Wanted to see if displacement worked with blended material. It does !
The current preview scene is not really appropriate with that kind of material, so I replaced the sphere with a simple curved plane (the circle around the logo is where the plane intersects with the sphere).
To create the displacement map, I followed that tutorial
: it's a height map based on real geometry, made in blender. It takes slightly more time than creating a map from a photography, but it's much more accurate. Though in that case, a 16bit images wouldn't hurt.
Regarding the grass, I second BbB, I don't think you can create nice-looking long grass with displacement, the leaves are too "straight". It's ok for a short grass, you know, where you play golf.