[JennyHallu]

That was a contract:

Unclaimed land was purchased, in plots of a set area (usually an acre, which is why the Midwest is such a perfect patchwork), by "staking a claim", which meant living off the land for so long a time.

To "claimjump", one waited until someone had done the hard work of clearing the land, and then moved in while they were away (for whatever reason), then defend that land from the rightful claimants. That was wrong, and illegal, even if the claimjumper felt the claimants were not properly using the land. The only stipulation was that they supported themselves on that land.

None of that land had a previous owner, besides the Federal government when the land was ceded to the United States.

Farmer B is a claimjumper.

EDIT: and who cares if A let his land lie fallow? It's his decision. Perhaps he hadn't the hands to work it himself, but was planning to send the field as his daughter's dowry when she wed. Perhaps the land had been poorly stewarded and overworked by a previous owner, and needed to lie fallow for more time. Perhaps the man wished to put cattle on it, but was saving his money to purchase the livestock. The Rohirrim are not serfs, are they?