I found a site where a student had done an experiment/project where equal parts of straw and dirt for the best "strength" of the bricks. This was from someone who's parents and grandparents where natives of New Mexico (I believe) and had been using adobe as the natives had (at least the grandparents, from what I gathered). So I figured that they were probably reliable [img]/images/graemlins/wink.gif[/img]
Another one that I liked, did NOT state how much straw, though he talked about making adobe.. he instead gave info on using cement and/or lime additives (lot of good info here):
http://sleekfreak.ath.cx:81/3wdev/VI...1/STABERT2.HTM
So, equal parts dirt and earth... for water, add enough to make it workable, but not so much that the bricks lose their integrity once you lift the mold off of them.