Legitimacy of dynamic accumulators?

I just came across this article from permaculturenews.org...
http://permaculturenews.org/2015/04/10/the-facts-about-dynamic-accumulators/

It says that the benefits of dynamic accumulators haven't actually been proven, but have been widely accepted by people quoting whoever they heard it from, sort of similar to a lot of the information out there on companion planting. Does anybody have any evidence that can support dynamic accumulators? I'm still going to keep spreading comfrey and my other dynamic accumulators. If nothing else they are still great mulch plants, but it'd be great to find any evidence on the nutrients being made available by these plants.

Hey Sam, I saw that article as well. Good idea brining it up. Common acceptance of pseudo facts bugs me too. That being said I always have considered nitrogen fixing legumes to be a scientific proof that soil components do actually " appear out of nowhere" in the soil. The writer of that article sort of breezes over the well proven science of N fixing legumes and offers an opinion contrary to the general theory of dynamic accumulators.

It is scientifically shown that some plants accumulate what is in the soil in their plant bodies.

It is scientifically proven that some plants have deep roots that go into subsoil where rocks and minerals might be found. If everyone waited for scientific studies to catch up than we would be in even more of a world of hurt than we are now.

. In addition, we cannot use anecdotal reports about dynamic accumulators. People will often site their own garden as “proof”. Unfortunately, this anecdotal information is not scientific evidence. 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? Was it mulching, composting in place, biomass accumulation, biodiversity, microclimate creation/enhancement, etc.?

I think what could have led to the broad acceptance of dynamic accumulator ideas is the facts of early succession. Many supposed dynamic accumulators are early succession plants. Among their duties: biomass accumulation, microclimate creation, mulch creation, biodiversity, and eventual compost in place. That is the natural function they serve when there are disturbed soils in nature. They do there job quite well and have prepared the ground for many forests, this is evidence they function to accumulate life. It is not actual scientific proof that they accumulate minerals to be made available in the top soil. But I am not really holding my breath for scientific proof on this one. Growing things is more complicated than just having the right minerals in your dirt, it takes life!

If there were scientific proof of dynamic accumulators than maybe more commercial farmers would use them, but outside of that does it really matter?

Just because things haven't been proven by some people doesn't mean they don't exist. The thing about people quoting other people is that there's always some percentage of people that actually use that advice upon it being provided. If it turned out to be a failure, they would talk about it and the information that it didn't work would spread.

Unfortunately, neither the information of how it works that's provided, nor a statement of it's being useless would matter to a skeptic, since most immediately discredit anything as anecdotal evidence that doesn't have a scientific study to back it up.

Me, I'm going to continue using them as usual. The article does offer enough solid reasoning as to why it would not or could not work- only a long way of saying there hasn't been any official research about it.

I found this link.
The uplift of soil nutrients by plants:
http://www.esajournals.org/doi/abs/10.1890/03-0245

Nitrogen "appears from nowhere" because it is fixed out of the atmosphere by bacteria. He is correct in saying that if there is no P in the soil (and he catches the "bringing it up from deeper" argument by saying "or subsoil") it can't appear from nowhere. To me that's a sensible reminder about what dynamic accumulators can't do, not a blanket denial that they do anything at all. Although I would prefer it if he knew the difference between "site" and "cite". He acknowledges that some plants will mop up certain elements when they are available. Then he goes on to make the same sort of blether that people who hate the idea that homeopathy works make, i.e. "I know it works, but I don't understand how, so I'm going to say it doesn't work and it's probably working by x y and z instead, so as to feel better about it". He even admits he's going to go on using dynamic accumulators, so in a way the whole article is a bit pointless. He would probably be perfectly satisfied if someone just came up with an alternative name for the concept that more pedantically described the process, like "nutrient availability facilitators".

I think a lot of Feng Shui makes sense as well, I just look at it sensibly and don't go so far as to hang red threads on external corners in my living room. I also believe you can get rid of horsetail if you "never let it see a Sunday" but I don't believe it has some sort of religious sensitivity, just that that was a catchy way of reminding people to hoe more often.

