Dynamic Accumulators – Do They Exist?

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Robert Pavlis

Dynamic accumulators, like comfrey, have become a hot topic. These plants are reported to have extraordinary powers to absorb more minerals than the average plant. This makes them very useful if you are trying to make nutrient dense compost for your garden.

Imagine how great it would be if you could grow a plant that increases the nutrients you are lacking in the garden. That is precisely what people are doing with dynamic accumulator plants – or at least that is what is being claimed.

In this post I will examine the idea of accumulator plants and try to figure out what they are. Do they exist? In a future post I’ll ask the question, how can they be used in the garden? Do they add any real value?

Do dynamic accumulators exist?
Do dynamic accumulators exist?

Dynamic Accumulators, What are They?

Let’s start with a definition. Wikipedia (ref 1) says the following:

Dynamic accumulators are plants that gather certain micronutrients, macronutrients, or minerals and store them in their leaves.”

There are a few key points here. First, they are plants – good thing since this is a gardening blog.

Microbe Science for Gardeners Book, by Robert Pavlis

These plants gather nutrients, but the type of nutrients are not specified. The amounts that are gathered are also not specified.

The gathered nutrients are then stored in the leaves.

Given this definition, almost every plant is a dynamic accumulator since they absorb nutrients and store some of them in the leaves. An exception would be the leafless orchid. This does not seem like a very useful definition.

The Permaculture Research Institute (ref 2) defines dynamic accumulators this way:

plants (often deep-rooted ones) will draw up nutrients from the lower layers of the soil, and these nutrients will be stored in the plants’ leaves.

Any nutrient in any amount qualifies, provided that it is taken from the lower levels of soil – whatever that means. Is 3 inches deep a lower level? Does it need to be 6 inches deep? Is it subsoil? This definition is also not very useful.

What is very surprising is that I was not able to find a better definition. Several other authors (ref 2 and 3) have also looked for a definition and the origin of the term. They concluded that “there are many definitions, all similar, and all fairly vague”, (ref 3). I Also checked Google Scholar for scientific papers on the topic and it seems scientists do not use the term.

The term ‘dynamic accumulator’ is used mostly by permaculturists and they tend not to define their terms and ideas. The whole permaculture ‘thing’ is a very squishy, non-scientific, affair where undefined terms are common – maybe even prefered.

By definition, dynamic accumulators are what you want them to be.

As an aside, the terms biodynamic accumulator and dynamic nutrient accumulator seem to be the same as dynamic accumulator.

Origin of the Term Dynamic Accumulators

Maybe the origin of the term will shed some light on our understanding?

Even this seems to be a mystery. The Permaculture Research Institute (ref 2) suggests that the term might have been started by Robert Kourik who, in his book Designing and Maintaining Your Edible Landscape—Naturally presented a list of dynamic accumulators.

If this was not the first use of the term, Robert Kourik certainly popularized the term by making the list of dynamic accumulators available. The list has been copied many times, with some modifications, and forms the basis of the current lists found on the internet.

This is what Robert had to say recently on The Garden Professors Facebook Group; “Most accumulator lists originated with the 2-page list in my 1986 book Designing Your Edible Landscape Naturally. I no longer believe that list is useful“.

New Definition for Dynamic Accumulators

Since there is no good definition for dynamic accumulators, lets create one.

A dynamic accumulator is a plant that will absorb and retain, in the leaf, at least one nutrient at levels that are at least 10 times higher than the average plant.

Where did the ’10 times’ value come from? I just pulled it out of the air. Without some value the definition becomes useless. Given the variability between plants and soils, a ten times factor seems reasonable.

Some might argue that an important point is missing from this definition since it does not talk about where the nutrients are gathered. Many people believe that dynamic accumulators have high levels of nutrients because they have deep roots. The deep root gives the plant access to extra nutrients. I’ll discuss this in a future post, but the idea that higher nutrient levels are the result of deep roots is mostly a myth.

Do Dynamic Accumulators Exist?

Given the established definition the answer is yes – any plant fits the bill.

What if we use the new definition? The answer is still yes, but not all plants qualify.

