Does Rock Dust Increase the Nutrient Density of Food? 

I am quite late to the party and I'm not disputing the results but as an analytical chemist, I would find the results more compelling with a few changes to methodology. First is the assumption that the bags of soil mix were identical. To eliminate any bias, all the soil components should have been thoroughly mixed then split between the two beds. Then composite samples are taken from each and analyzed as a baseline. Small amounts are taken from several areas of each bed and thoroughly combined for testing (each bed is kept separate, of course). This confirms an 'apples-to-apples' comparison and gives a sense of the relative error for each component. Then the rock dust is incorporated and the soil from that bed is sampled and analyzed again to measure the contribution of the rock dust. My concern is the much lower concentration of some of the elements-if they were supposed to be equal before the rock dust, where did they go? Even if the rock dust somehow bound it up, it would have been recovered in the testing (I'm guessing acid digest and ICP). Otherwise they would have migrated completely out of the bed and I don't see any scientific rationale for that to happen, if they weren't present in the plant tissue. Also, in the veg testing phase, it might have been better to take larger samples of more than one pepper, weigh them to get an equal amount then puree and submit that as a sample. Again, large sample, totally homogenized. The sample size for metals testing is typically small-one gram or less-so the need for a homogenous sample is critical. Actually, even better would be to test each sample separately before combining to get an idea of the distribution. So, take 9 scoops of soil from different spots, remove half for testing, combine the remaining halves, mix and test the composite. I know it's expensive and a pain but to quantify such small concentrations it's the only way to be sure. 30 years of lab experience here. Lastly, it would have been nice to see the remaining plant tissues tested-leaves and stems. I'm not a botanist but is it possible micronutrients taken up by leaves contribute to the health of the plant but don't show up in the fruit? Just some thoughts.

Fascinating stuff. From the research I've done, it appears that soils with adequate microbiology can actually mine all of the minerals from the parent clay/silt/sand particles. The plants actually can release specific sugars from their roots that attract specific microorganisms that mine for specific minerals. So if the plant needs selenium at one point it will release the right sugar to attract that biology that will accumulate it and then release it as soluble plant-form selenium when it the bacteria/fungus dies back.

Fascinating rock dust lab results, Stephen! While I'm not very surprised that rock dust didn't increase the nutrient density of the peppers, I am surprised by the lower level of trace minerals in the rock dust amended soil. Thanks so much for going the extra mile and having these results analyzed!

1) Could the minerals missing from both the soil and the fruit have wound up in the stems/leaves/roots of the plants? They had to go *somewhere*, and now I'm eager to know where. 2) Idea for a fourth bed: base mix + rock dust + biochar. 3) Idea for a fifth bed: just compost, but try compost made with all your ingredients right from the start. Assuming you make your own compost, try adding the rock dust, worm castings, & biochar right up front; mix it into the raw browns & greens that first form your compost pile. That's how I get everything to incorporate as the compost gets made & turned, thus "inoculating" the biochar and letting the rock dust & worm castings interact with the composting microbes.

It seems obvious to me that the height difference in the bed is the reason for the differences. The heavy elements are leeching out due to a flooding condition in the bed that is 3 1/2" lower. How is this system watered. If it is in a reservoir that should allow the heavy minerals to leech faster as the test showed. Either way any good researcher would look at this and see a major difference I. The control group. Just do it again and do it correct. If you need simple common sense advice on the rest of the Errors in your experiment please let me know.

It is very hard to get farmers in the Philippines to stop farming in areas on the sides of dangerous volcanoes. The reason is because the mineral rich volcanic soil produces very good plant yields. This is proof that rock dust works in the long run, especially in areas that may have excessive amounts of rainfall. Of course, in the very long term, most rocks decompose into clay. Probably the best cheap source of rock dust is the local granite quarry. It is a byproduct of rock crushers.

