I read on the buckbeans page that the beans will tolerate small dosages of roundup.
http://www.tecomate.com/content/index.php/site/comments/tecomate_seed_buckbeanstrade
Not sure if this is true or not, would be nice if it’s true, as I’m in the same boat as you (though I’m not quite as worryed about the clover and chicory), I just want to control the weeds (broadleaf and grasses). According to Ed Spin you can spray clovers with a low dosage of Round Up in spring and it will not hurt them (will stun them for a bit but they come back).
hopfuly some one can answer this for us…
F