egg laying female, 2nd round? what soil to use?

Hi all,

This is my first post in this forum. Rosie laid about 22 eggs about 3 weeks ago. She's had a better appetite this spring then she's ever had, even as a baby/juvie beardie. The first egg laying go round was unexpected as the eggs were found in our bed when we were going to put them in their tank. I'm wanting to get ideas of what soil to use to get a lay box ready for her next go round. I feel we have time because she's not going nuts trying to get outside yet, which she did the month or so before laying the eggs the first time.
I can't help worrying that I won't get it right and she'll have physical problems. I know I may be worrying for nothing but I can't help it.

Any suggestions are appreciated. I have one from Deb (canada) about using sterile potting soil with no fertilizer in it abut I'm not sure it can be found locally and I don't know if it's necessary to get something special or what's the best to get. We have a lot of dirt outside as we live in a AZ suburb with more dirt than concrete, but said dirt tends to be hard in most places, we do have sand nearby that we can get to mix with the dirt.

I used damp play sand when Emma laid her infertile eggs.

Thanks, I appreciate it!

Moist potting/top soil and sand mix here.
Anything along these lines as long as they can dig a hole and lay it really doesn’t matter a whole lot. Yes I would avoid anything with added fertilizers ect, just makes sense.

edit: the MIX just makes for easier digging.