When the vast expanse of rural Iowa was carved up for settlers in the 19th century, it was often divided into 160-acre lots. Four farms made a square mile, with a crisscross of dead-straight roads marking the boundaries like a sprawling chess board.

Within each square, generations of families tended pigs and cattle, grew oats and raised children, with the sons most likely to take over the farm. That is how Barb Kalbach saw the future when she left her family’s land to marry and begin farming with her new husband, Jim, 47 years ago.