"Nitrogen "appears from nowhere" because it is fixed out of the atmosphere by bacteria. He is correct in saying that if there is no P in the soil (and he catches the "bringing it up from deeper" argument by saying "or subsoil") it can't appear from nowhere."


You are right. I guess I should have said before the mechanics of nitrogen fixing were studied, people probably saw the nitrogen and thought it might have appeared from nowhere. They just did not realize nature was as complicated. Since the author does not know everything how can he really be sure no P will show up? the whole point of the article is to say no research has been done. There were people who said no N would show up, but there it is.

Nothing appears from nowhere, we just don't understand everything.

If there were scientific proof of dynamic accumulators than maybe more commercial farmers would use them, but outside of that does it really matter?

Yes, this is the only context I was thinking hard evidence would be necessary. Looking forward to a day when the U.S. government is spreading compost tea, N-fixers, and dynamic accumulators by plane over the many hectares of soil we've destroyed.
And of course as with many things in permaculture, and nature in general, we strive to wrap our scientific human understanding around something that is more complex than we might ever understand. I imagine somebody like Fukuoka would be laughing at this article. And apart from it's role as a dynamic accumulator plants like comfrey still remain an excellent mulch plant, medicinal, as well as animal forage.

Somewhat hilariously I just looked at the bottom of the page at the similar threads to this thread that I started about this same topic, but based on further articles that have been published. If any of you folks are still following this thread, and are interested, I began another thread this month on this same subject. Join in if you feel like it. The main differences are 1) the idea bouncing around about making up or encouraging others to study and accumulate data on when the minerals that accumulators accumulate actually become available to subsequent plants of other species, and 2. The context that I thought that it might be necessary to have some data is that we might want to talk about Dynamic Accumlators to permaculture students, and we might want to actually have information based on facts rather than on anecdotal evidence.

There is no doubt that the plants do indeed accumulate nutrients and minerals, but the question is when are those minerals biologically available to subsequent plants of other species. Someone needs to study this.

If there were scientific proof of dynamic accumulators than maybe more commercial farmers would use them

I think this another great reason to do this.

I imagine somebody like Fukuoka would be laughing at this article.

Yes; the thought did enter my mind as well.

Roberto pokachinni wrote:Somewhat hilariously I just looked at the bottom of the page at the similar threads to this thread that I started about this same topic, but based on further articles that have been published. If any of you folks are still following this thread, and are interested, I began another thread this month on this same subject. Join in if you feel like it. The main differences are 1) the idea bouncing around about making up or encouraging others to study and accumulate data on when the minerals that accumulators accumulate actually become available to subsequent plants of other species, and 2. The context that I thought that it might be necessary to have some data is that we might want to talk about Dynamic Accumlators to permaculture students, and we might want to actually have information based on facts rather than on anecdotal evidence.

There is no doubt that the plants do indeed accumulate nutrients and minerals, but the question is when are those minerals biologically available to subsequent plants of other species. Someone needs to study this.

If there were scientific proof of dynamic accumulators than maybe more commercial farmers would use them

I think this another great reason to do this.

I imagine somebody like Fukuoka would be laughing at this article.

Yes; the thought did enter my mind as well.

When do the nutrients accumulated become available to other plants? As the accumulators decompose around them. This would be one of the fundamental concepts of the "chop and drop" mulch technique.
I get frustrated with the dismissal of anecdotal evidence as somehow inherently invalid. The kneejerk dismissal of anecdotal evidence is invalid. Scientific inquiry frequently begins based upon anecdotal evidence. In those instances, scientific inquiry that reaches similar conclusions has not verified or legitimized the anecdotal evidence, but rather has confirmed what was already known. In instances where the scientific research produces contrary results, it is important to examine the researchers methods to determine whether the differences are due to flaws in their methodology, rather than with the anecdotal reports.

