Buried Wood Bed (sunken hugelculture) and Terrace Combo

This is my third attempt to tame the sloped area that I call as “lower garden”. It has a slope of 40-50 degrees. There is a negligible layer of topsoil, underlaying soil is mostly clay and rocks. Erosion is a major issue and roots cannot penetrate in this south facing slope. When they reach a certain height, all the trees either die in summer due to lack of water (clay gets baked) or topple over in fall/winter due to wind or snow.
It was a sun baked, bare clay eight years ago. All the topsoil was washed away. For my first attempt I covered the whole area (roughly 1 acre) with leaves, glass clippings and any organic matter that I was able to get my hands on.
I brought in many bags of leaves from nearby forest (obtaining those permits were just pain).
Covered with leaves:


I put branches over leaves to hold them down and carpet bombarded with seeds balls of all kinds of weeds and some radishes. I made mushroom slurries from all sorts of wild mushrooms and even brought in earthworms since the land seemed that it didn’t have any. I went to a public land, poured buckets of soapy water, picked the worms, gave them a clean bath and brought them to the garden. The land responded very well; weeds started to grow, and we had epic harvests of radishes, garlic, winter squashes and so on. Trees, whatever were left, ceased to die. I don’t know whether mycelium can stop trees from toppling over, but no unexpected tree falls happened since the day we started to observe mushrooms. Occasionally a sick or injured tree might come down, but those were windstorms/snowstorms doing the work instead of me. I was very happy with the results.
Jungle of radishes:


Unfortunately everything started to move. Nothing like a landslide or such, it was erosion. As the worms and critters were digging and opening tunnels, they were loosening it. When it was dry, worm castings turned into hard soil balls and rolled down the hill side. When it was wet, worms were busy digging new tunnels, but newly formed topsoil was not able to hold against water and gravity. Pathways were covered with foot-deep soil and leaves after any major rain event. I put more leaves and many layers of branches and I was able to stop erosion from happening. Unfortunately, this solution turned into a problem. It stopped erosion, but the branch layer was 2 meters (6ft) deep. I gave up and let the invasives take over the show, wild blackberry and tree of heaven. I can’t get even get in or walk on pathways, but it stopped erosion immediately. Part of the garden turned into a safe zone for birds and other critters. Unfortunately, occasional blackberry harvest is all I can get.
Soil balls:

For my second attempt, I tried to create a table top hugel bed with a reservoir. Water is always an issue for this south facing slope. Reservoir didn’t work and table top hugel design didn’t perform as intended. I came up with solutions such as putting a drip line over hugel and now it performs quite good, but the eventual solution was complicated and also required watering. I want something simple, something straightforward that can be repeated with ease. The solution that I am seeking might not be simple for initial set up, but it should not require any major burden to get meaningful harvests.
Table top hugel:


This is my third attempt. I am terracing! This solution is very simple and straight forward. My terraces will not be as impressive as what Incas did or Filipinas, but there are no reasons for it not to work.
As always, I have limited access to most of potential resources:
Very limited budget
Limited available time – I am busy as usual
Limited external labor input – can’t effort it at the moment
Limited farm resources such as manure, straw and hay – cost prohibitive to bring in
No wood chips (nobody does that), no grass clippings (all parks are adjacent to major roads) or leaves (can’t get any more permits recently, leaves from parks are mixed with all kinds of trash)
No concrete – can’t use concrete without permit and they don’t give permits.
No excavator – can’t afford and, again, permits.
No humanure – I just don’t like it.
On the other hand, I have access to stones, rocks and a lot of clay, wastes from the garden, occasional help for labor, a lot of expired dog/cat food, coffee grounds and some kitchen scraps. I have free access to many stuffs that permies would avoid such as chemical fertilizers (funny story) and mostly avoid such as cardboards. I am going to use these terraces for food production, so chem’s or cardboards will not be used. Himalayan salt and fish scraps will be added for micronutrients and mushroom slurries will help to turn compacted clay into top soil. I have 20 bags of aged manure, which makes me feel lucky.

