This is basically a compost heap. Here, the local sanitation company does the same on a large scale, with what we call "bio waste". Thats everything from cut down trees to food leftovers, everything that rotts. To speed up the rotting they shredder the big stuff like wood first. The way you do it, it will take several years to turn into soil. However, during that time, it will be a valuable refuge for animals, from insects and reptiles to small mamals.