There has been quite a bit of work done on hyperaccumulators and phytoaccumulators. These are plants that remove specific pollutants, such as heavy metals, from soil. Specific plants have been identified that are particularly good at absorbing things like lead, or chromium. Once the metals are in the leaf of the plant, the plant can be removed from the site, reducing the contamination in the soil.

A hyeraccumulator is defined as “a plant that can accumulate: 1000 mg/kg of Cu, Co, Cr, Ni and Pb, or 10000 mg/kg of Fe, Mn and Zn in their shoot dry matter” (ref 4).

This is interesting but does it really help gardeners? Are there plants that will accumulate the nutrients plants want? More importantly, can dynamic accumulators be used to improve the growth of other plants in the garden? Does it make sense to grow accumulators? These are good questions that I will tackle in a future post.

 

References:

  1. Dynamic Accumulator; https://en.wikipedia.org/wiki/Dynamic_accumulator
  2. The Facts About Dynamic Accumulators; http://permaculturenews.org/2015/04/10/the-facts-about-dynamic-accumulators/
  3. What Is A Dynamic Accumulator?; https://palmettopermaculture.wordpress.com/2014/08/16/what-is-a-dynamic-accumulator/
  4. Accumulation of Pb, Zn, Cu and Fe in Plants; ijagcs.com/wp-content/uploads/2013/03/426-432.pdf
  5. Photo source: Ling
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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

25 thoughts on “Dynamic Accumulators – Do They Exist?”

  1. I run a horticultural association out of Humboldt and I have some data I would like to share regarding nutrient values for Comfrey.

    I am curious what people think regarding these spikes for calcium, magnesium, phosphorus, potassium, sulfur and chloride.

    I have paid a lot of money to perform fertilizer analyses on multiple “dynamic accumulators“, so far I’ve done comfrey, yarrow and nettle. So far it seems that there are distinct elements that have really high peaks and they are different in all of the plants ( with some overlap of course). My data definitely correlates with Dr. Dukes ethnobotanical database and I believe is an indicator that there can be reliable evidence to indicate the uptake of specific nutrients in higher quantities in “dynamic accumulators”. I believe the key limiting factor is soil nutrition, all of the herbs I tested were grown in nutrient rich areas. A lot to expound on there, curious to have some feedback on the results.

    I suppose the question I’d like to resolve is… does the nutrient accumulation of a dynamic accumulator have to be 10 times the baseline of its own elements, or 10 times the baseline of an average of a bunch of different plants? Because that will really change the definition…

    aluminum 72.80
    arsenic 1.46
    barium 19.12
    boron 24.44
    cadmium < 0.05
    calcium 6,305.43
    chromium 0.39
    cobalt < 0.05
    copper 17.92
    iron 68.52
    lead < 0.15
    lithium 0.15
    magnesium 3,231.40
    manganese 32.15
    mercury < 0.08
    molybdenum 3.01
    nickel 0.68
    phosphorus 8,164.72
    potassium 73,826.10
    selenium < 0.25
    silicon 854.96
    silver < 0.05
    sodium 191.27
    strontium 30.00
    sulfur 4,206.33
    tin < 2.50
    titanium 2.61
    vanadium 0.23
    zinc 43.70
    chloride 5,536.12

    Elements expressed as mg/kilogram (parts per million) on an as received basis.
    Total Nitrogen 4.246%
    Water Soluble Nitrogen 3.042%
    Water Insoluble Nitrogen 1.204%
    Ammonical Nitrogen 0.038%
    Nitrate Nitrogen 0.462%
    Other Soluble Organic Nitrogen 2.542%
    Total P2O5 1.870%
    Total K2O 8.859%
    Available P2O5 1.419%
    Soluble K2O 7.509%

    Reply
  2. I am an interesting character in that I worked on plant nutrition for 18 years in Academia, then in the last year, I’ve been learning about permaculture. It’s been so fun to be turned from a lab scientist into an ecologist, and look at what was my plant nutrition field with an expanded perspective. I lost no wisdom from what I gained in Academia, so I still have that view, but I also gained a bigger picture view of Interbeing from an ecological perspective. Simply said, plants in polyculture work together for their own survival above and belowground in ways that are not entirely understood, but involve each other and the soil food web in multiple ways, shapes and forms. Great, that’s “job security” for scientists that survive the hypercompetitive Darwinian cuts.

