The truth about Dynamic Accumulators: Science is needed!

Dynamic Accumulators have been spoken about by many people in permaculture circles and beyond, and have become such a part of the permaculture lexicon that they have pretty much become a go-to solution, (referred to by nearly everyone)-to many problems in soil health. The problem is that the information that has been broadcast about these wonderful plants has been disseminated in a circular pattern of referral. There is little to NO hard science to back it up.

This is not to say that an alfalfa plant, for instance, will not create a massive depth and breadth of organic matter, and become a community unto itself for it's lifespan, and beyond, or that it doesn't indeed accumulate certain nutrients in it's body that are different from say a carrot or dandelion, but there is no science showing that those concentrated nutrients thus deposited are actually available to other plants upon decomposition.

Most sources come back to the tables in the book: Designing And Maintaining Your Edible Landscape, by Robert Kourik. Kourik has told Toby Hemenway that he regrets ever publishing that table, simply because the data can not be verified.

Toby Hemenway, and Eric Toensmeier both used Kourik's table as a reference for their own in their books. Hemenway is removing the table from future editions of Gaia's Garden and is intending to replace it with a general note about accumulators, and Toensmeier says that he has stopped teaching about Dynamic Accumulators in his courses. They are both hopeful that studies will prove the merits of the accumulators. Kourik is in the process of accumulating data, as are some other academics.

A well researched article with various sources for further reading, including the statements by Hemenway and Toesmeier is available Here Some of these links within this article are not working for me today, but I have linked to all of them in the past month. The information must be searchable, so I am keeping the above link which connects you at least to the names of the people who are responsible for the other sources and you can search for it on your own.

One of the interesting things about this above linked article is that it flows further to discuss the merits of the best known dynamic accumulating system: building your Soil Organic Matter, mulching it, and not tilling it. The result is an intact community of beings, including fungi, who network to exchange nutrients and make all the minerals that are in your soil biologically available to plants. The more and diverse your plants, the more and diverse are the communities that associate with those plants as individuals and as a community. This results in your soil accumulating (within the network of various mycelia) biologically chelated minerals in forms that all your plants can use, and are in fact delivered to your plants by the interconnected fungal networks associated with individual plants in the community. The work of Elaine Ingham is quoted in regards to this process.

"if the proper sets of organisms are present in the soil, and you are growing plants so that there is food for those organisms, nothing else is needed. The plant puts out the exudates from photosynthesis to feed those bacteria and fungi that specifically make the enzymes to solubilize the needed nutrients from the rocks, pebbles, sand, silt, clay and organic matter… There is an infinity of all plant-required nutrients in any kind of parent material. There is no parent material on the planet that lacks the nutrients needed to grow plants. Until the day you run out of rocks, sand, silt, or clay, there should be no need to apply a mineral fertilizer"

This would lead us to think that soil tests might not be worth their weight either, although I'm not sure what to do with the knowledge that my area of the country is deficient in Selenium. Hmm.

I personally am not deterred from using dynamic accumulators, because many of these plants have great value to the soil systems for what we do indeed know that they perform. I just thought I'd throw this info out there into the knowledge base of the Permies community, so that the discussion about dynamic accumulators can take place, and maybe those with a scientific bent can take on the task of documenting what exactly is going on with hyper accumulation of minerals in living plant tissue, and what purpose this activity might serve to the greater soil and plant community when those plant materials decompose into the soil matrix.

Oh, there is plenty of hard science out there, you just have to know where to look. Many plants are investigated because of phytoremediation potential, but there your intent is to yank up the crop, along with their dynamically accumulated toxins, so that you can bury them in a deep, deep hole. Have you tried searching on Google Scholar? That's where I find a lot of interesting studies.

Thanks for your input, John.

Well I just tried to access two articles on that google scholars link and found that I was expected to pay US$36 for the privilege. Not tonight, especially with the CAN $ exchange rate the way it is right now at 78c US.

While I have no doubt that plants do indeed accumulate minerals, metals, toxins, or whatever they are geared to collect en masse (and then be torn out and thrown very deep in a hole if it really is toxic and nasty), and there is a quote (#4) below that I share connected to this thought, there is no real hard science done on their role in the permaculture. The topic of this thread is more about the role of plants who we have come to understand as Dynamic Accumulators in permaculture, and what exactly they do, and what exactly is the result of the decomposition of their tissues into the soil matrix to be used thereafter by other plants.

One of the links connected to the link that I had in the previous initiating post is from John Kitsteiner, who is a doctor (MD) and the author at Temperate Climate Permaculture. I just got the link to work here

Here is a few quotes that are not continuous but lead one into the other and are in order as they appear (#5 is a more so, but it flows and is in order):

1.) "The information I place on this site has been extensively researched before it is posted. As a physician (M.D.), I strive for scientific accuracy. I am well-versed in the scientific method and critical reading of scientific research articles. I understand the world of academia."

2.) "in brief, it is the idea that certain plants (often deep-rooted ones) will draw up nutrients from the lower layers of the soil, and these nutrients will be deposited in the plants’ leaves. When the leaves fall in autumn and winter and are broken down, those stored nutrients are then incorporated into the upper layers of the soil where other plants will benefit from their deposition...So, with our scientific minds turned on, does the concept of Dynamic Accumulators hold merit? In short, my answer is a non-committal 'maybe'."

3.) "I have to be very fair and state that I am not the utmost scientific-research-article-searcher in the world, but I am pretty darn good, and my lack of results was a bit disappointing."

4.) "We do have evidence that some plants accumulate minerals in high concentrations in their tissues. This concept has been significantly researched. In the botanical community, this concept is known as Phytoaccumulation or Hyperaccumulation. There are a number of hyperaccumulator plants that can grow in soils with high concentrations of certain minerals, often metals. These plants can be grown in areas that have been contaminated with heavy metals or high-value metals. The plants pull out these minerals (phytoextract) from the soil. The plants are then harvested and processed to extract the minerals from plants to be recycled or dealt with in a more ecological manner. This “phyomining” has been used, with success, on significantly contaminated sites."