Peter Ellis wrote: The kneejerk dismissal of anecdotal evidence is invalid. Scientific inquiry frequently begins based upon anecdotal evidence. In those instances, scientific inquiry that reaches similar conclusions has not verified or legitimized the anecdotal evidence, but rather has confirmed what was already known. In instances where the scientific research produces contrary results, it is important to examine the researchers methods to determine whether the differences are due to flaws in their methodology, rather than with the anecdotal reports.

So much love for this paragraph.

Not to say that it wouldn't be beneficial for some people who are stuck in that mind set to see laboratory results. I just think the mindset that needs that kind of evidence does more harm than good.

(Trial and error)=(testing and observation) It doesn't take a PHD or a laboratory to do real science. Anecdotes are the layman's version of testing reports. Just don't forget to collect multiple anecdotes, just as you would want to repeat an experiment multiple times to confirm the data.

In those instances, scientific inquiry that reaches similar conclusions has not verified or legitimized the anecdotal evidence, but rather has confirmed what was already known.

I disagree with the above statement. The simple reason for this is that there can be so many variables that create the result in an anecdotal situation, and that result can be repeated endlessly in oral and written folkloric patterns until they become 'law' (so to speak) but may not have any real validity. Scientific inquiry, if done with thought to the obvious variability in farmland and climate, can thus verify or legitimatize (or discredit) the anecdotal evidence that was assumed, or thought to be known, but may in fact not be. This can only be done if the methodology of the study is repeatable in such variable extremes of climate and farmlands.

When do the nutrients accumulated become available to other plants? As the accumulators decompose around them. This would be one of the fundamental concepts of the "chop and drop" mulch technique.

Yes, the chop and drop dynamic accumulator sacred cow of permaculture, which should never, apparently be questioned in any way... I disagree, but not in the way you might think. The problem is not in the fact that the decomposing mulch of the chopped and dropped accumulator plant tissue does boost the situation for neighboring mulched plants, but the actual availability of the hyper accumulated nutrient that much of the hype is about for dynamic accumulator species. There is no doubt whatsoever in my mind-or I think in the minds of the other people who are rehashing this problem(on this forum and in the scientific community)-that there are many great benefits to having these 'dynamic accumulator' species in our farming and garden systems; the question is all about when those minerals become available (water soluble) to our soil and plant systems. Mulching plants is great! Chop and drop is great! Nobody is questioning the great benefits of these permaculture techniques. I think those benefits are proven well enough. The legitimacy in question is not about these techniques, however; so if you are thinking that that is the case, then you are missing the point.

There is a reason why Toby Hemenway is removing the Dynamic Accumulator tables from his new addition of Gaia's Garden, and why Eric Toensmeier is no longer teaching about dynamic accumulators in his courses, and it is not, I believe, because they do not want to believe in the folkloric 'evidence', it's because they want to teach things that they know to be true.

The kneejerk dismissal of anecdotal evidence is invalid.

Perhaps. But anecdotes are not always true. The Sun does not circle the Earth, even though-to the untrained eye-it might appear to do so. If every hypothesis just sat on it's own merits, there would be no reason for science at all. It's not that anecdotes do not have there place, or are not amazing unto themselves. They do have validity, to the extent that they exist and that they can begin the process of further inquiry, just like a hypothesis does in a scientific inquiry, but it is the repeated (multiple times in and in multiple circumstances) experiment that actually makes it hold water. I definitely can relate to what you are saying, Peter, and I sympathize with this point of view as well, but I think that perhaps you may have believed strongly in the anecdote that the dynamically accumulated minerals would somehow be immediately available upon decomposition of the chopped and dropped accumulator plant tissues. This is the part that is unproven, and I would have to differ with it, for the time being.

Robert Kourik, who's book Designing and Maintaining Your Edible Landscape Naturally has the tables in it that have spread throughout the permaculture community and various books and articles. Apparently he regrets ever publishing this table. Why? Not because chop and drop is bad, or because mulch is bad, or because he thinks that these plants don't have a valid place in building soil and garden communities. It's because he can't prove that those hyper accumulated minerals are actually available to nearby plants upon decomposition. He, and other academics, are studying when these minerals become available, and once he has some validation he can give better information to people.

