There are several reasons for high turnover. One is hiring to a profile that is not in line with your objectives. Another is that employees do not feel that they are not appreciated or that they they do not have the tools to do their job.
And not all employees are motivated the same way. Therefore, it is important to understand how happy they are with their current job, including managers, peers and subordinates and what would motivate them to a higher level of satisfaction, and ultimately, productivity.