I agree the white on the soil sounds like some kind of salt/mineral build up. You mentioned the watering daily, which probably in AZ you have to do, even now. But you didn't say how you are watering. Is it sprinkler, drip irrigation or what? What you want is to be watering the least often you can, but deep into the soil. Dig down into your soil after the watering system has done its thing and turned off again and see how deep it is wet. You want it to be wet 6" down. If it is, you might not need to water every day. Especially true if you mulch your bed. The mineral build up is from water evaporating off the soil surface. Mulching helps prevent that, so you lose less water, don't have to water as often and have less build up.
So suggestions would be if it isn't already, bury your drip line so the water is under the surface. Water longer but less often. Put a good layer of mulch down on top of the soil.
PH 6 is a little bit acid, but lots of veggies like the soil that way, so that should not be the problem. But salt build up can be.
Here's a previous thread we had about salt build up in the soil