Heavy metals in rock dust

Highlife42

Well-Known Member
KNF is not a new concept in this world. Trace back the times where KNF was used and used well. Produced well.... man!
 

bodhipop

Well-Known Member
Wow...looked up diatomaceous earth on a whim. They only had one sample but it had 177 ppm arsenic, which is just off the charts. The kelp meal which is problematic usually has 30-40 ppm. I did not know this, but diatomaceous earth is apparently a well known source of arsenic, here is just one example: https://pubs.acs.org/doi/10.1021/acs.jafc.8b06062
thanks to your studies, I will never use diatomaceous earth. What else should we for sure stay away from or use with extreme caution? I will be making quite a bit of soil in the future and was planning on buying a mineral mix from buildasoil. They've been crushing it.
 

MustangStudFarm

Well-Known Member
Wow...looked up diatomaceous earth on a whim. They only had one sample but it had 177 ppm arsenic, which is just off the charts. The kelp meal which is problematic usually has 30-40 ppm. I did not know this, but diatomaceous earth is apparently a well known source of arsenic, here is just one example: https://pubs.acs.org/doi/10.1021/acs.jafc.8b06062
I was hoping that I didn't ruin your thread because it is very nice! I was showing it to my wife yesterday, she is close to getting her horticulture degree.
 

MustangStudFarm

Well-Known Member
I checked greensand on that same site and the numbers varied greatly among the different brands but was typically high in arsenic and lead, with one brand being the highest of any product I've seen recently in lead. Greensand is another thing I used to apply regularly, every three years or so.
I know that I keep talking about Greensand, but my soil tests come back very low in Mn and greensand was one of the very few products that naturally have Mn in it. Also, if you look at the other compositions of greensand, it is completely synergistic. Mn, Fe, K. My wife pointed out that "micronutrients" are metals themselves and it should be no surprise that they are contaminated with eachother. Makes sense... I'm now using Mn & Fe sulfate for my deficiencies.
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Rurumo

Well-Known Member
I was hoping that I didn't ruin your thread because it is very nice! I was showing it to my wife yesterday, she is close to getting her horticulture degree.
No not at all! I was thinking of getting it going again once I put together a living soil blend that has as little heavy metals as possible. I've got a ton of stuff on the way, it has just proven difficult because some products haven't been tested. I couldn't find any rock dusts that were free of heavy metals. Luckily, I did find some worm castings...and as it turned out, the castings that tested free of heavy metals were not fed rock dusts, so that was definitely the source of contamination. I also got sort of sidetracked looking into ways to mitigate the heavy metals that are already in soil-there is so much literature looking at that angle.
 

Rurumo

Well-Known Member
I know that I keep talking about Greensand, but my soil tests come back very low in Mn and greensand was one of the very few products that naturally have Mn in it. Also, if you look at the other compositions of greensand, it is completely synergistic. Mn, Fe, K. My wife pointed out that "micronutrients" are metals themselves and it should be no surprise that they are contaminated with eachother. Makes sense... I'm now using Mn & Fe sulfate for my deficiencies.
View attachment 4860916
I think some greensand deposits are pretty clean. I tried to contact one company directly to see if they had third party testing but they had gone out of business or something-their email kept kicking back to me and their phone number was disconnected lol. Hard times for greensand!
 

Medskunk

Well-Known Member
So glad im away from many of the stuff you re mentioning! Even though i have used some DE and very little azomite in my latest run. Ill have to get my hands on some oyster shells in the future.

Did you happen to get any info on indonesian bat guano?
 

Rurumo

Well-Known Member
So glad im away from many of the stuff you re mentioning! Even though i have used some DE and very little azomite in my latest run. Ill have to get my hands on some oyster shells in the future.

Did you happen to get any info on indonesian bat guano?
The only one listed in that heavy metal database was Sunleaves Indonesian Natural Fertilizer (which I assume is guano, it's 0-7-0, and it has 2.9 ppm Cadmium. Bat guano seems to be all over the place, some deposits have it, others don't. Oyster shell and gypsum are both great, and langbeinite is a pretty neat thing too, for K, mag, and sulfur, but very very potent.
 

Medskunk

Well-Known Member
Its very close yeah it looks like it. I always treated it as an explosive evaporating chemical lol the fkin clouds from a single "poff" on the soil

Gypsum also then properrrr
 

Northwood

Well-Known Member
Wow...looked up diatomaceous earth on a whim. They only had one sample but it had 177 ppm arsenic, which is just off the charts. The kelp meal which is problematic usually has 30-40 ppm. I did not know this, but diatomaceous earth is apparently a well known source of arsenic, here is just one example: https://pubs.acs.org/doi/10.1021/acs.jafc.8b06062
And then I read stuff like this: https://www.researchgate.net/publication/264829675_Insights_into_the_Adsorption_of_Heavy_Metals_from_Wastewater_using_Diatomaceous_Earth (Full access version)

I guess you can just call me confused. Lol
 

Rurumo

Well-Known Member
That's a great point. Another is Bentonite clay, which might contain some heavy metals to begin with but which is also used in heavy metal remediation. I just wonder how long they hold onto the metals before giving them back up-I'm no chemistry expert obviously lol. I've been looking into the use of zeolite in living soils. It's an aluminosilicate like bentonite and azomite so I'm not sure what that means for aluminum levels when using fulvic acid, but it has some very useful properties-huge surface area for rhizobacteria, high cec, water retention, etc, seems to have a lot of overlapping benefits with biochar.
 

bodhipop

Well-Known Member
I've found a few interesting studies on the use of zeolites in agriculture, and their ability to bind heavy metals in soil as well as bind to the heavy metals found in fertilizers. See the section "heavy metal traps" great stuff! https://www.princeton.edu/~ota/disk2/1985/8512/851210.PDF
Well just reading PAGES 133-136 has me wanting to try adding a little to my next mix. So we want Clinoptilolite Zeolite I'm guessing?
 

TimBar

Well-Known Member
Kelp can stay in the ocean as far as I'm concerned. I know it is arsenosugars - but the break down to human toxicity Arsenic.

Don't need the arsenic
 

quiescent

Well-Known Member

I watched the livestream and there were some nuggets for sure. Basically if you're already doing it right your chances of having a plant not predisposed to heavy metal accumulation testing hot in most modern mixes are very low.

Gypsum continues to be the thing people are finding mitigates problems they didn't know they had and allowing plants to express themselves fully as well. I've been using gypsum in all my gardens, something my grandmother taught me.

I wish that whole conversation was available, would assuage a lot of concerns.
 

TimBar

Well-Known Member
I think there is a market for quicker and better testing of soils and cannabis - something to fit the home brewer.
 

2cent

Well-Known Member
Mind metals start releasing when ph is out of range.... below 4 etc so shouldnt need to worry i was informed unless i fked ph up for the whole grow .
Oregon state has a page for confirming as they are strict as fuck if it has metal in it
Kelp and neem listed as the green safe amendments. Also bat poo.
They explained that the minority of unvetted companies selling high metal kelp and bat guano are responcible for the damaging myths and cheap storage near contaminants so note if you use proper ones not china orders will be safe from the dangerous ones.
The bad ones have labeled them all again discrimination on the poor kelps
 
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