We're almost done chopping down a tree stump in our backyard; it's about 6 inches below ground level and we plan on leaving the rest to decompose. The roots have all been severed at the base and there hasn't been any regrowth sprouting up again. I've read that a high nitrogen fertilizer can be used to help decompose the remaining stump by drilling holes into the stump and filling them with the fertilizer, which feeds the fungus that will help the stump decompose. Another method i've read about calls for covering the tree with caustic soda. I believe caustic soda can react violently when combined with water, and can be quite nasty to use. Since the stump is close to a flower bed which does get watered I would assume that the stump would have to be covered with plastic for a time. Does anyone have any personal experience with either methods, or even any other suggestions?