Why was slave labor so important to the economy of the southern colonies

The southern economy thrived on slave labor. Since this was forced labor, it didn't cost southern slave owners much to have a slave do their work. The south also produced what are known as cash crops: tobacco, rice, and cotton which were all very important at the time to the US citizens. The loss of slave labor would have crippled the southern economy because they needed the physical advantages that the African genetics provided.