Hugeculture Time and Gravity

I've found my best hugels are made using raised beds. The sides keep soil near level to prevent erosion. Depending on the rain amounts where you live? Here the torrential rains will erode topsoil off a hilltop. Unless the hilltop has continuous natural vegetation and leaf mulch. So again I think important for mulch or living mulch on beds. Dry mulch seems to be a problem over time as mulch ends up sliding down the mound. I like the design of the S shaped hugel, the hard part is to retain the soil on top. What are your experiences?
Also I'm a bit skeptical about the moisture retention. When I dig up and old root or log its many times dry and crusty. I think with periodic rain it would retain moisture. With a distinct dry season I'm not so sure unless periodic irrigation is used.
What are your thoughts on long term hugel production?? This topic has been blown off on other posts. I found the first year to be the best so far. I expected to be better with time. I'm not sure why? It may be because of my larger initial inputs of compost and manure mixed with rice husks and ash in the beginning. So again how has your hugel done after 2 and 3 or more years.

I have one that was created from the previous owners home burning down and the left overs being bulldozed into a mound. This happened seven years ago and it was on its own until last year when we started clearing our spaces. All the cut down saplings have been piled on this mound, they are not rotting yet but the underlying mound grows native grasses quite well. The wood inside has started rotting and some of it is actually biochar and acting like it. We do have some rabbits living in this mound. It does have some issues, such as metal rusting away, concrete blocks and bricks, some plastics are in there too. The offensive materials will be taken out in the next few years and the mound will be rebuilt properly at that time.

The other mounds we have were built with burnt logs, some of which were already decomposing, these mounds do hold water quite well. They are currently providing our passion fruits places to grow and this year we are adding some vining squashes and some cucumbers, along with a few other items to help build the soil. These mounds just got their spring haircut (chop and drop of the winter growth) and they will finish being planted in the next weekend or two. We have plans to do a few new mounds this year to hold our strawberries.

We built one mound last year using new cut logs, this one mound has been test dug after one week of rain nearly every day, the logs were dry, I attribute this to the fact that the logs have not begun to decompose since the mounds with rotting wood were found nice and wet at the same depth.

When I build a mound I try to start with larger diameter logs that may be fairly sound, from that single layer I try hard to only add decomposing wood, I feel that the decomposing wood will help get that solid wood on the way to decomposition faster than if all the wood was new, sound wood.

I have a friend that is an archeologist and I have seen wood found after being buried for centuries, it was still sound. If wood is buried in an anaerobic atmosphere, it seems to last forever. One example of this phenomenon is wooden ships that have been found in bogs, the wood is still fairly sound despite being soaked for hundreds of years. I've seen a Viking ship that was found in such an area, they were able to use the planks for patterns to build a brand new ship, completely down to the placement of the binding ropes that held the planks together. Such is the nature of wood and organic fibers put into just right conditions, they can be there for hundreds of years, waiting to be discovered.

All good info but keep in mind what actually breaks down the wood, it's the fungal network, or mycelium, that eats the rotting wood and turns it into something that can be used by plant root structures. So what I would recommend is burying soil inoculant in with the wood, even if it's still green, and then making sure there is air pockets around the wood. The reason a ship, or any organic material for that matter, wouldn't decompose covered under soil is due to several factors: extremely high or low pH (kills bacteria and fungus responsible for eating and breaking down organic matter), too dry for too long (bacteria and fungus will go dormant or die without water), and/or no oxygen (such as clay soils that essentially create a hard shell around the organic material). The reason a peat bog preserves bodies and plants so well is that it is full of tannic acid and so mummifies all that enters by inhibiting fungal growth.
I hope that helps! So even in an arid region, mulching, inoculating, and keeping moisture is the best bet for breaking down the wood in a HK berm.