It is going to be a repetitive process and very likely that it will span a couple of years. I want to document and demonstrate how it begun. Nothing very impressive or jaw dropping. This is the story of how I turned a “impossible” land into a vegetable and fruit garden with a budget of roughly 8$ per square meter (1$/ft2 - 42tl/m2) for materials and a lot of exercise for labor (45 days).

It is going to be a very long, boring and mundane work. If I let my inertia free, it has a potential to burn me out. So instead of focusing on the results far in the future, I divided the project into smaller pieces. Each piece will be standalone. In other words, instead of building a 100 m long wall and then working on soil the next year, I am going to complete a 10 m section and get some produce to enjoy. If I feel like it, I will continue. As they say, start small.

There is a thin layer of topsoil that formed by my initial experimental endeavors. Eventually I will need to create top soil. The best method to turn this terrible clay and stone mixture is hugel beds and I have some experience with hugels and buried wood beds. Also, RedHawks soil treads are immensely helpful. I think buried wood beds works better than mostly or totally aboveground hugelbeds for the region I live in. They are, as hugels, are the best tools to build soil if you are into digging.

Initially I cleared the area from brambles and marked the area where I will be building the dry-stone wall. It will be no higher than 1m (3ft) and will have a minimum thickness of 50 cm (1,6 ft). Just rule of thumb.


As I started to lay down stones, I used clay from the hillside to fill the gaps between stones. I have had problems with snails and they love cool dark places between stones. I had to take down a 25 m dry sacked wall as it turned into a snail and slug factory. I am no expert on dry-stacking, but I tried to place each stone locked in place by other stones. It turned out to be steady.


After I finished my work with the wall, I leveled out the terrace area. Topsoil is reserved for future use. I need to fill some pits in the garden from previous projects, so excess subsoil was separated. The white tarp you see in the pictures are put to protect subsoil from getting rained on. Clayey soil gets very heavy and sticky when wet.

This project is not “hugel culture on contour”.  I am not going to go into why I think it is a bad idea. This is a project of terracing a slope-side but instead of importing topsoil for each 60 cm deep bed, I am using permaculture techniques to create my own top soil. Moreover, I am going to divide the terrace into 4-5 m parts in the longitudinal direction. Each part will be separated with a wall of original subsoil of 50cm to 1m thickness. It won’t be visible, but it gives me opportunities to experiment. This part of the terrace has a utility line cutting through. In one part I will be digging in 30 cm deep steps. The other part will have a constant depth of 60-75 cm’s. Both will have packed earth of 40-50 cm thickness on the wall side.


Fist 30 cm deep step:


While I was digging, I came across some decomposing roots and buried pieces of wood. I found them interesting as new roots were using them as a highway through hard clay.
Through a decomposing root:


opened a bit:


Through a buried branch


This picture is to give an idea about the soil I am dealing with. Please discard the top third and bottom quarter of the picture, they don’t show the soil profile. As you can see, top 20-30 cm of soil has roots. The very top 10 cm of soil has a darker color. There are no or very few roots below 30 cm mark, since clay was impermeable. I realized that it was bone dry, even though the whole area was covered with leaves, branches and bramble for over 4 years. So, evidently rain cannot penetrate more than a foot deep.

After the digging was complete in the first part, it was time to fill it. The first to go in was invasive stuff. My first hugel beds were 80% wood and 20% soil, which turns out to be a very common mistake. Some hugelculter images in the internet can be misleading. It was very useful at promoting wildlife, but not so good for veggies. Now, I aim for 40% wood, 30-40% soil, and rest is topsoil, manure etc. I aim for 50-60% for underground wood beds and include more of greens. I add a thick layer of topsoil mix (topsoil, compost, leaves and coffee grounds) on those beds each year anyways. I put larger sized bits of wood over the “invasive layer” and gaps are filled with coffee grounds and soil. It is thoroughly watered (flooded couple of times) after it is covered with a 10 cm thick soil layer. Some can claim that flooding and adding green materials such as coffee grounds and fresh green leaves of invasive species can create an anaerobic environment, but this layer will be alive with all those earthworms and such. Wood will absorb any excess water and oxygen can travel to this depth quite easily if the soil is alive. This concludes the first layer.
Digging is complete:


Bigger sized stuff:


First layer complete:


Second layer is built in a similar fashion, but this time with smaller branches and lack of invasive plants.  I was planning to add kitchen scraps from a nearby restaurant, but the deal was delayed, and I tried to compensate that by adding more coffee grounds and green waste from fall cleaning.

Green waste:


The final layer is the topsoil-mix. Topsoil that was put aside, was mixed with fall leaves, coffee grounds, manure. It has a thickness of 20-30 cm’s to compensate the soil settlement that is going to happen in the first year.

For the constant-depth buried wood bed, I wanted to test some ideas.
Constant depth bed:


I think wood of some alien species act as if bad wood while they are not so problematic in their native environment. Tree of heaven is an example for my situation. If you bury it, it is not going to rot. So, years back, I separated bad wood and made a pile for future biochar projects. Funny thing to see them getting colonized slowly by fungi. Even though I don’t know their names yet, I know which local fungi is compatible with whichever “bad wood”. I added some colonized branches for my hugel-raised beds, and they made a substantial impact. Here are the pictures of some colonized tree of heaven


and walnut (not 100% sure about this one though, can’t remember) branches:


Tree of heaven goes in:


Other invasive or problematic stuff:

Put logs (one of them is a log stayed submerged in our pond for over a year),


covered it with coffee ground and soil,


and got the pit flooded:
https://permies.com/t/96241/a/67943/thumb-DSC_0257.JPG

Second layer goes in, smaller branches covered with green material and top soil mix.


This time I added some gypsum to the top soil mix:

General layout:


Couple of layers of stones are added over the dry-stacked wall to reach its final height. The whole bed is covered with top soil mix.


Planted right away 😊 Radishes, swiss chard and parsley:


and:

Built a low tunnel to prevent crows from digging and future winter protection:


After all is complete, first delivery of green waste (kitchen scraps and veggies from restaurant).


Built a compost pile and the goal is to spread it before spring-summer planting.


What’s next? I am going to build various compost piles for future terraces. Hopefully some biochar will be added to terraces.  I am going to flood these beds for couple of times when excess rainwater is available, so that those dry logs can absorb more. Winter is here!

Last but definitely not least. Thanks to everyone who helped this come true:  all the folks here in permies for sharing their experiences and trials, learned a lot. Thanks for this forum environment and hard work :) Thanks to all that helped digging! And thanks for piles of coffee grounds, starbucks!

Thanks for sharing all these pictures.  I also have a "tree of heaven" problem, it's interesting that you've found it doesn't break down as quickly as the native species.

I like it. Very well done. I have many similar slopes that I must start working with. The few flat zone 1 & 2 spots here are already well underway. Have the same basic terraced hugelkultur plan as you showed. Thanks for sharing.

Good looking dog too!

These are great pictures and really interesting ideas.  Thank you for showing us how you do it.
John S
PDX OR

Thank you so much for this post!  I also have slope and clay,  although not as extreme as yours, and have been struggling with how to deal with it, as my topsoil each year runs down the yard.  I built a couple low retaining walls, to try and stop, but I LOVE the idea of incorporating the hugel beds!   W fortunatly have access to free loads of compost from our town, and I have been using that to level out the layers (but moving 10 pickup loads of compost with a wheelbarrow is hard work.  Like you, I have found picking a small goal and feeling the accomplishment is a great way to get a big project done!

What is your gardening zone and elevation, may I ask? And, is your soil alkaline?

Thanks again for posting!

Sandy

Be careful the hugelkultur doesn't act as a swale, because misery may result:  https://permaculturenews.org/2015/11/06/dont-try-building-hugel-swales-this-is-a-very-and-i-mean-very-bad-idea/

Be sure terraces can drain, rather than trapping water.

