Landscape layer as mask for landscape grass mesh?

I have a landscape grass spawning in my landscape material. I have the grass masterial nested in my material as a function. I am blending the landscape between dirt and grass layers. I’d like the grass to turn brown in the transition between layers. I’m tried using the ground texture sample as a mask, but the grass mesh doesn’t seem to have “access” to that data.

Is there a way to accomplish this? Without virtual textures – I’m in 4.18.

Just to visualize what I mean, I have the grass texture BC set to its layer sample – I’d like the white part to affect the color of my grass mesh color.

Image