Interesting concept known as Hügelkultur is growing as water becomes less plentiful in many areas. Many people use part of this method already. Here is a link to learn more
https://www.permaculture.co.uk/articles/many-benefits-hugelkultur
The idea of using wood in the ground is foreign to me as it locks up nitrogen. Perhaps it’s not a bad thing if done correctly.
" Hugelkultur, pronounced Hoo-gul-culture, means hill culture or hill mound.
Instead of putting branches, leaves and grass clippings in bags by the curbside for the bin men… build a hugel bed. Simply mound logs, branches, leaves, grass clippings, straw, cardboard, petroleum-free newspaper, manure, compost or whatever other biomass you have available, top with soil and plant your veggies.
The advantages of a hugel bed are many, including:
The gradual decay of wood is a consistent source of long-term nutrients for the plants. A large bed might give out a constant supply of nutrients for 20 years (or even longer if you use only hardwoods). The composting wood also generates heat which should extend the growing season.
Soil aeration increases as those branches and logs break down… meaning the bed will be no till, long term.
The logs and branches act like a sponge. Rainwater is stored and then released during drier times. Actually you may never need to water your hugel bed again after the first year (except during long term droughts).
Sequester carbon into the soil.
On a sod lawn Sepp Holzer (hugelkultur expert) recommends cutting out the sod, digging a one foot deep trench and filling the trench with logs and branches. Then cover the logs with the upside down turf. On top of the turf add grass clippings, seaweed, compost, aged manure, straw, green leaves, mulch, etc…
Sheet mulching (lasagne gardening) is like composting in place. Above: just a suggestion as to sheet mulching layers. Nitrogen-rich material such as fresh grass clippings or green leaves put right on the hugelkultur wood would help jump start the composting process. Could also include seaweed, straw, dead leaves, leaf mould, etc…
The first year of break down means the wood (and fungi) steal a lot of the nitrogen out of the surrounding environment, so adding nitrogen during the first year or planting crops that add nitrogen to the soil (like legumes) or planting species with minimal nitrogen requirements is necessary, unless there is plenty of organic material on top of the wood. After the wood absorbs nitrogen to its fill, the wood will start to break down and start to give nitrogen back in the process. In the end you will be left with a beautiful bed of nutrient rich soil.
Tree types that work well in hugelkultur:
Hardwoods break down slowly and therefore your hugel bed will last longer, hold water for more years and add nutrients for more years. But softwoods are acceptable as well, a softwood bed will just disintegrate quicker. Mixing woods with softwoods and branches on top, to give off nutrients first, and hardwoods on bottom, sounds like a plan if you have access to multiple types of wood. Yet the newly decomposing softwoods at top will eat up a lot of nitrogen at first, so compensate for that.
Woods that work best :
Alders, apple, aspen, birch, cottonwood, maple, oak, poplar, willow (make sure it is dead or it will sprout).
Trees types that work okay :
Black cherry (use only rotted), camphor wood (well aged), cedar/juniper/yew (anti-microbial/anti-fungal, so use only at very bottom or unless already well aged. Cedar should be broken down before new plant roots reach it), eucalyptus (slightly anti-microbial), osage orange (exceptionally resistant to decay), Pacific yew (exceptionally resistant to decay), pine/fir/spruce (tannins and sap), red mulberry (exceptionally resistant to decay).
Tree types to avoid :
Black locust (will not decompose), black walnut (juglone toxin), old growth redwood (heartwood will not decompose and redwood compost can prevent seed germination)."
In Kansas these methods can attract the wrong kind of interest, namely termites! Don’t do this by your home if it’s made of wood! Perhaps in a really dry area it doesn’t matter but here in NE Kansas we get 34" + of annual rainfall so a 2x4 laying on the ground will be attacked by wood ants and devoured in 2 years time.
Here is a video on this method of gardening
Don’t get me wrong we have used parts of these concepts for decades but never so dramatically as this. If a large ditch formed on my property I filled it with hay, logs, and corn stalks, straw or hay and filled the top with dirt. We always used wood chips around trees to conserve water but this is much more than just sheet gardening with some old hay. Here is another video showing the concept on a larger scale
In my area we mostly see the slash and burn methods being used. Some farm families burn all organic waste and have done it in their families for generations. As people cut up firewood the piles of branches are typically burned the following year. When I was a kid the old timers taught me to leave piles of branches for rabbit and Qual habitat then later we would return to eat them. As I aged I didn’t bother to return to eat them as I had plenty. Some of the old timers were living in poverty because of their methods of doing things. The ones who burned their brush were poor and often went without later. The old timers who taught me to leave brush piles wound up with the most land , full freezers, larger amounts of spending money, their methods transformed into wealth. Cedar trees when added to a pond create habitat for baby fish which provide us more food. Looking back on my life I realize to the next generation we will appear very ignorant as many things we have done were ignorant.
Wood is sometimes available in large quantities like it as after a storm. Normally that wood is burned by the home owner or sent to a landfill where it is burned. Maybe 6 feet piles seem odd but their are multiple methods of hegelkultur if your not comfortable with large piles. Years ago I had an ash tree several feet in diameter that was in the way when we built the large pond. I’d never heard of Hugelkultur but I took it and all organic degrees and buring them under a 15 feet pile of dirt that was mostly mond muck from the bottoms of the mud Ponds. Years later it had all turned into fine dirt I used when constructing the barn foundation. Free soil appeals to me though that’s not the best use for it.