I want more ground-targeting.

[Rosenstrauch]

Can you macro it to yourself instead?

That's what I said, yeah. The macro would look something like this:

/merror off
/action "Salted Earth" <me>
/micon "Salted Earth"

This disables macro errors, so you won't get error messages spammed at you if you click the button multiple times. It then attempts to place Salted Earth directly at your own feet. This happens immediately upon clicking the button. Finally, the last line just changes the macro's icon to Salted Earth's.

As a warning: This macro will immediately attempt to drop Salted Earth at your feet, so if you push it while still locked into another animation then nothing will happen, and if you push it too late then you'll be locked into the animation for it and clip into your next global cooldown.