The story
Possibly nothing more than a case of real estate as wager stakes, but also plausibly because farmers cannot avoid gambling and the stakes are financial ruin: they must make many decisions (such as which crops to plant each year, and how to manage livestock), and outside factors such as weather or changing commodity markets can dash their hopes. Thus, when making a decision they must ask themselves whether they are confident enough to bet the farm as the wager stakes.
Etymology from Wiktionary, CC BY-SA 4.0.