Wow! For some strange reason for a second it felt like it was one of those paternity tests you see on TV. The suspense was dense :-)

First off, rock dust takes years to break down and affect the soil, so I wouldn't draw conclusions from just one season - glad you're following up each year. Further, plants do not uptake minerals without help from the microbes in the soil. Build the soil so that it is full of life, and nutritional value increases. Also the soil is more porous and aerated, so the land is more resilient to drought an floods, and as an extra bonus, carbon is drawn from the atmosphere and stored in the soil. Some principles of building healthy soil full of microbes include minimal disturbance of the soil (no tilling), keeping living roots in the soil year round, increasing biodiversity, minimizing chemical and biological disturbance, incorporating animals into the mix (in home gardens, that might mean beneficial insects, birds, etc.) Microbes consume the sugary exudates from the roots. Bacteria and fungi are essential partners in delivering minerals and nutrients from the soil.

This whole trial has been very informative throughout the growing season and now detailed analysis of the soil and plant samples. It makes you wonder what sort of soil reaction with the azomite caused a decrease in some of the elements. Or some other variable ? Very interesting and looking forward to next years trials.

Very interesting results Stephen. I am glad that I didn't run out to try amending my soil with rock dust. Two thumbs up buddy!

I wish you did a whole series on different soil additives such as trace minerals and different lava rocks.

Thank you ver much for your video. You have just saved my a huge chunk of money. I was going to spend thousands of dollars to put rock dust over three acres, preparing for the growing season in 2015. This is the third video I have watched tonight that showed no major deference between the test subject and the control. Thank you again:))

Thank you for being so committed to examining this and other popular gardening advice. I wonder if the solubility of rock dust is a factor. It may take a very long time for the rock dust to break down where it's minerals are available, and if in the mean time, the rock dust binds the trace elements that are in the original compost/casting soil? Your research leads to a lot of questions that really need full scientific field trials and research to answer. But the most important thing your results did show is that adding amendments is not always helpful, and perhaps has the opposite effect than what we desire.

The most significant results in the Rock Dust Trial are in. Does Rock Dust increase the trace minerals in soil and increase the nutrient density of the food grown in it? Check out these surprising results! #rockdust #homegardenfieldtrial #trials #science #citizenscience #nutrientdensity #traceminerals ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-mwF3TFOzIik.html

Hey... very good. I like the science behind the scenes. I think it is important for gardeners to understand what products are, what they do and how to use them sensibly. I would suggest you might look at the plants themselves. You hit the soil and the fruit which was excellent. You have the roots system, stems and leaves. It is possible in my opinion that the plant itself might have used the elements as they use N-P-K and Mg-S-Ca. Maybe composting the different plants will release elements back into the soil at different levels. Just a thought.

I speculate that the free granite dust I got from a granite fabricator will improve my poor florida sandy soil for decades if for no other reason than it adds a different particle size to help hold water. I also speculate the rock dust soil tested poorer because it takes ongoing bacterial action to release the minerals in the rock dust, so the same amount of soil tested lower do to hidden inaccessible minerals. Regarding a comment below: For meJohn Kohler of "Grow your.Greens" was the primary motivating force in this movement to grow eatables on urban property. I am experiencing in your undertaking (1) a beautifully articulated refinement in practicality and (2) great science!, also beautifully articulated. Your efforts compliment and enhance the efforts of the early way-showers in the evolution of this movement.

Very interesting results! Makes me wonder about what other soil amendments may be either useless or causing a negative effect on our home garden crops. Makes me think of a conversation I had with a commercial farmer this summer, he told me that if rock dust was as good as some people say then all of the farmers would already be using it. I think he may be right.

Thanks for taking the time to find out if rock dust does improve plant intake of vitamins and minerals.

throwing a ton of rock duct into a small area was crazy. it's a pinch of rock dust per plant. the soil more than likely had no microbial bacteria to digest the minerals. your experiment would be the same as giving someone 10000 carrots, and seeing it his eyesight is better after your test. the soils in the US are depleted of minerals, any test can be rigged to shift any way you want, but for me rock dust is as important as compost.

I'd just like to add my thanks to you, Stephen, as well as Patrick for the effort you've both put into these rock dust and biochar trials. Fascinating stuff. Curiouser and curiouser.

