Posted by & filed under Compost, Food Forests, Food Plants - Annual, Food Plants - Perennial, Fungi, Irrigation, Land, Plant Systems, Soil Biology, Soil Composition, Soil Conservation, Soil Rehabilitation, Structure, Trees, Waste Systems & Recycling, Water Conservation, Water Harvesting.

What is it?

Hugelkultur is a composting method that uses large pieces of rotting wood as the centerpiece for long term humus building decomposition. The decomposition process takes place below the ground, while at the same time allowing you to cultivate the raised, or sunken, hugelkultur bed. This allows the plants to take advantage of nutrients released during decomposition. Hugelkultur, in its infinite variations, has been developed and practiced by key permaculture proponents such as Sepp Holzer and Masanobu Fukuoka for decades.


Photo: Cricketbread

Building… above ground

Building a hugelkultur bed can be as simple or as involved as you want. You can make small, 60cm mounds of rotting wood right on the ground. Place the wood like a puzzle, allowing as few gaps as possible. Add grass clippings and other finer nitrogen-rich organic matter to fill the gaps left between the logs. Lastly cover the whole heap with 5cm of top soil and plant on and around it. These smaller micro hugelkultur beds can be built if you just need to dispose of some smaller woody material. A pile of sticks of any size can be covered over with grass clippings and a layer of soil. Add a little bit of urine here and there to provide some nitrogen to stimulate the sticks breaking down and the plants growing; after one season, digging into the pile, the wood should be unrecognizable. The size limits of hugelkultur beds are up to you, but beds up to nearly 2 meters tall and/or wide are not uncommon.


Photo: Cricketbread

What’s going on in there?

The most obvious fact is the rotting wood acts as a carbon source and the grass clippings are a nitrogen source, alerting you to the fact that some decomposition is going to take place. By using carbon-rich fresh wood, you may decrease the overall nitrogen content of the pile in the short term, because the wood will initially rob the surrounding matter of nitrogen. This is counteracted by using rotting logs that have absorbed much or all of their total nitrogen holding capacity, and by adding strong sources of nitrogen, like grass clippings or manure, to the hugelkultur as it is built. Adding urine to the hugelkultur bed periodically to feed the nitrogen need of the wood is also highly effective. After fresh wood absorbs nitrogen to its maximum capacity, it will start to break down faster and start giving nitrogen back in the process. If you use wood chips, or many smaller twigs and branches, you have a greater surface area to deal with in regards to nitrogen absorption and should add the appropriate amount of “greens”.


Click for larger view

As the wood breaks down further, it will create air pockets that bacteria and mycelium can invade, further hastening the decomposition. These pockets will eventually collapse, shrinking the size of the hugelkultur over the first year or two. This is normal settling and can be counteracted a bit by adding a fresh layer of chop and drop green manure or compost to the surface of the hugelkultur bed each year. It can also be accounted for by starting out with a bed slightly larger than you intend it to be once settled.

Building… below ground

Hugelkultur beds can also be installed completely below ground, or even with the top layer a bit sunken in arid environments. Simply dig a ditch, fill it with the logs and some nitrogen-rich organic matter, and bury the lot of it under a layer of top soil. The deeper you bury your woody material the better; as roots grow into the rotting core of the hugelkultur, they are going to be treated to a nutrient rich, reasonably constant water source. When buried, hugelkultur beds will retain even more water than raised beds.

Benefits

A pile of wood has a lot of energy in it — imagine burning it in a bonfire. This release of energy is equal to the energy produced during the decomposition, but consolidated into a short period of time, while the decomposition process takes months or years. As the hugelkultur bed decomposes this energy will generate heat to help stimulate root growth as well as extend your growing season. This energy also takes the form of fuel for all the life in the soil: mushrooms, worms, termites, beetles… everything! If things like termites end up in abundance to the point of being overwhelming, simply run some chickens over your hugelkultur bed to turn a nuisance into an asset.

To get the most benefits out of a hugelkultur bed, build it to an initial height of 2.1m! This will shrink to 1.8m or less within the first few months to a year. An often overlooked benefit to having larger raised beds in the form of mounds is an increase in surface area available to plant.

