After slavery was abolished what type of cheap labor did plantation owners rely on

Sharecropping and tenant farming.

Explanation:

After the Civil War, many African Americans were freed but they did not have land and couldn't find jobs because most of them could not write or read. With that, Tenant Farming and Sharecropping became the main form of labor for them and cheap labor for landowners. The worker would get the land and in return, they should give 2/3 of the crops that were planted for the owner.

Some slave owners still used slaves, but after it was abolished they used rhinos to dig up crops with there horns.