The Science of Hugelkulture

Permaculture is a gardening method that is modeled on the ecological and biological principles found in nature. Sepp Holzer has based his revolutionary gardening methods on a concept he calls Hugelkulture. But what is going on in his berms that are generating such amazing results? The following information is a textbook study. I hope it is informative.
                                              The Science of hugelkulture
The world’s largest organism is the mycelium fungus Armillaria solidipes commonly called the honey mushroom and located in the Malheur National Forest in Oregon. The small editable mushroom is estimated to cover 2,200 acres and maybe between 2,400-7,200 years old.
Previously, another giant honey mushrooms were found near Mt. Adams in Washington State, covering 1,500 areas. The first giant honey mushroom was found near Crystal Falls Michigan, covering 37acres.
Mycorrhizae fungi are enormously important components to natural ecosystems and Permaculture agriculture. Almost all plants evolved alongside and established a beneficial relationship with a fungus, for the exchange of essential nutrients.
Mycelium fungi are well adapted to decomposing almost any carbon- containing organic matter. Have been shown to benefit certain grasses and other non-woody plants by synthesizing toxins that deter herbivore insects and animals or by increasing host plants tolerance of heat, drought or heavy metals.
Mycorrhizae (fungus root) are the beneficial relationship and mutualistic joining of roots and fungi. There are two connective methods employed by the fungus to join the two organisms.
Ectomycorrhizae are associated mostly with woody plants, including pines, spruces, oaks, walnut, birch, willow and eucalyptus families. A fibrous tentacle like structure coming from the fungus called a hyphae, encapsulates the plants roots. The hyphae increases the surface area of the root, allowing for greater uptake of water and also supplies the plant with phosphate and other minerals absorbed from the soil.
Arbuscular mycorrhizae do not have a dense mantle sheathing the roots. The fungi filaments enter only the outer epidermis cells and cortex. The association is found in 85% of plant species, including crop plants such as maize, wheat and legumes.
Roots can form mycorrhizal unions only if exposed to the appropriate species of fungus. In most ecosystems, these fungi are present in the soil. But if seeds are collected in one environment and planted in foreign soil, they may not be able to form a mycorrhizae bond with the local fungi because they didn’t evolve together and don’t recognize each other.
Mycelium fungi secrete powerful enzymes into its surroundings that breakdown complex molecules, stimulate plant growth, produce antibiotics that protect roots from pathogens found in the soil.  It is a main decomposer and recycler that is responsible for the decomposition of large organic matter. Without this partnership most forms of carbon, nitrogen and other elements would remain tied up in the organic structure and would be unavailable to most plants. Fungi are also more efficient at absorbing minerals than the roots themselves.

The soil fungus Arthobotrys produces a fibrous tentacle like structure. They are modified as hoops that can constrict around a nematode (roundworm) in less than a second. The fungus then penetrates its prey with the hyphae and digests the prey’s inner tissue.
Mycelium fungus should be encouraged in urban or former industrial sites, because of its ability to consume toxic materials and improve poor soil conditions, such as mineral deficiencies, acidity, salinity,  poor drainage and chemical contamination, such as house paint, heavy metals and jet fuels that have accumulated in the soil.
Foresters commonly inoculate pine seedlings with mycorrhizal fungi to promote growth and protect against pathogens.
                                                Double edged sword
The mycelium fungus Armillaria solidipes located in the Malheur National Forest of Eastern Oregon, was discovered after larger numbers of pine trees started to die off. The trees were becoming overly stressed due to outside forces, such as low perspiration do to global warming. As the ground dried out the honey mushroom used its tentacles to shut off water and nutrients from going to the roots and killed the trees, in an effort to save itself. The trees die, eventually falling to the ground, became covered with decomposing biomass and soils. The mycelium spread through the wood decomposing everything, offering storage space when it finally rained and providing an open area for new plants to establish themselves.
The timber industry considers the honey mushroom a forest disease and are introducing a new monoculture to the area. They are planting a few species of trees that don’t  appear to be affected by the ancient fungus. In some areas the diseased forest has been clear cut and bulldozers brought in to tear out the infected stumps and the mycelium fungus.

Tear down paradise and put up a parking lot.

The local permaculture group was gracious enough to install a hugulkultur bed on my property. I had read about this technique, but most of my efforts were elsewhere (switching to multi-story perennial polyculture, putting in swales, etc). I have been quite surprised by the vigor of the plants growing in the hugulkultur bed!! The same species are growing in various places around my land, but are doing much better in the HK bed. I cannot believe that the wood buried in that mound is highly decayed yet - it has only been 2 months or so since it was created. Certainly, some fungi are gearing up to digest the wood, but it cannot be as fast as compost (can it?).

Not sure how it works, but it does!

