This model icludes six variations. Stand - Wheatfield, Stand Upgrade First - Wheatfield with Windmill, Stand Upgrade Second - apple Orchard, Stand Upgrade Third - a vegetable garden, Stand Upgrade Fourth - vineyard. Updated: I replaced the sunflower farm on the dairy farm. Added and improved some details.
Since people might want to grow farms on a variety of tilesets, you should probably just use dirt for the foundation. It would be more realistic that way, anyway; you don't grow grass underneath crops. So you'd be killing two birds with one stone by switching it.
And why does it do 180 flips and 90 turns in different upgrade animations? Wouldn't it be better if they were all turned the same way so that people could actually upgrade it in different ways? It would look awkward to upgrade your farm and all of a sudden the whole thing's completely moved and turned.
I also think this could have been more useful with attachment points to make these changes, such as putting crops in, adding the chimney to one animation, and such.
Cool model and very useful with animations. Though in my own view, that part wood attached to the Windmill atop looks unfitting. Maybe you could plainly make the windmill white and remove that wood texture of some sort.