for my dio i used some of that pink insulation board as a base. if you go to a lhs you can find some woodlands senic "turf" it is greeen powder used on model railroads as grass. sprinkle it on, then use thinned white glue (not sure on the mixture, have to get back to you on that one) in a spray bottle to get the grass to stick. for the road, it really depends on how you want the road to look. you can use again woodlands senics matterials, real dirt, or just paint. if you use the pink insulation board you can make holes, rutted roads, craters, by cutting into the board with a hobby knife. with the extra pieces you can make hills, rocks, buildings, etc.
found it! it is 50/50, 50 white glue, 50 water. this was for gluing ballast (rocks under the track) but ti should work.
i hope this helps