I think this is brilliant!  Thank you so much for all the time and effort you've taken to share this with us.  Please continue to update this thread as your experiment continues.

Fascinating project. For reference, I don' know much about hugelkulture on hillsides, other than what I just read here. I was apprehensive while reading of your first attempts to keep leaves and organic matter on that extreme slope. My apprehension I believe came from worrying that the hillside would continue to slide. Beautiful dog by the way. I liked the way over the years you addressed issues you observed during the first years, but somehow I kept coming back to the cute dog down below that mass of organic material and clay. Then I came to Tyler's link to  JACK SPIRKO's discussion of combining Hughelkulture and swales. Naively I had no notion why I worried until he described what happens when the watershed above saturates  the organic matter. Jack emphasizes that scale is important, but math needs to be done to determine how much water might present to the hugel bed.  
Here is a link to the Youtube portion of that link

I hope this is helpful and not lecturing.
Brian

Tyler Ludens wrote:Be careful the hugelkultur doesn't act as a swale, because misery may result:  https://permaculturenews.org/2015/11/06/dont-try-building-hugel-swales-this-is-a-very-and-i-mean-very-bad-idea/
Be sure terraces can drain, rather than trapping water.

Brian Rodgers wrote:
I hope this is helpful and not lecturing.
Brian

Thanks for raising concern. We are on the same page on this actually. I gave exactly the same link Tyler shared, in the 4th post (link is: bad idea):

s. ayalp wrote:This project is not “hugel culture on contour”.  I am not going to go into why I think it is a bad idea.

That being said, I guess I need to clarify my situation.
Firstly; this is not a finished project. It is the very first trial run. I am planning to repeat the process changing and upgrading design based on observations. My observation for this land is that, I can put a packed earth partition behind the dry sacked wall without raising water table (my second attempt: table top hugel). Water can not pass through the bottom clay layer (reminds me rice terraces link) in the figure: layer 8 is an impermeable layer. Besides even if it does, there are cracks in the bedrock and water will drain very well. I might have added a drain pipe to drain excess water or put a layer of plastic under the bed; but I wanted to observe how it performs before opting for more complex solutions.
It is not a swale if it is only 4-5 meters long. That's the reason why I used the utility line as an opportunity to divide the underground parts.
It is hand dug. Definitely not something similar what Sepp does with excavators. Hand dug and built rice terraces are better to compare. They do hold water and some organic matter.
Finally, I did do some calculations! It meets required factor of safety values for global stability, bearing capacity and such. I had to assume many parameters though. Heavy wet logs do not differ min FoS significantly (applied as surcharge load). On the other hand, it is not possible to achieve global stability and bearing with high water table.

Lets see how these perform. I'll update :)

Sandy Smithsson wrote:Thank you so much for this post!  I also have slope and clay,  although not as extreme as yours, and have been struggling with how to deal with it, as my topsoil each year runs down the yard.  I built a couple low retaining walls, to try and stop, but I LOVE the idea of incorporating the hugel beds!   W fortunatly have access to free loads of compost from our town, and I have been using that to level out the layers (but moving 10 pickup loads of compost with a wheelbarrow is hard work.  Like you, I have found picking a small goal and feeling the accomplishment is a great way to get a big project done!

What is your gardening zone and elevation, may I ask? And, is your soil alkaline?

Zone 9b, Mediterranean climate, elevation 82 to 100 meters (terrace is located at 95-96 meters I believe). The property is located in a deep valley, we have very strong micro climates. Currently these terraces do not receive sunlight more than 5 hours. It is slightly alkaline, around 7.5. Thanks!

