Checks out. Bees get pretty triggered by vibration. You sure wouldn't want to run a cabinless combine anywhere near a hive. My apiary is in a dip and i shut off the motor 25 meters out and coast in. It's a shame they didn't give bees a bit more depth than a little yield boost. Putting hives around a crop would probably flavour the honey too (I move my hives on a trailer to follow the Heather bloom here in Scotland)