I read through this posting, and it sounds like the OP is a stand up guy and just wants to move on with his life, but I definitely would have handled it more aggressively. I have background in commercial real estate in a different state.
I would have broken the lease like many here had said and forced it to court. I think any reasonable judge would see this is ridiculous, would have made the new owner paid the farmer back his lease money and terminated the lease, and the issue would have been settled. IS the judge really going to side with a farmer that has 3000 acres for his crops and force the new homeowner to honor a shady lease on 2 (which is a significant part of the new owner's land) for the next 20 years. I would then have my lawyer give the cost of the settlement, along with my legal fees, over to the title company to pay. This would be an airtight case and they would cough up the money.
There might be hard feelings from your farmer, but I wouldn't give a damn about what the farmer thought about me, he's been a ***** through this whole matter. Trust me, this farmer is laughing at you behind your back. He's had every opportunity to step up and do the right thing, and in addition make some extra money with a reasonable settlement. I know we have this image in this country of farmer's being the salt of the earth and always noble, but they can be greedy bastards just like any other human being. I have a lot of farmers in my family, and believe me, their not perfect. The amount of government subsidies they think they deserve is absurd, in a lot of ways it's no different than welfare.
I hate that matters can't be settled honorably, but sometimes people need to be a ******* to get justice in this world.