For the second UVW map modifier, I set the channel to 2 and renamed the modifier to C2 (Channel 2). As I needed to add more "noise" to the base, I set a bigger gizmo (Fig.25).
For the third UVW map modifier, I set the first channel to 3, and renamed it C3. Then I adjusted the white line's position and scale (Fig.26).
After finishing the settings for the basic diffuse map, it was time to set the other maps.
First I needed to copy the second diffuse texture to the reflection node, and adjust its brightness and curve (Fig.27).
Then, for the bump map, I linked the first diffuse texture to the bump node directly!
Now I had all the map settings done, with some simple material settings, I went on to create a good ground shader.
Strictly speaking, you could choose not set the bump/glossiness/normal etc., textures to gamma 2.2, but I find these tech details make things boring, so in shader testing I set all textures to a default gamma of 2.2 (Fig.28).
The material parameters can be seen in Fig.29.