    If we don’t know how something works, but it has been observed, then it becomes a subject of interest and hypotheses.

    Now I’m a baby permaculturalist, but this plant nutritionist is fascinated by noticing how pre-permaculture, I only trusted Science. I look back on it now as a constraint on innovation, on actually listening and heeding observations more. Right now here in the state of Washington, academics and indigenous tribes have joined forces to understand Puget Sound better. AAAS had a seminar on Indigenous Wisdom this May. Centuries of observation meet scientists. Indigenous people talk about a new PhD telling them about their thesis, which was something they already knew from their great grandfather. Great minds think alike! Wow, to join those two knowlege bases together means to push the outer limits of scientific knowledge more. Thank you people for collaborating. It makes me smile!

    Many traits fall into a Gaussian curve. We CAN quibble about any definition with an attitude of all or nothing thinking. However, it is not “required”! Instead, what are the different viewpoints? Permaculturalists think in 50 year plans, so small benefits add up over many years, and become more and more observable. Conventional ag thinks in much shorter time periods, so they’d miss the small benefits accumulation from excellent mindful stewardship. They both have wisdom to share, and knowlege to gain from each other, from all of their observations.

    Random examples from a quick scan of what others wrote:
    – Will a “chelator plant” comment trigger a scientist to test the expression of metallothionein RNA in a bunch of so called dynamic accumulator plants?
    – Postdocs are moving on to applied positions from what I read just this week in Science Magazine. Academia needs to be really careful to keep up with public thinking to get grants, and even harder, hire postdocs.
    – We are in an agricultural Darwinian system where a permaculture wave is happening by social evolution, and I expect it to only get bigger and more dominant over the next 50 years. It just makes sense even from my geeky science persepctive. Young scientists are getting awards for polyculture ag, which permaculture relies on for long term resilience above and below ground.
    – If some plants turn out to draw deeper nutrients up to the surface by dropping leaves in the fall, well that’s a dynamic system in that nutrients are being moved around in the soil. We incorporate designs with roots that go 5-20 feet deep, combined with the little herbs and grasses that are shallower. Roots are considered as a resilient system in combination with the soil food web. Small benefits add up over long time periods. Grants for the next 3-5 years simply can’t study these phenomena seen in long term views.
    – Citizen scientiest observations have value, whether they have been explained or not. It’s revolutionary to become an ecologist then look at plant nutrition from an entirely different perspective. It’s simply a bigger picture, and I know even better what I DON’T know. To be free of the constraint imposed in my brain by Academic thinking, to return to childlike wonder., to just observe my little piece of land on a daily basis. What fun!
    – Thank you everyone for pushing the boundaries of our shared knowlege from all sides, that wonderful place where the unknown gradually becomes known. That is what I loved about Academia. I still love it, but I’m no longer constrained by it, and that has made all of the difference.

    Reply
  3. Hopefully by now you may have read Gaia’s Garden. Toby Hemenway. Or:
    Bill Mollison, David Holmgren etc….
    I’m sure with your knowledge you can find their publications. Enjoy!
    Kind Regards, Elizabeth

    Reply
  4. A well written article with a fairminded, rigarous approach imo. However, your bias is shown most strongly by the assumption implied in the question (in comments section):

    “What do you do when your observation is in direct opposition to science?”

    Answer: You look to see how science can explain the observation and try and replicate the observations.

    Afterall, science IS explaining observations and trying to replicate them.

    Put another way, an observation cannot be in opposition to science, merely the explanation of the observation. Often scientific explanations change as more data (observations) are collected.

    Reply
  5. maybe the reason permaculturists don’t define things carefully is that they’d end up wasting 2 thirds of an article on finding a satisfactory definition when the term dynamic accumulator seems pretty obvious: anything you use to dynamically accumulate nutrients.

    i was raised by scientists but i still think there is a time and place for accuracy and another time and place for observing the world around you and acting on whatever you notice. sorry if you find that confusing or ‘fluffy’.

    Reply
      • The problem with your definition is that it’s stripped out the central point of why the term exists. The idea of a dynamic accumulator is that you’re gathering nutrients that wouldn’t be available to the rest of your plants. If you’re pulling readily-available nutrients out of the top levels of the soil and then composting the accumulators to put them back in, you’re just wasting time. If there’s no such thing as a dynamic accumulator in this sense, that’s fine, but redefining it this way seems to be like saying, “since there’s no such thing as a unicorn so let’s redefine it to be a horse.”

