Al,
Yes, it is a Plasticville that i shortened by sectioning out the middle with a Zona saw. Below is a little better photo of it.
INMO real dirt, in this case a medium fine washed sand ($4 for 80 Lbs.) does the job best and is inexpensive as well. In the yards and similar areas i simply spray (rattle can) it with a light mist of black to give it the oiled effect.
jackson