If they can gain a few feet they will, every time.The place I see most often that does this, in the fall always has 1-3 rows un-harvested and falling/eroding into the banks of the river.
Working for the railroad for years, it was almost a given over the last couple decades especially since ethanol, that farmers will encroach further and further outside their boundaries.
Saw it all the time. One year you see the farmer remove the line fence that has been there for 100+ years. The next year oh Im just gonna plant a couple more rows, then the next a couple more, then bam, right up to the ballast, all the way to as close to a crossing as possible. (Because people at that crossing dont need to see a train coming, and 7ft tall corn doesnt block visibility)
What finally stopped some from doing it was the maintenance crews would go out with bull dozers, bull dozing the crops over to the RR property right of way. But it usually took a couple years of doing it for the farmer to realize he was just wasting money. Hell they put right of way markers on the line in one place and the farmer planted around the markers instead of staying on his property line. Some never get the hint and continue to try to get away with it every year.
These are usually the farmers that dont stop at crossings, and wonder why they get hit. Every year especially at crossings near grain elevators, you have farmers that dont look and dont stop, and after daily close calls, the luck runs out and someone gets hit.
Problem is there is no one looking out for or maintaining the waterways to go out and enforce property lines and setbacks on the waterways. And the DNR now is a joke, they are only out there to make sure there are enough deer to maintain their hunting fees to keep their paycheck coming in. They only do something when a spill etc happens, which is usually nothing more than a bandaid and a slap on the wrist, instead of actually doing something beforehand to prevent it.