Richard - the reason Zinc isn’t shown in the guaranteed analysis is that it falls below minimum amount that can be shown on a guaranteed analysis. Zinc has to be greater than 0.05% to be shown. That’s equivalent to 500ppm. The Zinc content in Azomite has only 64.3ppm


The zinc in Azomite is in igneous metallic form.


If it is in metallic form it would almost certainly be leached by weak organic acids. Once in solution I am guessing it will become available for fungi.


From what I gather, azomite is mined from a welded tuff deposit. These are the deposits that form during pyroclastic flows like those that covered Pompeii in A.D. 79. It is essentially a rock deposit mostly composed of tiny little glass fragments that are hot enough that they are still somewhat molten when they are emplaced on the land.

Azomite contains about 10% montmorillonite, and if given long enough would be the most likely final end product of its weathering. For example, older Cretaceous rocks in Wyoming have been extensively altered to bentonite clay that is widely used for all manner of industrial applications. (Source:, Source #2:

But that alteration takes geological time, and I’m skeptical that putting azomite on your soil is going to do much.

Here is a study published in a reviewed journal that suggest azomite had little effect on fruit seedling growth over the short term.


I too am skeptical, and have been gun shy about this product for years. For me there doesn’t appear to be a glaring need, so why bother? On the other hand, I do have great results with things that are often poo-pooed by others (mycorrhizal inoculum, humic acids, organic principles, water insoluble N, BYOC, not urinating in my garden, and a glass of wine in the evening (for me)) so I’m not ready to disregard someone else’s recommendations out of hand.

That said, will somebody just buy a bag and trial it? Or better yet, if you’ve trialed it in the past please report your experiences/results. Plants don’t grow on paper, they aren’t fertilized by talk (it takes a different kind of BS), they don’t care about our numbers, and they certainly don’t care what we think. Empirical wisdom does have some value.


A guy on you tube( Alberta urban gardener) did a trail last season, complete with lab work ups on both the beds tested one being the control .I will not be using rock dust again.


My opinion is if you need it you will know it right away when you apply it. There are trees that I give it to in poor soil where you can sure tell a difference. Most of the time I would say we don’t need it. Blackberries are a good example of a plant I planted 20+ years ago. They started out in the row I planted them in and grew like weeds 15 or so years. The berries send out rhizomes that sprout up 5-10 feet away. 5 years ago those blackberries died out in the original row and are going strong in the rhizome row and I mow down everything else. I went in and mowed down the original dead blackberry row and that organic material adds to soil richness. The soil I planted them in was pure clay but now is rich black soil that is loose. The rhizomes tunneling helped to break the soil down and dead roots, leaves, and stems build organic matter. The worms were attracted back to that soil and mycorrhizal fungi. Blackberries don’t require spray. The clay is good mineral soil but the minerals are locked up and can’t be used by everything but the blackberries did use the minerals and that’s obvious by the soil changes. A soil like that has used some of the minerals and might benefit from some of the azomite. The glaciers went through this area so most of the time azomite is not needed. A 50 pound sack of azomite I bought several years ago is 10% used. There are other things you can use to add back minerals from depleted soil as well so azomite is not the only product of it’s kind. My point is one particular type of plant will deplete soil of certain minerals that it needs over time. Weeds are a good example of plants in action doing what they are supposed to do. Lambs quarter grows where the soil is rich, mullein grows where the soil is poor, elderberry grows where there is plenty of water as examples. So when lambs quarter disappears from a ground it once grew on that’s natural and the imbalance has been corrected but if you add manure again the lambs quarter will come back. If you spend 15-20 years depleting soil by growing blackberries you need to put those minerals back some how with manure, biochar, azomite, the berry canes or whatever but those minerals have been used. If you raise cows on land and ship them out to the sale barn every year how much calcium left that year in those cows bones? What about over 40 years? Same goes with apples they will benefit from calcium. Just put back what you take out or I should say what someone took out before you. You will only need azomite if those minerals were taken from the land in the first place. Can you use wood chips? Sure why not trees take nutrients from 30-50 feet down and when they break down you have put those minerals back it just takes longer. Cow manure is just grass that’s went through the cow so again if you put it down you are adding back phosphorus. Some minerals as we are all aware are locked up by other minerals so just because you put it down does not mean it’s usable. Most of the time trying to correct problems may create more which could be the case with to much azomite or applying if it’s not needed. In Kansas we have low organic content in most of the soil so adding manure on top of the ground and some wood chips over it around fruit trees will typically drastically improve the growth and fruiting of the trees. The trees need the extra water wood chips hold and those trace minerals from the wood chips and phosphorous from the manure.


Largely agree with Clark. I defended the theoretical possibility of azomite being useful, but I would not use it myself. After you have manured your garden twice, or your orchard once, it is all biology all the time.