Kohler just jumped off his roof! This is a fantastic trial and scientific analysis. I think you hit the nail on the head in the beginning by saying remineralization is more beneficial in poorer soils - like farmland that has been depleted because of the industrial practices using petro's and not replacing matter back to the soil. Great job buddy.

Wowzers! Great work ***** ... keep up the scientific studies to help us all become more informed gardeners. I like the idea of using rock dust as a feed supplement for livestock then using the manure as compost. The minerals will benefit the animal first then re-mineralize the soil. This would be a very gradual way, but perhaps more beneficial... time to go test some poop.

Just wondering if you think the source of the dust would make a difference.. I have seen one popular brand is rock made from volcanic ash where what we get here is a basalt powder, still volcanic in origin but is formed differently.. Then there is the glacial dust too.. Just curious..

Thanks so much for your diligence in supplying this "real data" on this first of the trials. The differences sure do raise questions as to the validity of the claims. Year 2 will be the results I look to the most. Once again thanks so much. Cheers David.

Thanks for taking the test to this level of analysis. It sure beats seat of the pants guessing. I got the rock dust last spring and added it to my plant medium but I think I will hold off before doing any more.

As a new subscriber to the channel I am impressed by a scientific approach to gardening and its nutrition requirements, and wait for the results. As a keen gardener with experience in Chemical Engineering I can give advice in order to avoid experiment bias and in sampling errors. Firstly I would diminish the variation caused by parentage of the seeds that are planted. By this I mean that the seeds that are used in the trials come from the same parentage and therefore will have similar genetic codes, so that no freaky plants are used that give abnormally high yields. Different plants with different parentage can lead to greater or reduced yields and this must be taken into consideration. Secondly different crops in the same bed can distort the results and each variety have different nutrient requirements, as competition from different crops need to be minimised. It is best if a bed of one single variety of a crop, with the same parentage, is planted at the optimal spacing in rows and plant distance. In this way competition between crops and within the plants of the same variety is minimised. This would mean that 4 beds for each trial, one for each crop and therefore 12 identical beds are required Thirdly I would space the beds more apart so that cross pollination that will take place between the beds are minimised, effecting results. Also getting a representative sample- a sample that represent the whole bed- (of soil) is a complex field and many books have been written about it. AS you can image if I take a sample at different locations and depths, and have it analysis for element composition, the results would be different for each location and depth, so how can one sample represent the whole bed, The size of the sample (in weight) and the number of samples therefore become important, and it becomes an art of where to sample to get the best results. This is when statistical analysis comes into play that will tell you what size of sample that is required and how many. For some systems this may be a few grams, whist for other it may be a few kilos and it is generally excepted that a minimum of 25 samples is required to give a balanced analysis. As you can image this can get very expensive and time consuming, as the results you present could be totally wrong and the results can be reversed. A simple way to overcome this is to sample at various locations and depths and then mix those samples together to get 1 overall sample, and use this as a means of analysis. In this way bias will be minimised. Sampling itself will cause bias in the results, as any device used will cause particle segregation to occur and therefore cause a bias in what particles will be sampled and what will not. I am sorry to go into this, bur sampling can cause all your results to be meaningless. What I would recommend is to sample at the beginning of the trials in each bed, some in the middle and finally at the end. if you need any help in analysing results please let me know, and I will help. Thank you and kind regards for all your effort you put in.