5.) "...an extensive database put together by botanist James “Jim” A. Duke Ph.D"
"... Specifically, and for our purposes, the database provides information on concentration of minerals found in the tissues of plants"
"... Using the information from Dr. Duke’s database, a free, downloadable Nutrient Content Spreadsheet was created."
"... found it on Build-A-Soil.com."
"...With this information we can connect the dots for Dynamic Accumulators. For instance, we can see phosphorus (P) concentration in Lambsquarter (Chenopodium album) is over 36,000 ppm (parts per million). This is a high concentration. Therefore, it would make sense to grow Lambsquarter on our site, let the Lambsquarter die back in the Autumn to be composted in place, and then have higher concentrations of phosphorus (P) in the Spring. Unfortunately, while this scenario sounds good, we have no proof that it will work. Our logical pathway sounds plausible, but the reality is that Nature is never quite so simple as we would like. Minerals don’t appear out of nowhere (alchemy is still not a science!); if the soil has no phosphorus, then the Lambsquarter cannot accumulate it. If the soil has no biology, i.e. Dr. Elaine Ingham’s Soil Food Web, then there is a good chance the phosphorus may not be bioavailable to the roots. And while our scenario sounds good, we have no scientific proof (research data) that if the Lamsquarter did accumulate phosphorus it would indeed be returned to the soil in a usable form to future plants. Maybe it will, but would it take 1 year, 5 years, 25 years to become available again? This is information that we just do not have."

6.) "I am not saying that their soils did not improve with the planting of Dynamic Accumulators, but was it the dynamic accumulation or another factor that caused the improvements such as mulching, composting in place, biomass accumulation, biodiversity, microclimate creation/enhancement, etc. As a good friend of mine likes to say, “The plural of anecdote is not data.”


There are two bits of data on a Permaculture Dynamic Accumulator, studying the effects of Comfrey

Here's a quote from the first, less scientific study: "After 5 years of comfrey, the topsoil in this sample shows a lower pH and higher percent organic matter than any of the previous samples, and the nutrient levels are practically off the charts – a 47 to 232% increase over the previously observed highs. I did not test for calcium or magnesium either before or after, but just on the basis of NPK the comfrey is completely vindicated.

It appears I owe comfrey and its promoters an apology, but still this is just one data point. To really make the case for comfrey, we will need lots of data from lots of soil types, and we need to publish the results in a reputable source that can be cited by Wikipedia, PFAF, and all the reference books we turn to for authoritative information. And we need to collect negative results (if any) as well as positive ones. Do you have any data on comfrey to share?"

But that is one plant, and one study, by one person, and it wasn't a very controlled experiment... but it is something.

It's a start. But like the author said we just need more.

In the comments below that article, a person wrote this: "Lawrence D Hills carried out extensive trials, at his Henry Doulbeday Research station and Trial grounds, at Brooking, Essex, UK. His experiments and analysis were though and scientifically rigid in their methodology and presentation. His results were presented in the Comfrey Report (published by the HDRA in 1975). There is also a good summery of these experiments in Hills book ‘Fertility Without Fertilisers,’ also published by the HDRA. All of the results were laboratory tested by the Michaelis Nutritional Research Laboratory. The HDRA later changed their name to Planet Organic."

So this is the other information I found that connects comfrey with some data on it's dynamic accumulator function, but I have not found the studies by Hills to read myself, so I can not tell you or anyone what information it contains.

For my own purposes in my garden, it doesn't matter. I really don't care if this plant accumulates this, and that plant accumulates that. I'm interested in building bio-diverse systems of plants/animals/fungi/soil microbes.

The reason that I started this thread, and the need for study, is so that when we are talking about something, and teaching something, and are giving information about something, like Dynamic Accumulators, we actually are speaking from fact, and not anecdotal or folkloric information, or information that is written in books but was never really researched. There is a reason that Hemenway, Toesnmeier and others are pulling this information out of their books, and it is not, I believe, because they do not want to believe in the folkloric and anecdotal evidence, it is because they do not want to give out information that may not be true. The proof is in the soil; lets get it.

Roberto pokachinni wrote:
Well I just tried to access two articles on that google scholars link and found that I was expected to pay US$36 for the privilege. Not tonight, especially with the CAN $ exchange rate the way it is right now at 78c US.

Hey, I'm a cheapskate too and you won't find me paying $3 for an article, let alone $36. One thing I do when searching is to add "filetype:pdf" into the search box. Often researchers will have a pdf of what has been published in a journal sitting on their university website where it can be had for free.

Very well thought out posts Roberto. Thank you for starting this topic.

I've been wondering this for a while, but haven't had a chance to really look into it yet.

If I was still in university, I would look for a meta-study that looks at all the research that has been done so far, and gathers together the actual data (sets) and puts them in one paper. This would be a great starting place. We could see what we think we know and what evidence we have available to back up our interpretation. (I'm oversimplifying it because not everyone who comes here is fluent in Ivory Tower Speak). From there, we (or I should say they because I'm not 'sciency' and won't be doing any of this) can start gathering data and fill in the gaps.

I wonder if there is a meta study already available. Most libraries have free access to scholarly journals. If you make a note of the article you want to read, the librarian can find out if they have it in paper or online subscription. If not, you could always buy a year pass to a university library, they usually have full online access to scholarly journals. If you want to read more than one or two articles, this might be the way to go. If you find a good article, please let us know.



