Hugelkultur, Mound Gardens

sand_puppy
By sand_puppy on Sat, Oct 12, 2013 - 12:09pm

Is anyone using Hugelkultur gardening techniques?

We live in Central Virginia on a residential lot where the topsoil was apparently scraped off when our home was build 30 years ago.  When we dig beneath the thin layer of sod, we find only hard packed red clay.  

Last year we started gardening.  We had a 5" layer of top soil / compost trucked in and dumped.  Our garden did not grow well last year and the veggies were kind of anemic, the carrots little and woody and the beets didn't thrive.  So we are exploring how to make the ground fertile and rich again.

We have a big compost pile, but most of the organic mater available is fallen leaves and wood scraps from trimmed bushes and tree branches.  We add a few food scraps, and during the summer, grass clippings (but summer is over and the grass is not growing these days).

Sooooo, we are trying Hugelkultur. Basically, this involves burying wood under dirt to simulate a "forest floor" environment.   I have dug a 4' wide trench through the garden area and am having a load of firewood delivered next week.  I'll put it in the trench and burry it in compost (a truck load of compost is also being delivered) and wood scraps, then cover that with the topsoil/compost mixture.  It will sit for the winter, then be a "mound garden" next spring.

The picture below is not me, but it shows the strategy of a trench filled with downed wood, which will later be buried in compost and dirt.  I needed to dig a trench, rather than just build on top of our lawn, in order to come up with the dirt which will be put back on top of the wood.  And trench digging is really hard work.

 

Anyone else working with this type of approach?  Any pointers on how to get the soil fertile and organic and rich?

14 Comments

Grover's picture
Grover
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Just thoughts

sand_puppy,

I've seen the effects of it in the forest. I've never tried it at home so these are just thoughts, not actual experiences. I used sawdust as weed retarding mulch one year that was subsequently tilled into the soil, but there wasn't enough to notice a difference. (It did keep down the weeds that summer.)

If you're going to put firewood in there, I'd suggest putting the cheapest kind possible - use cottonwood rather than hickory. The wood will eventually rot anyway. Cedar and other rot resistant woods may not be as good. Can you get some firewood that has sat out too long and is halfway rotted already? It would probably be cheaper and work better. I personally wouldn't use any pressure treated lumber; however, 2 X 4 ends from a local construction project might work as well. Construction folks have to pay to have these removed. They'll gladly give them away.

Also, I wouldn't just stack the firewood and then pour soil over it. When you look at the idealized drawing above, you see that all the wood pieces are isolated. I'd place a layer of wood, then place a few inches of soil, and then repeat until your hole is filled. Mark the corners with something durable (like steel T-posts) so you know exactly where your experiment is located. Perhaps you could make one end with a lower percentage of wood and the other with a higher percentage.

It would be interesting to extend your rows beyond the hugelkultur so you can see the effects on the crops from the treatment area versus your standard garden experience. My guess is that you'll see better results as time progresses. It takes a while for natural processes to work. The first year, your best results may be in the undisturbed area just outside of the hugelkultur trench.

Good luck and keep us informed of your progress. I, for one, am very interested in the outcome,

Grover

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jturbo68's picture
jturbo68
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Hugel culture

Sandpuppy

 

i have built several hundred linear feet of 5' tall hugel bed on my property and scattered seed in a poly culture.  The results have been quite good!

 

i would suggest focusing on building them steep as opposed to broad.   Perhaps 3' - 4' wide on the wood will lead to a 5' tall hugel.  I also agree with the layer of wood then a layer of dirt concept so that the hugel is dense and not airy inside.  

 

I have had a fox nest inside mine because I left it airy inside.  

 

I fell ell like you could also build them more like a standard garden raised bed as well.  

 

John 

 

BSV's picture
BSV
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Hugelkultur

I have about 140 linear feet of hugelkultur beds here on my Central Texas farm. They are about a year old. This being a hot, dry region in summer, I elected to trench instead of building up. The first trench I dug by hand and it was very hard going in the rocky, limestone ground in my back yard. So I hired a friend and a mini-excavator to dig the remaining trenches. They are four feet deep and four feet wide. Two of the three trenches were filled with partly rotten wood, leaves and twigs from my farm, and the third trench I filled with spoiled hay and manure from my barnyard (it's an experiment). The three trenches were then topped off with good soil before planting.

