Which type of labor was most needed for the growth of cash crops

For the growth of cash crops, slaves were the type of labor that was most useful and needed. The slaves were bound to work in the farms of their owners for continuous hours without getting paid.  

Cash crops can be defined as the crops which are grown by the farmers for the purpose of making profit or money by selling to companies or parties separate from a farm. The price of these crops are not set by the government but in the commodity market with global scope.