A few points: there are different types of rock dust from different sources with different elemental compositions and ratios. Therefore, to be thorough it would be a good idea to test several different types, or alternatively, to mix several types of rock dust together and then mix them into the test soil. When you create two soil mixes from identical ingredients and mix them thoroughly, there should be identical, or nearly identical, concentrations of each element in each sample from each of the mixes. Then, when you add something extra (e.g. rock dust) to the test soil mix, there should be increased concentrations of certain elements that were present in the rock dust in that mix, not lower concentrations. It is unlikely to lower the concentrations of the various elements by adding something extra, especially when that "something extra" is already shown to contain higher concentrations of the elements that you are testing for. There are a few possible reasons why Stephen obtained the results that he did, especially pertaining to the soil samples. Firstly, minerals can leach out of the soil. The raised beds in the video were at different heights above the ground, and it looked like it was possible that leachate from the higher bed could have found its way into the lower bed, thereby transferring minerals from one bed to the other. Secondly, it's highly possible that Stephen mixed up the soil samples, and from looking at the results from the elemental analysis of the two samples, this seems to be the most likely scenario. I could understand if both samples had similar concentrations of each element, but to have lower concentrations of elements in the test sample compared to the control was a red flag that there was some problem with the methodology or the execution. Thirdly, it is also possible that the initial soil mixes were not mixed thoroughly and that would have resulted in areas of relatively high and low concentrations of the different elements in each mix. Finally, it would've been helpful to see how he took the soil samples. For example, if he took a soil sample from an area with lots of roots, then it is reasonable to think that the soil minerals would be depleted in that area, relative to an area with few or no roots. One improvement to the methodology would be, when preparing the soil, to mix the soil for the test and the control together in one large mixer, like a cement mixer or a proper soil mixer, remove the soil for the control, then add the rock dust to the remaining soil in the mixer, mix thoroughly, and then use that in the test bed. This would ensure that the soil mixes were more homogeneous, and differed only in the addition of the rock dust. Probably the most important results were the tissue sample results, which showed no significant differences in the nutrient levels between the peppers grown in the test soil (with rock dust) and the control samples. This would seem to indicate that as long as you start with a rich soil mix (as he did) that the addition of rock dust will make no significant difference in the final result. This makes sense and seems to be a totally valid finding. One caveat that I would add is that if you are working with a relatively poor soil, then maybe rock dust would make a difference in the nutrient levels in the resulting produce. That might be an interesting test to do next.

Great work Stephen! I will be interested in the results a few years down the road as it does take years for the rock dust to break down enough for the plants to use it. Thanks for all your time and energy.

Perhaps, due to the molecular weight of the dust (being relatively unprocessed by nature), the charged particles attach and drag other trace minerals to the bottom during watering. I would like to see the bottom of the soil tested at the end of the experiment. I essentially think the dust is food for bacteria and fungus. They deliver minerals to the plant. It's all very interesting anyways. Kudos for them testing anyways..

I am very interested, i am glad that you are continuing the trials for two more years. because maybe it takes time to either build up or more must be added then one pound per square foot. awesome findings, thanks.

Stephen,I find all this fascinating. I have been following your videos as well as Patrick's. I do have some questions,or I should say, observations. I follow John Kohlers videos and was stunned with the one where a lady only used a 3 year covering of wood chips,rock dust and mushroom spores and got huge plants that tasted fantastic. It makes me think that rock dust alone, without the other components of soil bacteria from the wood chips,and the action of the spores,as well as the fact that worms would also be abundant and plants would be grown in non-raised bed that would allow mycelium to gather nutrients from a wider area, isn't the answer. But--I've heard experts in soil say that to get minerals into our food,we have to have minerals in our soil. But--these same experts say that unless mycelium act upon the minerals,the plants can't absorb those nutrients. Geoff Lawton had videos where a food forest suburb that had been growing for 30 years had fruit trees that produced fruit that was on the whole sweeter than he had ever tasted, and he believed it was because of the fact that swales gave the trees the ability to mine the minerals deep in the soil. It seems to me that taking components like rock dust, and trying to isolate the function,might not be giving us the whole story. We need minerals in our soil--if we need them and they aren't there, how do we supplement the soil? If not rock dust--what do we use?

Excellent video Stephen! Thank you both Patrick and you for doing the hard work in doing this trial.

Stay analytical, and keep giving us the real facts. good video.

Rock dust can improve poor soils. The problem is that one mineral may lock other minerals out of the useful mix, example - phosphate will not dissolve in salt water but if the phosphate is already dissolved salt can be added. Adding large amounts of rock dust will in all cases lock up one or more minerals. The idea is that a little of everything is good in the mix, a lot of one thing is poison. rock dust contains much needed minerals and can be used to benefit plant growth it can also make life difficult for the soil bacteria and fungi if used in large quantities. A few ounces will usually suffice for a large garden applied as a fine dusting once every three years. Plants can only use dissolved minerals in solution when you eat plants you are getting your minerals all ready dissolved and ready for your body to use.

