Carl,, thanks my friend. I used real ground up dirt for the tracks . I have family members located all over the globe who send me little packages of native dirt. One sample of particular interest is from a nephew (in the US Air Force) who gathered some dirt from a WWII concentration camp site while he was stationed in Germany. So, I have a bunch of little screw top plastic paint type jars area labeled with ground dirt from all over the place.......... Pennsylvania, Texas, Kansas, Hawaii, West VA, California, South Carolina, United Kingdom, France, Germany, Qatar, Greece, etc. etc. (pays to have family all over the place sometimes... ha)
This ground up "dirt" application could not be more realistic (in my opinion that is). It is simple, easy to apply and has many varied applications. I did try to airbrush once, but met with less than favorable results. I pretty much stick to brush application dry or wet or a combination of both.