I Have some problem with farmland

I've try to do a farm on the skyland i've build on a normal map in creative

What I expected to happen was...:
expected that the farmland will grow plant

What actually happened was...:
but the farmland never work and after 1 hours a strange farmland structure appear on my island (I don't know if it's linked or not but I think it's probally linked)

i've put some screenshot and a backup of my map