Soft, sandy, soil groundwork

With plans for a small vignette. What’s my best bet to depict soft,.sandy. soil. Think, Russia, summer ,1941. I want to show a vehicle in difficulty, being pushed by the riders and other troops.
Thanks in anticipation.

I’ve mixed fine beach sand into my Celluclay mixture and that turned out pretty good. If not near a beach, then craft stores sell crafting sand.

They also sell sand at some home improvement/ hardware stores to be used in kids sandboxes and to fill in between paving stones.
OP - go as fine as you can to keep it in scale.