Why were slaves high demand in southern colonies?

The Southern colonies of the 13 American colonies were suited to large plantations that yielded cotton and tobacco. Both products were in high demand in Europe. Economy of scale created the most efficient way grow and harvest these crops. From the 1600's onward, slave traders provided the manpower required to field the plantations. They were inexpensive compared to paid American laborers, thus the demand was strong for imported slaves. The Portuguese and earlier, the Dutch dominated the slave triangle. Ships would leave Europe for West Africa with enough sought after products that could be used to buy slaves. These ships, then headed to the Western Hemisphere where the slaves were sold. In return these ships would be laden with colonial goods and farm products and sail back to Europe.