Water retention

One of the main benefits to using a hugelkultur bed is that they can retain water better than humus alone. Think about a rotting log in the forest, if you break off the decomposing top layer, you will likely find a moist environment full of small life right under the surface. This moisture-containing life will remain constant in all but the most scorching of droughts. Our buried wood serves an almost identical function as a sponge buried in the ground. After a rain, any nutrients in the top soil are washed deeper into the ground, but in a hugelkultur bed this water and nutrients are captured by the rotting wood. In dry times, the plant’s roots can lick at the moisture contained within the rotting logs. A 60cm tall, above ground, hugelkultur bed can maintain a usable level of moisture for about 3 weeks after it is saturated. Larger beds of 1.8m can hold enough water for an entire growing season. All of this extra moisture retention in areas that receive moderate rainfall can often lead to riparian species growing where you would not otherwise find them. As the bed decomposes, the moisture retaining wood will become humus that can not hold water quite as well as the rotting wood, but makes up for this by being able to hold onto other useful nutrients and oxygen better than the wood alone.

Waste management

A comment from a farmer in North Carolina noted that hugelkultur is a useful way to dispose of unwanted woody organic matter. By simply pushing their brush into a pile, burying it under some grass clippings and some excess poor quality soil, they solve the problem of the getting rid of all their “waste”. The side effect to this activity was to create a fertile bed that provided a good potato yield the first year.

If you are harvesting the woody matter locally, by installing a hugelkultur bed you can save a lot of energy that would otherwise be used just in disposing of it. Often times municipalities have green waste programs, such as tree clearing around power lines or keeping the sides of the roads mowed, that can offer you a free local source of waste material to build a hugelkultur bed in an area with no available brush, such as in a suburban neighborhood. Also look toward local businesses such as arborists or landscapers to acquire larger logs. All of these activities can help reduce the load of transporting these materials to a waste site while at the same time fueling a fertile plot of productive land. Since the logs can be used whole in hugelkultur you don’t even need to spend energy chipping them.

Soil life… fungus:bacteria

The content of a hugelkultur bed being what it is, predominately rotting wood, there will be more saprophytic fungus — fungus that feed on dead things — than bacteria, which prefers an environment more akin to the humus we will eventually create. This leaves a few interesting opportunities to the would-be hugelkultur bed designer. One opportunity you have when first building your hugelkultur bed is to choose to inoculate the wood yourself with a desired species of fungus. To ensure successful inoculation, you can cover the ground with a few layers of cardboard before building the hugelkultur bed. This acts as a temporary barrier to other fungi and becomes food later in the process, after your inoculation has taken hold. The higher initial ratio of fungus to bacteria will promote tree growth. The fungus interacts with the roots of the trees, trading nutrients for starches. The mycelium also aid in the distribution of the water stored in the rotting wood to the surrounding areas. .

Time stacking

The next opportunity comes from the soil changing dramatically over the first 3-5 years in the hugelkultur bed. It will start off with all that dense, rough, woody material that things like squash, melons, or other vining plants will love. Trees planted on or around the hugelkultur bed will see improvements with the extra fungal life in the soil. Masanobu Fukuoka noted that planting trees beside coarse organic matter, such as in hugelkultur, improved their growth. As time passes your hugelkultur will consist of more and more humus — eventually you will be left with a mound of deep rich soil. As the trees reach maturity the fungus of the rotting wood will subside to reveal a more vibrant bacterial life more suited for smaller plants.

As well as advocating burying coarse organic matter, Fukuoka suggests that a hugelkultur style bed offers “gradual soil improvement by planting deep-rooted trees, grasses and herbs” and that “channeling and capturing nutrient-rich water from upland forests above the property… is an important part of sustainable, fertilizer-free agriculture.”


Mature hugelkultur raised bed.
Used by permission from paul wheaton’s hugelkultur article.

Some of the more desirable woods are:

  • Alders
  • Apple
  • Birch
  • Cottonwood
  • Poplar
  • Willow

Less desirable woods include:

  • Cedar – lasts long because of natural anti microbial properties
  • Black walnut – contains the toxin juglone
  • Black locus – resistant to rotting, may be more useful in humid areas
  • Pine and fur – both contain tannins

A few interesting resources I found while researching for this article can be found below:


Comparison: traditional bed at left, hugelkultur bed at right

40 Responses to “Hugelkultur: Composting Whole Trees With Ease”

  1. Edith Wiethorn

    Very interesting! as I am considering creating some extensive, sustainable food gardens at a property where the entire south side has been overplanted in conifer trees. Some of the conifers will remain to retain the Japanese look of the house & landscape, but many will come down to make way for productive gardens, designed to harmonize with the house. This is my first glimpse of hugelkultur & after scanning it again I wonder – is sappy conifer wood suitable, or is the wood pictured & discussed for this method exclusively from deciduous trees?