        Reply
        • 1) provide a reference of your definition.

          2) Provide a reference to support you claim that they “gathering nutrients that wouldn’t be available to the rest of your plants”.

          Reply
  6. First off, I found this a very reasonable assessment of the dynamic accumulator controversy. I do, however, take issue with one statement.

    You say, “The whole permaculture ‘thing’ is a very squishy, non-scientific, affair.”

    Why the hate for permaculture? I think it is unreasonable to call a movement based on the observation and emulation of nature “very squishy” and “non-scientific,” when the root of science is the observation and analysis of natural phenomenon.

    At best, you could question the methodology of permaculture because it rarely uses controls in its test. However, one could argue that modern industrial agriculture is one giant control group.

    Reply
    • The reason for the statement is that almost none on the ideas that are specific to permaculture are supported by science. And the proponents of the method seem to shy away from doing proper testing. Show me one report that includes published references to support their position.

      Reply
    • There is no such thing as a chelator plant. Chelation is a type of chemical bonding that takes place between two molecules. So you can have a molecule that chelates certain other molecules or ions, but the concept can not be applied to a plant.

      Reply
  7. I’ve never thought that Dynamic Accumulators give any benefit over other plants. Sure all plants will take something different or different quantities of nutrients out of the soil but what normally happens is a plant with a big thick root is singled out because it goes deep. After reading http://soilandhealth.org/wp-content/uploads/01aglibrary/010139fieldcroproots/010139ch9.html I realised that a lot of plants can put roots down 3 or 5 feet and more so many many plants can pull nutrients up from way down and make available near the surface.

    Reply
  8. Robert! Absolutely love your comments!

    Here – Pittsburgh area – they plant a lot of plants to help clean the destroyed soils of the old steel and chemical plants… However, I’ve yet to witness them removing any plant material! They brag about how the plants will clean it all up – but, anyone with even my half a brain knows one has to remove those plants! Although, once removed, I wouldn’t be shocked if they wouldn’t just dump it as (fill) material at the local dumps…

    Shame, isn’t it?

    Reply
    • If the pollution is due to heavy metals then the plants must be removed to have any effect. For pollution due to organic contaminants, you do not need to remove the plants.

      Reply
  9. I use Dynamic Acculators each and every Fall!

    Tree Leaves!

    I call them Dynamic because their roots grow deep… (well, except the roots that grow on my lawn surface… That I trip over…)

    Wonder what Washington and Jefferson called their mix of Doo and leaves?

    Reply
  10. Robert goes where others fear to tread!
    Your piece is very well argued. It is a lovely idea that plants mine deep nutrients – I have talked about it myself. When you think about it deep in the ground any subsoil/sand/rock is a very infertile place and clay particles are likely to hold far less nutrients than those fully charged with plant nutrients at the surface.
    Some gardeners imagine substantial nutrients can be extracted from rock. Not so unless you have a few thousand years
    It is also quite fascinating how plants can extract metals as you quote. I understand arial photography of vegetation can detect metals brought up a very long way

    Reply
    • What is deep soil like? it may be devoid of nutrients, but maybe since roots rarely go there, there is a lot of nutrients? If rock is continually decomposing then nutrients might accumulate.

      It is also true that nutrients slowly leach from upper layers to lower layers. Even Potassium, which moves very slowly, does move and eventually pollutes water ways.

      But I suspect you are correct. Most nutrients will be in the upper layers, especially in soil that has a good organic layer which allows microbes to continually recycle nutrients.

      Here is an interesting question. If plants can accumulate heavy metals – are any of the vegetables doing this? Wouldn’t it be funny if we find out spinach is a lead accumulator?

      Reply
      • No, that would not be funny I eat a lot of spinach and I do not like to think that I have been eating lead
        Another thought: when plants accumulate heavy metals what happens to those metals when the plant dies

        Reply
        • Over time the plants decompose and the heavy metals are returned back to the soil. Remediation only works if the plant material is removed from the site and treated to extract the heavy metals.

          Reply

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