Is is it possible to create single layer with opacity mask in landscape?

All I want to do is to create a landscape layer that has transparent in parts so it wouldn’t have a big white spots on sides. Yet I can’t seem to get that effect. I could use pattern in landscape brushes, but they seem to be very imprecise. And I already tried using material attributes as suggested in: ,
but it never let me to create a material that is transparent. Also I have tried some different blending options. None of which gave me desired effect.

How it shouldn’t look:

Landscape material:

Sorry to bump a really old topic, but I’m having a similar issue.

I’d like to have the landscape layers behave as if they were a masked material, but I’m doing something wrong. When painted onto my landscape they look like the op’s screenshot.

Here’s my material right now. I’ve set the material to Masked.

edit: To clarify, I’m not trying to actually mask out parts of the landscape (ie. landscape visibility). I have one layer that is fully opaque that is painted over the entire landscape, and then I have a bunch of partly transparent textures that I would like to use as layers to paint on top of the first layer, but the transparent parts of those textures appear white when painted onto the landscape