Gamma Correction
I use an undemanding LWF as this makes practicing easier.
First I set the 3ds Max gamma. I set the display gamma to 2.2 then changed Input Gamma to 2.2, because most of my textures were 8-bit images. Then I set Output Gamma to 2.2, because my composite work flow is not a linear one and I use Photoshop (Fig.14).

Fig. 14
Then I set the V-Ray Gamma, enable the VFB and activated the sRGB button (Fig.15).
I set the color mapping values to the settings you can see in Fig.16. The Don't affect colors setting is a partner of the sRGB button; they make sure that we can get a gamma corrected image in VFB, but in the system memory, the image is still a linear one. (If you disable the sRGB button, you will get a linear image).

Fig. 16
Now I'd finished the gamma setting, I could render in a linear space and composite in a nonlinear space. If you want a linear composite work flow, just set the 3ds Max output gamma to 1.0.
Materials: Ground
The ground was my first material; the key of this material was composite texture. You can composite your textures in the Photoshop, but I always use the composite texture, because I can adjust the textures directly and easily in Max.
First I created the diffuse map, taking a ground texture as the base layer (Fig.17).
Then I added a more complex texture as the second layer to add more details on the ground. I set the map channel to 2 and the opacity to 40, with the blending mode on Darken. For easy adjusting, I added a color correction node to the bitmap (Fig.18).