There is definitely something to this Dynamic Accumulator theory. We can see it locally in some of the forests. Especially one forest where the salmon spawn every year. Because our local salmon die after procreating, there are a lot of bones leaching calcium in the soil. The Big Leaf maple trees grow there. These trees almost never grow unless there is calcium at a certain level in the soil. The leaves fall each year, and sometimes they get stuck in the crock of a branch. The leaves decompose there, and become Big Leaf Maple leaf soil. There is a specific fern that grows on this arboreal soil that requires high levels of calcium to grow, and usually only grows on specific rocks where they can break the rock down with their rhizomes to get the minerals they need. As usual it's more complicated than that, involving specific moss and lichen in the mix. The point is, we can see the effects of the calcium move up from the soil, into the maple leaves, which then compost in a maple leaf only soil, which then grows a plant that requires high calcium.

I can go to this river, and see a Dynamic Accumulator at work. However, how long did it take for the forest to create this relationship between the species? There is a lot more to it than just fern and tree. Also, the point you make about how long the minerals take to become available to the next plant in the chain. Some of these trees are almost a thousand years old. Does the maple leaf take a hundred years before it releases it's calcium, or is it available to the fern after one year of composting? What would happen if the lichen wasn't there to help convert the minerals into a form the fern can absorb? Or maybe the arboreal soil is just a substrate for the fern to live in, while it really gets the calcium from the bark and not the leaf mulch.

It's a very complicated subject. I'm going to enjoy reading everyone's thoughts on it.

Roberto pokachinni wrote:

In the comments below that article, a person wrote this: "Lawrence D Hills carried out extensive trials, at his Henry Doulbeday Research station and Trial grounds, at Brooking, Essex, UK. His experiments and analysis were though and scientifically rigid in their methodology and presentation. His results were presented in the Comfrey Report (published by the HDRA in 1975). There is also a good summery of these experiments in Hills book ‘Fertility Without Fertilisers,’ also published by the HDRA. All of the results were laboratory tested by the Michaelis Nutritional Research Laboratory. The HDRA later changed their name to Planet Organic."

So this is the other information I found that connects comfrey with some data on it's dynamic accumulator function, but I have not found the studies by Hills to read myself, so I can not tell you or anyone what information it contains.

Hi Roberto, I'm thinking on how to share my thoughts on this topic and will take my time. Just one thing on Hills work, you can find it at soil and health public library, ask a legal copy of the works it is free but if you want you can give a one time contribution of 10 AUD I think, I paid a few years ago and in any case they send you a link where you can download a copy of the book. The link they send lasts thirty days, in any case I'm not going to share it valueing there work I think it is important we contribute to there existence in a correct way.
There you can find two of Hill's works, russian confrey and comfrey report, the first is of 1950's and the second is of 1975. They are in my comfrey folder ready for reading.

It seems like this would be a fairly easy topic to test. All one would need is some unused land to subdivide into test plots, a nominal amount of money to take periodic soil samples and time. As an example, one could establish several tests plots (being minful to eliminate as many exogenous variables - hours of sun, soil type, etc); take soil samples from each plot at the begining of the test to establish a baseline; keep one as a control plot, plant one in dynamic acumulator 1, Plant another in dynamic accumulator 2, one mixed da1/da2, etc; mow, water, etc the same for each plot; take soil samples periodically... If part of the establishment involved sheet mulching the test plots, have one plot that is just sheet mulched initially and then allowed to do whatever it wants to do... I'm not a research scientist so maybe i'm missing some important considerations but the general framework seems fairly elementary.

The permies community could even develop a "crowd science" study, where a simple protocol could be debated and developed by the forum and implimented by anyone anywhere who wanted to take part. Results could be shared on this site.

We could turn the "anecdotal evidence" into a tsunami of hard data with a little structure and a community of participants. At that point who cares if the data hasn't been published in a journal...

Phytochemical Database http://www.ars-grin.gov/duke/

includes references

Thanks for posting that Tyler!

There is definitely something to this Dynamic Accumulator theory.

I definitely agree, R. Ranson I have a strong suspicion that with a little more study that at some point in the future the tables will be returned to the books and R. Kourik's regrets will be put to rest, but you all can, perhaps, see why he's putting energy into it, and why T. Hemenway, and E. Toensmeier are not wanting to keep spreading the information.

The permies community could even develop a "crowd science" study, where a simple protocol could be debated and developed by the forum and implimented by anyone anywhere who wanted to take part. Results could be shared on this site.

O. Donnelly, I don't know if I can give an apple but I would give you one for your suggestion! This is basically what I was hoping for, but didn't write (for some unknown reason). Thanks!

Lorenzo Costa, thank you for posting that link. A did manage to locate Hills' work also available for sale on Amazon, for those who are interested. It seems he was rather passionate and prolific about studying comfrey.

Wow, somebody put a bunch of exclamation marks on this thread. Cool. That's never happened to me before.

Roberto – THANK YOU for raising this important topic and providing all that background information.

So let’s come up with a strawman proposal. Roberto perhaps you should even start a new thread that asks specifically for input regarding a crowd-sourced science experiment protocol. Coincidentally I have been putting together plans to do something similar but without the rigor. I may change those plans now.

I’m in the middle of building a house and have been preparing a portion of the land for an orchard, with about 30 fruit trees coming in the spring (I posted some details here: https://permies.com/t/52334/trees/Apple-Orchard-planning-tree-placement). My plan is to spend summer / fall 2016 preparing a garden area – fencing, hardscaping, building beds, building soil, etc - for spring 2017 planting. The garden will have a southward open U-shaped perimeter of fruit and nut trees and shrubs, berry bushes, etc surrounding the garden proper. In the garden proper I plan to reserve approximately 1/3 of the space for annual vegetable beds, 1/3 for perennial and annual insectary plants, and 1/3 for dedicated biomass crops (although there will be some overlap and mixing among the categories). Within the biomass beds, I planned to have a Comfrey bed both to produce biomass as well as act as a nursery to propagate more for my orchard. I was going to wing it on other biomass beds – perhaps a crimson clover here one year, alfalfa there for a couple years, etc. Nettle, sunflowers, clover, vetch, buckwheat, etc were all on the potential list. I had planned on adding nutrients to the beds as needed.

