plant can handle, but the lack of just one minor can prevent it from thriving.
The theory was popularized by Justus von Liebig who is considered to be the father of the fertilizer industry and modern agriculture.
It was based on work by another German chemist, Carl Sprengel.
We owe quite a bit to these dudes. Next time you have some kratom tea, lift your glass to them and shout Prost!