    Reply
    • KL

      I have 50 dump truck loads of wood chips of all sizes much of which is both cedar and pine and have spectacular results right away.

      Reply
      • Surya

        I liked your comments. can you send me pictures of your plants. i would like to try the same thing in my patch

        Reply
  2. Edith Wiethorn

    P.S. I see that conifers are “less” desirable because of tannins – but where does that put them on the spectrum for functional hugelkultur, practically speaking? We also have access to downed cottonwood here & I could broker the conifers to other uses.

    Reply
  3. Marion Lennon

    Fantastic info and perfectly timed. we recently bought the urban permaculture DVD and are in the process of doing a complete garden makeover as a result,to plan the garden beds we needed to cut down a very large palm tree,the base of which would be about a meter across which is too big for us to mulch,so it was about to be cut up and sent to the green waste depot. Now you have me thinking that perhaps it could be utilised in a hugelkultur bed.
    would the palm be suitable for this method?

    Reply
  4. Mark Feineigle

    All wood will work in this application, some are just better than others. For the less desirable wood, make sure to let it rot more extensively before burying it. While it might be a little slower going with a tanin-rich pine, the process will still end with great humus. Stunted growth the first season is all I would expect, if that. Keep it topped off in nitrogen and see if there is a fungus that thrives on your “problem” wood.

    Reply
  5. Mark Feineigle

    If the conifers are making the mound too acidic, add some sulphur to the bed as you build it.

    Reply
    • Surya

      calcium would be much better. or eggshells absorbe acid and turn it into calcium salts

      Reply
    • Tony Cuthbert

      Adding sulphur crystals will make the bed more acidic by forming sulphuric acid. However, I am glad you are using the correct spelling for sulphur.

      Reply
  6. Kev Coleman

    Excellent idea. I have a heap of partially rooting wood/coarse vegetation which i was going to burn (again) as it was too coarse for the compost heaps. Now I was also about to build some raised beds. I have the railway sleepers ready but I can now put them to better use re-building the rotten steps up to my main garden. The raised beds can be the Hugelkutur variety. I also have a load of very rotten branches and large logs which I will use. Funny thing is I am at home this weekend and I was planning major garden work.
    Thankyou for a brilliant article.
    Kev C

    Reply
  7. Edith Wiethorn

    Thanks, Mark – I see that conifer will go into one experimental Hugelkultur bed & that we will compare it with a couple of beds based on Cottonwood. I really appreciate your comment re seeing what fungus shows up in the conifer bed, since I plan to inform my gardening & growing more & more with soil microbiology. I am starting my study with Dr Elaine Ingham’s SFI approach – Soil Food Web Institute. Any further links to good explainers – welcome! The conifer soil pH will be useful if consistently more acidic – Blueberries, for example.

    Reply
  8. Richard Clarke

    What a fantastic article. As an Australian Broadacre farmer coming up with broadacre permaculture ideas in a transitional system I really value such experimental work outlined here.
    So there is a use for those fallen pine and cypress trees that were traditionally heaped and burned. As for adding nitrogen, animal manure, particularly the manure washed out of handling yards, could be ideal? Burying the logs on contour in the path of the manure feeding more green manure and fruit trees for farm workers to enjoy.
    All those farms in Western Victoria that are ripping down and burning ten year old blue gums to sow wheat could really be burying the rows of trees and growing more productive species using poultry manure as a nitrogen source.
    Mind you, it does cost a lot to dig a hole…

    Reply
  9. Aapo Leinonen

    Greetings from Finland!

    Are hugelkultur beds anaerobic? Won’t they produce methane when the trees decompose? Is there any research done over this issue? I think would be important to know witch GHGs hugelkultur beds will produce, before pushing the method to very large scale use.

    - Aapo

    Reply
  10. Edith Wiethorn

    Good question, Aapo! A framing question for those with experience in field soil-microbiology studies : Assuming you have good soil in the range of “normal” – into what depth in the soil is the soil microbiology considered identifiably “aerobic”? For example, perennial alfalfa has a very deep root system – is the whole life cycle of alfalfa aerobic? From my beginning readings of Dr. Elaine Ingham’s work with The Soil Food Web – she does seem to say that areas with a root-zone rhizosphere can be anaerobic, depening upon local conditions, having mostly to do with water saturation excluding air. Back to Hugelkultur – I was thinking that beds the size I was envisioning – maybe 4-5′ across & 4′ high – would tend to be aerobic throughout due to having good drainage & no compaction to exclude air enough for aerobic microbes.

