Hi Michael, looks good.
So a few ideas to try, I like to use an old toothbrush (or very stiff bristle brush) to flick mud onto an area, gives it a decent splatter. You can also load a brush up and blast it with an airbrush to get a similar effect with a bit more control. Try varying the tone, wet mud will be darker, and you can play with gloss/satin clear coat after to give it a wet shine. Some mix in bits of static grass to create a turf look as well.
Keep at it!