By Ellen Galvin, for GrowingAGreenerWorld.com
Rock minerals are the building blocks to healthy soil. Photo by Ellen Galvin
The secret to growing healthy and nutritious food begins with the soil.
Naturally healthy soil contains billions of living microorganisms—from bacteria to nematodes, fungi, protozoa, arthropods and earthworms. Together, they join in a carefully choreographed “bacterial ballet” in which each organism has a specific role to play, from the recycling of nutrients to the decomposition of organic materials.
Yet organic matter is only part of the story.
While compost is a key component of healthy soil structure, no amount of organic matter can make up for mineral deficiencies. Missing minerals are just that—missing. The end result is poor and infertile soil.
Moreover, minerals that are missing from the soil are minerals that are missing from the fruits and vegetables that it produces.
It’s why the kale that you buy in the grocery store may have a very different mineral profile from what nutritionists recommend as part of a healthy diet.
As consumers, we might feel a little “ripped off” for being sold inferior produce. But the ramifications are much larger—and they have implications for the future health of our planet. Things will only get worse if we continue using commercial farming techniques that strip essential minerals from our soils without putting them back.
Rock minerals—the building blocks of healthy soil
One of the keys to restoring the health of our soils is through the process of remineralization. As proficient as plants are, they can’t make the minerals that are essential to human health and nutrition. We also can’t rely on Mother Nature’s old “standbys,” i.e., volcanoes, glaciers and floods, to do the work for us.
The modern day solution is to add mineral fragments back to the soil with rock dust.
Also known as rock minerals, rock flour, rock powder, stone dust, soil remineralizer and mineral fines, rock dust is finely crushed rock containing micronutrients and trace elements that are important to the life cycle of plants and which enhance the ability of beneficial microbes to flourish.
Simply stated, rock minerals are the building blocks of healthy soil.
Results include improved plant structure, increased resistance to pests and disease, and more intense flavor profiles for fruits and vegetables.
Although some retailers classify rock dust as a fertilizer, it does not have the necessary amounts of nitrogen, potassium and phosphorus (N-P-K) to qualify as such. Instead, rock dust contains minerals like calcium and trace elements like iron and manganese which are difficult to replace once they’ve been depleted from the soil as a result of natural weathering and/or over-farming.
Is all Rock Dust Alike?
A rock is a rock—right? Not quite. Igneous rocks like basalt and granite have the highest mineral content, with basalt providing a greater balance of nutrients for optimal plant health and vitality.
Created through the cooling and solidification of magma and lava, basalt is the rock material that makes up most of the soils around the world. It continues to deliver a steady flow of nutrients over time, even as it decomposes. Basalt’s slow-release benefits make it an effective way to minimize deficiencies, particularly with fast-growing crops that experience periods of rapid nutrient uptake.
A Stone-Age Science
The benefits of adding fresh sources of rock minerals to the soil are not new. Some of the richest, most fertile soil on the planet is found near active volcanoes, which explains why people throughout civilization have been willing to settle near volcanoes despite the potential dangers.
In the 1930s, researchers in Europe used finely ground rock dust to treat and improve the productivity of degraded forest lands. One of the most comprehensive studies of the benefits of rock dust came from D. Hotman de Villiers who conducted a series of long-term field trials on highly degraded soil that led to increased sugarcane yields on the island of Mauritius.
Today, scientists across the globe continue to validate the benefits of rock dust. Brazil has made soil remineralization part of its agricultural policy—a major step forward in generating global awareness and interest in the importance of rock minerals and how they help grow healthier, stronger plants with higher yields and higher levels of nutrients.
Biology & Geology: A Marvelous Interaction
Healthy soil is derived from a marvelously complex interaction between soil biology and geology.
As decomposing rock material reacts with soil microorganisms and plant material, the rock material releases elements like calcium, magnesium and iron. Remineralization with rock dust is a low-cost, high-impact way to aid in the regeneration of soil by closely mimicking natural geological and biological interactions. The result is optimal and sustainable plant growth that leads to healthier people and a healthier planet.
Expect to hear much more about soil remineralization in the year ahead since the United Nations has declared 2015 The International Year of the Soils.
About the Author: Ellen Galvin writes for Central Oregon Basalt Products, LLC, manufacturer of Cascade Minerals Remineralizing Soil Booster. Made of 100% finely milled volcanic basalt from Central Oregon, Cascade Minerals Remineralizing Soil Booster is an all-natural soil amendment listed by the Organic Materials Review Institute (OMRI) for use in organic production in both the U.S.A. and in Canada.
