A noisy noise annoys

There is some big machinery working in the field next door, making a racket.   The farmer is cutting down what I imagine must be the raw ingredient for silage.  As far as I can tell, it's all random weeds, I don't think he sowed anything there this year.

The machine doesn't turn very easily, and the technique seems to be to go around the field a few times widening the swathe each time, and once there is enough space for a turning circle, to go zig-zag from the top of the field to the bottom.

The machines look quite menacing, parked up for the weekend.