What is planted there?

This field looks like something has been planted, with big parts in between without these plants.
However, the light parts are grass, whereas the dark parts are just soil (with some grass). It looks like the farmer sowed in streaks. But why? Grass is normally sowed abundantly. Or indicate the streaks without grass that the soil is somehow not healthy for (just) grass?
I will have to wait a week or two to know more.