Soil Science... Mind blown

I would like to say a big thank you to Mirai and the Asymmetry podcast crew for the 2 episodes with Ian Hunter and the third with Ian, Casey and Keisha as well as the feature content.
This has shaken up my reality!
Did you listen? What did you think?
Plants dump sugars into the ground to feed microbes when their leaves are cut! WTF!!
It strikes me that for bonsai, this knowledge about the complex communities living in soil stresses even further the importance of getting our watering right and maintaining the balance of water and oxygen. How easy is it for us to wipe out microbes? How easy is it to get them back?
I have tried a couple of compost teas, but when and how often should these be applied?
I’m off to turn mu compost heap again!


I loved all three of these podcasts and second your gratitude @AndyK. Thanks, Asymmetry podcast crew! How great would it be if Ryan and co. managed to have Dr. Elaine Ingham as a guest for the next one in the series? :heart_eyes:

So much information in these particular podcasts. They’re amongst my favourite Asymmetry episodes. I didn’t think about the chlorine or chloramines in tapwater wiping out microbes (not all, of course, but a definite negative impact). Previously it was the hardness of the water in my area that struck me as the primary negative to using mains tap water (which I tried to counteract by top-dressing with Kaizen’s Green Dream ericaceous organic ferts), but the chloramine aspect makes complete sense and a reason why I’ve recently bought a powerful garden pump for my waterbutt so I can use my watering wand with it (takes so much longer with a can).


It blew my mind as well! Thanks a ton Asymmetry!

I have been searching for research related to this topic ever since.

This does shed light on something I’ve heard over and over that made no sense to me forever. It now makes sense to prune deciduous trees that hold a majority of their energy in the vascular system. I also read in an article that the roots are typically the places of highest concentration of carbs, which backs up that idea.

Also makes me happy I’ve started to address the alkalinity in my water.


Hi @Ralph
I will be looking for a pump now. I’m also big on Green Dream (feed those microbes!)

Hi @Nate_Andersen
It feels like dots joining themselves together!

I think the pump I bought claimed 4.7 bar pressure and 4000 litres/hour, so if all goes to plan that’s plenty for my Kaneshin watering lance. :crossed_fingers:t2: I’ll hopefully get to set it all up next free weekend.

From the three podcasts, do you think we could recap and combine notes on what actions we can take and the additives we can use?

From memory, this is what I’ve got so far:

  1. As always, ensure the balance of water and oxygen.

  2. Start using the best possible water you can get your hands on. Be it rainwater, well water, RO/distilled or pH and chlorine treated tap. [Because of both the chloramines killing microbes and the unfavourable alkalinity of hard, dissolved lime laden tap water in some areas]

  3. Start inoculating soil with mycorrhizae powder when repotting. [Question to if these products are legit or a marketing ploy]

  4. Stop using chemical fertilisers. [Why – do chemical ferts actually impede the health of microbial population or simply unnecessary?]

  5. Start using solid organic fertilisers such as BioGold or Green Dream. [Organics are naturally broken down by the microbes and provide a beneficial environment for the microbial population]

  6. Start using cold-press fish hydrolysate. [Anyone remember why, specifically, other than nutrients for the microbes?]

  7. Start using a liquid seaweed fertiliser. [Promotes cytokinin production which encourages a spreading ramified growth pattern]

  8. Start using humic acid additive (whether liquid or granular / top-dress form?). [Adds attachment sites for the bacteria and fungi. Acts as Velcro to hold nutrition in place. Does also have nutritional content]

  9. Start own composting and steep compost “teabags” in the watering reservoir just prior to watering. [Compost tea inoculates with a broad range of microbes]

  10. Continue pruning and defoliating (shouldn’t be a problem for us). [Plants dump sugars into the ground to feed microbes when their leaves are cut]

Will have to re-listen to expand on this but by all means anyone please chip in and add/amend.


From what I understand, chemical fertilizers give the plant simple versions what it wants in an immediate form without the need for micro-biotic activity, and thus the microbiome does not get well established.

It’s like eating a tablespoon of refined sugar vs. 4 carrots (or whatever is roughly one tablespoon of sugar). I don’t think it hurts it, per se, but it doesn’t help promote the right micro-biotic activity.


I think some of this needs to be expanded once we narrow down this list.

