Where did Cabot get the farm to begin with? Had he co-owned it with his first wife because he already owned it when he married her? Or did he marry the second wife to obtain it?
Cabot bought the farm. The land is the whole driving point behind the story. Cabot didn't want anyone to have the farm, because he had put so much work into himself when he first bought it. At the time of him buying it, the farm was nothing but rocks and stone. Cabot cleared all of it himself and began to farm the land, therefore he believed that no one else deserved it.
Everyone in the play, just about, wants the farm. Eben buys out his two brothers portions so he can have it. When Cabot returns with his new young wife, Abbie, she becomes obsessed with the farm as well. Even the sheriff wants the farm.
The land is really the most important "character" in the play. Desire Under the Elms is one of the greatest tragedies that we have.