This page contains a bunch of different products, mostly derived from various types of rock.
Other than perhaps the first two, rock dust and calcium carbonate, you won’t generally use them unless you have a deficiency of specific minerals.
If you just need 20-40 pounds of something, it will probably be worth it to get it from me to save yourself time trying to find it locally.
If you need more, go local – just be prepared to search for a while, because some of these can be hard to find…
Glacial And Basalt Rock Dust
Glacial rock dust and basalt rock dust are broad spectrum, organic mineral fertilizers that everyone can use without a soil test.
In the last century, our actions have caused a depletion of soil minerals to the point where many of our soils are severely deficient in minerals.
One of the ways this problem gets fixed is when volcanoes erupt, distributing minerals around the earth, and during periods of glaciation, when glaciers break up and redistribute many different kinds of rock as they move across the land, resulting in big changes in soil fertility.
But we obviously can’t wait until then to improve our soils – and besides, it get awfully hot and cold during either of those processes 🙂
Fortunately, we’ve learned that we can do a little work ourselves by taking basalt rock dust (from volcanoes) or glacial rock dust (ground up and brought together during the last period of glaciation), and we can add them to our soil to boost fertility.
The reason we prefer either glacial rock dust or basalt rock dust is that they’re a mix of many different kinds of rocks, so they offer a wide array of minerals. That’s the goal of remineralizing the soil with rock dust minerals, to get a broad spectrum of minerals back in there.
Now, I know it seems kind of crazy to bring some ground up rocks into the garden and expect the benefits will be worth the money, but using rock dust for gardens and farms has been researched for over 70 years with amazing results, often producing bigger, tastier and more nutritious foods.
In my opinion, using either glacial rock dust or basalt rock dust can be one of the most important things to do on depleted soil.
I used to always go for glacial rock dust, but then I found a basalt that had a significantly higher mineral count pretty much across the board – for the same price as glacial.
So that’s what I use now, and that’s what I sell here.
But if you’re looking for bags of rock dust from your local fertilizer supplier, both glacial and basalt are great.
Remineralize the Earth is doing a lot of research on rock dust for gardening.
They recommend between 150 and 500 pounds per 1000 square feet. Still, good results have been seen with less than 5 pounds per 1000 square feet on some occasions.
If you’re getting dust from a quarry for a good price, I say go for it.
But if you’re buying it in bags, I recommend 50 pounds per 1000 square feet as being a good number.
Even then, it seems that applying less can still bring some great benefits, so just do what you can, even if that’s only 20 pounds per 1000 square feet.
In summary, basalt rock dust is:
- Used to remineralize soil with dozens of trace minerals that are needed for optimal plant health.
- The best form of dust because it contains many different rocks, meaning a more diverse nutrient profile.
- Worth it to buy from me for a small garden, but too expensive for a big garden.
Calcium is one of the most important minerals for both plants and microbes, arguably the most important.
Calcium is so important that everyone can feel pretty safe adding just a little calcium fertilizer onto their soil, even without a soil test.
Without enough calcium in the soil plants can’t access or utilize nutrients very well.
Likewise, foliar fertilizers and microbial inoculants won’t have as big of an effect if there’s a major calcium deficiency.
Obviously, calcium fertilizer should be applied when a soil test indicates a calcium deficiency.
But this is the main mineral fertilizer other than rock dust that I recommend anyone can apply without a soil test if they use only 10 pounds per 1000 square feet. It’s just so important to have the calcium out there and most of us will benefit.
You don’t want to go applying more than that, though, unless a soil test says you need it, because it is possible to use too much.
A lot of gardeners use dolomite lime, but that’s generally an inferior product. It has too much magnesium in relation to calcium for most of us. What we really want is calcium carbonate…
Calcium Carbonate Fertilizer
Calcium carbonate – also known as high-calcium lime or calcitic lime – is the main calcium fertilizer used to increase soil calcium levels.
It’s not to be confused with hydrated lime or quick lime, which can burn crops as well as your skin.
Calcitic lime contains approximately 30%-40% calcium and often around 2-4% magnesium.
If a soil test says I need calcium carbonate, I’ll use 10-45 pounds per 1000 square feet in my garden, often spreading that out into 2-4 applications throughout the year, once or twice each in the spring and fall.
Gypsum is calcium sulfate, so it brings in both calcium and sulfur, both of which our soils are often deficient.
Phosphorus Fertilizer – Fish Bone Meal
Phosphorus is the other most important mineral after calcium.
It’s generally present in the soil, but often unavailable in soils with a low organic matter content and a lacking soil food web.
While in the past I’ve recommended soft rock phosphate as my favorite source of phosphorus, it can be hard to find.
And more recently I discovered fish bone meal, which has nicely “available” phosphorus, plus a little bit of nitrogen to boot, so that’s what I go with now.
Potassium And Magnesium
Potassium is involved in many plant processes, but extra potassium is not needed in the soil of most home or market gardeners who are using compost and mulch.
Same goes for magnesium – it’s an important mineral, but most of us have enough of it already.
That said, someone of us do need it. For example, my soil is a rare one that has plenty of calcium, but needs a little magnesium and potassium.
The first fertilizer below supplies both, so if you’re short on both potassium and magnesium, it’s a great choice.
K Mag (aka Langbeinite or Sul-Po-Mag)
If you do need potassium and magnesium, this is your best choice.
K Mag is well known in the eco farming world as a quality organic potassium fertilizer. It’s approximately 27% sulfur, 22% potassium and 11% magnesium.
It’s also known as Langbeinite or Sul-Po-Mag, and is one of the most useful mineral fertilizers – some soil consultants consider it to have a very positive energy for the soil.
It’s my favorite source of magnesium, much better than dolomite lime, and my favorite source of potassium, too. Most of us will benefit from the sulfur as well.
Magnesium Sulfate (Epsom Salt)
Contains about 10% magnesium and 13% sulfur.
This is great if you need those 2 minerals, and a much better source of magnesium than dolomite.
Potassium Sulfate (0-0-50)
Also known as sulfate of potash, it contains 50% potash and 18% sulfate.
This is great if you need those 2 minerals, and a much healthier source of potash than potassium chloride.
Greensand is a sandstone with approximately 7% potash and a fair amount of iron and silica, as well as a very broad spectrum of trace elements.
Although the potassium is tightly held and slowly released, I do like greensand because of the benefit of the silica and trace minerals that come with it.
I don’t recommend it all that often, but if you need potassium without the magnesium, this is exactly what you need.
Nitrogen – Feather Meal
You can get most of your nitrogen by composting and making good use of your grass clippings, but occasionally it’s worthwhile to have some more.
Feather meal is perhaps the best source of nitrogen. It’s organic, yet contains around 12% nitrogen.
These are some extra specialty fertilizers that are used in small amounts, generally when a soil test says you’re deficient in specific minerals.
They’re generally used by people who know a bit about how to use them.
*The prices change depending on how many pounds you add to your cart.
Here’s what these specialty fertilizers do:
Humic Acids (aka Humates)
Humic acids come as a black powder. They’re used in foliar sprays along with organic fertilizers to help the plant better uptake and utilize the nutrients in those fertilizers much more effectively.
The quality of humic acid products varies widely. This one is very good, containing over 90% soluble and contains a minimum of 85% humic acids.
Before application, first dissolve the powder in warm water at 5 Tbsp (1/3 cup) per quart of water. That quart will cover 2000 square feet, but doesn’t have to be used right away – you can store it.
When you’re ready to use it, mix that liquid with at least 50 times as much water, which is again 5 Tbsp (1/3 cup) per gallon of water, or 3 gallons of water for each 1 cup of the liquid.