Hi Jonathan
Thank you for responding to my posting. You are right there is a lot more to this hugelkulture grow method. So you got me wondering how fast does it take to grow the mycelium, once it has entered the mound. So I torn into a decorative wooden border of old log slabs. I had constructed the mound ten weeks ago. The slabs had mycelium streaks in the wood, but it had gone dormant. The slabs were stacked on wet cardboard and the back sides were back filled with green and brown mulch. Upon examination, where the wet cardboard and wood came into contact, there were patches of thick fungus. But I don't think there were any roots in contact with the fungus, yet.

Control experiment
The hardest part of doing a comparison experiment is designing an Experimental-vs.-control study. The control group is practically identical to the experimental group, although the experimental group is changed according to some key variable of interest, while the control group remains constant during the experiment.
OBERSERVATION
“It has been theorized that well rotted logs will retain a lot of water and can act like a water reservoir when placed in a Hugelkulture berm. This will help reduce the amount of water used in the growing season. Studies have shown that the growth of mycelium fungus can play an important role in plant growth.”
A Control Study has already been performed by many of the Permies enthusiasts and I didn’t have the resources to duplicate their studies at this time.  Instead an Experimental study was constructed using cardboard logs. Various sized boxes were used with the top flaps folded into the box, then smaller boxes were fitted inside each other and any empty spaces were filled with old newspaper, used paper towels, fresh grass clippings and brown waste. The cardboard logs were lined up and covered with brown waste consisting of pine needles, pine cones, saw dust, coffee grounds,various mounds of leaf litter found around the campus and then covered with green grass clippings. More brown biomass was added weekly, with just enough green waste to hide the brown materials. No manure, preprocessed mulch or soil was added, fertilizer was only supplied by the rotting of organic materials added to the piles. Occasionally human nitrogen was added while watering.

Preliminary results are suggesting that cardboard logs are just as efficient as well rotted logs in retaining water and promoting plant growth. Lack of mycelium fungus does not seem to hinder the growth of the plants. Omission of processed mulch, manure and even dirt to the mound seems to have little effect. (Time to set up a true comparative experiment.)
This study suggests that a SF Bay Permaculture garden can be established with limited resources and time. A more in depth explanation of how and why this garden was constructed the way it was, will be posted under “SF Bay area Permaculture” in the future.
In the last two weeks the potatoes and some of the sunflowers have taken a big hit from the slug and snails. Just put out beer traps.

When planting blueberry plants into a hugelkulture , I dig up some soil from around the native huckleberries that grow on our place and place it around the roots of the blueberries. I can not find a commercial mycorrhizael inoculant for vacciniums so I hope blueberries and huckleberries share the same mycorrhizael associations.

for 2 years now I have been building hugel beds in my gardens and I have had wonderful results. This year one of the beds that I had built had one of my 3 apple trees that I put out in the same garden, 2 were not in hugel beds...one was.

the one that was has 3 times more growth on it than the two that were not.

I also had used bark pieces for mulching around my blueberries now for 2 or 3 years and it hadn't seemed to be helping much until this year I noticed that they are taking off, and growing so much nicer than they had been, I'm assuming that it is cause the bark has begun to rot more thoroughly and is beginning to host mychorr. which is now feeding my blueberries (and 2 serviceberries).

I haven't had much time to really work with the beds as I have had other pressing things going on, but I hope to continue to add more hugel beds and also to add more wood products, branches, twigs etc to the existing beds as a mulch..esp gathering partly rotted wood products form the woods

also the idea of getting soil from blueberry areas makes total sense, if i can find time to get out into the blueberry areas in the wild to gather some up, thanks

Hi Brenda
Great ideas, the soil should have mycelium spores in it, but might I suggest you also collect any old rotted wood found in the area. Look for white streaks under the bark or coming out of the ends.
I would like to share a video I stumbled across that you might find interesting. Google “Paul Stamets: 6 ways mushrooms can save the world”.
Mid May I was trying to figure out how I could promote or even grow dormant mycelium that I was finding in some of the wood that I was putting into my berm. I measured out equal wood samples, placed them in plastic zip lock bags and added different solutions that I thought would work.
The best results of mycelium fungus growth, was an old formula developed by Jerry Baker, one of the first TV gardeners. He swears by different variations of this recipe as a general remedy for everything.
For my experiment I added to the quart size baggie, 31 grams of rotted wood, 80ml of Root Beer, (Jerry likes cola, but warns against using diet soft drinks which has no nutritional value) a squeeze of Suave shampoo and 1.10 grams of Epsom salt.
So as an experiment, you might try throwing some of your collected top soil and rotted wood into a garbage bag, premix and add 1 can regular cola (not diet) 1 cup shampoo and a tablespoon Epson salts.  Add enough water so that everything is damp but no standing water. Tie shut and store in a cool dark place for three weeks. Check weekly for water content. If you find mycelium growth, try planting one of your blueberry bushes into this grow medium.
I’m sorry, I know this sound like voodoo and I’ve lost all credibility and everyone’s respect. Please keep a notebook and report back your findings.   