If I were to put some rigor around the plans, what should I be considering? A few questions that come to my own mind: (i) one would need to either add amendments to each plot uniformly or not add any amendments to any plot for the duration of the experiment. Preferably the latter, if the goal is to determine what each DA contributes to soil fertility? (ii) assuming that no amendments are added to any of the plots, what are the challenges of growing these crop in isolation without added fertility? For example will a plot of comfrey thrive on its own without associated nitrogen fixers, additions of compost, manure, etc? Should each plot have a nitrogen fixer along with the dynamic accumulator?; (iii) controlling for site preparation – if one were to sheet mulch, cover crop, etc. to prepare a bed for a subsequent experimental plot, I assume one would need a bed that has been prepared and then left to do whatever it wants to do to control for such site preparation. I think that argues for preparing the experimental plots with a thick sheet mulch, to impede the ability of pioneer species from emerging for as long as possible? Or perhaps prepare a stand of a perennial nitrogen fixer and then plant the dynamic accumulator into the nitrogen fixer (with the help of localized sheet mulching)? (iv) if a thick sheet mulch were used, would that not impede the soil food web from recycling nutrients (especially nitrogen)? (v) Other than comfrey, what would folks vote for the SECOND best all-around dynamic accumulator to test? (vi) nuts and bolts – how big should the plots be? What nutrients should be tested for? Sample spacing? Sampling protocol? Test duration?

Thanks, O Donnelly, I was thinking along the same lines. I will check out your thread.

While at work today I was contemplating coming up with another thread asking for a plan to study plants in a scientific method way. It's been a looonnng time since I did any real science, but I have a basic understanding of the scientific method. The framework which has the best controls for plant studies must already exist. Crazily (since I started this!), I don't know how much energy I will have to put into the project. This year, I hope to be be building a house, a root celler, a greenhouse, expanding my gardens, and beginning my orchard {basically start on the retirement dream}-all while holding down a full time job! I don't even know if I can afford all of this yet.

I started the thread because this information was new to me, and because I was a bit shocked by having the sacred cow shot, and because I know that most other permies were of the opinion that these plants work in exactly the way we thought they did, and had not heard that the sources of this information are questioning it. I just wanted to get the information out there, so that those who do have the scientific bent, and have the cash (or a study program at a university, maybe!) for testing the soil, and the time and energy to develop a good set of controls could get on it.

I think that all of your suggestions have merit, O, Donnelly. I'm not sure that we should focus on planting a nitrogen fixer with it. I think it might be best to do it in raw land, with no amendments of sheetmulch or nitrogen fixer crops at all. Test the soil, then seed or put the cutting in, and let it go, and then test the soil after the plant begins to lay it's above ground material down, or dies completely; and then continue to test it annually to see if the available nutrients change.

one would need to either add amendments to each plot uniformly or not add any amendments to any plot for the duration of the experiment. Preferably the latter, if the goal is to determine what each DA contributes to soil fertility?

The way I see it, this is true. If we sheetmulch (for instance), we are creating a soil organic matter situation that may act as the dynamic accumulator. Also, everyone's sheet mulch material will be somewhat (or substantially) different, and thus be hard to 'control' (in the scientific use of the term)--but come to think of it that is probably not an issue if we do multiple controls at each garden. While our plots could have an additional control that includes amendments, I think that there must be one plot that has no amendments at all, and one that has nothing done to it (no accumulator either) to be the true control.


All of that said, I just sort of sat on my hands and stopped typing my thoughts out for a minute , and then came up with this:

For example (I'm going to use comfrey as the example, since I actually am getting some in the ground this year for sure, but we should probably focus on some other plants since comfrey is already the one with the most study):

Plot 1 could be just a two inch comfrey root of a certain weight planted two inches below the ground.

Plot 2 could be like plot one, but with the addition of white clover.

Plot 3 could be like plot one, but with the addition of a sheet mulch of the gardener's choice.

Plot 4 could be like plot 2 but with the addition of sheet mulch.

Plot 5 could be the control in which nothing is done.

To be a good test, the same plot system could be done in several different soil types (and feral/wild guild areas) in the same farm. For instance, I have an 8 acre field and there are a number of areas of different soil types and feral or wild areas, as well as some areas of open poplar forest which I would at some point like to experimentally garden in.

How does that sound?

Maybe I should leave this to the science peeps.

Not certain I understand this or how relevant it is, but thought I would share it with you incase you can use it.

I was talking with a well recognized naturalist about this discussion today, and he said that when plants draw up minerals (like the calcium I talked about above) from the soil, they do so in a "soluble form" which makes it easy for future plants to use it AND easy for rain to wash it away.

It's what he said. I trust his knowledge on this, but you (probably) haven't met him, so... take from it what you find useful.

Regarding the sheet mulching issue: I think it would be very difficult to establish a pure stand of a test crop without some amount of soil preparation. Conventional farmers would either till / plant / cultivate, or apply herbicide / plant. Organic growers would either till / cover crop / till / plant, or sheet mulch / plant. Given that one would have to engage in some type of intervention to establish a pure stand, that intervention would need to be isolated and tested to determine its impact on the experiment. If I decide that the best way to prepare the experimental plots is to sheet mulch, then I should have one plot where all i do is sheet mulch.

On the nitrogen fixer issue: I haven't grown comfrey before, but what I have read is that it requires added fertility (principally nitrogen) to thrive. "It does well in most soils but prefers a rich soil with a lot of nitrogen...It is best to dig in manure between the rows in the fall or spring. Raw manure will not burn it. Comfrey loves nitrogen. You will get a lot more yield." From http://www.nantahala-farm.com/comfrey.shtml . Others who have actual experience growing the plant can comment. If this is indeed the case, then one would either need to add nitrogen rich fertility to that plot or grow the comfrey with a nitrogen fixer. One would either have to add the same amendments to all the plots (including the control - which is not ideal) or have a plot dedicated to testing the impact of added amendments.