Hugelkultur works, no doubt about it. But some patience is required. For example, you should expect a nitrogen deficiency for the first year or so as the carbon in the wood, leaves and twigs breaks down. This can be overcome by adding a nitrogen fertilizer as you plant. The decaying wood will gradually break down, building thick, rich soil. You can expect some subsidence and you'll need to add organic matter each year to compensate.

Wood contains and absorbs moisture and the idea is that the plant roots can tap the moisture in the wood over time. When you go the trench route, you are creating what amounts to a sponge. When it rains the trench will absorb water and release it to the plant roots on demand.

You need to be careful what kind of rotting wood you put into your hugelkultur beds. Certain species are allelopathic (they suppress competing species) and you want to avoid that. For example, don't use walnut, pine or related species. Oak, ash, pecan and similar wood is fine. I would avoid sawdust. Here we have a lot of ashe juniper, and it's not suitable. Do a bit of on-line research about trees in your area before  you begin to dig or mound.

A well crafted hugelkultur bed should require little fertilizer once established and it should be good for many years of service. Last spring I planted certified seed potatoes and was very pleased with the results. Due to time constraints this fall I planted a cover crop (Austrian field peas) to fix nitrogen in the soil. The next planting will be in the spring. Our best gardening season here is fall and winter, and most of my vegetables are in raised beds and my keyhole garden. The hugelkultur beds will lie fallow until spring. Also, I want to add another layer of topsoil before I plant again, and that will just have to wait.

Anyone seriously interested in hugelkultur should also check out keyhole gardens. You'll find good information on YouTube. Look at the excellent series of short how-to-build-one videos by Dr. Deb Tolman. Dr. Deb lives in the next county (she moved here from Portland) and she has really gotten folks around here fired up about keyhole gardens. In her rural county of perhaps 18,000 people, there are now more than 60 keyhole gardens. In my much more populous county they are also starting to catch on. That's because they really work in our climate here. Check it out, and good luck.

Thrivalista's picture
Thrivalista
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HugelKultur is working for us

Our first hugelkultur beds are 2 years old, built and planted during a drought here. We only had to water the blueberry and beach plum beds once that summer, at the start of the season. Haven't had to water them at all since, except when we water in a new transplant.

We used a mix of semi-rotted and fresh wood, placing the fresh on the bottom. We also threw a lot of green material in on the top, and sprinkled liberally with Liquid Gold (note: we're not talking furniture polish here) to provide nitrogen.

It worked so well that DH is converting all of our perennial food crop beds to hugelkultur.  I think it was Paul Wheaton, over at permies.com, who said hugelkultur beds will boost fertility, and decrease watering needs, for the 30-year life of the bed.

HTH

sand_puppy's picture
sand_puppy
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Hugelkultur, supplying nitrogen

Thank you Thrivalista, BSV, jturbo and Grover.  Both for encouragement about this gardening technique and the specific information.  I'll summarize here what I have just learned:

The idea of making 30 YEAR LONG IMPROVEMENTS in the fertility of one's garden beds sounds like a good long term strategy for a food garden that one might need to depend on in the years to come.

I had heard that the issue of low nitrogen in the decaying wood layer of the Hugelkulture mound was a problem.  But I wasn't sure what I could do about that.  Sprinkling  in Liquid Gold fertilizer sounds like a good answer.  Green mater/grass clippings are another--but those are in short supply in Virginia in October-- and planting Austrian Field Peas to fix nitrogen in the soil as a cover crop in the off season--again, not feasible for Virginia winters as sub-freezing nights are very common.  

I've enjoyed Paul Wheaton's videos at permies.com and will look into Deb Tolman's keyhole gardens.

Question for jtubo (and anyone else):  What is the advantage to a TALL Hugelkultur mound?  4' wide by 5' tall?  It sounds like the sides would easily erode and it would be easier to make and maintain the mound if it were lower and flatter--unless there is a clear value in height.  I saw some of Sepp Hozer's video's showing tall mounds.

Our area of the country gets about 40 inches of rain.  So water conservation only sporadically emerges as a critical issue.  However, I understand that once every 7-10 years there will be a 4 week period during the mid summer without rain and everyone's gardens die.  So, a garden bed design that retains water sounds really smart (along with a rooftop rainwater collection system and holding tank to get one through the rare dry spells).  Pictured below is a 300 gallon "IBC Tote" available for about $100 on craigslist.