  1. Should be changed to using the best possible water you can get your hands on. Included with that is the idea that alkaline water as a constant will continue to cause a problem and needs to eventually be addressed for highest level care. You can combat it other ways, but best water is best practice.

Rainwater > Distilled Water > pH Treated water > Reverse Osmosis Water > Alkaline Tap Water?

How do we arrange those waters?

  1. I thought I remember Ryan saying that inoculating with mycorrhizae was a marketing ploy (Randy Knight stream iirc) and that using organic fertilizers should be sufficient in terms of mycorrhizae, maybe I’m wrong though…

  2. Touched on above me, but doesn’t feed the rhizosphere, doesn’t necessarily actively harm it iirc. I think that chemical fertilizers fall under what they mentioned about Glyphosate about how we don’t have the right thing to use/break it down. Or I might be crazy. Either is very likely.

6/7. I remember one more thing being mentioned. It was Kelp/Seaweed, hydrolysate, and something else and they all did something in particular that was beneficial. Might’ve been that they have the right type of nitrogen origin or something.

Today’s Live Q&A was disappointing in this regard. Ryan said he’s pumping the brakes, not seeing good results from the compost extract. It will be interesting to hear or read more updates since it’s such a different feel from him than the podcasts.

After the first one, I’m suddenly much better at growing cannabis. I’ve never done it before and don’t have plans to do so in the future, but I now know weed.

I’m searching the web for pink-pigmented faculative methylotrophs. I want to cut down on my gibberelic acid. I have reasons other than usual bonsai growth. PPFM…


Right around the 33:45 mark, Ian discusses how fish emulsion is a heated product. The heat breaks down the long polymers into a water-soluable fertilizer that is becoming an inorganic fertilizer. But he doesn’t get into why the longer polymers are better for the fungal growth in your soil.

Good point, I’ve amended it to “using the best possible water you can get your hands on”. Not everyone will have ample supplies of rainwater.

RO and distilled water are stripped of more or less everything, including all the good trace minerals and micronutrients. Not sure if that will have any long term implications for watering our trees. It’s possible to remineralise with additives (powders) from the pond or aquarium trade. Is that better than pH treating hard tap water to buffer the alkalinity, or about the same, I don’t know? Also, it’s possible to use a conditioner to remove (or neutralise) the chloramines in tap water.

I’m by no means an expert but I’d arrange it:

Rainwater (and well water?) > Remineralised RO or distilled > pH and chlorine-treated tap > RO or distilled (not remineralised) > Alkaline tap

Ah, interesting – will have to check that out and catch that bit. The thought has crossed my mind before when repotting my trees, sprinkling it on, but I figured I’d rather try it anyway in case it did help. Would love something conclusive on this though.

That’s true :thinking::laughing:, I was waiting for that bit as well but Ian went on to speak about other stuff. Perhaps it’s just implied that if heated means denaturing and breaking down to resemble more of an inorganic fertiliser, then cold-pressed and longer polymers are more beneficial for the same reason organic ferts over chemical ferts are: organic is less available to the plant right away, but better for the microbes. Feed the microbes, not the plant, wasn’t it? :relieved:

Just to clarify, my well water is 7.8 pH, so maybe not all well water.

It does feel that even with a microscope and the relevant microscopy technique, this can be extremely complex. As an ammeter I’m looking for a short list of doos and don’ts and then I’m happy to muddle my way forward on intuition and gut feeling. Speaking of gut, you do realise this is all going on inside us as well?

Rain water all the way, you can literally see the difference in plants following a serious rain or a thunderstorm. In the next 24 months, I’m investing in massive underground rain water storage… we’ re aiming for 10m3 (~2600 gallons) but may increase later. Right now I have 1m3 above ground, which is not enough for both my use and the amount of water dumped on my roof when it rains.

I’ve done it in the past and I still have some powder stashed away. It does speed up the process for bare rooted trees, but normally the trees should still have mycorrhizae in their roots if they weren’t pressure washed. The exception would be seedlings/cuttings/layers done in a sterile substrate… I would inoculate those. When I used it, the pot was fully colonized by the next spring after repotting. In the ones where I didn’t, it took a bit longer.

