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Dynamic Accumulators – Do They Exist?

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.

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
Robert Pavlis
Editor of GardenMyths.com ,
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. 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!

I hope you find Garden Myths an educational site that helps you understand your garden better.

12 Responses to 'Dynamic Accumulators – Do They Exist?'

  1. Dan OConnell says:

    Would you call a plant such as this a chelator plant, or is that type of bonding different?

    • 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.

  2. Andy says:

    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.

  3. John says:

    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?

  4. Karin says:

    You pick very interesting topics! I may now mulch with Moringa since I have three trees. Can’t wait for the next post! Thank you!

  5. John says:

    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?

  6. Roger Brook says:

    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

    • 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?

      • Inger Knudsen says:

        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

        • 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.

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