Karl, in my dio "Kfor- Portuguese service" started not long ago (you can see pictures of it in my gallery), I used real earth used for plants, ie. to put into vases! Have a look and see what you think of it! There's also a base for a figure in my galery built the same way (American Soldier)! I hope it helps you in any way! If you need more info don't hesitate to contact me!
Cheers and happy modeling!
Prato