There are an awful lot of variable involved here, but in a place like
Maine where I am, I've heard you could grow all the wood you would need
for heat through the winter on 5 acres. I've also heard you could eat
very well if you gardened 5 acres, with a lot of extra to put away or
sell for cash. I think I remember Eliot Coleman saying in one of his
books you could make a decent living growing on as little as 5 acres.

HTH



One issue is the question of how much physical space would be
needed to grow enough food to completely support myself?