David, I've used the same colours on the track as I used on the base for the garage/shed diorama (the base will be getting redone sometime in the New Year).

Clockwise from left: Noch 6mm beige, Woodland Scenics 2mm light green, Noch 4mm ochre and Noch 6mm light green. To this list I've now added Noch 12mm beige.

Mixing my own blend has allowed me to vary the colour across the track but still keep some continuity over the whole table. More beige on the high points where the grass would have burned off a bit more, a little more green in the blend in the areas where the water would run, and yet more green at the base of the hill.

The variation doesn't really stand out all that well in the photos. And it's far too even for my liking.
Beneath the concrete flyover I dropped the green out of the mix completely and was quite sparse with application as there would be very little natural light getting through, except for one patch inside the apex of the corner. Here I added just a hint of green. Probably a pointless adjustment, because it's not an area that can really be seen, but I know it's there.
From there, long grass has been added with dyed sisal.

I'll possibly go back into the first parts of static grass and a second coat to some of it with the 12mm fibre in the mix. I just want to get some of it thicker and patchier.