When I've done alfalfa and CRP land I always hayed it, let it regrow a little and spray to kill it in the fall just before frost.   Then I no till in soybeans in the spring.   In your case you'll have spray hard to kill it in the spring but it should still work.  No way would I use a chisel plow or a disk, it will be rough and you'll dry the ground out too much.   For me, the crop was never quite as good as the land that had been in production for a while but it always came pretty close.