Avoiding walnut, pine, juniper and cedar wood sounds good as they secrete chemicals (allelopathic) that inhibit other growing things.  Old 2x4s from a construction site might be a cheap wood source, but avoid pressure treated lumber as it contains ARSENIC. 

Using a mini-excavator to dig trenches.  Smart.  Thanks.  I would put this in the category of using petroleum based resources wisely while they remain available to make a post peak-cheap-oil world more to our liking.

Thanks again.  Now back to work.  Where's my shovel?

Thrivalista's picture
Thrivalista
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Tall mounds have more surface area for increased growing space

And will also provide some wind protection. And would outlast mounds with less wood in them.

kevinoman0221's picture
kevinoman0221
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Jack Spirko, Woody Beds

Jack Spirko over at The Survival Podcast has talked a lot about Hugelkulture and experimented with it. He mentions it in several podcasts and has some videos on his Youtube channel. (He also talks a lot about permaculture). If you click over there you can just use the search box.

Jack has taken to calling what he is doing "woody beds" because he does not build them as tall as regular Hugelkulture mounds. His are more like raised beds with a wood core. He is a big believer in them, not just in their ability to store and hold water and nitrogen, but also to encourage fungal growth, as it is believed the fungal network that grows in the bed helps to transfer nutrients where they are needed.

I will certainly give them a try when I have some land to work with.

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Wendy S. Delmater
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Good thread

I found this all very fascinating and took notes. Good thread Sandpuppy!

Oliveoilguy's picture
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Available Nitrogen?

I assume that the wood is low enough in the ditch so that more mature compost is in the root zone of the plants. I had always followed a rule of thumb  "to not bury raw materials"  because the decomposition process would tie up the nitrogen and not let it be available to the plants.

Obviously Hugelculture works...by all the successful accounts. So, I've learned something new today.

kevinoman0221's picture
kevinoman0221
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Nitrogen

Tying up nitrogen is a common concern people raise with hugelculture or woody beds. Spirko has said that there may be an initial drop in nitrogen, but don't think of the nitrogen as going away; it is more like filling a sponge. He has recommended putting some organic nitrogen fertilizer on it the first year to counteract this, or, what I think he himself does, is just plant it with a cover crop with lots of nitrogen fixing plants and let it sit the first year. I believe he often mentions Cow Pea and Vetch by name, but there are probably other good plants for this too.

Oliveoilguy's picture
Oliveoilguy
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thanks kevinoman0221

As an organic grower, nitrogen is always a concern. We are fortunate to have lots of horse manure and always have a compost pile that is ready to go. I'm thinking of trying the Hugelculture ditch and mound system with more decomposed matter.  I really like the water "reservoir"  feature since I live in a drought prone area of central texas.

Cheers

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Perennials

I would stick with perennials in the hugel.  I had trouble finding a satisfactory way to plant and harvest annuals, and keeping the weeds down.  When you weed, all the soil falls down, and transplanting also seems to scatter dirt to the bottom, as does removing a harvested cabbage root.  There doesn't seem to be a material advantage from the extra surface area of a steep sided mound.  Wind protection on the leeward side, or if you had multiple rows would be an advantage.  We did have a good crop of tomatoes, but they were invaded by bugs, and inedible.

I have now built a raised bed with a layer of wood on the bottom, it's still early days, but weeding and transplanting is a lot easier.

Grover's picture
Grover
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Longer Term Insights?

Since this thread is about 4 years old, anyone who has tried hugelkultur has about 3 years under their belts or 3+ years more experience under their belts. Perhaps, you can share some more "long term" insights.

My neighbor just cut down some big cottonwood trees and asked me if I wanted them. The trunks (30"+ diameter) all had heart rot while the branches up to a foot diameter are pretty solid. I've got adequate supplies of fresh->aged horse manure compost. I plan to use the garden for perennials (asparagus, rhubarb, currant bushes, lavender) and non-root vegetables like peas, beans, and squash.

So here are my questions:

  • How much has your hugelkultur pile consolidated over time? Give approximate dimensions of what you constructed and what it became?
  • Was there any nitrogen deficiency due to rotting wood? Was the wood in your pile fresh or aged? Was the nitrogen deficiency only a concern the first year? What did you do to compensate?
  • Have the watering requirements diminished as well? From what I have read, the first couple of years may need additional watering. Does your experience support this claim?
  • Finally, would you do it again knowing what you know now? What would you do differently if you had to do it over?

Thanks in advance for sharing information ...

Grover

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