have you guys used biocar in conjunction with hugelkulture? i am in the process of building 6 hugelkulture raised beds for new fruit trees (all semi dwarf, cherry, mulberry and apple) and thought the addition of biochar would be helpful. Any thoughts

Hi Westspartan
Have you googled the video, "Secrets of El Dorado"?
Biochar is just another piece of the puzzle that nature has laid out through evolution.
Think of your Hugelkulture as mimicking what happens in nature. Fire is just another part of the process.
Scientists in the video seem to think that the biochar absorbs nutruinces from decaying organic materials; will hold the compounds as a reservoir until the plants can get their roots down into it. They theorize that once biochar has been charged with fertilizer the reservoirs can last up to 40 years, before it needs to be charged again. In the video, the German scientist’s yearly experiments seem convincing, but to my eye pale in comparison to what is going on in the hugelkulture berms.
The only way to tell for sure is to make two berms, one with biochar and one without and report back to us in a couple years your results.
Oh yes, I personally believe the biochar berms were part a pit fire ceramic industry and the remaining pot fragments were pots that exploded during the firing. So I wouldn’t start throw broken pots and rocks into your berm, just because that’s what the scientists are finding. But then again that calls for another experiment; do I see any raised hands for volunteers?

hi biologybill,

not to derail the thread
i was looking for a video that showed a technique of growing IMO indigenous micro organisms on biochar but can't seem to locate it. this video is similiar except they put it in the soil istead of the biochar

this should get a hugelkultur bed cookin
http://www.youtube.com/watch?v=kW9cqgRij08&feature=related

almost all of my hugel beds have homemade biochar from small twigs and such that we get from our property. sometimes the chicken manure is turned to biochar too.

anyways all beds with biochar are doing better hands down. char holds A LOT of water.

hubert cumberdale wrote:

anyways all beds with biochar are doing better hands down. char holds A LOT of water.

Good to know! 

To innoculate biochar I've used a few methods. The best is to mix the biochar with a finished compost that includes native soil from around healthy, older plants - bamboo and native trees, and also very healthy crops. 1:1 char/compost left to sit for a few days/weeks (probably longer in colder areas) shows fuzzy white hyphae all over the char bits. mixing the biochar with soil from established trees and good pasture works very well. A commercial biochar opperation nearby waters the biochar with compost tea (uses much less compost per unit of char) Anyone who hasn't look at Korean natural farming should google it. It's alchemy that works.

Gather leaf mould from nearby forest and compost it with whatever you got, then mix that finished compost with your biochar. Works for me!

What about planting around the stumps of dead (ESP nitrogen fixing) trees? Natures own hugelkulture. Althou many trees might exude allelopathic compounds for years even from dead root systems...I'm think of eucalyptus in particular.

Aloha to the forums!     

biologybill wrote:
Hi Westspartan
Have you googled the video, "Secrets of El Dorado"?
Biochar is just another piece of the puzzle that nature has laid out through evolution.
Think of your Hugelkulture as mimicking what happens in nature. Fire is just another part of the process.
Scientists in the video seem to think that the biochar absorbs nutruinces from decaying organic materials; will hold the compounds as a reservoir until the plants can get their roots down into it. They theorize that once biochar has been charged with fertilizer the reservoirs can last up to 40 years, before it needs to be charged again. In the video, the German scientist’s yearly experiments seem convincing, but to my eye pale in comparison to what is going on in the hugelkulture berms.
The only way to tell for sure is to make two berms, one with biochar and one without and report back to us in a couple years your results.
Oh yes, I personally believe the biochar berms were part a pit fire ceramic industry and the remaining pot fragments were pots that exploded during the firing. So I wouldn’t start throw broken pots and rocks into your berm, just because that’s what the scientists are finding. But then again that calls for another experiment; do I see any raised hands for volunteers?

That is a very interesting video, I just finished watching it. I am visiting family in Kentucky for the next week, but I can't wait to get back to New York and start building my beds. I think I have my strategy down!

Hi Duane
You realize you just made my head explode, Thanks for the video tip (duane-June21 posting)
The best I could do with my little experiments was to activate mycelium fungus that was already in the rotted wood. Master Cho is growing mycelium, seemingly everywhere.  I hope Brenda Groth views this video for her blueberry experiments.
It looks like I’m going to be taking a trip to Costco for a big bag of rice. You’ve just started me on a new course of research. I will also be sharing this with one of our professors who is studying algae
Thanks again, that’s why I love this site.