Can you tell us your dysfunctional family secrets on how they did the ground cover on the module? 
It'll be my pleasure!
First I laid down a coat of brown craft paint. I used "brown" for the land (because it comes in the big bottle) and switched to burnt umber for the track and right of way. I painted EVERYTHING, including the tracks.
Then I sifted unsanded grout over the entire thing while the paint was still wet. Including the tracks.
I used an acid brush to brush the dirt off of the tops of the ties (you don't have to be gentle).
Then things diverge for the right of way, "forest" area (the green bushes will eventually have trees over them) and "grass" area.
For the grass area I then used a mix of a bunch of my "on hand" scenery materials for the first layer of ground cover. As far as fine ground foams, I think there's "burnt grass", "earth" and the generic medium green blend from woodland scenics in there. The important thing... sprinkle this on, don't cover everything. Let some dirt show through. In fact, let a lot of dirt show through.
For the forest area I used my regular "leaf litter" superleaves from Scenic Express, then some other stuff on top (I don't know what it is, maybe sawdust? tea leaves?). Then a sprinkle of the various fine green ground foams. Again, keeping it very light. I then sprinkled on some medium green (I think) "Superturf" from Scenic Express (
http://www.sceneryexpress.com/SuperTurf/products/1243/) as the bigger brush.
The grass side was left alone until AFTER I applied glue. I cannot stress this enough. Do NOT do what I did (originally) and have to do it again (like I did).
The right of way had some of my ballast mixes (of grout) sprinkled on. I then applied sprinkles of the green ground foams for weeds.
Once I was liking the look of stuff I got the whole thing gently wet with a mist of water and then hit it with white glue diluted considerably with water.
With everything nice and wet with glue I then applied the "grass thatch". It's Heki Decovlies-Wiesengras. Mine came from Scenic Express (surprise!) but I think it's on Amazon too. I took the mat from the package and stretched it out a bit to get a nice natural spread AND ragged natural looking edge. Then I put this on the area to be covered and lightly pressed it in. You don't want the glue soaking into it to, just holding it.
And then I let the whole thing dry.
The first time I did it I put the Wiesengras down first and glue on top of that. Don't do that. It did NOT turn out well and I had to pull it up and do it over.
The real trick to all of this though (aside from the Wiesengras) is to apply things in layers and slowly build it up.