In addition, tests like this one remind me most medical tests this days that look at the body at one single point in time, when in fact our body PH and fluids are changing throughout the day non stop changing all these levels... Test the plants in that bed next year and the year after see what will happen then report your results..

I was glad to hear your findings.

So glad you and Patrick did these tests. It will save the rest of us a lot of money I'm only out $30. I got in on the big sale that another channel convinced me to take advantage of. Never again. Thanks so much.

The main concern I have with this is: The starting soil was already very "amended" with minerals/etc. from the Humus and Worm Castings In my garden (which has been growing things for 22+ years) was tired soil. This year I amended with 1/lb of Rock Dust per 10sq feet of garden and I went from an average of 70lbs of San Marzono Tomatoes from 18 plants to 140 lbs this year with 17 plants. This cannot be a coincidence. Plants from the same source and same garden soil. Only change was the addition of the Rock Dust.

John Kohler will pull his hair off once he sees this

Excellent video Stephen!! Thank you for putting this together. Before Kohler and others were promoting and advertising for products like azomite and gaia green, I remember listening to a geophysicist and soil biologist discussing this very same matter. As I recall, their findings were that most of the micronutrients in azomite are bound up in their calcic forms, and not plant available. I'm not an "ologist" in any form, so I will always take the advice of someone educated in the field who doesn't have anything to sell me.

Well I must say I wasn't expecting this! It just proving how you don't need to spend lots of money to improve garden soil. Like other people said, If John saw this he'd not like it at all because he as saying how amazing it is but your results have contraindicated the claims and also what other companies say. It is also harder to trust companies claiming things without the evidence like the trial you have done. I really wasn't expecting this but it really did prove a point and thank you so much Stephen for spending time getting all these detailed results. The next 2 years should be very interesting and I can't wait to join in and see what I get! The science behind growing veg is awesome and I'm excited to see how this trail will d and whether the soil improves over time, a fantastic video my friend! :)

Microbes, algae and lichens, etc transform the minerals in rock dust into protoplasm making bio-available minerals for the plant. This takes time. You don't just add rock dust and expect immediate response from the plants because the minerals need time to be unlocked within healthy soil biochemistry. I was disappointed that this was not taken into account or even mentioned within the video - hence the disappointment and even dismissal of the rock dust within your comments section which sadly you have not tempered with the facts. Glad you are willing to keep the experiment going a couple more years. Adding rock dust with lots of compost and Efficient Microbes is how people are correctly advised, and then giving time. Nothing empirical about these results yet - experiment is incomplete.

"Hear! Hear!" for the Citizen Scientist! (or, is it "Here! Here!"...I was never sure what the British meant by this)

Interesting results! It's strange. That the rock dust beds had less minerals. Could it have changed the composition of the soil and allowed the minerals to leech quicker? Where did they go?!

Nice...I bet all them gardeners that use everything but the kitchen sink to grow a tomato plant are mad because they live by rock dust...I am a old time gardener put it in the dirt and leave it!!!! Great compost and soil is all you need with a touch of H2O.

Ok this makes me a little relieved because I had considered purchasing rock dust. But I think the "ideal" soil presents itself in the forest where leafs and wood have decomposed over time, along with the aid of fungi

look at learnhowtogarden channel video is called rock dust in gardening --- the myth and the facts , you cant believe these guys on utube they are salesmen , dont fall for everything that comes down the pipe , this is a good video , listen to what he is telling you . he is not selling you something you dont need !

Excellent video, Stephen! I don't know about everybody else, but you don't know just how much I appreciate all of the time and research that you, and Patrick put into this stuff! It's like I always say, "keep it simple" There is no need in investing in things that aren't going to do you any justice! I mean, man has been growing food forever, without nothing more than what mother nature provides, with great success! Thank you for sharing this with us, my friend!

ya I always knew this, rock dust is not in a "nutrient available" form to your plants. Good compost, fungi, and proper bacteria is all your plants need. don't let john from Growing your Greens see this lol, he probably already thumbed this down.