Surely some Zn in my plots comes from cow salt lick, but just the same, if you give your twice-manured plot some carbon every year, in the form of organic matter, it will thrive, cycle nutrients and be fertile. In regard to replacing what you took away, it is a good idea and I do it, but unless you are making hay and taking all vegetation 3 times a year, your nutrient balance in a high biology soil can be stable over many decades (the nutrients cycle).


I would also largely agree with Clark.

But in some ways, all these trials and anecdotes don’t mean all that much because most leave out one important factor, what nutrients/elements were in short supply to begin with. If your soil is low in something (Fe, Cu, Zn, Mn, B, etc), then putting on a supplement which has what you’re lacking will help. Maybe not immediately, depending upon how available that element is in your supplement and how much bio activity you have in your soil. But eventually it will help the imbalance/lack (assuming it isn’t highly water soluble and washes out before it can be used). But it also means that what worked great for you may not do anything for someone else who has a different issues going on.

If you know your plants need some element, you should supply it. Depending on which one and how sever the shortage, you might want to do it by soil additions or by foliar sprays or even both.

It is possible to have too much of a good thing and that can lead to problems too. So you probably don’t want to throw the “kitchen sink” at it approach without some understanding of what you are working with.

Unfortunately testing can get expensive, especially for small growers. But in the ideal world we would all just do soil tests and leaf analysis to check these things out before proceeding.


Glib, I do exactly what you suggested. I use compost once or twice a year, and always mulch with leaves, straw, or pine straw (the carbon). Sometimes it’s messy and some blows away. What I try to do is lay leaves, then cover with compost to keep them there. usually in the fall and spring, or any plants that need it. I constantly refresh mulch. I have extra leaves right now, so i want to get them down. More leaves in the fall. I shred them also.
I drink a lot of coffee, so coffee grounds are added to the garden too, sometimes food scrapes I’ll bury in bare spots. Or dig a trench in fall and throw them in all winter and cover in the spring. I don’t have room for a compost pile, so use alternative methods to compost.


I’ve used Azomite for decades. Everything I grow tastes better. You need organic matter to ‘make’ nutrients bioavailable to plants. The onus is not on the mineral itself. Also, regulations for guarantees are different here than in Europe. Don’t get hung up on the US label. This stuff has been around for decades and there’s a reason it’s sold in 70 countries. University of Florida IFAS Extension Horticulture Agent, Sally Scalera recommends Azomite all the time. Here’s one of those times:

This is the European label:


People who are accustomed to conventional agriculture can not wrap their head around organics. They can not seem to get it through their head that you are not feeding the plant, you are feeding the soil. Organic growers are worried about the condition of their soil 50 years from now. Organic nutrients are not the magic fertilizers modern agriculture has become addicted to. They take time and high microbial activity to become available. I don’t think I would apply it oudoors, but it has its uses in container gardens that have a low mineral component in the mix.
Toss out the azomite, and use cottonseed meal for micros, IMO.


i also use in in containers but very sparingly. ill dust my compost pile with it occasionally. a little can’t hurt.


If you bought it use it, I for one like to experiment with stuff to see if it make a difference, if not, use it up ,and buy something different next time. Some advise on any forum can be bogus. Years ago when I joint a forum, the moderator told me just tell them what you do, so I don’t tell nobody how to do things. I buy my stuff at this place.A short drive.


i also use green sand.


I just bought a 50 pound bag of crushed oyster shells for 20 bucks. It is sort of like lime, which I need little of. I mostly want it for the small amount of chitin in the shell. It attracts chitin eating bacteria which cannot tell the difference between this chitin and the chitin in beetle larvae. No need to buy bacteria, lay it down and they will come. Plus the grass likes calcium. I also will add a touch to my potting soil. Just a touch. Crab shells are better but oyster are cheap!


Where did you get them…

I remember oyster shell driveways back east and always loved the look…


Oh, yeah…I have a bag of Azomite that I had misplaced in the garage (and found it last year when re-roofing my garage)… Maybe I’ll spread (some of ) it out on one bed this spring and see ifI can notice a difference


Oyster shell in bulk bags is usually available at feed stores as well as agricultural supplies. You can find smaller quantities at most all garden centers, Down to earth sells one.


I met a new fig grower Susan in our area. She bought it for me somewhere? I’ll find out. Susan is a medical doctor. A very interesting grower. She has been over a couple times this year. She knows another local fig grower with a greenhouse. He has three in ground in the greenhouse for decades.


i thought of doing this too. i already have some for the chickens. going to add a little in my beds, pots and around my plants/ trees. also coast of maine products contain lobster shell which would also meet your needs in that respect. their compost is great stuff.