Quick update: I’ve completed the basic ground work and base coated the soil. I added more debris, made a few small touch-ups and started the vegetation work. I plan to have a lot of high grass around the tank. On the opposite part of the diorama (facing the ruined house) it’ll be mostly dirt and some abandoned stuff (barrels, ammunition boxes, jerrycans, etc).
Adding all that grass is tedious, but the final result will hopefully be worth it.
As for the colours, don’t worry if you think they are still a bit too contrasted: I’ll wait until pretty much everything will be in place and then use pigments and washes. Some light spraying with the airbrush might also be useful to simulate a subtle coat of dust on the whole diorama. I’ll do some tests beforehand of course, but I think it will be good.
Enjoy the pics!