Half buried hugelculture in a Mediterranean climate

This conversation was split off the thread Project: Intense Food Forest in the Mediterranean Coast of Valencia, Spain. Land rehabilitation as it is a GREAT topic in it's own right.

Abraham Palma wrote:About hugels, I'm not convinced that they are good for our climate. I'm trying the buried version of it, as recommended by a turkish fellow who has a climate more like ours. Thing is, those logs need water to decompose, and they will dry if left on the surface, even if you cover them with dirt. No water, no hugel.
I have no water at all, so I am trying a buried hugelkulture, you can see my progress in the thread of   the sunken bed.
Since you have some water and can irrigate when needed, my suggestion is to make a half-buried hugelkulture. Dig a trench on contour of 40-50 cm, place the logs without overlapping, cover with clean dirt, stones removed. Keep putting layers of logs, smaller as you proceed up to ground level, then add clean dirt with some compost until you form a small hill of 30-40 cm tall, not more. When it rains, it will hold running water thanks to being on contour, and it will keep it for longer thanks to having plenty of wood. You plant roots won't be bothered by the logs if they have 40 cm to develop underground, but the soil will keep moist for longer. That's the theory.
Just after you are done building the hugel, irrigate it completely so the logs start decomposing faster. Keep adding organic matter every year on top, as the logs decompose. In ten years there should be no more logs, only decomposed organic matter mixed with your dirt.

I was thinking about hugelkultur in Mediterranean area for some time and is there a way to have them despite those hot and dry summers and long draught periods that are happening more and more often. I like the idea of a half-buried hugelkultur.

Some backround: I'm on a small Adriatic island, beside above mentioned summers we also have mild and wet winters (usually). Very important factor is also a really strong and dry NE wind, cold during winter and hot during summer, specific for eastern Adriatic coast (local name "bura"). It drys out everything, and since it leaves a coat of sea salt over everything it can easily 'burn' the vegetation. Soils are shallow and rocky, depth at my place goes from just some 5 cm up to cca 30 cm depending on the site (not counting areas where I added a lot of organic matter over the years), so sunken or flat beds with burried wood are not really an option.
Hugelkultur would come in handy on a few locations to add protection from the wind - vegetables garden, new beds for herbs and veggies. Soil building and added area for growing that come with hugelkultur is a huge benefit with my soil. Also capturing more of that winter rain in the soil so plants can use it when draught kicks in.

I was thinking along the same lines as Abraham described above, only shallower and maybe a bit higher due to the conditions I have. Probably would use logs on a thinner side - what would be optimum in this climate? and for that size of mound?, and mix bits of other types of organic matter in it too. Wood that already started to decompose would be better than fresh cuts I think. I believe the timing of building could be really important in our climate. The idea is to build it at the end of the summer/drought period so the system can get 'up and running' during the wet winter/rainy period, when water isn't the problem. I would try to build it to catch first proper rain.

Another thing - establishing a good biology in the soil of the hugelkultur as fasts as you can is also important, it's biology that will make all that wood and other organic material into nice spong-like soil. So some fastgrowing ground cover all over it as soon as it is built, we need growing plants to feed that biology. Diversity is the key here because it adds to resilience of plants that are growing. Also it's important to have it established before heavy rains start due to erosion and stuff. Densely sowing mix of 10+ different species of annuals from different families can do the job of covering whole area fast and build a good soil biology in a short amount of time. For example mix legumes, clovers, grains, buckwheat, flax, facelia, sunflower, other flowers/aromatic. Also planting some aromatic perennials like creeping thyme and origano on top, sage, Helichrysum, lavander etc., shallots or other perennial Allium. Plant something at the base of hugelkultur all around. Ground cover mix can be cutted down to different heights when needed for adding perennials and sowing other annuals/veggies, kind of chop and drop, with patches of it left to grow and harvest and/or reseed.

I'm hoping this could be a good way to kind of jumpstart the whole process and that having a diverse ecosystem above and below "ground" would better deal with hot and dry periods.

Things to have in mind long term: keep the diversity going - more species is better & sow/plant as mixed as possible/practical, some kind of ground cover all the time (annual or perennial), adding organic matter. And seed saving.

Antonio Hache wrote:Also I will keep exploring on how much, how dense and how often to plant for family consumption. It is all trial and error and I have also the other "between rows" beds.