Thanks a lot Julia, Mike, John, Brian and Marco (:

Wow! What a beautiful job you have done with your combo! I solved a similar problem (although on a much less steep slope) by first planting alfalfa on the slope, the deep roots helped stabilize the soil  while i did my digging. It has this consequence that you are pretty much stuck with the alfalfa for life after that, it self seeds in alkaline clay and survives any amount of drought and heat once rooted. Makes a great mulch if you have time to chop and drop and always a welcome addition to the compost heap, but if you cannot spare the time to keep a hand on it you will spend your days keeping it out of your lovely beds.

Hi everyone!
I am continuing my endeavor to terrace our property. This year has been very strange for all of us, but it has been very tough on me. I don't want to flood this thread with personal stuff, so I am not going to go into details. Let's call it destiny, it is just things over things, financial, health, loss, kind of a break up, let downs etc. It was roughly 3 weeks ago, I wanted to cry, but I couldn't because I wanted to yell. I couldn't yell, because I wanted to punch something.

I had to do something.

So I started digging. Again!

I completed the first phase of my fourth attempt to tame this land. Digging didn't help a bit frankly. It was really hard to sleep when your whole body is hurting, and it is really hard to feel optimistic when you don't sleep. I planted some beans and some corn with neighbors and their kids two days ago. Joy on their faces made me feel better. Best part of it, kids won't fake it. So that is nice. There are problems ahead, actually none of them are resolved. BUT, If I still have the strength to brighten a day of mine and others during probably the darkest part of my life, I think I can manage. Instead of breaking things or punching, I forcfully transformed negative stuff into something positive.

That feels good.

Enough with mumbling, details ahead.

Originally, I gave myself 4 to 6 months to finish this work. So we started slowly and tried to enjoy with tea breaks etc. Then, as I said, I overtook to whole work. Lockdowns helped a lot. It is roughly 40 square meter of growing area added to my vegetable plots. Here is the figure:

It will be 3 terraces, each roughly 1.2 meters wide (4ft) with 30 to 40 cm (roughly 1 ft) pathways in between. Beds will be hugels as I like to do in this climate. I guess I can call them as burried wood beds, but I dont want to complicate definitions. Lets call this kind of hugels, one side burried and the other covered with sheet of wood as terrace-hugels.

Yes, I know, it is not wise to build hugels on terraces. Especially perpendicular to the slope. BUT I am a structural engineer and, yes, I made some calculations. It will hold with a safety margin triple of my third attempt. So, it is fine. If one does not know how to calculate slope stability and basic foundation engineering stuff, please don't attempt to build hugels on slopes.

My third attempt cost almost nothing. On the other hand, it didn't take advantage of the whole area and it was very labours to build stone wall and dig under the terrace level. This time, I used 1.5 meters long half inch iron pipes and 4 mm thick sheet of wood. I know, wood is going to rot probably less then 2 years. Frankly I dont care. It is so cheep and easy to build that I can change them each season in the next 20 years, and it will be less labours than my third attempt. Pipe-piles are roughly spaced 50 cms to limit deformation of wood sheets. Beds are 55 cm high, which I found to be ideal to reach ahead. I used the rule of thump to hammer the pile in twice the length that is above soil level (50 cm above soil, 1m below). It roughly costed 1500 turkish liras to build 40 square meter of growing space, so 6.25 dolars per square meter, or 0.6$/ft2. It took roughly 3-3.5 hours to transform the slope into 1 square meter (roughly 10 sq ft) of growing space by manual labour.

It is in four layers. First layer is the larger sized logs covered with green stuff. It is covered with a bit of soil and then another layer of branches and soil. The third layer is compost over soil times 2 to 3 times, which is covered with the forth layer of store bought topsoil (cheapest that I can find). The foruth layer is there just to give a nice finishing and easy planting. It is only 1 inch thick. As they tend to dry out, logs and branches should not touch sheet of wood so I left a 10-20 cm thick layer of clay soil in between.

I didn't go below the pathway level and gave a gentle slope towards it just to shed extra water to the bed below and it was easier to dig this way.