Similar to what Roberto was thinking, I am considering the following plan:

Plot One: Control (existing diverse pasture, no intervention other than periodic chop and drop)
Plot Two: Site Prep Control (whatever site preparation is used - sheet mulching, cover cropping, etc - would be done on this plot. No other intervention throughout the experiment)
Plot A - Y: Dynamic Accumulator Monocultures (sites are prepared as in Plot Two, planted in dynamic accumulator monoculture, periodically chopped and dropped)
Plot Z: Dynamic Accumulator Polycultures (sites are prepared as in Plot Two, all tested dynamic accumulators are planted, periodically chopped and dropped)

Or possibly include a nitrogen fixer in each test plot:

Plot One - Control (existing diverse pasture, no intervention other than periodic chop and drop)
Plot Two - Site Prep Control + nitrogen fixer (whatever site preparation is used - sheet mulching, cover cropping, etc - nitrogen fixer planted. No other intervention throughout the experiment)
Plot A - Y - Dynamic Accumulator Monocultures + nitrogen fixer (sites are prepared as in Plot Two, planted in dynamic accumulator monoculture with nitrogen fixer, periodically chopped and dropped)
Plot Z - Dynamic Accumulator Polycultures + nitrogen fixer (sites are prepared as in Plot Two, all tested dynamic accumulators are planted, periodically chopped and dropped)

On the issue of water soluble nutrients, plants do NOT make all their nutrients "available", at least not all the time. Google "calcium oxalate". True, the Ca must be water-soluble for the plant to uptake, but then it is bound to other materials, making it insoluble. I am sure the soil organisms (which ones?) have ways to make this soluble again, otherwise you'd lock it all up over time.

Phytoremediation studies show us that yes, some types of plants are very good at mining. What isn't clear is, once their residues are laying on the surface, which minerals are water-soluble, and how long does it take them to become soluble? It seems impossible that any of these minerals are locked up forever (even hard rock phosphate breaks down over time), but that time scale would be critical when soil building with Dynamic Accumulators.

Has anyone looked into grants to actually start some solid science on these issues?

On the nitrogen fixer issue: I haven't grown comfrey before, but what I have read is that it requires added fertility (principally nitrogen) to thrive. "It does well in most soils but prefers a rich soil with a lot of nitrogen...It is best to dig in manure between the rows in the fall or spring. Raw manure will not burn it. Comfrey loves nitrogen. You will get a lot more yield."

Indeed, comfrey is a nitrogen hog. For healthy growth, it needs the addition of Nitrogen, and Phosphorus. It seems to find enough potash (K) deep in the soil, but it does best with ample & frequent applications of fresh manure.

Lawrence D. Hills recommends planting it near the poultry house, or pig pens to assure a frequent supply of manures (the needed nutrients).

I really appreciate everybody posting. I was expecting this to be a pretty interesting thread, and to draw attention, but I was not expecting this. And now, we were mentioned in Paul's Daily-ish Email. Hmmm. I wonder: if we are really gaining momentum now, how big this will go?

Jim Tuttle is re-phrasing things well:

I am sure the soil organisms (which ones?) have ways to make this soluble again, otherwise you'd lock it all up over time.

This is certainly true. The issue is, I guess, whether it is the soil organic matter, particularly fungi (likely in my opinion), who are solely responsible for the release of the locked up nutrient into the available nutrient stream, or if this would happen all alone, given enough time, in poor soil conditions, with the plant just happening to be there?-does it get locked into mineral form and that's it, if the soil is poor? Which brings us to the crux of the problem, and to the next quote by Jim:

What isn't clear is, once their residues are laying on the surface, which minerals are water-soluble, and how long does it take them to become soluble?

Exactly, and under what conditions? The plant may hyper accumulate minerals, but are they available, and if they do become available, when, and with the help of whom?

R Ranson seems to have the answer:

I was talking with a well recognized naturalist about this discussion today, and he said that when plants draw up minerals (like the calcium I talked about above) from the soil, they do so in a "soluble form" which makes it easy for future plants to use it AND easy for rain to wash it away.

but is this accurate, when considering what Jim T astutely brings up here:

Google "calcium oxalate". True, the Ca must be water-soluble for the plant to uptake, but then it is bound to other materials, making it insoluble.

I personally think the jury is still out. This is not cut and dry.


Which makes me wonder, if the plots should be prepared, and if so: how? So O Donnelly mentions this:

Conventional farmers would either till / plant / cultivate, or apply herbicide / plant. Organic growers would either till / cover crop / till / plant, or sheet mulch / plant.

But this isn't how nature operates. Nature throws seeds out and some land in ideal circumstances and many do not. Some thrive anyway, in spite of these less than ideal conditions. Fukuoka advocates a different approach than is conventional or what is historically done in the organic movement where preparing the land extensively is quite normal. Many others who practice no till and those who broadcast seed, do so randomly to produce the strongest, most resilient seed or plant stock. Sepp Holzer, for instance, gathers seed from the strongest looking plant that thrives in the poorest conditions. Now, I'm not saying that we should do, or should not do, anything in particular, but I am thinking that if we are going to have controls, then we need to figure out for starters what we are trying to do? Are we trying to demonstrate what the plant can do, on it's own, regardless of circumstances. If this is the case then we need to just let people do as they will, so long as they are doing before an after tests and documenting as much as possible, what is present and what changes. I don't know. I'm just typing away here...

