rotting wood creates heat and holds moisture and provides a very long term release of nutrients as it decomposes and is metabolized by soil microbes.
if you bury a bunch of wood with an appropriate amount of nitrogen rich starter material, then cover that with a thick layer of soil, you've got a drought resistant, self-feeding bed that is ready to plant before ground thaw, and stays warm past first frost, plus it improves each year with no additions.
that's the theory anyway. i'm dying to try it for myself!
theres some gorgeous ones in full production mode in the documentary "the agro rebel
." sepp holzer is one of my favorite farmers. i've watched this short film a bunch of times---very inspiring. plus that yodeling soundtrack is so haunting! watching it transports me to alps, following sepp's pigs around on a tour of the krameterhof
it's good to see them on video. a lot of attempted hugelkultur beds i've seen american permies make are way too short. they need to be deep and tall to function 100%.