How to boost Employee Productivity ?

Make sure you are a good manager to begin with. 

Reward those who work hard. Make sure they are happy, even though their happiness isn't your responsibility. Although if you want to keep good employees then it's best to make sure they are happy anyways. If you want to give employees more work and responsibilities then have a little talk about possible raises depending how they do. Give them more work but no raise and they will leave. 

Don't allow employees to perform poorly. If they are doing so poorly, find out why. Threatening with write ups doesn't really solve anything. Coach them. Show how employees can do better. Sometimes I've seen workers do things the hard way and showed them the easy way and taught them the value of working smart. It helps them become more efficient.

Punish those who don't do their work. Some employees just flat out don't want to do sh**. Managers who are too soft on these employees are the worst. Shows you are not effective as a leader and it's unfair that those who work so hard get stacked with more work to pick up the slack. If the employee sees they can get away with laziness then they will make a habit of it. Write them up, suspend, or terminate if they keep it up.

8 Ways to Increase Productivity in the Workplace

1. Be Efficient. Consider how your business is currently operating, and be open to the potential of changing the way you work.

2. Delegate.

3. Reduce Distractions.

4. Have the Right Tools and Equipment.

5. Improve workplace conditions.

6. Offer Support and Set Realistic Goals.

7. Practice Positive Reinforcement.

8. Ensure Employees Are Happy

Threaten them with termination if they don't kick it up a notch or two.

Keep them happy. I had a boss once who thought the angrier he made the workers, the harder we would work. Two-thirds of us just ended up quitting.