Trains run in straight lines, farm equipment has various widths and it's not just 'tractors' and you're going up and down rows of farmland that might be tens or hundreds of acres wide and that aren't always in the shape of a square or rectangle (it's often far easier to work around large glacial boulders or trees for example, as well as ditches/running water/property lines etc). You'd have to string millions and millions, if not billions and billions, of miles of electrical cable across fields.
There's 915 million acres of active farmland in the U.S., that's 1.4 million square miles/3.7 million square kilometers. The larger combines can be about 40ft wide so if every scrap of farmland was in literally-square acre parcels you're going to need 5.2 power lines minimum to cover the width of a literally-square acre so you're easily talking 5 million miles of power lines.
Trains run in straight lines, farm equipment has various widths and it's not just 'tractors' and you're going up and down rows of farmland that might be tens or hundreds of acres wide and that aren't always in the shape of a square or rectangle (it's often far easier to work around large glacial boulders or trees for example, as well as ditches/running water/property lines etc). You'd have to string millions and millions, if not billions and billions, of miles of electrical cable across fields.
There's 915 million acres of active farmland in the U.S., that's 1.4 million square miles/3.7 million square kilometers. The larger combines can be about 40ft wide so if every scrap of farmland was in literally-square acre parcels you're going to need 5.2 power lines minimum to cover the width of a literally-square acre so you're easily talking 5 million miles of power lines.