O. Donnelly writes:

I haven't grown comfrey before, but what I have read is that it requires added fertility (principally nitrogen) to thrive. "It does well in most soils but prefers a rich soil with a lot of nitrogen...It is best to dig in manure between the rows in the fall or spring. Raw manure will not burn it. Comfrey loves nitrogen. You will get a lot more yield."

and I get that, and appreciate John Polk furthering this

Indeed, comfrey is a nitrogen hog.

Hills recommends planting it near the poultry house, or pig pens to assure a frequent supply of manures

, but I've seen comfrey plants thriving jammed against a south facing concrete house foundation and an old and compacted driveway with very little visible soil organic matter, where it had self seeded at a place I was renting. The house was 90 years old, and so there was some advancement to the soil culture over time, for sure, but it certainly wasn't ideal circumstances. Sure, it will reach it's full potential as a plant if it's seeds land in more ideal circumstances, but i think that the testing should not necessarily be solely in ideal circumstances. The test is to see what the plant does, not necessarily what it does given perfect conditions. Those known perfect conditions can also be part of the equation of various plots, but I don't see why a selection that is less than ideal for a baseline, should be avoided.

For healthy growth, it needs the addition of Nitrogen, and Phosphorus. It seems to find enough potash (K) deep in the soil, but it does best with ample & frequent applications of fresh manure.

I will certainly be planting it with lots of organic matter, particularly sheep manure that I can get in abundance for free locally, but my intentions with that are to make a multiplier crop to eventually spread out through division into my field, not to test the plant necessarily.

I think that since Hills focused on Comfrey, and it seems to be the one that is most likely to have the effects studied the most already, perhaps we should focus on another plant. It's my mistake for choosing it in the first place, as my example, but I did state that perhaps we should focus on another plant, or many other plants, besides comfrey.

For example (I'm going to use comfrey as the example, since I actually am getting some in the ground this year for sure, but we should probably focus on some other plants since comfrey is already the one with the most study)

How about Chicory? Any other candidates people are interested in?

Jim T asked:

Has anyone looked into grants to actually start some solid science on these issues?

There are people studying, according to what I read-but none were named, except for Robert Kourik. I don't know if anybody on Permies is doing the science end of things. It would be great if there was an academic, who is also a permie, who could lead this discussion from this point on. Not that I am absolving myself of pushing this ahead, but I would certainly bow to those who's knowledge and experience would give us the most gains.

That's all I got tonight. Eight hours of hard labor on the railway today and a yoga class this evening, and a big supper after before I finally logged on, and now storming my brain,... all this is making me sleepy. Ciao.

I posted your request to home garden field trials check out the tests they have done so far on rock dust, biochar, ashes and leaf compost.

Thanks Hans. I will check it out.

Here was the answer at least for comfrey.

I read Kitsteiner's article some months ago, and it really got me thinking, but I was never concerned that the Accumulators hypothesis might not be true. (Although I always thought the "Dynamic" descriptor was unnecessary, but that's just me splitting hairs.) While I look forward to a concise confirmation that will convince skeptics, I'm not waiting for it.

Kitsteiner points out that plants accumulating elements is well documented, but then wonders whether the nutrients in a plant are going to be available to other plants after decomposition. This, frankly, seems silly to me. (Although, to his credit, he recites the adage, "Lack of evidence does not imply evidence of a lack"). Does the C:N ratio in a compost pile matter? Yes, because a certain amount of carbon and nitrogen, in certain proportions are necessary for life... and matter and energy cannot be created or destroyed. It has to be there, and when it is, it is used. Same goes for all other nutrients.

Deep soils of Iowa exist not because Mammoths were fond of using Miracle Grow and superphosphate, they're here because living things break down soil particles and they use, and are composed of, nutrients and when they defecate and die those nutrients are returned to the soil from whence they came. That's all obvious. I wouldn't call that folkloric; it's at a higher level than that, it's common sense. (Of course, we also have to thank those helpful glaciers for conveniently stealing a bit of Canada's fertility a few times, which has been recycled and added to ever since...well, most of the time since then, until we started losing it in vast quantities, but that's a separate topic.)

This is not to say that all soils will eventually become perfect if they just have the right plants growing in them. Some parent materials are devoid of certain elements, and if you need those elements (i.e. if you're not going to follow Shepard's advice to know your biome and limit yourself to what already belongs there), then you will have to import those. The well-established concepts of phytoaccumulation and decomposition are all that's necessary to explain the Accumulator hypothesis.

I know I'm taking a lot for granted, but it is granted. No?

As usual, an article casually posted on Permies has knocked my socks off and got me all hot and bothered...

Im an undergrad so I cannot claim science, but I do have some thoughts. DA seems like a massive subject to approach with simple questions - just like anything else, any answer you get is going to be very circumstantial to the specific experiment.

* Nothing exists in a vacuum. We can study Comfrey in a lab all day under perfect conditions, but what does that tell us about what it will actually do in MY yard? Does animal testing give us accurate, helpful data, or does it let us vaguely assume an LD50 that may or may not mean something to us humans? Makes me wonder if 'crowd science' is actually going to be *more* scientific on this issue - in the way of producing helpful and accurate information applicable outside of a lab.

* Simplifying the questions may help. Instead of "Do DA's work?" Perhaps "How long until a certain mineral is water soluble from plant X?" so that we can get puzzle piece answers, or at least ~educated direction~ in our inquiries that's more micro than macro.
Maybe we should forget the taproots and all that and focus on the fun-guys? Perhaps they're networking and storing minerals specifically to confuse us? Mayhaps intense UV rays alter these minerals at leaf fall? Smaller questions may be easier to answer and make use of.

Noel Deering wrote:and matter and energy cannot be created or destroyed.