    Reply
  11. Scott Hall

    I am interested in using hugelkuture as a solution to some of the problems with the country we are working. The soil is basically structure-less decomposed granite, which becomes a waterlogged slurry when wet, and sets like concrete when dry (we can have decent dry spells). My idea was to use the beds as a swale, so it can absorb the water when it rains, but excess water is free to run away. Has anyone had any experience (or have any advice) with this? Also, the two main timber species growing are radiata pine (plantation) and eucalypt (native), does anyone know how eucalypt would go?

    Reply
  12. Taiss Quartapa

    Great article. Is there any feedback on Australian implementations with local wood sources?

    Whilst I love the idea of implementing this, I can see the cost of cartage from the apple orchards to my place in NC Vic could be horrendous (on top of the costs of digging holes) making the venture horribly difficult to justify.

    Reply
    • Gardener in Eden

      Great idea if we could share this info.
      Fast growing trees can be planted on your property to be used in future for this purpose.
      I would like to find out if this works with Camphor Laurel trees – a class 4 weed in the northern rivers NSW…we have acres of it!

      Reply
  13. Christopher Towne

    Hi – I just heard a story about forest fires in the US Southwest, claiming that people have disrupted the fire-cycle in the region. There are more standing trees per acre than there were before European settlers came there, so crown fires are more common.

    I was wondering about the applications of hugelkultur in the region. It seems like this tecnique could be used to cull trees, bury carbon and increase water retention in the dry climate!

    Has this been tried before?

    Reply
  14. Jane ferguson

    I can’t wait to try this method. I have tons of logs, branches and leaves I could use.

    Now I’ll have the trenches dug. I’m getting lots of help, I’m. wWOOFer Host. Lots of
    Young WWOOFers have been helping me here in Beautiful Bowen Island.

    Reply
  15. Austin Marino

    I have implemented this around my property. I’ve noticed that in my sandy property plants seem to grow a lot faster in the hugulkultur bed. I live in the desert.

    Reply
  16. Jessie - Rabid Little Hippy

    What a brilliant idea and imagine my excitement upon seeing poplar as a desirable wood! We’ve just moved and the property is overgrown with poplars which initially was bad news as they’re a pain to eradicate BUT we’ve just about used every part of them now – goats can and will eat the leaves and smaller branches and even the bark and now garden beds from the thicker branches and wood. YAY! I found this post this morning and already my first bed is half built. :D

    Reply
  17. Terrapin

    Would a large felled date palm tree make a good foundation for an Hugelkultur bed ?

    Thanks for any reply, sooner the better – one nearby was just chopped down and hacked into nice-sized half circle chunks. But it’s set out for heavy trash pickup. Should i grab a few chunks ? Or seek some other kind of tree ?

    Reply
  18. Paul Miller

    Hugelkulture looks promising as a way to manage small acreage dry forest in the Sierra. I would like to know more about larger scale attempts to apply this to reduce the potential for crown fires. I’m modifying my Unimog forest tractor/backhoe to experiment with this on 25 to 50 per cent slopes. Looking for recipes for a reasonable start in my effort. Have quite a bit of standing dead Pacific Madrone on Sites clay/loam soil 3-12 feet deep. Clay already stores lots of water through the dry summer and fall. Trees (Ponderosa pine, Sugar Pine, Doug fir, Incense cedar, Madrone, Dogwood) already grow very fast. Objective is to break up continuous forest in favor of clusters of trees and promote health of larger (more fire resistant) trees. Have too much duff and understory because of fire supression. Would like to use high beds as part of rotational grazing scheme to keep fine fuels under control. Also planning keyline plow or swales or tiles to move water from seasonal spring blackberry patch covered valley to ridges. We get about 60 inches of rain annually, sometimes 6 inches in a day but not much runoff other than compacted areas due to the thick clay/loam. Again, the primary objective is to reduce the chance of a crown fire.

    Reply
  19. Marina Kecman

    I would like to know if other kinds of trees are suitable for hugelkultur such as pear, plum, beech, linden, maple, cornel, oak, elm, chestnut, ash, hazel, elder, etc.
    Thank you.

    Reply
  20. Paula Collier

    This sounds great as I am just starting to clear years of brush and fallen trees which I was afraid to burn as we have a lot of poison ivy about and w/o leaves is hard to identify. I am wondering if there would be draw backs to burying some of the poison ivy within my instincts tell me that as it will not be dug into all would be fine…?

