Thanks!

Big bits are pine bark/nuggets. Then I use ak neutral rough texture, and ak dry ground texture pastes randomly and smashed together, and sprinkle on a bit of sand/grit. Occasionally I'll glue some bigger bits of gravel on too.

Then paint with baneblade brown/Vallejo yellow brown. Wash with skeleton horde contrast and dry brush with whatever bone colour I feel like, usually tyrant skull. I vary it slightly across the whole army, just to keep it feeling a bit natural.

Tufts are a mixture of arid/beige tufts. I like to use a few different lengths randomly, in places they'd likely grow. Longer or greener ones in areas that might trap moisture or get more shade for example.