About Joe Lamp'l
Joe Lamp'l is the Host and Executive Producer of the award winning PBS television series Growing A Greener World. Off camera, Joe dedicates his time to promoting sustainability through his popular books, blog, podcast series, and nationally syndicated newspaper columns. Follow Joe on Twitter
I remember seeing a BBC production about plants that revealed that it wasn’t just the rock dust, because the plants could not access the minerals in rocks directly. It turns out that there is a fungus that grows all through forests that are often found intermingled with the roots of trees and other plants directly, This fungus itself was also found incircling the tiny bits of stone in the soil, dissolving them for the tree/plant as the plant gained by this by its better health, the fungus benifitted by also getting nutrients from the plant. It has been proven that when this fungus has been added to potted plants, where the only difference was the addition of the fungus to one of the two plants, the one with the fungus did remarkably better than the one without.
The addition of this fungus is easy, just find a forest and dig down a bit. The fungus looks like tiny white strings matting together the soil around any evergreen tree. Please don’t ruin the tree, we are talking about maybe a hole four inches in diametre in size, and just under the soil/ under-tree detritus of leaves/needles. I say evergreens because I did this experiment but live in area that has mostly evergreens in the forests near me, so I haven’t been able to test out the deciduous patches yet. Feel free to experiment where you live. In my experiments the finer the milling, the better. A feeling like flour or dust the better. Sand doesn’t really work, because soil with sand in it as iit drains too fast. The smaller the particles the less work the fungus has to do.
Good luck with your experiments, I apologize for not remembering the name of the BBC show that would back up my comments, if I do remember, I will come back and add it retroactively. : )
Magdalene
For anyone interested in purchasing a Remineralizing Soil Booster, they are also sold online. If you are specifically looking for the Cascade Minerals brand, you can do a Google search and several options come up for places to order from.
Greetings. I recall seeing a product on your site a year or so ago.. it was a “plastic” type raised bed product.. they “clicked together” so you could add length, as well as stack them. I cannot recall a name nor an address. Can you help?
thank you. peace. jtk
Hi Joe. I don’t recall a plastic raised bed product that “clicked together”. The only quick assembly raised bed product we’ve demonstrated that I can recall was in episode 804. But the boards slid into corner concrete builders blocks. But they were stackable but definitely did not click. Here’s the link to the show if you want to check it out: https://www.growingagreenerworld.com/episode-804-gardening-butterflies-beneficial-insects/
Are you at liberty to say what brand you use that blends the rock dust and compost? Where do you get it?
Hi Terri. There is no brand. It’s just locally sourced from what is available. Where you live will be different than mine. But the key is to get those local minerals into your soil.
Hello Joe, very informative article.
I live in the state of Florida Id like to know if perhaps you knew where I can acquire rock dust to use in my small garden!
Thanks Louie. Not living in FL, I don’t know. But I would try contacting your County Extension Service, Horticultural suppliers, and asking the professionals at the reputable independent garden centers in your area. I happened upon mine by chance at a landscape supply company that sold bulk soil products. They no doubt are in your area also so seek them out and ask them about what they have that would be similar. Good luck.
Louie Ray, we carry a colliodal mineral replenisher, a high grade rock dust. You may contact us at 530-741-0873 for more information, or to place an order.
If you are looking for organic garden amendments, check out MightyGrow Organics. They are located in SW Alabama and actually manufacture a trace mineral enhanced fertilizer. You can find out more at: http://www.mightygrow.com
Ask for Michael, he’s the person I dealt with when I ordered.
As I was taught in geology :
“The geology controls the biology “
How can I detect what type of rock dust I have …. it was pulled up when drilling our well ..its light gray and there is alot !!! I want to find out if its mineral content will be wonderful for our organic gardens ~~ ♥
I hope someone can help me with this information ~~
Blessings !!
Mary, I would send it off to your county extension service for analysis. But call them first to know they will offer this, along with cost and other details. Here’s how to find the extension service info near your: http://nifa.usda.gov/partners-and-extension-map?state=GA&type=Extension
I’m not sure you’d bother with identifying exactly.
Try germination and seedling growth relative to a control soil of whatever is abundant for you to farm with.
Topsoil & coresoil individually, a fifty fifty stock mixture that you split fifty fifty again and again. It’s more important to have more replicates of each mix concentration and you’d want to try a 3-5 percent minimum for sure (four dilutions).
Childsplay if time consuming.
cheers,
L
lucasiciliano at hotmail.com
Could I use chicken grit as a soil amendment and also get the mineral benefits?
Yes, I believe so Dawn. I haven’t done any analysis on this but I’m sure it is mineral based and very similar to what I see that I’m using in my garden. I’m not sure how you go about testing this but I’m sure your university extension service can analyze it for you if you’d like. It won’t be hard to find out if you try to contact them. The mineral formulation I use is a granite dust base which is what I belive is in the chicken grit we use here at the Garden Farm.
