How do I stop my dog from treating the yard like a construction site?

My dog is supposed to be white, but lately, that's more of a theory than a reality. Every single day she goes out, digs like she’s looking for buried treasure, and comes back completely gray.

I was giving her daily baths, but it became a never-ending cycle: I’d dry her off, she’d head back out, and immediately rub herself in the fresh dirt to "fix" the fact that she smelled like shampoo. It got so frustrating that I’ve stopped the baths entirely, but now she’s just permanently filthy.

I'm at my wits' end. Does anyone have tips on how to break the digging habit or stop the "dirt-rolling" ritual every time she steps outside?

She is a border collie mutt