we've just built a greenhouse and a bed that runs on the length of it is ready to be filled. I was thinking of adding some wood at the bottom, a bit of home made compost and chicken litter (in wood shavings) and fresh comfrey.
We live in Shetland, so needless to say there aren't many trees around... We have some unusual stuff : massive beams of douglas fir that have spent about 20 years at the bottom of the north sea (hubby got them of work and used some of it to build the greenhouse). They've been out of the sea for a couple of years now and lying outside. Do you think they'd be any use for a hugel bed? Other option would be to use driftwood.
You can use either in the bottom. The Douglas Fir is a fine wood, especially since it is recovered wood so you might want to decide if your going to build anything else before using it in a mound.
The drift wood is really good to use in mounds, it will not have the sea mineral content of the douglas fir so it will not possibly be detrimental at all.
Once you have the wood laid down it would be a good idea to soak it down with fresh water before starting to pile you compostables and dirt on, that will get the wood saturated with water and help it begin the rotting process.
I should also mention that research has shown sea minerals to be perfect complements to growing food gardens and livestock. Seaagri is a company founded on the research and they have the data to back up their positon on the use of sea minerals for healthy plants and the animals that eat those plants.
They increase the flavonoids of fruits and vegetables, work as a mineral supplement for most animals and animals given free choice of grass/ hay grown with and without the sea minerals always choose the grown with sea mineral offerings.
I can gather seaweed very easily here and was planning to incorporate some into the hugel bed. Don't like mulching with it too much as it's difficult to prevent it from touching the plants or seedlings (and it's very windy up here). I've incorporated a few bags of it to the garden soil in Autumn instead... Hope it makes sense to proceed this way!
Sheep that have access to a beach often graze on seaweed, especially in winter.
I much prefer to use seaweed the same way you describe. I put it into the ground instead of using it as a mulch. I also add it to the compost heap. My problem is the expense of bringing it to Arkansas.
The reason you see sheep grazing on kelps (seaweed) is for the mineral content.
I've taken to using a product called Sea-90 from Seaagri which has 90 minerals and trace elements, the stuff is simply amazing and cheaper for me than getting seaweeds.
I'm jealous, wish I was where I could gather my own seaweeds. Since I'm land locked, I use the Sea-90 now for keeping my costs down.
Chemical analysis of land plants shows their mineral and trace element content falls very short of the analysis of seaweed.
The reason; guess where all the minerals, trace and compounds go when the rains leach them from the soil. Answer; the oceans.
While you could perhaps be able to make up a compost with many of the compounds but most plants tested seem to be missing quite a few of the trace elements.
This is most probably caused by the manipulations over the past hundred years or more, once a mineral or trace element has leached away, it is gone unless you manually put it back in place.
This means that if you grow just about anything in soil that has not been fully amended, you are growing plants that are missing those elements, compost them and the missing elements do not magically reappear, they are still missing.
I am a remediation kind of soil scientist, I tend to build my own soils to as complete as is possible in every aspect.
Contrary to some beliefs, salts are needed by plants and animals, it has only been in the last 60 years that salt was said to be a detrimental thing for both, now it is being proven that the previous thinking was very far off base.
My farm is a laboratory for plant and animal nutrition experiments which I carry out in an effort to find optimum techniques for growing the absolute best foods possible.
Nutrition is the prime goal with productivity being secondary or even tertiary in the end goal.
Currently my focus is three fold; Proper balance of components for agricultural soils, Mycorrhizal remediaton of soil for better nutrient up take by plants and extending the work started by Dr. Manyard Murry in the 1970's.
Sounds very interesting! Shame you're on another continent, I would have liked to visit your farm.
The technic I've heard (apart from home made compost) to regenerate soil "quickly" is the ramial wood chips. I'd love to experiment with that but I'd have to ship it here and it's just too expensive... So I'll stick to seaweed!
if you get the chance, do a taste test of the same food (tomato works well for this as do radishes and lettuces) grow some in soil with no seaweed added and some with, take a sample of each when ripe for harvesting and taste them one after the other.
I would be surprised if you don't find the sample grown in the seaweed soil tastes better and it will last longer in storage. The plants will also be markedly healthier.
The sea-90 has been tested and found to stop many diseases in fruit trees, Dr. Murry even grew some peach trees and gave them curly leaf virus and they didn't develop the disease.
We did something similar Aurore. Built a raised bed garden with concrete block sides 24" tall. I call it a semi-hugel... I used 4" perforated tube right down the center for good drainage, then added 16" of wood chips, rotten logs, rotten wood, and such. Topped with 8" good topsoil specially built in another area of the garden.
This is the second year we've had it running, and I like that you can sit and work, we're both 65... Sounds like your greenhouse ought to work. I am a bit surprised at the settling in our raised bed. You would benefit to have plenty of good soil set aside for settling.
I used douglas fir, white fir, and pine, along with some charred slash in my greenhouse beds. It's worked out really well here in North-Central Idaho. If you click the link in my signature line it will take you to an in depth article about how I constructed my greenhouse with raised hugel type beds. It seems pretty much to be what you are talking about. I like these beds much better than planting into the ground (better water retention, warm up earlier in the spring, and really easy to work on) or on tables in the greenhouse. I say go for it, you won't be disappointed!