Hi,
Are you aware of any local growers that sell at farmer’s markets etc.? I am in the Portland area, but would not mind traveling. Any information would be greatly appreciated
Thanks
Hi Colleen. Yes, plenty of farmers markets allow local growers to set and sell their produce. But you have to go through an application process first. I would check with each city government office and find out who to speak to. Or better yet, check their website first. A lot of times that info and application are posted online. You’ll just have to do some searching for it.
What is the difference between these rock minerals & volcanic ash? we’ve bought & applied the volcanic ash 2 seasons now & we do notice a lovely difference in our plants – edible, ornamental & Both!
Thanks
Does granite dust contain the same variety/supply of minerals that volcanic rock does? Does it have to be decomposed?
I am new to this conversation. I have been gardening for some years now in Northern Utah. I recently have been visiting different websites and from one in particular, Intelligentirrigation llc.com I will be using Azomite this year. Azomite is mined in Nephi, Ut. and is from volcanic rock. For more info: www. Azomite.com or Azomite Mineral Products, Inc P.O. Box 21 1078 West 5300 South Nephi, Ut. 84648
Hi Joe,
Looking forward to what you find out about sources for Cascade Minerals back east. We are in Ohio. In my research there is a company in Dufur, Oregon that is carrying the Cascade Minerals and it looks like they could ship to Ohio. However, we would sure like to have a more local resource. Great info by Ellen and kudos to you for sharing that with us! And by the way, Dufur, Oregon is about 14.3 miles from where I grew up in The Dalles, Oregon. Tomorrow, 3/28/2015, Five Rivers Metro Parks here in Dayton, Ohio is having a program on Spring Garden Prep. I will be interested to see if they broach the subject of mineralization as thanks to you and Ellen I now understand how important it is. I have tilled in previous years but this will be my first season for no till gardening. Keep up the great work you are doing. You are much appreciated.
Sincerely,
Marnie Moore
Azure Standard
79709 Dufur Valley Road
Dufur, OR 97021
Phone: 971-200-8350
Fax: 971-645-4759
You didn’t say how much should be added to the soil….or did I miss that?
Hi Marilyn. I add about an inch of the compost / mineral mix to the surface twice a year, in spring before summer planting and after summer crops come out to prepare for my fall plants. I scratch the mix lightly into the surface of my raised beds. It doesn’t sound like much but keep in mind, most roots are close to the surface. The minerals and compost nutrients will be available to the roots as they are converted to a form the roots can absorb.
Looking forward to your next newsletter with info on where to purchase it locally. I’ve heard about rock dust in some you tube videos on gardening but didn’t know where to get it. Thanks for the info Joe.
Thanks for the info. It’s always nice to hear of ways to improve soil.
can’t wait for the specifics Kathleen asked about.
I was very interested to read this article. And pleasantly surprised to read at the end that Ms. Galvin writes about a product from my own Central Oregon. I moved here two years ago from coastal Virginia, where I had a large garden. I’m learning the differences and similarities of gardening in Oregon and found this article helpful.
Great article. Thanks!
Rock dust, where do you get it? Nursery? Sand and gravel company?
Could you give some practical tips on how a gardener can get the rock dust and the best way to apply it to soil? Dig in? Add to compost? Layer on surface around plants?
Thanks,
Kathleen
Hi Kathleen. I’m going to put together some info. on where you can source rock dust locally. My goal is to have that info avail by the next newsletter in 2 weeks. And I’ve contacted Ellen about this. She might be able to offer some help here.
As far as use, I add about 2 inches to the soil surface twice a year. Once after winter and once after summer. Then I simple scratch it in (not till), into the soil surface so it’s blended into the existing soil in the top two or three inches. Since carbonic acid will dissolve the minerals over time and most of the roots are near the surface this is adequate. Water, worms, and other microorganisms will work it further down into the soil.
If you can’t add it to the entire bed surface, then it is most important to add it around the root zone of your targeted plants. Start with that and work out from there as able.
And compost is always a good thing. So feel free to add compost as able. I do twice a year as well. In fact, the rock dust I add, is already blended with compost. So I get to add both at the same time. It’s a huge time saver and super productive since you’re adding the two most important amendments at once.
But keep in mind, the minerals / rock dust is to help complement the organic matter of compost. You need both. As Ellen said in her article, its the interface of biology and geology. Love that!
Hope this helps.
Thanks Joe!
