What is the main reason why the southern economy was dependent on slave labor?

The main reason why the Southern economy was dependent on slave labor was because enslaved workers planted and harvested crops on plantations. There were many farms in the South, far more than in the North, and with cotton plantations and other crops, they needed more people to do the work. That is why they though this was the perfect job for slaves, which kept the whole economy going. 

Thomas edison created the light bulb.

The south should of one they the