So we started digging the slope for the second terrace (so we can pile soil on to the fist ones place)


added logs


added green stuff and covered with soil


and repeated the same for the second layer


and layers of compost and soil

repeated to process for the scond terrace and started to dig the first terrace.


digging and pileing stuff


crosssection of first terrace


digging and adding


Started digging and adding material - the third layer

boards arrived


you can see the soil layer between logs/branches and sheet of wood to hold moisture (cross section of third terrace)


compost layer added


a bit of overlook


and


digging and digging


started to look better

store bought top soil arrived


I almost forgot to completely soak the beds


another angle


almost complete


digging....


and


logs for pathways

and DONE


I might continue though. Probably we will have lockdowns for the next few weeks .

We had lockdowns, so I kept on chasing my endeavour. IFor any meaningful harverst, 15th of june is the last day to plant summer crops in Istanbul. so I chose that date as a deadline.
I was able to add an additional 20 square meter of growing space, but I was only able to plant half of it. It is funny that I was able to do all that hard work for weeks and then had no time to plant the rest. Whatever, I am going to plant some flowers in the remainder section.

All the seedlings suffered initially. It took some time for their roots to reach the layers of compost. As each one reached that layer, boom!, peppers, eggplants, corn and pumpkins are putting out leaves and growing like crazy. It was a quite late for planting this year. So I dont expect harvest per plant to be high, but in total, unless a mishap happens, I will get a lot more than last year.

So digging and piling what ever left to burry:,


Board and covering with dirt (this one had only a single layer of wood)


And tidying it up + planting


Final view:

Update,
Terraces are performing as they were intented. No drainage problems, no excessive settlements. No fertility issues. No landslides,

Here is the one that I built 2 years ago, covered withbeans and tomatoes.


And this is the mid july picture of the terrace that was built this year during covid-19 lockdown. As of 9th of august, Corn is taller then me with some 2-3 ears, peppers and eggplants are covered with fruits, snake beans are performing very well, scarlet runner beans are suffering from heat. Pupmkins and squash are doing good also, considering that this is the first time that I am growing these varrities.

Thank you, s. ayalp, for this informative and inspiring post!  I've been struggling for some time to determine the next best move to continue the transformation of my hillside.  My terraces were cut in 3-1/2 years ago and poke weed and brambles quickly took over.  With your very detailed post I now know how to do the next right thing.  I will link to my progress posts here soon.

Thank you again!

Last sunday was the end of harvesting summer crops. I devoted most of the top terrace to saving seeds from trials. I was able to harvest more than 100 kgs of eggplants and 80 kgs of peppers (most of it hot peppers) from lower terraces. I was not expecting yields to be high, but we had hotest septermber and october in record. So yeah, I'm glad!.

Before planting fall-winter vegatables, I added gypsum (to help with clay), bad guano and bone meal. I tilled the top shovel depth. I planted garlic, swiss chard and broccoli with winter radishes.

Chard with radish:


Planting garlic and lime+gypsum+bone meal


Final:

fantastic and inspiring work!  

I've come to be of the opinion that, given an individual

1. is not trying to cater to specific plants that need better draining soil
2. is not in the path of too much water flow
3. is not trying to sunscoop or airflow manage a micro climate
4. does have drought/water stress as the primary limit of plant growth (seems like most places!)
5. does have some elevation change to work with
6. probably something else....

the hugel terrace is the better design.  It's going dry out slower come hot hot summer.   If it's plugged into seasonal groundwater flows, it's going to dry out a lot slower.  

I haven't had an issue, and have had water success with the "conditionally legitimate no no" of making a hugel swale on contour.   With the condition that the maximum depth of the swale is like a foot, and the hugel terrace is like 10 times wider than the swale, and the "swale berm terrace" is colonized with roots before the swale floods, using a watcher catchment that's juuuust the right size to soak the hugel terrace can make for damp soil 2" below the surface, meanwhile the raised mound berm is bone dry to a depth of 10" after so many weeks into the dry season...

Also this post made me realize that I should have spent $500 on guano, fishbone meal and gypsum 5 years ago!  Whoops.  Thanks for the hot tip and super post.