While totally agreeing with your post, I would just amend that when transferring energy, whether it be calories or heat or electricity - there is a loss every time that energy moves. When calories move through trophic levels in a forest, that mouse will 'become' the hawk, but that hawk will burn ~75% of that mouses 'energy' before the remaining ~25% can be assumed to "stay in and move up" the trophic levels. Same with electric and water - the city or watershed sends it out, but a percent is always lost in the transfer. Not destroyed, just... diffused.
Im assuming no one here is trying to disprove Dynamic Accumulation - just get some hard data on exactly what the energy transfer and loss rates may.... or may not be.

Sometimes Im just blindsided by the realization that.... we don't know much :p

Hi Noel and Ian, thank you for posting.

I will quote a bit of what you wrote and give you my take.

So a few quotes from Noel, and my thoughts:

I was never concerned that the Accumulators hypothesis might not be true.

Noel, my concern, and the reason for posting, is not about whether the plants actually function to accumulate minerals, or whether those minerals will eventually be made useful to the surrounding plants, but the lack of data on when individual minerals are made available.

While I look forward to a concise confirmation that will convince skeptics, I'm not waiting for it.

Nor am I, and I would never suggest that people stop using the plants known as Dynamic Accumulators.

Kitsteiner points out that plants accumulating elements is well documented, but then wonders whether the nutrients in a plant are going to be available to other plants after decomposition. This, frankly, seems silly to me.

Before I comment I will post another two quotes:

Deep soils of Iowa exist not because Mammoths were fond of using Miracle Grow and superphosphate, they're here because living things break down soil particles and they use, and are composed of, nutrients and when they defecate and die those nutrients are returned to the soil from whence they came. That's all obvious.

It has to be there, and when it is, it is used. Same goes for all other nutrients.

The article in question, and the purpose of this post is not about the long term usefulness of said minerals accumulated; Certainly the soils of Iowa were developed and their minerals made available through a variety of processes, but the processes of glaciation, the resulting deposition of soils, the wetlands which preceded the prairies, the herding that followed the grasslands, and the many, many changes in the plant communities over thousands of years while all this was taking place will create a depth of living soils and a usability of the nutrient and mineral base that no gardener or single plant could match, but this is not at all what we are concerned with. Over time, I think that all the minerals accumulated in a plant will be made directly available (given a lack of leaching or erosion and the stability of the soil food web), but the question, as stated above in this post, as well as numerous times in this thread is how much time will be necessary before the minerals are available? I'm not sure how multi millennial primal soil ecosystems relate to this topic. Maybe I'm missing something.

When you say

and matter and energy cannot be created or destroyed.

I think that you are under some impression that there are people who have posted that are making this assumption. I can't remember anybody making this claim in any form. Individual elements and energy sources can not be made or destroyed, but they can be made insoluble and thus unavailable for plants to pick up on their own. Through the mediation of a volume of time, or though a symbiotic relationship with a fungal partner, or through some other dynamic in the synergistic soil food web, or through some combination thereof an individual accumulated mineral becomes available to other plants. While in some instances, the accumulated mineral might be available directly to subsequent plants in a soil made up partly of the decomposing hyper accumulating plants in a pretty much immediate fashion, the subject of this thread is figuring this out. In this way, or as a result, we as permaculture practitioners and teachers, can give good information, based on fact, rather than running on theory and unproven hypothesis of what we think is common sense.

Ian, I think that you are bang on with this suggestion:

Simplifying the questions may help. Instead of "Do DA's work?" Perhaps "How long until a certain mineral is water soluble from plant X?"

Your next suggestions,

Maybe we should forget the taproots and all that and focus on the fun-guys? Perhaps they're networking and storing minerals specifically to confuse us? Mayhaps intense UV rays alter these minerals at leaf fall?

are perhaps the subject of other projects. Although they have merit, I think it might be even harder to study these then the soil around a plant over time.

A couple quotes together before I comment again:

We can study Comfrey in a lab all day under perfect conditions, but what does that tell us about what it will actually do in MY yard?

Makes me wonder if 'crowd science' is actually going to be *more* scientific on this issue - in the way of producing helpful and accurate information applicable outside of a lab.

I guess the way that I'm thinking when I read your post is that with enough "crowd science" we will have a range of information on individual "My yard"s and from this, a range of data that can be averaged out, to show indeed whether the minerals are becoming available, and when, and under real world (non-lab) conditions in a variety of locations and climates. I think that is what you are getting at.

I appreciate your thoughts and analogies about matter energy in systems, and I agree.

Sometimes Im just blindsided by the realization that.... we don't know much :p

The more knowledge we gain, the more we should realize this truth. The Universe is many times more complicated than we will ever know. There is a favorite quote that I will paraphrase here: "The Universe is not only stranger than we know, it is stranger than we can know." This is not to say that we should not seek to find answers or to make sense of things.

Tyler Ludens wrote:Phytochemical Database http://www.ars-grin.gov/duke/

includes references

Interesting database, but does not really speak to the issue at hand.

I want to pose a question regarding this discussion.

What, precisely, is the purpose of having "scientific" determination of which plants accumulate what minerals, and how, when and where the accumulated minerals are returned to the soil?

We know, with a rather high degree of certainty, that plants return to the soil and their component parts are broken down and recycled. It has been going on for many millions of years. We know that fungi actually break down rock, pulling minerals directly from stone and making them available to other organisms and that they came onto land and started this process well ahead of plants. Indeed, fungi are key to the initial creation of soil.

Do we have a need to know precisely what is accumulated precisely how, when and where? Or is it sufficient to have the general information that we do have regarding which plants accumulate which nutrients, with issues of how they do it, where they get it from and so forth being put to one side as not actually necessary to our purposes?

As for some sort of "crowd science" process - How would that be any more substantial than our current level of anecdotal evidence, really?

I believe present day US culture has an unhealthy obsession with "science" and "experts", with its tendency to think that nothing is legitimate until some expert has blessed it. At the same time, we are hopelessly poor at evaluating expertise and choosing our experts to trust.

