chiseling or deep ripping might have made the difference in the soy ground------ie leaving it a little more open for more deeper and frequent "sharp freezes"----------but using that rototiller behind the ripper would seem to seal that ground mostly.............so you must merely get cold enough------deep and continuous---------to handle the bugs.

(or maybe "ripper-roto-tiller combo" is not what it means in southern IA------ya know, you Canucks talk funny!!!!!)

heh, heh, heh.........