Can you just use a 160 watt mercury vapor bulb for your lighting for a bearded dragon or do you need other lighting if so what?

Beardies need 2 types of lighting, Basking/UVA and UVB. The Mercury Vapor is a good source for the UVB and some heat, it will work on it's own for a smaller tank but remember you need 2 temps a basking spot of 100-110F and the cooler side of 75-85F. If you can get these temps with just the mercury vapor bulb awesome if not you need a second light.