Yeesh, I didn't even know there were consumer grade WiFi transceivers that were strong enough to cover such a massive area. Was it a small farm or just a big property? That had to have been a pretty expensive WiFi system regardless. Did you use Ubiquiti directional access points or something?
I have a sister that runs a small family farm and she asked my brothers and me (3 of us have IT backgrounds/careers) for viable coverage solutions to their various livestock areas. We settled on just running copper to one barn from her house and broadcasting from there with a few repeaters equipped with trunk channels in order to maintain full duplex.