    Reply
  21. Tony Cuthbert

    I have buried X Cupressocyparis leylandii in what I call trench hugelkultur. This conifer has very sticky, resinous sap which some gardeners say is allelopathic. However, when buried with other woody material about 600mm deep there is no effect on yield of nitrogen hungry vegetable plants. When digging down about three years after constructing the hugelkultur bed, I could find no trace of the X Cupressocyparis leylandii except a lovely friable layer of organic matter that could be incorporated into the top soil.

    Reply
  22. Kathleen Roberton

    Very excited about this technique! Couple questions – how large can the logs be? I have about 15 massive logs 2′ x 3′ to bury along with a ton of branch debris. Do you recommend digging a ditch of a couple feet or just piling this on top of the ground directly?

    Also, I have a ton of invasive ivy. Can this be included in the Hugel or how do you recommend getting rid of it? Thanks!

    Reply
  23. shawn

    I have three beds of dry, rotted pine and eucalyptus. Added BIM, Lacto Bacillus extract to the beds They have produced 200-250 kilos of sweet potato and ihame along with tumeric and ginger. I have about 30-40 more pine and eucalyptus to harvest so will be making alot more hugelkulturs next year. This what I have to work with and it works. good info.

    Reply
  24. Anthony Cuthbert

    Some good questions. How large can the logs be? I doubt if there is any limit to the size of the logs but I have not seen any literature to back this up. The problem is covering the logs with top soil. The only way that I can do this is by digging out a trench and putting the logs at the bottom then returning the top soil to cover the logs. So I think that digging a ditch about two feet down will give you some top soil to begin covering your logs. However, lots of people just put the logs on the top soil and cover with soil obtained from elsewhere.

    Reply
    • shawn

      hi anthony….I have used both methods you mentioned. If you don´t have an earth mover of any kind which I don´t cut the logs so you are able to pick them up with help. simple as that. my first experiments in hugelkultur was 4 years ago. made 2 x30-35 foot beds. I just started throughing rotted logs various types of tree branches lots of green bios mass, woody bushes mixed with green manure(cow shit) and various mushroom, fungi extracts and kept adding material for a year… didn´t add soil of any kind due to compacted and the distance to haul to the site. I also just keep adding material to the beds. I decided not to break my back and let nature make the soil. The other method was making beds with large pine and eucalytus trunks. I have used a mix of green and dry or rotted wood. Added lots and lots of branches and green biomass..whatever i can get my hands on around the farm. just through stuff on them everyday . added clay soil mixed with sharp sand from the river and cow manure be it green or otherwise. cover with lots of mulch and start planting. I have fig trees, tumeric, sweet potato, ihame-taro, ginger, various herbs and annuals…just experiment.

      Reply
  25. Brenda

    What if the trees have poison ivy vines all over them? Would you not do this then?

    Reply
    • Tony Cuthbert

      I must admit that living in the UK I have little experience of poison ivy, however many people avoid composting rhubarb leaves because they have the mistaken impression that they are poisonous. Microorganisms have an extraordinary ability to decompose a vast array of chemicals and this includes the oxalic acid of rhubarb and I would conjecture the irritant in poison ivy.
      Taking precautions – just as you would handling euphorbia- I see no reason why poison ivy would not rot down to carbon dioxide, water and a few minerals in a hugelkultur system. I would be very surprised if any of the poison ivy irritant remained in the soil just as I would oxalic acid from rhubarb leaves.

      Reply
  26. katy

    Great article. Friends of mine in Grass Valley CA are putting this into practice. One row. Also it seems to be an intensifying of what forests already do. And nitrogen fixing plants (alder, etc) would be good as mentioned. And in view of the current drought in CA, this looks like good practice.

    Reply
  27. Terrapin

    BTW, went ahead with the palm chunks i asked about a year ago – seems to be fine.

    However – made the MISTAKE of using some branches pruned off of those fruitless decorative Bradford pear trees. (only since then discovering they are a listed invasive) Those things are like zombies from the grave – sending sprouts growing up through the hugel, even after lying on the ground drying out for many months before burial. Cut them back over and over, they keep on growing.

    Reply
    • Tony Cuthbert

      There are a number of plants I would not add to a hugelkultur bed. Calystegia sepium; Equisetum arvensis; Armoracia rusticana and especially Persicaria wallichii. All of these are invasive plants.

      Reply

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