Hello Kathleen, Ellen Galvin here – a bit further down, I’ve provided some general information on how to apply finely milled volcanic basalt to your garden and containers. While I cannot speak to other companies’ products, I can say that ours is available at select nurseries, garden centers, and home improvement/hardware stores across the country (the list is growing every day). There are also a few online distributors that ship directly, including Azure Standard and Down to Earth Distributors (if you Google their name and the product name you should arrive directly at the appropriate page). I hope this helps!
Wow, that is a lot of rock dust! I have a relatively small garden, it is 20′ x 20′ so I would need 68 cubic feet f ruck dust to treat it. If I also, wanted to teat all my flower beds and God forbid my lawns, I would need to purchase it by the truck load.
Yes, but that’s just about 2.5 cubic yards. Not so bad and well worth it!
This was an interesting read, thanks for putting this one together. How is rock dust used? Does it need to be mixed in with compost? Can it be just sprinkled on top of the soil? How much should be used and how often? Questions, questions, questions! 🙂
JAS, I just commented on this from someone asking basically the same questions. Please check my reply right next to your comment. I think it will answer your question. Glad you liked the read.
Such great questions! Joe asked if I might be able to offer some insight, and while I cannot speak to any other company’s product, I am happy to share our recommendations for applying 100%, finely milled volcanic basalt to your garden and/or planting beds. At the time of planting, we generally recommend using about 10 lbs of product per 100 square feet (lightly scratch the rock dust into the surface of the soil, as per Joe’s description above). During the growing season, we advise using another 5 lbs as a top dressing (rake in lightly and water thoroughly). For containers, we recommend 1 cup per cubic foot of potting soil. For best results, mix prior to planting. For surface applications, use 1 tsp. per every inch of pot diameter then lightly stir into the top of the soil and water thoroughly. Last but not least, finely milled volcanic basalt is a FANTASTIC addition to compost. We recommend 2 cups per cubic foot. Hope this helps!
We have been using Texas Green Sand for it’s mineral content.
how about wood ash? i have a fireplace that i use fairly regularly.
i have used it sparingly in the garden because my very sandy soil has a high ph. but the soil on my hugelbeds should be, and should stay, considerably lower. (should test this, but i think it is safe to assume.)
in one of my previous incarnations i was a potter, and using ash for glazes is as old as pottery. different woods yield different colors because they have different mineral content. copper is common, and most simple ash glazes are green.
my first thought here is that i could spread some of the mineral grit that i supply for my chickens. but i am thinking that i will start spreading that ash.
any comments on this?
Be careful adding wood ash to your garden and beds Mo. A little bit is fine from time to time in a light dusting. But too much will through your soil pH off. I dispose of my wood ash by walking through my woods and lightly dusting the ground as I shake it out of the bucket–kind of like a flower sifter.
If you start adding the wood ash, monitor the performance of your plants. They will tell you if the ask is adversely impacting them by how they look. My suggestion is to take a soil test from the area you plan on using the ask “before” you apply any. Use that as your baseline reading. Then start gradually adding ash. After a few months, send in another soil sample which will include ash traces. Then see what the report says. If it’s still in line you’re good to go. Or you’ll make adjustments accordingly.
PH is such an interesting thing. We (in St Louis MO) have tap water with a 7.5 ph!! So adding lime or wood ashes is a disaster. I do save “biochar” from our wood burning stove (with its catalitic converter) to put in the chickens yard/compost. Not sure if it is really biochar, but seems like charcoal. Loving Steve Solomon’s book “The Intelligent Gardener”, and hoping that remineralizing per his COF (Complete Organic Fertilizer) will boost our nutrient content of veggies this year. And really like the Back To Eden movie (available online) showing that the wood chip mulch helps moderate everything. Fingers crossed!!
I am in concert with using minerals, but don’t know enough to know what to purchase. Is it possible to provide us with a variety of brands or details to know what is considered good for us to use? And, maybe typical sources for these products? Since Oregon is the opposite side of the country, are there different sources in the east. Thanks much!!
Hi Alan. I’m going to work on this. I’d like to include this follow up piece in the next newsletter. Thanks for the suggestion.
I lived in Maine for 5 years, and belonged to MOFGA. Rob Jonston of ‘Johnny’s Seeds in Albion , helped get me started on Granite Rock Dust. Great stuff!!!
Good article. I guess I should have my soil tested and add the minerals along with the compost. Thanks
What brand of rock minerals do you suggest? How much is used? When is the best time to apply?
Thank you for the clear and concise article. Very glad you that have written about this very important soil amendment. We have been using a fertilizer that contains glacial rock dust at our organic perennial nursery and botanical gardens for many years. Simply amazing results!
We have been using Texas Green Sand for it’s mineral content.