So Interesting! You have saved me the mistake of forking out 40 bucks for a worthless produce Azomite. Thanks!!

I'm pretty sure rock dust was an idea for poor overused soil on farm lands. There should be no difference when in great soil because they will be able to pick up the nutrients needed.

Very interesting! I will be interested to see if more nutrients break down in the rock dust beds over time. Thanks or sharing!!!!

Hi Stephen, thanks for sharing your test results and the corresponding data. A few questions: Have you had the actual rock dust analyzed at a lab? I'm interested in seeing the actual composition of the stuff you used. Also, do you think it would be good to analyze both soil samplings BEFORE adding the rock dust? Two bags of the the exact same brand of castings / compost could in fact have different compositions. Compost and castings can fluctuate so easily. A simple test, beforehand, would rule out whether this is the case. The rock dust soil had only 1/4 as much lead as the control. Wet tissue showed twice as much lead in the rock dust peppers. One might wonder if the rock dust altered the bio-availability in such a way that more lead was absorbed. To be honest, some of these results befuddle me. Why is there more K in your control DRY wt, but more K in the Rock Dust WET wt? That data makes no sense to me.

Any future trials should involve taking a sample of both beds before and after amending with rock dust. I am curious on where you collected the samples as well and how. Did you simply scoop dirt from the top of the box at the same spot or did you re-mix the soil first and then take the sample. Regarding the missing elements. You should take a sample of the plant tissue - leaves and stems - not just the fruit. I would also be curious to see if yield rates are better or worse. While rock dust may not make the food "better" it could make the plant healthier and subsequently have higher yields. Also, were the plants significantly different in appearance, size, etc.? Keep up the good work. Thanks for taking the time to do this.

You've merely confirmed that YOUR SOIL is already mineral rich - it says nothing about other people's soil.

I'm speechless. I can't believe rock dust actually lowers certain trace mineral level... After watching this video, I may skip the rock dust trail and only test the Bio Char. Wow, just wow...

Hi your test results are interesting , I just started gardening about six months now and been following you and onyardrevolution as well as others for some time now .For what I have been reading about rock dust and some other form of minerals, I will like to see what happens with the other tests next year because some minerals takes a long time and the wright conditions to breakdown and be available . Thank you guys for your posting I have learn a lot from you all . Be bless.

I knew it! Great job Stephen! A certain "green grower" will not be happy to hear this! My contention has always been COMPOST, COMPOST, COMPOST! Thanks for the great work!

If you started with soils that had equal amounts of calcium, etc, and you add something that has calcium in it, you shouldn't end up with half the calcium. There is something mysterious going on.

The error in your test is the form of the rock dust. If you used volcanic ash which never crystallized, the key elements are greater than volcanic rock which is crystallized. Crystallized rock takes longer to break down than volcanic ash.. Volcanic ash puts the key elements into the soil faster.

Wow... Very surprising! The fact that mineral content in both the produce and soil was actually lower doesn't make sense. What do you think caused that to happen?

Was the rock dust used azomite? Any studies using kelp liquid fertilizers or worm castings? Thank you

Very interesting. Now that it has been two years since this video I'd be interested in learning what the lab results say now. Do you have a follow up video? If so, please provide a link.

If I understand things correctly this might support the ideas of Elaine Ingham that soils ALL have enough fertility but that it is the microbes of the soil that determine whether they are available to plants or not. This was a useful test. Keep up the good work.

Well done chap. Good work. We need more of this sort of experimentation,there are too many suppliers of miracle products out there that need to be called on their claims.

Just did some research- it depends on the action in your soil. So measuring it the first year and saying it does nothing is bad information.

A fantastic job. I'm looking forward to more testing and results. Thank you very much Stephen.

Why are the control soil RDL values twice that of the rock dust soil RDL values and how does that affect the results if it does?

