I have built a new hugelkultur system that is basically a steep slope against a wall facing south-south-west. The concept is similar to the one discussed here. The aim of the system is to provide a warmer climate and a longer growing season by using the thermal mass of the wall.
In the picture: the dig, the biomass (part of it), the complete slope, deep mulch of leaves.
Questions for the experts:
1) What would you sow in it (considering 2 priorities: fertility building and slope stability)?
2) Would it be profitable to blacken the wall and the blocks for more heat storage?
3) Would it be useful for water retention to dig a small trench or swale in front of the blocks line?
Any answer, suggestion or comment would be mostly welcome. More pictures of the system's evolution coming soon on ortomontano.
Cj Verde wrote:It doesn't look right but it could be a trick of the photo. It should have logs or at least substantial branches say 3" or 10 cm surrounded by soil. It looks like a pile of brush with leaves on top. If that's the case, the small branches will lock up N and seeds might not sprout if there's no soil to make contact with.
I have dug a 30cm + deep pit and I have put logs in it, let's say 20% of the biomass is wood. Part of the logs are fresh and part are rotten and spongy because of fungi. I have used wood of hazelnut, apple, plum, maple, fig tree and willow (yes, I took that risk). I used only biomass found in walking distance. In the pic you can't see the wood because it is in the pit with twigs and branches on top (second picture, top right). In the third picture (bottom left) you can see the soil (30+ cm) put on top of the brush pile. In the last picture (bottom right) you can see the slope heavily mulched with leaves, tree barks, twigs and hazelnut shells. Under the mulch there is plenty of soil for seeds to make contact with.
I have mixed emotions regarding painting the wall black:
Black would retain more heat (and slowly release it after the heat of the day passes).
White would reflect that heat back onto the back side of the plants during daylight hours.
I guess it boils down to do you want it warmer during the day, or do you want to prolong the hours of warmth?
John Polk wrote: Water seepage, if sufficient could under mine the wall's foundation.
I think this might only be an issue if the water is entering from behind the wall. If the wall has a proper foundation, moisture in the hugel doesn't seem to me like it would be a problem, as it would not be exerting pressure from behind which might compromise the wall.
Not an expert, just what I'm thinking based on reading, not experience....