The folkloric or anecdotal evidence has validity to you, Peter, and so you needn't worry about this. For my own garden/farm purposes, I am not worried about it either. Your belief, whether verified by science or not, has it's own validity as does your experience in your garden. But the purpose of studying it has nothing whatsoever to do with your personal experience or your garden, IF you are not testing your soil to verify that said minerals are actually bio-available, or whether they are deposited in insoluble forms and may take many years to become available to neighboring plants.

(Trial and error)=(testing and observation) It doesn't take a PHD or a laboratory to do real science. Anecdotes are the layman's version of testing reports. Just don't forget to collect multiple anecdotes, just as you would want to repeat an experiment multiple times to confirm the data.

I completely agree, Cassie. I don't think that this needs to be in a lab, though the testing of the soil needs to be done with proper analysis to legitimatize when the hyper accumulated mineral is available to other plants. I think the farm is the lab for the actual experiment; and that this part should not be done in a lab.

"Permaculture teaches that a SPECIFIC SUBSET OF PLANTS are ESPECIALLY WELL ADAPTED, based on their long taproots or other features, to accumulating nutrients faster / in higher quantities / from different sources than other plants." (from permie.com) So very often people make the assumption the dynamic accumulators work because of a deep taproot. Often they state deep taproots are considered the only way dynamic accumulators work. This assumption is false. Take stinging nettle as an example. It is famous by permies as a superior dynamic accumulator. Stinging Nettle, Urtica dioica (shown on the left) is said to accumulate , K, Ca, S, Fe, Na It is famous for iron. This can be substantiated by leaf samples. It is documented as a iron-nutritious iron-rich food. But it does NOT have a taproot. It's roots do grow 4-5 feet wide (as shown in the drawing on the right) but have only shallow roots. The roots are more like shallow rhizomes. I think they may accumulate more of some nutrients, but it is from a genetic "programing" that distinguishes dynamic accumulators. There are other examples of assumed dynamic accumulators that don't have taproots.

The thing about nettles and other shallow-rooted species that are found to be high in certain nutrients is that all they are doing is cycling what's there, and may be competing with other crops.

Deep-rooted accumulators like comfrey may bring nutrients up from lower soil strata where they would otherwise be unavailable to other plants.

I emphasise may: there is so little good research that this remains unclear.

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! Young plants have more "side-ways" roots than a deep taproot. One drawing done by "mapping" the root system by excavation it I have in my book Understanding Roots shows comfrey roots down only to 24 inches (each square is one foot) and the taproot appears to be withering. Here's another drawing of comfrey roots I have found no documented taproot down to 10 feet.

Robert Kourik wrote:"Permaculture teaches that a SPECIFIC SUBSET OF PLANTS are ESPECIALLY WELL ADAPTED, based on their long taproots or other features, to accumulating nutrients faster / in higher quantities / from different sources than other plants." (from permie.com) So very often people make the assumption the dynamic accumulators work because of a deep taproot. Often they state deep taproots are considered the only way dynamic accumulators work. This assumption is false. Take stinging nettle as an example. It is famous by permies as a superior dynamic accumulator. Stinging Nettle, Urtica dioica (shown on the left) is said to accumulate , K, Ca, S, Fe, Na It is famous for iron. This can be substantiated by leaf samples. It is documented as a iron-nutritious iron-rich food. But it does NOT have a taproot. It's roots do grow 4-5 feet wide (as shown in the drawing on the right) but have only shallow roots. The roots are more like shallow rhizomes. I think they may accumulate more of some nutrients, but it is from a genetic "programing" that distinguishes dynamic accumulators. There are other examples of assumed dynamic accumulators that don't have taproots.

That's why I included "OR OTHER FEATURES" in that quote.