Ghost in the machine. A John Deere 7930 tractor rumbles across a canola field, buggy in tow, and eases alongside a rolling combine to collect grain. Speed, distance, and timing are synced in a farming ...

A turn of the ignition says all the machine needs to say. Sixteen pistons vibrate a body that weighs over 100,000 pounds. Twin plumes of black diesel smoke flee silver exhaust pipes above the cab.