The native earth thing comes from vampire lore outside of the game. It was originally referring to dirt from the vampire's original grave. The vampire is supposed to be attached to a physical location, and not able to go wandering the world (or, if they do, they risk losing the native earth they bring along, and not being able to get more.
This lore, of course, comes from a tradition where there is no planar travel or control of planes, or magical transformation of Earth. Traditionally, the vampire is stuck, or at risk. Such is the price of the power of undeath.
Then, to be in the proper spirit of the thing, we should make this extremely difficult for the vampire to pull off. And I'm not sure "drain a bunch of humans" is really a price - I mean the vampire wants to drain people anyway, right?
I suggest that the ritual be more about changing the vampire than the dirt - to have different native earth, what counts as "home" for the vampire should change to the new location.
hmmm arent there actual rules somewhere for making spells in a technically rules approved way? Would a spell that is bases off simulacrum but is transmutation or conjuration instead of illusion and the same level (seeing as it may be a fully actual duplicate instead of just really close but is also not a duplicate of a living being therefore easier and thus around aame level) suffice?It's hard to get a rules solution to what isn't a rules problem. The game doesn't define in rules terms what properties native earth has. About the only way to get around that is with a spell that allows you to make your own definitions, such as Wish.
this actually looks pretty good. If i go the route of making a spell ill probably use the 30 day thing as well. And maybe making the bodies into a weird enchanted mulch lol. Probably about as close as im gonna get to RAW is ising a spell that qualifies under the guidelines for making new ones.If you mean RAW, nope. But there are clearly a lot of ritual and lore beyond RAW.
As GM, I would make such be an elaborate ritual over time involving sacrifices to transform a new patch of desecrated ground into dirt that the vampire can use.
I might borrow the "for 30 days in a row" found in some spells and go with cultists, daily sacrifices of folks and doused with the vampire's own blood for a period from one new moon to another - perhaps only during a blue moon period - where two full moons fall on a calendar month.
Gives a decent period for PCs to come in in the middle and then try snd stop it.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.