What kind of "rock dust" was used in the trials? Basalts, granites, oil shale, igneous, metamorphic, sedimentary?? I would think there could be a dramatically wide spectrum of chemical reactions depending on the chemistry of any given rock type.

I know someone who plans to garden in the desert... great guy, but he said he had plans to "improve the soil with rock dust". See, here is the thing. Wind erosion is common in deserts. Basically, everything is sandblasted by the wind, which creates tins of rock dust. So I thought his idea was like adding peat moss to a bog. However, if you are gardening in a bog, perhaps rock dust might help. Also, peat would help a desert. In most garden soils, you have a high content of natural rock dust. Particularly if you are on clay or alluvium or sand.So if you are messing around with this stuff, I'd advise getting your soil analyzed first, then comparing it to the analysis of several rock dusts, and see if one of the rock dusts has an abundance of minerals that your soil is lacking. Otherwise, you're just throwing your money away. You're better off buying wood chips with your cash and putting down a thick layer.

WOW!! These are important findings! Have you seen any other test results that confirm your own, Stephen? Based on your findings, rock dust may be a waste of money/resources in the garden. Thank you for performing this test and sharing your findings.

This is confusing Stephen. The introduction of minerals in the water has to be a factor but I fail to understand how Ca, a major element in Rock Dust can register lower. I wonder if the soil was obtained with a core sampler at different depths what the results would yield? Could the Rock dust have simply passed through the shorter raised bed media? Outstanding work and thanks for the info!

Very interesting results. Thanks once again for taking the time and sharing your experiences and results. I have enjoyed your balanced analysis and note that in some ways the trial raises more questions than it answers. Such is science

Thanks for the information, much helpful....

Steven, as a scientist (Physics), I love these kinds of quantitative (and seemingly unbiased) tests. This will be our first *_big_* year at the Itsy Farm and I will NOT be using Rock dust. Now I am anxiously awaiting similar tests for AZOMITE (A to Z Of Minerals In The Earth).I do plan on using AZOMITE in our outside beds and in the hoop house beds. Heck, I might even do my own tests! Thanks again for great work.

It seems you have already used rich soil before you added the rock dust, please try the experiment again with a poorer soil. Some soils are so rich, that anything you do to them can only make them worse.

Can you explain why the rock dust bed had lower the soil mineral levels as compared to the controls? Also perhaps conduct some tests on the difference in soil microbiology. Goodwork

I was actually more concerned with the slightly elevated Arsenic and Aluminium quantities in the trailed rock dust, which for me would be turning rockets from a potential amendment to something with negative effects.

thanks for this test. try bigger plots next time and more plants to even out genetic differences between plants

I have incredibly poor soil. Mostly clay and sand. I've been throwing in everything but the kitchen sink, to make it better for everything from gardening, to growing plain old grass. When I mow, I create a dust storm, as do most of my neighbors, but my grass is actually starting to fill in, from all the amendments. I haven't used rock dust yet, but hearing all the rave reviews, I ordered some the other day. Then I find this video...story of my life! I suppose it will probably help my soil though.

how do you expect to see any improved growth when the control soil is already replete with all the nutrients being assessed?

both beds should have been tested at the start and before amending the rock dust bed. this would produce a better data set and may also generate some insight into what happens during the growing season. it could be that the mineral in the rock dust never were there or that they were leached out of the bed due to watering. the greater amount of minerals found in the control bed does not make sense. They should be similar at least and this result is counter intuitive.

