All my terrain and miniature bases get the "trampled grass" look. Here is how to make it
Grass around a bunker that has seen a lot of fighting is going to be trampled and muddy all right
Glue some static grass, leaving irregular patches of flat areas that will become mud. Press the grass with something flat like a painting cup bottom immediately
Spread a thick layer of un-thoroughly mixed gypsum plaster to the patches of mud
Paint the whole grass with heavily diluted dark green paint. I use Humbrol 105 Marine Green mixed with turpentine — it will protect your models against bugs as well :-)
Paint some areas of grass with diluted earthly brown (as Humbrol 113 Rust) and matt red paints
The patches of mud are painted with an irregular mix of dark green and brown
The mud is subsequently painted with a semi-glossy varnish
This topic is the elephant in the room in any cardboard crafting projects. Therefore I updated this classic article with new, detailed pictures to show you how this works in practice and what can you do about the problem »