Plants in nature grow in a tremendously complex environment that we are a very long way from fully understanding, certainly not in a detailed scientific manner. Yet there are a great many people who are very capable of successfully growing crops, without being able to quantify and detail in scientific fashion.

What, precisely, is the purpose of having "scientific" determination...

Knowledge is another tool that we can put onto our tool belt.
The more we understand the how, and why something works, the better we can apply it to our practices.
Knowledge allows us to fine-tune our application to achieve a greater benefit, rather than just taking the 'shotgun' approach.

False information is pretty damning to Permaculture, and I think quantifiable information protects Permaculture from naysayers... in that regard.
The establishment has the money to throw around studies and science, we need to tread lightly.
We, as Permies, know these things work and to some degree 'how', but if I walk onto someones property as a Designer expecting money, They are going to expect answers beyond "It depends". While an accurate answer to most questions in this field; if I want to win any accolades from Jimmy Cattleman, Id better be able to tell him with relative accuracy why his stuff wont work, or he'll categorize me as a "stupid hippie" and go hire the local landscapers.

If I can tell him what he can do without a passionate plea for him to go study ecology - and it works and seems scientific - it will also seem legitimate, but without a big sciency degree that demands I go do ConAgs bidding.

I don't imagine we're going to solve our cultural fixation with 'experts and studies', but we can.... tiptoe around it?

Ian Rule wrote:False information is pretty damning to Permaculture, and I think quantifiable information protects Permaculture from naysayers... in that regard.
The establishment has the money to throw around studies and science, we need to tread lightly.
We, as Permies, know these things work and to some degree 'how', but if I walk onto someones property as a Designer expecting money, They are going to expect answers beyond "It depends". While an accurate answer to most questions in this field; if I want to win any accolades from Jimmy Cattleman, Id better be able to tell him with relative accuracy why his stuff wont work, or he'll categorize me as a "stupid hippie" and go hire the local landscapers.

If I can tell him what he can do without a passionate plea for him to go study ecology - and it works and seems scientific - it will also seem legitimate, but without a big sciency degree that demands I go do ConAgs bidding.

I don't imagine we're going to solve our cultural fixation with 'experts and studies', but we can.... tiptoe around it?

I would not want to try and tell a client with an existing operation why what they have been doing can't work. That, I expect, would be one of the best ways to get myself dismissed. Because he knows his stuff does work. My message needs to be that the stuff I am recommending will work even better than what he has been doing, and I want to be able to present that not in terms of micrograms of selenium the nettle brings up, but in terms of how productivity can be kept up while costs of production could be reduced.

This is a really interesting topic. I like how we all assume DA's work, but we want to know more about how and how fast they work, and which plants do what...now, let's explore ways to gather that information.

There are so many different tools we can use while learning about DAs and permaculture in general. Folk Lore is one, personal observation, and science.

For me, I find this kind of science useful. Not because it has any actual influence on how I do things on my farm - I'm far more a 'look at nature and emulate what works' kind of gal. This involves lot of diversity of plants, and not worrying about how DAs work and what plant is doing what. Rather, all this sciency stuff is useful to talking to people who are indoctrinated into the mainstream. Mainstream people seem to need science as a kind of foundation for their view of the world. It's no good telling them that I've been growing fava beans for X number of years and have the same experience as humans have been having since favas were domesticated Y-thousand years ago. Tell them that, and they scoff. Tell them I do it this way because science said so, and they listen.

Science is just another tool in the giant tool kit that is permaculture. Reading this thread, I think most of us agree, that science is just ONE tool... how we choose to use it (or ignore it), is really up to the individual farmer.

Thank you R. Ranson. I completely agree with your last post.

More on the topic of science and scientific pursuit than dynamic accumulators:

I attended a local ag conference last weekend. Not permculture, mainstream / conventional ag with progressive leanings.

My favorite talk was presented by a couple of retired soils scientists, formerly employed by the extension office or NRCS.

They said: a few really innovative farmers started planting cover crops after they harvested their annual cash crop. They said the costs were returned twice. Once when they grazed that cover crop, and the second time with decreased inputs and improved harvests the following year. (anecdotal information which we originally thought was bogus)

We got curious. We quantified costs of seeds, labor, seeding irrigation etc of the cover crops. (There were charts for several different properties of these "progressive" farmers.)

We quantified returns at these rates, and without correcting for the improved quality of the forage available to the cattle (the cattle gained more weight than cattle at similar stocking rates on stubble without the added cover crops), the cattle did not require protein licks or other supplements. The cattle were healthier.)

The subsequent year's crops required less fertilizer, and the per acre yields were higher. (Again, they had their numbers and their charts)

The "progressive" farmers were right. The end (for this year).



I loved it. 'Science'/ scientists/ local experts got curious about what's happening around them, and rather than marginalizing the "progressive" ways, they documented the formerly anecdotal evidence.

Folks, fellow Permies, often times, WE are those 'progressive' farmers, with 'new' ideas that work.

The upper horizon of the soil is where the most nutrients are liberated. One of the most famous deep-rooted, supposed dynamic accumulators is comfrey (Symphytum officinale). (Dynamic accumulators are those plants thought to gather more of particular minerals than other plants.) When it comes to the accumulation of NPK and silica, the anecdotal opinion is that comfrey is a dynamic accumulator plant with long roots that mine minerals and nutrients from very deep in the soil. (There are reports of comfrey roots reaching as much as ten feet into the ground.) As to comfrey being a dynamic accumulator, it’s hard to find any data. I was able to find a study that showed that the immobilized tannins prepared from lateral roots of comfrey chelated (pulled out) 3.5 times more lead from the soil than those from the taproots. Yikes—comfrey as a lead-accumulator plant! On the left we see a young plant where there are more "side-ways" roots than a deep taproot. The drawing on the right shows comfrey roots down only to 24 inches (each square is one foot) and the taproot appears to be withering. I have found no documented taproot down to 10 feet.