Thanks for your reply Stephen, all this research and is well worth it. I cant get enough of it. However I dont feel that playing down the value of mineral rich volcanic dust makes sense. Take for example the rivers of the Punjab in India which overflow during monsoon and enrich the land with silt. The rivers flow from the Himalayan mountain range and take the minerals downstream to the fertile plains. If the land is lacking in minerals then our crops are going to be nutritionally deficient. The science shows that our brains need trace elements some ninety in total. We dont need large amounts but we still need them. Also our metabolic enzyme production is dependent on a proper supply of minerals. I am taking supplements but wish my food contained these things. So I am still working at it. thanks again for your valued research and efforts Joe

I'm NOT a rock dust advocate, I'm only seeing if I should buy some myself and I probably won't. But I don't like this experiment ...One, because its a sample size of 1 and you cant test for significant differences with this sample size. And Two, because if the plants have all minerals they need available to them they will only take up what they need and both plots had what was needed. This only means that you don't need rock dust not that it does nothing. Another point is that trace minerals cannot be made available to the plant without a good microbial presence to change those minerals into a form that the plant can take up.

What a conclusion of fabulous trial. Thanks for sharing.

Use my rock dust for my worms for grit in their gizzards. Also quite using kelp directly and started feeding it to my worms as well. Worms are happy but I am sure I wasted my money since leaves are free and I still have four bags of them, and ground egg shells work for providing grit. Live and learn.

Stephen, Thanks for doing this study. The cost of rock dust is too much to have results such as this. I will stick to my slower long term plans with wood chips, this next growing season will be the third my garden is covered in chips. I was hoping to make a quicker work of decomposition and better planting results with rock dust. I won't now. I am very appreciative you did the work. Steve

Thanks so much for all your efforts! This is very interesting and very surprising considering the prevailing garden wisdom. It certainly does make me want to take a second, more thorough look at my gardening practices. Can hardly wait for the results of your further trials!

Excellent trial and very interesting results! I'm not particularly surprised though especially within a single season. I can't imagine rock dust, regardless of how finely ground it is, could become soluble and available to plants that quickly. I'm no professional, so I could certainly be wrong. I'm most surprised with the soil vs soil results. were the soil samples taken at the beginning or end of the experiment (or both). I just wonder how much is lost to leaching. The analysis should likely included before and after samples. Just a thought.

I think this is a really good and a worthwhile experiment. Thank you for being objective as I heard much good talk about rock dust. Since rock dust might be one way, I just wanted to mention that there are numerous ways to amend your soil with minerals. Rock dust just might be the flavor of the month.

Isn't this not only working in mineral depleted soil. Like where there bin growing crops for Many years and the soil is depleted from many minerals.

Where did the minerals go? They don't disappear. They must have gone into the roots and maybe the rest of the plant. You never commented on the size of the roots comparison or the sturdiness of the stems. In other words a healthy plant. How about resistance to pests, mildew.

it is my understanding that in order for the plant to absorb rock dust it must become soluble.

Since some of the nutrients "disappeared" from the rock dust soil, is it possible they were taken up by the other plants grown in the soil? I know you tested the peppers because they're most often cited in the literature, but would it be possible the other plants took up the nutrients? And I might have missed it, but what was the rationale behind having the control group soil deeper than the rock dust plot?

As they were both new beds, the test on Rockdust would be low as it needs micros to break it down so plants can use it, it appears you don't know much on the cycle of soils

great video to spark discussion. it doesn't make sense how the rock dust soil would have less nutrients... there is definitely a missing puzzle piece

Robert Pavlin and Camp Rand are quite right. There is Rockdust and then there is Rockdust. Without a thorough analysis of the content of trace minerals and minerals in the Rockdust used, the test is lacking some vital factors. I am the Danish distributor of a Scottish basalt rockdust and the results we see are very good. Maybe not the first year, but the following years.Give it time. Check www.reminscotland.com/ Regards, Claus B Henriksen Denmark

Awesome trial! I would be curious to see the test redone in a couple of years, inorganic minerals are thought to break down slowly over years correct?

I liked this video ,its very interesting. this is only my 3th yr gardening and its so cool to read the comments from the people im subscribed to..i wish john kolher would comment too .but I think I know what he would say. .anyway keep making great videos like this thanks

Humus is obviously the most important part of any garden soil. But we also add things to address soil STRUCTURE. Things like perlite to help with aeration and vermiculite for moisture retention. I wonder if rock dust is useful for soil structure. After all, most soil found in the "wild" contains it. I wonder how you could test the benefit of rock dust as it pertains to soil structure?