Micro Nutrients Educate Me Please

Informed by Buidasoil that Basalt Rock Dust is rich in micros, I added 2 cups to my soil and a Soil Report showed all micronutrients (except for Iron) were very low.

According to BAS: "We've found a local Basalt that we're excited about. Basalt rock dust is packed with micronutrients like magnesium, iron, and calcium".

This caused me to wonder if I should forget about adding micros to the soil and instead, use something like Big 6, TM-7, or Jackpot to add them when I water.

What strategy do you utilize for micros? Do you add them to the soil and have adequate micro levels; if so, what is your formula?

Or, do you just add them to them to you water? If so, what product do you use, how much and how often?

TM-7 as a soil drench, once per month at 1/8-1/4 tsp per gallon of water.

Basalt is good stuff, however even in dust form it will still take multiple waterings (years, in fact) before it dissolves enough to provide any nutritional content. The reason Basalt is often favored over other rock/mineral dusts is due to its high CEC capacity;

"Hence, finely ground basalt is a promising natural material that can be used to restore negative charge and base cations and suppress Al and Mn contents of highly weathered soils, which in turn, have a great impact on preventing cation leaching, increasing soil nutrient availability and reducing elemental toxicities."

"The topsoil and subsoil representing the natural and severely eroded conditions, respectively, were incubated with various rates (up to 80 t ha− 1) of finely ground basalt (< 50 μm) under ambient laboratory conditions for 24 months."

Basalt will also increase Ca, Mg, Si, K, and Na levels, however as mentioned above this takes 1-2 years. As a result, Basalt/minerals are typically used for their CEC properties as you won't see much nutritional value from them for a couple of years.

I just use TM-7 to avoid the headache, personally.


Source: "https://www.sciencedirect.com/science/article/abs/pii/S0341816214002707"

If you have an adequate or high Iron level already that's where the Big-6 may offer an advantage over the TM-7 as it's really just a tweak of the TM-7 recipe that BAS had made for them based on their observations of several soil reports where the iron levels were fine (or high).

Also I believe someone on some thread was claiming they work as a foliar better than a soil drench but I forget where that claim was made & by whom. I've been using as a drench myself but sparingly...

Kratos has a great response and not much to add to it regarding the rock dust.

What I will add however is there are many ways to achieve our shared end goal. For example I do a homemade supersoil organic medium, and all of the components I add provide those needed elements. Each component has certain elements and a combination of them (most soil recipes including buildasoil) will achieve this goal as well as any other supplement.

It becomes a bit of an art reamending the soil but it is pretty cool to be able to add whatever you think is missing.

In organics, kelp meal is king, and is the basis of most amendment mixes for the purpose of micros and several other benefits.

ComfortCreator said:

Kratos has a great response and not much to add to it regarding the rock dust.

What I will add however is there are many ways to achieve our shared end goal. For example I do a homemade supersoil organic medium, and all of the components I add provide those needed elements. Each component has certain elements and a combination of them (most soil recipes including buildasoil) will achieve this goal as well as any other supplement.

It becomes a bit of an art reamending the soil but it is pretty cool to be able to add whatever you think is missing.

In organics, kelp meal is king, and is the basis of most amendment mixes for the purpose of micros and several other benefits.

Click to expand...

BAS gave me the impression that Basalt Rock dust would provide the micronutrients I need, but the soil test
(displayed at start of this page), except for Iron, showed inadequate micro levels. Most people don't do soil tests, so they would be under a false assumption their micros are good if they added the rock dust to their soil.

In addition, I made two batches of soil and each batch had 2 cups rock dust. Iron was optimal for one and sub-optimal for the other. All other micros in the two batches were sub-optimal. If I am using rock dust and also supplementing with Big 6 or TM-7, I could be ending up with too little or too much iron unless you did a soil analysis to see what you have.

It might be best to leave out the micronutrients and just use TM-7. Otherwise, the grower having nutrient issues may think their micros are okay and overlook this as being the problem

Regarding Kelp, although it has micronutrients, the amount is too low to be consequential.

The3rdMan said:

BAS gave me the impression that Basalt Rock dust would provide the micronutrients I need, but the soil test
(displayed at start of this page), except for Iron, showed inadequate micro levels. Most people don't do soil tests, so they would be under a false assumption their micros are good if they added the rock dust to their soil.

