Anywhere near the rustbelt is going to need their soil thoroughly tested for contamination. But maybe that's not too big a deal when you amortize the cost over the entire life of a farm.
Apple orchards in particular up until the 70s often used lead arsenate pesticide sprays. Yes, you read that right; lead and arsenic. Sprayed onto plants. It accumulated in the soil and basically never leaves, and is a serious potential health hazard.
There has been insufficient discussion of this, overall, and it's basically "buyer beware" for land.