I think Woodland Scenics' Fine Turf (Earth) would match that colour scheme. I have a bag here and it looks really close. (It's a green not a dirt, case it's not obvious) I would very much suggest taking it with you and comparing though.
Also, really, I'd suggest using a different colour, like a sand, or "dead grass" instead to help make your models stand out more, and it'd match the zandri dust stripes.
Unless of course you're just dead set on them all being the same colour on the base

I can see if you're going for a camo type look that might be what you want to do.
Anyway, just a suggestion