I think that the trend is to see how to decompose organic matter, wood included, in order to maximize abundance on a determinate climate... with minimum effort

What do you (and others) think, does my ramblings sound like something that might do ok in your area? Either way I will follow your hugelkultur journey with much interest.

Oh, this post might also be of interest, I just stumbled on it: https://permies.com/t/52077/Buried-Wood-Beds#422133

Hi Mare Silba. I believe your nice ramblings make perfect sense. I’d like to add that it all depends on your location and circumstances.
If you happen to have lots of old wood in a hot arid climate and you want to make it rot and act like a sponge for soil life maybe location is the most important aspect.
I could imagine doing that on a small scale as an experiment out of the wind close to a hedge which blocks a lot of sun already. But that would be feeding your hedge basicly. Which could totally be appropriate at times.
But a lot could happen with wood. Chipping appropriateit up for woodchips and mixing that with animal manure makes a very nice compost apparently. Woodchips on path, woodchips on beds to kill oxalis..
Or make biochar to add to the soil. Or make bed edges with it. Or just leave it in a pile as a niche for wildlife while creating another windbreak.
But in this case it was about Antonio’s question on how many to make on his land to feed his family.

Hi, Silba, you have quite a challenge there!

My approach would be the following:
1. Protect my gardening zone from the salty winds with a windbreak or a shelterbelt. You said there's roughly no earth there, only rock. But can you find lots of rocks? If so, build a big berm around your gardening area with the rocks, something 'U' shaped, where the opening is facing South-East, or even 'L' shaped. On top of this big berm place some dirt and plant some salt resistant bushes: rosemary or better mastic (pistacia lentiscus). The higher the better. Think of this as a raised hedge. Plant this hedge densely, without openings. It's purpose is multiple: It's stopping the wind strength that dries your soil, filtering the salts in the air, improving water retention inside and reducing temperatures a little bit.
2. Concentrate resources. Instead of having large zones with just 5 cm of soil, I would gather soil where I'd like to plant so I can have 50-60 cm of soil, even if I have to leave bare rock exposed around. Otherwise I can't see how I could plant anything significant.
3. With this patch of land having 60 cm of soil, I would start by planting some nitrogen-fixing dwarf trees or big bushes. Broom is a favourite around here. Legumes will provide nitrogen, cereals will provide carbon fast. They combined will be providing the organic matter for soil expansion as I cut/prune them every year.
4. To help soil expansion over bare rock, I would use small walls of rocks, as if I were building raised beds, but they will be not raised beds. They could be 1x1m boxes or a ring over my initial soil patch. This is just to offer more water retention and thermal mass around the working patch, and habitat for wild plants. In time the expanding soil will be deep enough for planting more bushes or crops.

This is a very long term project, so if I had the resources, I might bring some external resources, (loose earth, a good mix of sand, silt and clay) to speed up the process.
EDIT. I had added a picture of what I meant.

Just a quick review of my “semi hugel”: at this point, radish and beans are sprouting there. Lets see how many seeds grow, but it has been on,y 15 days since I planted everything, I cant complain. Maybe not high, not sunken, just something in between, might work. I sill keep you updated

My experiments with “half hugels” (wich, not being elevated, are not hugels) are going okay. But we are having more rain than usual, so let’s see hiw does the summer affects the whole thing.

I’ve done three things so far, getting inspirarion from the “bury logs thing”

1.- A small hugel. Elevated, but not too much.

2.- Ground level. Deep, with all the logs, branches, leaves, etc etc, but planting the vegetables just ground level.

3.- Regular bed with branches and leaves buried. This is, not logs.

The thing is experimenting with adding wood and leaves to decompose inside, but adapting it to the mediterranean need of water retention

I think a major variable is whether you irrigate. In a truly mediterranean biome you don't irrigate, and little plants survive; be it from the draught be it from the heat.

I bet one of your experimental beds is ideal for irrigation and another different one is ideal for non irrigation.

Abraham Palma wrote:I think a major variable is whether you irrigate. In a truly mediterranean biome you don't irrigate, and little plants survive; be it from the draught be it from the heat.

I bet one of your experimental beds is ideal for irrigation and another different one is ideal for non irrigation.

Hola Abraham. All 3 are without irrigation