How are the grass turfs in football stadiums maintained so that the pitch is visibly segmented with different shades of green?
All down to direction of mowing. The mowers blades spin in a particular direction, clockwise or counterclockwise. The spin of the blades then blows the grass in a particular direction. As you may or may not know, grass has a different finish on either side, a glossy side and a matte side.
So if the mower travels in one direction, the blades blow the grass over revealing the glossy side (dark green on the pitch) and when the mower goes the opposite direction, the matte side is left facing up (light green on the pitch).
The groundsmen can get pretty creative in how they cut the grass in order to reveal simple or elaborate patterns on the grass.
Most of the football clubs use the same type off grass which is a mixture of different types of grass with artificial grass.
You can see the difference at a club who has an artificial pitch, on an artificial pitch the colour in uniform.