I have finally got round to rebuilding my pallet compost bin, adding a second container to dump green stuff whilst the other container contains material in the process of rotting down. All the pallets are securely screwed together to make the whole thing solid and robust, at least until the pallets start decaying. Having shifted rotted material and replaced with the big pile of stuff that I piled up over last year because I had inadequate bin space, I have found a load of long thick stems, mostly old brassicas like kale that had finished last year but the stems are so hard and thick, they haven't rotted at all. Ideally I would like to return them to the soil somehow rather than throw them into the green waste at the local tip. Is it possible to ultimately get them to rot down by burying them or chopping them into small pieces and putting the choppings into the compost bin (if feasible)?