I still have a 10kg/20lbs bag of a FulHumin “soil activator” that is basically a mix of lignite, fulvic acid, humic acid and basalt meal. I started using it with cheap organic fertilizers (pelletized cow dung) as it would neutralize the fertilizer smell and bring in tons of micro-nutrients. It does make a difference in growth/health for the trees that receive it. For example, I had a Pinus parviflora var miyajima which grows very slowly once potted (3" growth per year in the ground) but made 8"+ shoots after mycorrizhae colonized the pot and I applied FulHumin.

That specific soil activator is no longer available on shelves but… as the recommended application is only 100g/m2 (3.5oz/10sqft) per year, that bag should last me a lifetime. There’s a good chance a similar soil activator is on the shelves in the US.

I believe the mycorrhizal mix/soil conditioner is a bit of a misused tool. Mycorrhizae inocculants are often going to have requirements and are only going to pair with certain species. So in order for an oak to gain from an inocculant mix it would need a generalist fungi or specific fungi to the oak in question. That’s why ian hunter’s company compost is so diverse- To try and find as many fungal species to make sure the plant gets the right mix of microorganisms to inocculate the plant in question.

1 Like

Yes @Emawman
I think you are right. It does raise the question, could we compost vegetative material from a specific tree (I’m thinking leaf, twig and root cutting) to encourage specific fungal spors to grow, and the reinoculate the original tree? I am going to have a go keeping some cutting in an open pot under a bench.

1 Like

I apologize in advance for the wall of text :slight_smile:

There are rough families of mycorrhizae, and the vast majority of plants can only host one of those families.

A tree can host several ectomycorrhizal relationships at the same time, and an ectomycorrhizal relationship can include more than one tree. In that second case, an exchange of carbohydrates between trees through the mycelium has already been observed. Some plants can also change relationship type during their development (start with endo, then migrate to ecto)

Here’s the list of trees by family for plants we use in bonsai.

  1. Endo/Arbuscular (~95% of plant species)
  • Acer
  • fagaceae (Quercus, Fagus, Castanea)
  • oleaceae (Fraxinus, Olea, …)
  • tiliaceae (Tilia, Populus, …)
  • ulmaceae (Celtis, Ulmus, Zelkova, …)
  • non-pinaceae conifers (Araucaria, Chamaecyparis, Cryptomeria, Cupressus, Cupressocyparis, Ginkgo, Juniperus, Metasequoia, Podocarpus, Sequoia, Taxus)
  • rosacea (Crataegus, Malus, Prunus, Pyrus, …, generally fruit trees)
  • shrubs like Abelia, Berberis, Buddleia, Buxus, Calistemon, Callicarpa, Caryopteris, Ceanothus, Cercis, Chaenomeles, Lonicera, Choisya, Cornus, Cotinus, Cotoneasters, Cytisus, Deutzia, Eleagnus, Escalonia, Euonymus, Forsythia, Genista, Hamamelis, Hebe, Hibiscus, Hypericum, Ilex, Lagerstroemia, Laurus, Mahonia, Nandina, Pyracantha, Ribes, Spiraeas, Syringa, Viburnum, Weigelia…
  • the majority of tropical trees
  1. Ecto (~2% of plant species)
  • fagaceae (Quercus, Fagus, Castanea)
  • tiliaceae (Tilia, Populus…)
  • betulaceae (Carpinus, Alnus, Betula, Corylus…)
  • salicaceae (Salix…)
  • myrtaceae (Eugenia, Eucalyptus…)
  • juglandaceae (Juglans…)
  • pinaceae (Pinus, Cedrus, Larix, Abies, Picea, Pseudolarix, Tsuga…)
  • other species like Acacia, Robinia
  1. Ericoid (~3% of plant species)
    Orchidaceae and most Ericaceae

  2. Arbutoid
    Arbutus and Arctostaphylos

  3. Orchid

Alnus, Eucalyptus, Populus and Tilia are special as they can host both Endo and Ecto at the same stage of development.

Most mycorrhizal mix you can buy will either be a mix of Endo/Ecto inoculants, a mix of purely Endo inoculants or a mix of purely Ecto inoculants. I still haven’t found an Ericoid or Arbutoid mix on shelves. You could also make your own inoculants from the spores of an appropriate fungus.

Some ‘species specific’ fertilizers may also contain the appropriate mycorrhizal inoculant… the Neudorff Azet range is one example.

1 Like

Thanks @Michael_P
Sounds like you know your stuff. Do you use inoculates your self?