Organic Method of killing weeds
 

I have a huge back year most of which is planted with bermuda. Unfortunately
the dollar weed, broadleafs, and dandelions have moved in. Is there an
organic option to killing these weeds? I am especially concerned about the
dandelions which practically took over last year. I don't want to use Weed
and Feed. Please do not recommend pulling them by hand, there's not that
much time left in the universe:-)

I did find an organic pre-emerge which I used around Christmas and that
helped eliminate many weeds. However my home is adjacent to a large field
and I think weed seeds just blow in over the fence.