Why did most sharecroppers go into debt and/or extreme poverty?

Sharecropping is a type of farming in which families rented small amounts of land from a landowner in return for some off their crop. In the South it was typically practiced by former slaves. Problems arouse between many landowners and blacks wanting to be free. The southern landowners usually were cheating the slaves out of money and other things they need. It was very unfair to many people.