Once again, for several months running, I find that I have no use for fertiliser. I used to have to use it to increase the quality of my hay. But for several RO's now the hay is at 20 without any help from fertiliser.

Crop quality is based on weather, from the game guide. It's been raining a ton because lots of stables come together with rain dances, so I really don't think this is a bug.