The way I understand it, in olden times bone meal was manufactured from fresh bones, perhaps with some meat scraps still attached. Today, bones are steamed to extract fats from the marrow, used to manufacture who knows what, soap perhaps. And bones are mechanically scraped clean of meat scraps (that, in these BSE-conscious times, I hope is used for pet food and not hot dogs.) So much of what previously would have been incorporated as a plant nutrient is removed. Besides, all the skunks in my neighborhood dig for the bones they think are buried. One fertilizer I used to get was leather tankage, a good dust-fine nitrogen source produced in the manufacture of leather buttons at some Long Island factory. Any other odd materials you've used and found valuable? Judy in still cold, still snow-covered New Jersey