Hi Neil, and Luke.
The tank came there after the bombing, at least this was my initial thought.
Now concerning the mud, first of all It was not done yet, so yes a little mud will be placed on the tank. Yes the tracks should be fixed but it is just a test.
Now the mud is actually real earth from a smal flowerpot, mixed with some very very small leaves and a substance called compost. First I sprayed a mix of white glue and water and then I put the earth on it while I was rubbing it in my hands. And the small leaves you will see in one of the pictures under the tree is thyme...