This is equivalent to stating the obvious.
Grass, gravel, etc. Has no real reflectivity/specularity at a distance.
Up-close maybe.
Possibly if it has water on it.
But even then very, very little.
Here, have a random landscape picture from my stuff: (note that this was very Damp, the grass is all wet. still no reflections from the sun off to the left hand side)
And compare it to this one where there is actually supposed to be a reflective value:
