My choice to have a disposable urn for my own burial is not only for practical reasons (what to do with the urn once the ashes are dispersed) but also for esthetic reasons. I do not like the idea that the last image my family has of me is five pounds of dust. Burying the container seems a more dignified way to leave this earth.
Where to place the urn
Whether you bury, burn, or place the urn in water there are a few simple rules to follow. For example, for a water burial one must keep a certain distance from the shore. Ask local authorities if you have any doubts - when I called I was told to use common sense.
More and more cemeteries have a special area reserved for degradable urns, and I'm certain you can bury an urn in places like the desert. For special "green" burial locations in the US check the following sites: