As a result of this thread, a committee consisting of representatives of both horse and hiker leadership met and had a serious, intellectual discussion about you know what. There was shouting, crying and in the end, even laughter.
The conclusion in general terms was that horse will no longer drop their manure on trails; however, humans can no longer ride horses. Details to be worked on.
Sorry if this is an inconvenience to any affected parties. Such is life.