In addition, I made two batches of soil and each batch had 2 cups rock dust. Iron was optimal for one and sub-optimal for the other. All other micros in the two batches were sub-optimal. If I am using rock dust and also supplementing with Big 6 or TM-7, I could be ending up with too little or too much iron unless you did a soil analysis to see what you have.

It might be best to leave out the micronutrients and just use TM-7. Otherwise, the grower having nutrient issues may think their micros are okay and overlook this as being the problem

Regarding Kelp, although it has micronutrients, the amount is too low to be consequential.

Click to expand...

BAS is technically right about the Basalt, but I'm quite surprised about the lack of mention about how those micros won't be available for 12 months at a minimum. Perhaps they assumed their consumers would already know this?

It's very similar to Greensand or Rock Phosphate, they'll provide nutrients but over the course of multiple years.

TM-7 is going to your best bet a majority of the time, I haven't been without it for a little over 5 years now.

The3rdMan said:

BAS gave me the impression that Basalt Rock dust would provide the micronutrients I need, but the soil test
(displayed at start of this page), except for Iron, showed inadequate micro levels. Most people don't do soil tests, so they would be under a false assumption their micros are good if they added the rock dust to their soil.

In addition, I made two batches of soil and each batch had 2 cups rock dust. Iron was optimal for one and sub-optimal for the other. All other micros in the two batches were sub-optimal. If I am using rock dust and also supplementing with Big 6 or TM-7, I could be ending up with too little or too much iron unless you did a soil analysis to see what you have.

It might be best to leave out the micronutrients and just use TM-7. Otherwise, the grower having nutrient issues may think their micros are okay and overlook this as being the problem

Regarding Kelp, although it has micronutrients, the amount is too low to be consequential.

Click to expand...

Have you actually experienced issues related to micro-nutrient deficiency, expressed in the newest growth at the top of the plant?

I saw your latest test results in the other thread. MYSOIL? WHAT is that? Link?

BAS claims a micronized basalt which is why I think they arent overly concerned.

Again to OP, dont overlook the fact that every plant on earth has been successfully grown without a micro supplement.

I combine many amendments which contain all the micros, and by adding the rock dust, over time that adds it too.

A few different folks have done this...soil tests and been surprised something is low. But low in a soil test may or may not be an issue. The poster above this points that out.

Put another way...in organics I have a lot of stuff in there and the plant pulls what it needs from it. There is certainly too much of some things relative to others as there is no way it could be perfect. No chance a soil test comes back with a perfect cannabis soil balance, whatever that would be.

BUT my plants say it works great. So just my 2c, dont go looking for a problem that may not exist!

waktoo said:

Have you actually experienced issues related to micro-nutrient deficiency, expressed in the newest growth at the top of the plant?

I saw your latest test results in the other thread. MYSOIL? WHAT is that? Link?

Click to expand...

I don't know if I've had micro deficiency. The link to MYSOIL: www.mysoiltesting.com

The3rdMan said:

I don't know if I've had micro deficiency. The link to MYSOIL: www.mysoiltesting.com

Click to expand...

That looks a lot like the Soil Savvy test. Was it rebranded?

waktoo said:

That looks a lot like the Soil Savvy test. Was it rebranded?

Click to expand...

I saw soil testing kits offered from both MYSOIL and SOIL SAVVY on Amazon at different price points, so I do not think so.

The3rdMan said:

BAS gave me the impression that Basalt Rock dust would provide the micronutrients I need, but the soil test
(displayed at start of this page), except for Iron, showed inadequate micro levels. Most people don't do soil tests, so they would be under a false assumption their micros are good if they added the rock dust to their soil.

In addition, I made two batches of soil and each batch had 2 cups rock dust. Iron was optimal for one and sub-optimal for the other. All other micros in the two batches were sub-optimal. If I am using rock dust and also supplementing with Big 6 or TM-7, I could be ending up with too little or too much iron unless you did a soil analysis to see what you have.

It might be best to leave out the micronutrients and just use TM-7. Otherwise, the grower having nutrient issues may think their micros are okay and overlook this as being the problem

Regarding Kelp, although it has micronutrients, the amount is too low to be consequential.

Click to expand...

Just gunna add in here, 2 cups is about half of what you need per batch. At least 1cf batch, not sure your batch size….

kratos015 said:

BAS is technically right about the Basalt, but I'm quite surprised about the lack of mention about how those micros won't be available for 12 months at a minimum. Perhaps they assumed their consumers would already know this?

It's very similar to Greensand or Rock Phosphate, they'll provide nutrients but over the course of multiple years.

TM-7 is going to your best bet a majority of the time, I haven't been without it for a little over 5 years now.

Click to expand...

They do have great information about all their products. Im curious now what there application instructions are……

just checked snd on the”how to use” it says coming soon. But it’s hard to explain proper mineral use. It takes a completely different thinking than typical industry branded products.

I think about minerals in the soil as “sweating” instead of dissolving. Single ions at a time, a single particle of basalt can sweat a long time before it’s gone. Forever really.

green_machine_two9er said:

Just gunna add in here, 2 cups is about half of what you need per batch. At least 1cf batch, not sure your batch size….

Click to expand...

BAS recommends 2 cups Basalt as you can find it here:

buildasoil.com/blogs/news/17627464-build-a-soil-from-scratch-in-2-simple-steps

The3rdMan said:

I saw soil testing kits offered from both MYSOIL and SOIL SAVVY on Amazon at different price points, so I do not think so.

Click to expand...

Well, it doesn't really matter. I looked at the tech'/extraction procedure. It's the same.

The point I want to make is that these types of tests aren't designed for the soil mixes that we build.

At the end of the day, a "saturated media extract" test is what you're getting when the sample is sent to the lab for analysis.

This pdf explains why micro-nutrients don't show up in appreciable amounts on SME tests. From the pdf...

"In peat and bark based root media, the basic micronutrients are complexed by organic compounds (10)."

"Humins" (humic and fulvic acids) in compost do the same thing.


If you want a more accurate representation of available micronutrients in your soil mix, you need to find a soil testing facility that uses DTPA extraction in their soil testing method. Your test does not do this. Logan Labs does not do this. Penn State offers one that does.

The3rdMan said:

BAS recommends 2 cups Basalt as you can find it here:

buildasoil.com/blogs/news/17627464-build-a-soil-from-scratch-in-2-simple-steps

Click to expand...

Are you using the gypsum and oyster as well?? And those recipes are recommendations not exact. I’ve had more success with higher mineral content. Currently I run 2 cups basalt, 2 cups Gaia green volcanic rock dust. 1 cup gypsum 1 cup oyster. It’s hard to over do it. And increases CEC in soils which is more helpful than the added micros. Just the increase in cation exchange will help nutrient bioavailability.

green_machine_two9er said:

Are you using the gypsum and oyster as well?? And those recipes are recommendations not exact. I’ve had more success with higher mineral content. Currently I run 2 cups basalt, 2 cups Gaia green volcanic rock dust. 1 cup gypsum 1 cup oyster. It’s hard to over do it. And increases CEC in soils which is more helpful than the added micros. Just the increase in cation exchange will help nutrient bioavailability.

Click to expand...

Yes, I use both. I just started doing soil tests to see what I have. My first soil test showed soil ppm for most primary and secondary nutrients were quite high and could possibly cause lockout, so I threw all that soil out. I've got a couple more batches of soil I'm going to have tested and should have results next week. As far as micronutrients go, I think I'm going to leave them out of my soil mixes and just use TM-7.

Best way to test a “coots” mix soil.
Plant in it.
Practice watering.

Just an update. I have continued to get soil tests on my soil mixes. I add a gallon of compost and a gallon of EWC to 8 gallons peat moss. Usually, Iron and Zinc are at Optimal levels while manganese, copper, and boron are sub-optimal. Sodium is also elevated. I cannot use Big 6 or TM7, but add the micronutrients separately for MN, CU, and B. Unfortunately, one cannot know this without A soil test. The macro nutrients are normally near optimal with some occasional adjustments to N, P, or K needed. Magnesium, Sulfur, and Calcium are usually fine, so most of the nutrients are coming from compost and Ewc alone.

From what I have seen, compost and EWC have more micronutrients than rock dust and much less expensive. But, the problem with both is that whatever source you use, you don‘t know if your micros are at sufficient levels unless you get a soil test.